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Патент USA US2404090

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July 15, 1945
G. w. PoNTlUs, 3D., Erm.
Filed April l1, 1942
8 Sheets-Sheet 2
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G. w, Pom-rus, 3D., ETAL.
Filed April l1, 1942.
8 Sheets-Sheet 3
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G. w._|`=oN-r|us, 3D., Erm.
Filed April 11, 1942
8 Sheds-Sheet 4
July 16, 1946° -
@.w. PQNTIUS, 3D., ET AL,
Filed April ll, 1942
8 Sheets-Sheet 5
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Filed April ll, 1942
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G. w. Pomme, 3D., ET
Filed April 1l, 1942
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Filed April 11, 1942
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Patented July 16, 1946
George W. Pontius, III, Arthur P. Wilson, and
Frank V. Kuzmitz, South Bend, Ind., assignors
to Bendix Aviation Corporation, South Bend,
Ind., a corporation of Delaware
Application April 11, 1942, Serial No. 438,602
9 Claims.
This invention relates to controls, and more
particularly to electrical power systems for oon
trolling the movements of a gun turret.
This invention will be described with reference
to a retractable turret for the lower surfaces of
airplanes and with reference to a turret for the
upper surfaces of airplanes. A lower turret in
which the invention is used is described in more
(C1. 172-179)
system including automatic indexers and limit
stops for retraction of the turret;
Figure 6 is a schematic isometric projection of
the mechanical parts and movements of the
Figure ‘7 is an elevation view of the rear of
the control box for the turret;
Figure 8 is a plan View in section of the control
detail in application Serial No. 391,911J ñled May
box along the line 8_8 of Figure '7;
5, 1941, on behalf of George W. Pontius.
Figure 9 is a detail side view of the control box
One of the most important considerations in a
showing the shape and construction of the rocker
power system for gun turrets is that of speed
arms which vary the electrical impulses;
control. The gunner must have any speed nec
Figure 10 is a sectional view of the control box
essary to keep his guns trained on a target. Fur
showing the breaker cams and taken along the
ther, this control should simply be obtained by a 15 line iû-Iû of Figure 7;
single manual control grasp for rotation in azi
Figure 11 is a detail sectional view of the con
muth and elevation.
trol box showing the elevation control cam taken
It is an object of this invention to provide a
along the line II-H of Figure 8;
power control for turrets having complete con
Figure 12 is a simpliñed wiring diagram of the
trol oi speed over a working range.
20 power circuit, showing parts of the turret in
It is an object to provide the power controls
dotted outline and having superimposed thereon
with a selective two-step application of power to
in full lines a modified power circuit; and
increase the range of sensitivity of the control.
Figure 13 is a complete wiring diagram oí the
It is an object to provide a control for elec
power circuit.
trical motors wherein intermittent shots of cur 25 The mechanical parts relating to the move
rent of variable duration and of the full avail
ment of the turret are shown in diagrammatic
able voltage are applied for speed control.
form in Figure l wherein the turret is shown in
Other objects and advantages of the invention
an extended position. The turret |632 as a whole
will be apparent in the following description and
is supported on a four-armed spider i ifi which is
30`secured to structural members such as H5 of an
In the drawings forming a part of this speci
airplane, not shown, and which has a central col
lar Ht. Ball bearings such as H8 rotatably
Figure 1 is an isometric view of part oi a tur
support an internally threaded sleeve |29 within
ret with which the control of the invention is
collar H6, which sleeve has an upper ring gear
associated with certain parts of the turret being 85 portion §22. A threaded column |24 is threaded
shown in isometric section, and certain other
into sleeve i2@ and is thereby supported within
parte being shown schematically;
spider H4. A head unit £26 rotatably rides on
Figure 2 is an isometric view of the control
the upper end of column í2fa' and is itself re
box which regulates the direction of rotation and
strained from rotation by a telescoping yoke
the speed of the electrical azimuth and eleva 40 member |22 secured to the outer end of one arm
tion motors, part of the shell being broken away
of spider |14.
to show the inner structure of the control sys
A single power source is used to rotate the
sleeve |20 in order to rotate the turret in azi
Figure 3 is an isometric view of a detail of the
muth or optionally to retract and extend the
control box, showing a rotating drum forming 45 turret. This power source is an electric motor
part of the control mechanism;
|30 suitably secured to 'the spider Hd. The mo
Figure 4 is a phantom View showing part of
tor |30 drives a motor shaft itil to which is se
the turret in dotted outline having superimposed
cured a worm |36. Worm |36 engages a worm
thereon in full lines a simpliñed version of the
wheel |33 which is secured to a drive shaft M3
electrical control system for the azimuth and ele 50 having suitable bearings which will be later de
vation motors;
Figure 5 is a phantom view showing the tur
A worm |42 on shaft M9 engages ring
gear |22, causing the sleeve lîii to rotate within
ret in dotted outline having superimposed there
spider collar H6. Through the gear train thus
on the complete electrical control system in full
described, electric motor |39 is made to rotate
lines for the azimuth and elevation motors, the 55 sleeve |20. The motor |39 can be reversed by
reversing the field current, thus reversing the di
rection of rotation of sleeve |20. The gear train
provides a large reduction in rotation allowing
the use of a very high speed motor, to provide
a high power to weight ratio.
movements. The reñexes of the operator or gun
ner are more accurates when all movement Íis
with one limb, rather than wtih the independent
action of several limbs. The construction of the
control box 500 is based on this principle, and
movement of the handle 504 alone controls ro
The column |25, and thereby the turret also,
may be rotated in azimuth or retracted and/or
tation in azimuth and elevation and depression
extended, by selectively connecting column |2f|
of the guns.
The control box 550 varies the direction of ro
with sleeve |20 or ’with non-rotatable head |25.
This selective connection is performed by an L 10 tation of theazimuth and elevation motors as
well as the speed in either direction. The direc
shaped key Ulli held in a hole through column |24
tion of rotation is changed by changing the po
and selectively engaging an internal notch |50
larity of the motor fields. The speed is varied
in sleeve |20, or an external notch |52 in non
by changing the amount of the armature current
rotatable head |26. The mechanism for moving
key |45 will be described later.
15 while maintaining the field currents constant.
In the past it has been customary to use rheo
When key |513 engages notch |52 in non-ro
stats to get a variable potential and thus to ob
tatable head |25, column |24 is restrained from
tain a variable armature current to vary speeds
rotation. If motor |30 now rotates ring gear |22, ,
and thereby sleeve |20, the column |24 will4 be
of motors. This type of regulation is inherently
raised or lowered according to the direction of ro 20 wasteful as any flow of current through a resist
ance creates heat, which is wasteful of current.
tation of sleeve |22. The head |25 is lowered or
This is a serious consideration on aircraft where
raised with column |25, and the yoke member |28
electrical energy may be supplied by batteries
will telescope and extend and will act at all times
which are heavy and therefore must be reduced
to keep head |26 from rotating. In this way the
extension and retraction of turret |02 is accom 25 to a minimum. Another drawback of rheostat
control of motors is that of poor performance
plished. When the turret itâ is extended the key
under varying loads. As the load increases on
|55 may be moved to engage notch |50 in sleeve
a motor for a given field and armature current,
|20 and the column |213 will rotate as sleeve |20
such as happens when the guns are swung into
rotates, and thus provide the operative move
ment of rotation in azimuth. It will be noted 30 the wind stream, the current in the armature
tends to become greater, due to reduced speed,
that in such case the key M5 will be out of
but this increases the I. R. drop across the rheo
notch |52 and there is no restriction on the movestat giving lower voltage across the armature.
ment in azimuth. The column |24 can be ro
Thus when the need for current is the greatest
tated continuously in either direction for any
given number of rotations.
35 the supply is the smallest.
The present control supplies intermittent shots
Certain parts of the turret are fastened on
of current under full voltage to the motor arma
the lower end of column |2Ll. These parts in
tures to regulate motor speed. Thus the speed can
clude a rotatable shaft |53 to which the guns | I0
be altered by changing the frequency and/or the
are secured. The details of construction for af
ñxing the guns to shaft |55` will be later de 40 duration of the shots, but we prefer in the pres
ent control to have the frequency remain con
scribed. A worm wheel sector |570 is secured to
shaft |56 and is engaged by a worm screw |52
stant and have the duration of the Ishots varied.
fastened to a drive shaft |65. Drive shaft läd
Ordinary breaker points are unsuited for this type
in turn is driven by a worm wheel |66 secured
of control as the almost continuous arc developed
thereto, which is driven by a worm |68 secured , è; under Some Conditions in using breaker points
to a motor shaft |10 of an electric elevation mo
rapidly melts them. The present control avoids
tor |72. II‘he driving mechanism described is
preferably positioned within a frame or housing
such a drawback and will now be described.
as will be described later.
.Also shown in Figure l
source is supplied to one end of a rotatable drum
system for limit cams.
an elevation gearing
Connected to motor
worm wheel |55 is a shaft Hl having a worm
|'|'|a secured to the outer end thereof. Worm
|'|'|a drives a worm wheel 6|2 which in turn
drives a shaft 5M. Fastened to the end of shaft
Gld are cams 505, 558 and 5|0. These cams ro
tate in multiplied synchronism with the eleva
Referring to Figure 3, current from a »suitable
5|2 by a brush 5M. The drum has conductor
segments 5|5 on its cylindrical face which are
in the form of a truncated triangle. These seg
ments are placed diametrically opposite each
other on opposite ends of the cylinder 5 | 2. A part
of the base of conductor segments 5|5 extends
clear around the drum so as to form a continuous
contact surface on each end of drum 5|2. rl‘he
tion movements of the guns.
surface of cylinder 5|2 between conductor seg
The elevating gear train and its actuating mo
tor are adapted to elevate or depress the guns, 60 ments is formed of a heat resisting insulator
material 5|8 suoli as ceramic. The conductor
depending upon the direction of rotation of mo
segments 5 | 6 are electrically connected inside the
tor |72, which is reversed by reversing its ñeld.
drum «by means (not shown) so that the current
The guns ||0 can be elevated above horizontal
applied to one conductor segment 5|6 by brush
as far as is permitted by the shape of the air
plane in which the turret is mounted, and can 65 Elfi i-s equally effective at the other conductor
be depressed to point straight down. The ele
The drum 5|2 is mounted within control box
vation arc as will be described for purposes of
500 as shown in Figure 2. A spindle 5|3 passes
illustration, will be limited to a 90° arc from
through drum 5|2 and supports drum 5| 2 for
horizontal to vertical.
The control box 500 for the direct current elec 70 rotation in a pair of frame plates one of which
is shown at 520. The frame plates are formed o-f
trical circuits is shown in Figure 2. It has been
found that the control of two related movements,
insulator material and are bolted to frame 522.
A pulley 5|5 is secured to one end of shaft 5|3
such as rotation of the turret in azimuth and
elevation of the guns, can best be accomplished
and is driven by a V-belt 524 driven by a small
when a single control member regulates‘both 75 pulley 520 secured to and driven by a constant
speed motor 528. The pulley end of motor 528
is suspended on a lever 529 which can be moved
later described) is actuated by yoke arm 534
everytime it passes dead center and this switch
to tighten or loosen V-belt 524 by an adjustment
reverses the field of elevation motor |72 to re
screw 530 held in frame 522.
verse its rotation.
The azimuth take-off at the drum for current 5
The operation of the control box of Figure 2
for the azimuth motor |33 is a brush 532 held
with respect to the turret is as follows. Assume
in a slider 5.33 which rides two rods 534 screwed
to frame plates 523 longitudinally to the axis of
ing that the turret is extended ready for combat,
the gunner will grasp handle 55d pressing hump
drum 5|2. Brush 532 is held to drum 5i2 by a
505 and thus passing power to the entire turret
spring 535 held in a recess> in slider 533. The 10 and to the control box including brush Elli (Fig
take-oil brush 535 for the elevation motor H2
ure 3') contacting drum 5|2. The motor 525 will
is identical in construction to the azimuth brush.
be energized and cause drum 5|2 to rotate. If
Detailed showing of brush 535 in frame 27 has
the gunner desires to rotate the turret to the
been omitted for simplicity and it will not be de
right, for example to train the cross hairs in the
scribed iurther than to say that while brush 532
periscope on a target airplane, he pushes the
contacts drum 5| 2 from above the elevation brush
handle 554 causing it to rotate clockwise on stem
535 as may be, seen contacts said drum 5|2 from
545. This movement causes arm 558 to move
the side.
clockwise also so that brush 532 contacts the right
The azimuth brush 532v and the elevation brush
conductor segment 5l5 (Figure _3), contacting
536 are moved over drum 5|2 by control handle
first the inner narrow end of the segment.
504 to get varying amounts of Contact with the
conductor segments 525. A bushing 538 is se
cured tothe top of control box 555 and round
stem 545 is fitted therein having an annular
flange 54|.
Control handle 543
is rotatably
mounted on an ear 552 of stem 5x5, and has an
integral hollow shank 543 on which is secured
a pinion
a thumb
544 button
by a nut
553 which
out a re~
sistance to give more current. It also has hump
505 of flexible material covering a dead-man’s
switch which cuts olf all power to the `system when
the gunner’s grip is relaxed on handle 552. A
flexible conduit 545 passing through hollow shank
543 contains the wires for the shunt switch and
the dead-man’s switch.
Clamped to the bottom end oi vertical stem
540 is a yoke arm 543. Its outer or yoke end
(shown dotted) embraces a projection of slider
533. Thus swinging of handle 554 moves slider ‘
While touching just the narrow inner end of
conductor segment 5|5, an intermittent current
is sent to azimuth motor |30- which is composed
of short shots of current and relatively long in
tervals in between. Under these conditions the
motor |35 will move very slowly and the turret
will rotate at an almost imperceptible rate. If
the gunner desiresV more speed he push-es- the
handle 504 further so that brush 532 will con
tact a wider portion of conductor segment 5i‘5.
The intermittent current will then have longer
shots of current and correspondingly decreased
intervals between, and under these conditions
the motor |35 will rotate at a moderate speed.
If still further speed is desi-red the handle` 555s is
pushed as far as it will go so that brush 532 con
tacts the continuous conductor band at the end
of drum 5|2, resulting in a continuous flow of
current to azimuth motor |35. If still further
speed is required the gunner presses button 553
533 along the length of the drum according to
on handle 504 and this shunts out a resistance in
the swinging movement of handle 554. A wire 5
series giving the drum 5| 2 the full available volt~
connected to brush 532 comes out the top of slider
age and current.
533 and extends along transverse arm 543 to a
To rotate the turret to the left the gunner
convenient point where it can be led out of the 45 pulls handle 534l toward him, causing it to swing
control box 53E) to azimuth motor §35 as shown
counterclockwise about stem 540. As yoke arm
in Figure 4. .A switch (not shown but later de»
548 passes the midpoint on drum 5|?. it actuates
scribed) is actuated by the yoke arm 542 as it
a switch which reverses the ñeld of azimuth mo~passes center to reverse the direction of the field
tor |35 reversing the direction of rotation. The
of azimuth motoy i313. This switch causes rota
brush 532 may then be moved to any point on the
tion of the azimuth motor |35 in one direction
left end of drum 5|2 that gives the desired speed
for one end of drum 5 I 2, and rotation in the other
at the particular time.
direction for the other end of drum 5|2.
To depress the guns HG, at any timey whether
Sliding elevation brush 536 along drum 5|2, is
the turret is rotating or not, the gunner twists
accomplished by rotation of handle 534 about its 55 the handle 554 “oven” rotating it clockwise as
axis. as contrasted to swinging about stem 54D
viewed from the right in Figure 2. This move
for control of the azimuth brush 532. For this
ment causes brush 53B to transverse the right
purpose a square bar 550 having a rack 552 on
one end is inserted in a square longitudinal hole
hand part of drum 5|2, and the speed regulation
is the same as that described for the azimuth
formed in stem 545. Rack 552 meshes with 60 brush 532. To elevate the guns the handle 554
pinion 544| on handle 554'. Bar 555 extends below
is twisted “under,” rotating in counterclockwise
the bottom of stem 545 where, through a swivel
as viewed from the right. As yoke arm 553 passes
connection 554, it supports a lower bar 555 guided
the centerpoint of drum 5|2 it actuates a switch
in a frame 522 and having a rack 553. Rack 555
which reverses the field of elevation motor |72
reversing its direction of rotation. Thereafter
meshes with
a pinion 558
to bar
555 and
to a journalled
current taken oil”> by brush 535 causes the guns
in frame 522. A yoke arm 554 is secured to the
to be elevated.
end of shaft 552 opposite to the gear 55B. The
If the turret is extended and it is desired to
arm 584 moves the slider for elevation brush 535
retract it, the guns H0 are elevated by twisting
in a manner identical with that in which the 70 handle 554, until the guns are horizontal. The
azimuth brush 532 is moved. A wire 4 leads from
turret is then rotated to the right until the guns
elevation -brush 535 out the top of its slider and
approach the rear of `the airplane, by pushing
down yoke arm 562 to a point where it can be
handle 504 forward about stem 555. When dur
led out of box 550 and down column |24 to the
ing rotation the guns reach the rear, the con
elevation- motor |72. A» switch (not-shown but 75 nector key |44 (Figure 1) will connectvthe col-V
umn |24 to non-rotatable head |26. Further ro--`
tation of azimuth motor |30 will cause sleeve
|20 to rotate and screw the turret up into the
airshíp in which it is mounted. To extend a re
tracted turret the gunner pulls handle 504 toward
him causing azimuth motor |30 to rotate sleeve
|20 and in opposite direction and screw the tur
ret down. At the lower limit of extension the key
|44 connects column |24 to sleeve |25 and the
turret starts to rotate and is ready for combat.
The control box 56E] gives reliable and accu
rate performance. Any arcs are extinguished on
drum 5|2 as the brush moves from conductor 5| 6
across the insulator 5|3. Further, when travel
ing from conductor to insulator there is a grad
ually reducing current through the brush so that
the final break is only of a relatively small cur
rent thus reducing arcing as compared to ordi
nary breaker points. Any desired type of >speed
increase curve 'is possible by merely shaping the
and elevation motors respectively. Wire 9 leads
to a two-finger, four-contact relay L3 having the
two middle contacts grounded. One ringer of
relay L3 is connected to a wire |6 leading to one
end of the azimuth motor ñeld Fl. The other
finger of relay L3 is connected to a wire Il which
is connected to the other end of ñeld Fl. When
relay L3 is energized it reverses the normal dí
rection of current flow through field Fi, revers~
ing the lield FI and thus reversing the motor |30.
Relay L3 is energized by the movement of
azimuth brush 532 over drum 5|2 in the control
box. Leading from wire 2 is a wire i8 which leads
to a switch S3. in the control box which switch
is mechanically actuated by azimuth brush 532
when it passes the center of drum 5 | 2 while being
moved to therleit. The other side of switch S3
is connected to wire I9 which leads to relay L3 to
energize relay L3. Thus for all positions of` azi
muth brush 532 to the right of center, switch S3
will be closed and relay L5 will be energized to
conductor segments 5 i S as desired.
cause current to iìow through ñeld F| as indi
The power circuit for the turret is shown in
cated in Figure 4. For all positions left of the
simplilied form in Figure 4. Since Figure 4 is a
simpliñed drawing parts are omitted in certain
center of the drum the switch S3 will be open,
cases for simplicity, but the basic wiring system 25 allowing relay L5 to assume a normal position
which causes current to flow through ñeld FI in
may be traced also on Figure 5 which shows the
complete power circuit. Parts of the control box
the opposite direction, thus reversing the direc
500 can be identified in Figure 13, The rotating
tion of rotation of azimuth motor |33,
rl‘he circuits for supplying current to the field of
drum 5|2 and its driving motor 528 are shown in
dotted outline, as well as the control box handle 30 the elevation motor |12 are similar to those for
534 near the top of the drawing.
azimuth motor |32. Wire 8 passes down the cen
Current is supplied to the turret by a battery
tral column and connects to a two-finger, four
or storage cell BI giving about 24 volts, although
contact relay L4. Connected to one finger of
a D. C. generator could just as well be used. Bat
relay L4 is a wire 2|) leading to one side of the
tery BI is grounded at one terminal to the 35 field F2 of elevation motor H2. A wire 2| leads
frame of the turret, and the other terminal is
attached to a wire | which leads -to a relay Ll.
from the other linger to the other side of ñeld
F2. Wires 26 and 2| are normally connected as
shown in Figure 4 but whenrelay L4 is energized
A wire 2 leads from relay Ll to series resistance f
RI, the function of which will be described later.
it causes current flow in the reverse direction, re
A wire 3 leads from resistance Rl to brush 5|4 40 versing the direction of rotation of elevation
contacting drum 5|2 where the current is dis
motor |l’2.
Relay L4 is energized by the movement of ele
tributed to azimuth brush 532 and elevation
brush 535 as explained with reference to Figures
vation brush '533 over drum 5|2. Leading from
2 and 3. Wire 2 supplies current also to a wire
wire 2 is a wire |5 which passes current to a
|4 leading to motor 528 which causes drum 5|2 45 switch S4. Switch S4 is normally open as shown
to rotate.
in Figure 4, but when brush 535 passes the cen
Leading from azimuth brush 532 is a wire 5
ter of drum moving right brush 53S closes switch
connected to the armature Al of the azimuth m0
S4, and when brush 535 is moving to the left the
tor |30. Elevation brush 535 delivers current to
switch S4 is opened. Switch S4 passes current to
a wire 4 which passes down the central column 50 a wire 23 which passes down the central column
to conduct current to the armature A2 of eleva
|24 to actuate relay L4. When relay L4 is ener
tion motor |12. Through the circuits described,
gized, the i'leld F2 is reversed, reversing elevation
controlled current may pass from battery BI to
motor |12.
the armatures AI and A2 respectively of the azi
In summary, with relation to Figure 4, the op
muth and elevation motors;
eration is as follows. The gunner grasps control
Also shown in Figure 4 branching from wire
handle 504 which closes switch S|, operating re
I is a wire |û which leads to a switch SI in the
lay Li to pass current to wire 2, through resist
control handle 504. The other side of switch SI
ance Rl , and to brush 514. At the same time cur
is connected to a wire || which leads to relay
rent passes through wire I4 to motor 528 and it
L| which is normally open. When the gunner 60 causes drum 5| 2 to rotate. Current nows from
grasps the control handle 534 he closes switch
brush 532 to armature A! of the azimuth motor
Sl which energizes relay Ll, connecting wire | to
|32 and iiows from brush 536 down the central
wire 2 and passing current to the whole turret.
column to armature A2 of the elevation motor.
Thus no current can pass to the turret until
The ñelds F| and F2 of the motors are reversed
the operator grasps control handle 554, The same 65 every time their respective armature brushes y532
circuit causes current to be cut off from the
and 53B pass the center of the drum 5|2. When
whole turret if the gunner relaxes his grip, thus
azimuth brush 532 passes center from right to left
providing a “dead-man” control. If the gunner
it opens switch S3, deenergizing relay L3 which
is shot While operating his turret, he will relax
then passes current to ñeld FI in a direction
his grip, opening relay Ll, and the turret will 70 opposite to that shown in Figure 4. When eleva
cease operation, preventing waste of current and
tion brush 535 passes center from left to right it
possible injury to the turret or the airplane in
closes switch S4, energizing relay L4 and passing
current to field F2 in a direction opposite from
which it is mounted.
that shown. When the brushes move pastcenter
Connected to wire 2 are wires 9 and 8 by which
current is supplied to the iields of the azimuth 75 in the other direction their respective ñelds are
reversed and are connected as shown at relays L3
and LA! in Figure 4.
The complete power circuit for the turret is
movement the head I2@ rises and allows switch
35 again to connect wires l 5 and E?, causing relay
L6 to break the connection to armature A2, in
shown in Figure 5. The basic functions illus
suring that the guns will remain horizontal at
tratecl in Figure 4 are included in Figure 5, but Ul all times during and after retraction and while
with .the addition oi more elaborate controls.
extending the turret.
Also Figure 4 is a siinpliñed power circuit and
Before the turret can be retracted the guns
therefore incomplete in some respects. The cir
must be elevated t0 a horizontal position so that
cuits will now be described with relation to Fig
their inner ends will not strike parts of the tur
ure 5.
10 ret when retracted. The retracting circuit is ac
One addition in Figure 5 over Figure 4 is the
cordingly rendered inoperative by the retract in
provision of a speed change switch in the con
rol handle 594. Branching from wire 2 is a wire
i2 leading into control handle 5de to a switch S2
dex cam 5536 which is synchronized in elevation
with the guns llo of the turret. A branch from
wire 8 at the lower end of the turret, wire 25
actuated by push button l593. A wire i3 leads
conducts current to a switch S7 which is actuat
from switch SZ to a relay L2 closing a shunt cir
ed by retract index cam EBS in the elevation com
cuit around resistance Rl. This shunt circuit
pensator WG. Index cam 5&5 keeps switch Sl
is formed by a wire 2a leading from wire 2 to relay
normally closed and opens it only when the guns
L2 and by a wire 3a leading from relay L2 to
are horizontal, at which position the cut-away
wire 3. Thus by closing switch S2, relay L2 is 20 portion allows the switch S1 to open. The other
actuated to complete a shunt around resistance
side of switch Si is connected to wire ‘El which
Rl. Shunting out resistance RI gives a greater
leads up the central column to switch S3 at the
effective voltage for the drum 552, thus giving a
control boX.
two-speed electrical range by closing or failing
It will be noted that inside the central column
to close switch S2.
25 and at the top there is a wire
branching from
Another part of the complete power control
wire 25 and leading to a switch S8. A wire 35
relates to means to render the azimuth motor
leading from wire 2l' is connected to the other
lili! inoperative in a retraoting direction if the
side of switch S3. Switch S3 is the retract lever
turret is already retracted or when the turret
switch, and is closed whenever retract lever, not
reaches the top of a retraction movement. Wire I i shown in this application, is actuated to retract
i9, which the wire energizing field relay L3 of
the turret. The operation of the retract lever
the azimuth motor when the brush
passes the
has been fully described in Pontius application
center of drum 5H? moving to the right, the re
Serial No. 391,911, ñled May 5, 1941, and Pontius
tract position has a branch wire Eil. liïire 24
et al. application Serial No. 497,468, ñled August
,casses down the central column and emerges at
19, 1941. If the turret is extended and the gune
the bottom to connect to a retract limit switch
ner tries to retract it while the guns are other
«Sc which is closed by an actuating pin 575 on
than horizontal, current will flow from wire 2
spider lis when the turret is retracted. Switch
to 8 down the column to wire 28, through switch
Se in turn passes current to a wire 25 connected
Sl to wire 2l, up wire El to Si?, through switch
to it. which leads up the central column to a 40 S3 to wire 29, into wire 25 to relay L5, where the
relay L5 interposed between wires 5 and il, the
current breaks the contact between wires 5 and
relay serving to break the azimuth armature cur
t“ and n-o current flows to azimuth armature AI
rent. Thus when switch Sli is closed, by the re
and the turret will not retract. If the guns are
traction movement or after the retraction is fin
horizontal and the gunner operates the retract
ished, no current can pass to azimuth armature
lever, switch Sl will be open and no current will
Al when the brush ""'l is pushed to the retract
flow across switch Si! to energize relay L5, and
to the rLht on drum 5i2. When
retraction will take place when current ilows to
is moved to the extended position cur
armature Al .
rent may be supplied to armature Al because
Switch Si; also serves another function: that
wire 24 is not then energized and no current can 50 of insuring that the azimuth motor will not turn
dow to relay wire
and relay L5.
in a direction to extend when it is desired to re
Another part of the complete power control,
tract the turret. If this provision were not made,
shown. in Figure 5, relates to means to render the
the central column would be jammed against the
elevation motor inoperative when the turret is
rotatable threaded sleeve i243 which retracts and
retracted. Accidental movement of the control 55 extends the turret. It will be remembered that
handle while the turret is retracted would result
when the turret is ready for retraction the gun
in injury to the turret and the airplane if this
ner will close retract lever and switch S3 by ac
provision were not made. Branching from wire
tuating the retract lever in a manner described
2 is a wire i5 leadi- to the switch member of
in the two applications referred to in the pare.
a switch S5. This switch has two contacts, one 60 graph above, and the guns will be horizontal thus
connected to wire
which leads to switch S4,
opening switch S1 and preventing ñow of cur~
the other connected to wire 2S! which passes down
rent to wire 2i at that point. rThis safety func
the central column to a relay Le.
tion is accomplished by a circuit through the up~
normally tends to connect wire l5
per end of wire 2l which is connected to switch
and wire
which actuates relay L3 to render the
S3. When the azimuth brush
moves to the
elevation ino-tor il?. inoperative. When the tur~
left part of the drum (extend and rotation~toret is fully extended, however, non-rotatable head
the-left) switch S3 is actuated to cause current to
i255 (not shown)
the top of the central col~
ilow from wire lil to wire 21’. Current will then
umn iii-1l descends upon switch S5 as the turret
ñ/ow into wire 2l at switch S3, int-o wire 35,
is extended and causes switch S5 to disconnect
through switch S3, down wire 29 to wire 25 and
wire 23 from wire i5 and to connect wire 22 with
through wire 25 to relay L5, which breaks the
This deenergizes relay Le allowing cur
current to armature Al of the azimuth motor i3d
rent to ñow to armature
and allowing cur
preventing extension of the turret. Thus the
rent to flow to» switch Sd to reverse selectively the
circuit just described provides a safety cut-out
elevation í'leld F2. At the slightest retraction
of the retracting motor IBG if the gunner should
inadvertently move the azimuth brush 532 in the
wrong direction for retraction.
The circuit just described also insures that the
gunner will not have his fingers injured by the
rotating turret when he is manipulating the re
tract lever. As shown in Figure 10 of Pontius
application Serial No. 391,911, the gunner presses
on the right side of the retract lever to move it
well as passing current into wire 23. At lower
limit switch SS, current passes into wire 3l from
wire 23 and energizes relay L4 which passes cur~
rent through the ñeld F2 in a direction to cause
motor |12 to depress the guns when current iiows
through the armature A2. If the depression of
the guns continues they will soon be pointing
straight down, the lower limit of their elevation
arc. At this point cam 508 rotates so that the
10 notch is opposite switch S9 which then opens,
deenergizing th'e relay Lft and causing motor i212
to reverse its direction and elevate the guns. If
the gunner persists in having the controls in a
depressed position, the gus will elevate only until
15 cam 508 closes switch S9 again and reverses the
field. Thus the guns will continue to alternate
between elevation and depression at the lower
limit if the controls are kept in a position to
depress the guns.
The circuit for stopping the guns at the upper
limit of their arc is actuated by upper limit cam
5H). It will be noted that the notch in upper
limit cam EIS has the the same relative position
as the notch in cam 536, and this is because the
25 upper limit of the guns happens to be at the hori
zontal position which is the position of the guns
when the turret is retracted. As stated earlier in
this description, the guns could be elevated above
left or counterclockwise screwing the turret down
horizontal if it were desired, and in this case the
ward. The safety circuit, effective in retraction
to prevent the azimuth motor from rotating sleeve 30 notch' of upper limit cam 5I!) would be placed at
to the left for retraction. If the turret, instead
of rotating to the right as it must to retract,
should rotate to the left, his ringer would be
wedged between the stationary head rest support
and the retract lever (Figure 5 of Pontius appli
cation Serial No. 391,911) as the lever rotates
counterclockwise with the turret. The safety cir
cuit described in the foregoing paragraph pre
vents this from happening and insures that the
turret will always rotate tothe right or clockwise
for retraction, which movement would lift the
gunner’s linger ol'f the lever if the turret did not
lock at the “straight back” or rear position at
the time of actuation of the retract lever.
When the turret is retracted and the gunner
desires to extend it, he does not actuate the re
tract lever, but merely moves azimuth brush 532
to the left part of drum 5&2. This causes
azimuth motor §33 to rotate sleeve §23 to the
|20 to the left, is not effective during extension
because the retract lever is not actuated and the
retract switch S8 is open. When the turret is
a more advanced point.
Upper limit cam 51E! actuates switch Si@ which
connects wires 23 and 26. Wire 26 is continu
fully extended the connector key |44 (Figure l)
ously energized because it is a branch of wire 8.
slips into notch |50 in sleeve |20 and the turret 35 When wire 23 is energized it can pass current
rotates to the left, ceases extending, and is ready
through switch S9 to actuate relay Ld. As ex
for use.
plained above, lower limit cam 508 keeps switch
The remaining Controls and circuits of Figure 5
SS closed at all points on the elevation arc ex
relate to the upper and lower limit stops for the
cept the bottom point, and for this reason switch
guns l IQ of the turret in elevation and depression. 40 S9 is closed at all times whenever it is desired that
This function is> likewise accomplished by cams
the upper limit stop circuit be effective. Switch
synchronized with the movement of the guns.
SI ß, which passes current from wire 23 to wire 23,
Lower limit cam 528 in the elevation compensator
is «normally open, and is closed only when the
H3 has a notch cutin a position with relation to
guns are horizontal at which position the notch
an actuated switch S3, corresponding to> the
in upper limit cam 5H) allows the switch SIG to
straight-down position of the guns which is the
lower limit of depression. Upper limit cam 5&0
While the guns are being elevated brush 536
also in the elevation compensator box, has a notch
will be on the left part of drum 5l2 and switch
cut in a position with relation to an actuated
S4 will be open so that no currentpasses to wire
switch S l 3, corresponding to a horizontal position 50 23. At the lower end of the turret, switch' SH3
of the guns H13, which is the upper limit of
will normally be open so that no energy passes to
wire 23 at that point. In such case, although
The lower limit switch S9, actuated by the
switch S9 is closed, no current flows to relay Ld
lower limit cam 5&8 is connected on one side to
and it connects the field F2 as shown. As the
wire 23, which is the Wire energized at the control
guns are elevated by the armature current flow
box whenever elevation brush 535 is moved to
ing through brush 536 and wire Il, they approach
the right or to a depression position on drum 512.
the horizontal and at that position upper limit
Therefore, while the guns are being depressed,
cam 5m allows switch SIU to close. Current
wire 23 will be energized passing current to
now ñows from wire 26 through switch Slû 4to
.switch S3. The other side of switch SS is con
nected to a wire 3i which-leads to ñeld control 60 Wire 23, through switch S9, and through wire 3i
to energize relay L4 which will reverse the íield
relay Lil, energizing it to reverse the current to
F2, causing the guns to change direction and de
field F2. At all points on the elevation arc, ex
press rather than elevate. When the guns have
cept for the straight-down or lower-limit posi
been moved in a depression a short distance, up
tion, the lower-limit cam 538 will keep switch S9
per-limit cam 5m moves accordingly until its
closed, energizing held control relay LQ when en
notch opens switch Siû. This breaks the circuit
ergy is passing into wire 23. As shown in Fig
to relay LA and the ñeld F2 is again reversed, and
ures ‘l and 5, the elevation brush 53E is in an
the guns once more start to elevate. Thus if
elevation position and current does not iiow into
the gunner keeps brush 536 on the elevation end
wire 23, and relay L6 is inactive even though
of drum 5I2 the guns reach the upper-limit posi'
switch S9 is closed.
The lower-limit stop cornes into operation when l
the gunner twists the control handle 504 “oven”
causing the elevation brush 536 to contact the
right hand side of drum 5l2. This movement
passes current into elevation armature wire 4 as
tion, which is horizontal, and alternate up and
down in a limited arc governed by the amount of
rotation of cam 5H] necessary t0 open and close
The operation of the lower turret is as follows.
Assuming that the plane, not shown, on which
the turret is mounted is flying and the turret is
shaft |49. Drive shaft |40 drives worm screw
|42 attached thereto, which screw meshes with
in its retracted position when an enemy plane is
and drives ring gear |22 attached to sleeve |20.
sighted or suspected, the gunner will iirst wish' to
Sleeve |20 is thus rotated, and acting through
extend the turret. Thereupon, he grasos handle
connector key |45 (Figure l), drives the column
5514 closing switch Si and passing current 'to the
|24 in rotation in azimuth.
turret, and swings handle 59e toward himself
If the gunner desires to rotate the turret to
causing brush 532 to move to the left part of the
the left 01‘ counterclockwise, he swings the control
drum EEE. This nio-vement causes switch S3 to
handle 594. toward himself causing brush 532 to
disconnect wires I8 and i9 and current is no 10 contact the left part of drum 5|2. In this posi
longer supplied from wire IS to branch wire 24.
tion current will again pass from brush 532
rfhus current can no longer flow from wire 24
through wire 5, through relay L5 and wire 6 to
through switch S? to wire 25 into relay L5. Cur~
armature Ai. The movement oi’ brush €332 to the
rent passes to armature AI and wire i9 no longer
left opens switch S3 so that current no longer
passes current to field relay .L3 and the relay is
deenergized to connect field Fl in an “extend”
flows from wire I8 to wire i9, and the ñeld relay
L3 will le deenergized, allowing the field wires
.Azimuth motor l
now causes sleeve |20 to
rotate to the
or counterclockwise and turret
opposite direction, reversing the direction of ro
tation of the motor |313. The motor |30 then acts
through the azimuth gear train to rotate the tur~
ret to the left or counterclockwise.
If the gunner desires to depress the guns ||0,
is extended. The sgoeed ’with which the turret is
extended depends unon, first, the distance which
control handle 5&4 is Aswung and the consequent
distance that brush 532 is moved away from .the
center of the drum 5 l 2 as explained in connection
with Figure
and second, by operation of the
button 533 on handle
giving to the drum 5|2
the full available voltage and current. As the
turret nears the bottom of the extension stroke,
connector key i 44 slides vertically past the top
of sleeve E28 because it is held within that limit
by pin läli. Further extension causes a pin (not
shown) to strike the top of sleeve |26 and the pin
is pushed up into itsrecess. .As the turret reaches
the iînal limit of extension notch lei! in sleeve
to rotated opposite key lil-'l and a spring
pushes key 544 into that notch. The turret now
starts to rotate and the gunner is ready for com
The final extension of the turret causes head
i‘ê and l? to pass current through ñeld FI in an
he twists the control handle 5M “over” or rotates
it on its axis in a clockwise direction as viewed
from the right end. This movement causes ele
vation brush 536 to move to the right part of
drum 5i2, passing current through wire 4 which
passes down the column to relay
through re
lay Ld and through wire l to the elevation arma»
ture A2. The movement of brush 53S to the
right closes switch S4, passing current from wire
22 to wire
which leads down the central co1
umn to switch
in the elevation compensator,
through switch
and wire 3| to relay L4. Relay
Ld when energized connects the field F2 in a di
rection opposite from that shown, reversing the
motor il?. Motor il?. drives its shaft lli! to
which is attached worm screw |63.
Worm screw
drives worm wheel idd attached to drive shaft
|64, which shaft also has worm screw H32 at
to disconnect wire 25 from wire |5 and to con
tached to it. Worm screw 5&2 in turn drives
nect wire 22 to wire i5. lïifire 2d being no longer
wheel sector ltd attached to gun shaft läd on
energized allows relay L6 to he deenergized and
which the guns are mounted, depressing the guns
the current may now now to elevation armature
Ai. Wire i12 passes energy to switch S4 allow 45 as wheel sector ißt rotates.
|2S (Figure 5) to contact switch S5, causing it
ing that switch to actuate to iield relay through
wire 23, switches .S9 and Sill and wire 3 l.
More sneciiically and referring particularly to
If the depressing movement of the guns con
tinues the guns will reach the lower limit of the
elevation arc, the straight down position,
Figures e and 5 for the electrical circuit and to
depressing movement causes worm wheel |56 to
Figure 1 for the mechanical parts and movement 50 drive shaft il? (Figures l and 5) which has a
there follows a more detailed description of the
worm Illu driving compensator worm wheel 5|?.
operation of the turret during combat.
Worm wheel 552 in turn drives compensator shaft
The turret is shown in an extended position
‘524 to which
secured cams
508, and Eli).
ready for combat in Figure i.. The connector key
When lower limit cam
is rotated to a posi
i442» (Figure 1) is urged outwardly by a spring 55 tion corresponding to the lower limit or straight
so that it nts notch |554 in sleeve |29, causing
down position of the guns, its notch allows switch
column i243 to rotate with sleeve E2G. To oper
S9 to onen breaking
e current through wire
ate the turret the gunner grasps control handle
3| to relay Ld. Field Fl is then reversed, caus
594 (Figure 5) closing switch Si, and thereby
ing the guns to start to elevate. When the guns
closing relay Ll to pass current to the turret from
have elevated a small amount, cam 563 will ro
battery Bl. Il the gunner desires to rotate the
tate in synchronif‘m closing switch SQ and the
turret to the right, or clockwise, he swings handle
guns will start to depress. ’Ihus when the con
531i away from himself causing azimuth brush 532
trols are kept in the depressed position the guns
to move to the right end ci drum 5 | 2.
will alternate at the lower limit between depres
This movement of kazimuth brush 53.2 causes
sion and elevation in a small arc governed by
' from it through wire
the amount of rotation of
5&2 necessary to
relay LE and wire d to the azimuth motor arma
close switch SQ.
ture Al. The same movement of brush 53.52 closes
If the gunner desires to elevate the guns he
switch »S3 which passes current from wire |8 to
twists handle 5de “under” or counterclockwise
wire lil and through wire la? to held relay L3 7 o when viewed from. the right end. This movement
which connects the azimuth _held FI in a direc
causes elevation ‘crush
to contact the left
tion to cause motor Hitt to rotate to the right or
end of drum
and current í‘lows from brush
clockwise, Motor i3@ drives its shaft i34 to which
535 to wire 23. The movement to the left opens
worm screw |35 is attached. Worm screw |36
switch S4 so that no current can
to wire
drives worm wheel |33 which is attached to drive
23 down the column to switch SQ and relay L4.
Thus relay L4 is not energized at switch S4, the
field is reversed from that required for depres
sion, and the motor will act through the eleva
ly moved to elevate the guns while the turret is
other than in a fully extended position,
tion gear train to elevate the guns.
When the guns reach 'the upper limit of the
elevation arc, cam 5|!) will allow switch S|0 to
If the guns are not horizontal when the gun
ner tries to retract the turret by pressing on
retract lever |56, which closes switch S8, the tur
ret will not retract. Switch S`| will then be closed,
close, passing current from wire 26 to wire 23,
passing current from wire 26 to wire 27, which
passes current up the central column to switch
S8. Switch S3 passes the current to wire 25
switch SN is eiïective, through switch S3, and
down wire 3| to ñeld relay L4. When relay L4 10 which leads out of the top of the column to ac
tuate relay L5 to break the current to armature
is energized it reverses the direction of field F2,
Al. Thus if the guns are not horizontal when
and thus motor |12, and the guns begin to de
retraction is attempted the azimuth or retract
press. Cam 5|0 rotates accordingly and after a
up wire 25 to switch S3, which is closed when
short movement opens switch Slß causing relay
ing motor will be automatically stopped.
If the gunner desires to extend the turret, he
L4 to once more be deenergized and the guns 15
does not operate the retract lever, but merely
will elevate. Thus the guns will alternate be
moves azimuth brush 532 to the left part of drum
tween elevation and depression if the controls are
5|2. This movement causes switch S3 to discon
kept in the elevating position.
nect wires I8 and I9, and branch 24 from wire
The triangular conductor segments 5 i â on drum
i3 is no longer supplied with current. Current
5|2 (Figure 3) allow speed control of the ele
can no longer flow from wire 24 through switch
vation and azimuth motors. The control handle
S6 to wire 25 and thus to relay L5, and relay
504 can be moved to give movement in azimuth
_L5 is deenergized allowing current to pass to
and elevation at the same time and at different
armature AI. Wire I9 no longer passes current
speeds. The stops of the upper and lower limit
of the elevation arc are automatic.
There are 25 to ñeld relay L3 and it is deenergized to connect
no stops in azimuth because the turret is free to
rotate for any given number of rotations in either
iield FI in an “extend” direction.
Azimuth motor |30 now causes sleeve |20 to
When the gunner desires to retract the tur
rotate to the left Vor counterclockwise and the
turret is extended. As the turret nears the bot
ret he must place the guns in a horizontal po 30 tom of the extension stroke connector key |44
slides vertically past the top of sleeve |20 be
sition and he twists or rotates control handle
cause it is -held within that limit by pin |55.
555 “under” to accomplish this. When the guns
Further extension causes pin |54 (Figure 6) to
Hi! reach horizontal the gunner should stop
strike the top of sleeve |20 and the pin is pushed
them. However, when the guns do reach this
up into its recess. As the turret reaches the
position they will oscillate back and forth slight
ly so that it is not diÍñcult for the gunner t0
iinal limit of extension, notch l5!)v in sleeve |25
is rotated opposite key |44 and spring |4461, pushes
stop them. After the guns are horizontal he
key |44 into that notch. The turret now starts
presses the retract lever which has been more
to rotate and is ready for combat.
fully described in Pontius application Serial No.
The final extension of the turret causes head
391,911 and Pontius et al. application Serial No.
|26 (Figures 1 and 5) to contact switch S5, caus
407,458, assuming that the guns are pointed to
ing it to disconnect wire 28 from wire l5, and
ward the rear so that retract lever is on the in
ner side of column |24 near him. Pushing the Y to connect wire 22 to wire I5. Wire 28 being no
longer energized allows relay L6 to be deener
retract lever for retraction closes switch S8 at
the top of column |24, causing it to connect wire 45 gized, and current may now flow to elevation
armature AI. Wire 22 passes energy to switch
2ï to wire 25 leading to relay L5. At the same
S4, allowing that switch to actuate the held re
time the gunner will rotate the turret to the
lay L4 through wires 23, switches S9 and SIB
right, which is the direction of rotation of sleeve
and wire 3|.
|20 necessary to screw the turret up into the air
The mechanical parts and movements of the
plane to retract it.
upper turret 202 are shown schematically vin Fig
As the turret rotates the guns toward the rear,
ure 6. At the bottom of the ñgure a high speed
key l44 will come opposite notch |52 (Figure 1)
electrical motor 228 drives a motor shaft 230 to
in nonrotatable head |26. The pressure of the
which is secured a worm 232. Worm 232 drives
gunner on the lever will act to pull the key |24
into notch |52, locking the column |24 to head 55 a Worm wheel'234 secured to a drive shaft 233 to
which is secured at the other end a driving Worm
|25, preventing it from rotating. As sleeve |23
23B. VDrive worm 238 engages a worm wheel 240 continues to turn to the right or clockwise it will
secured to rotatable column 258, and drives col
screw the turret up into the airplane in which
umn 203 in rotation in either direction depend
it is mounted. When the turret nears the upper
limit of its retraction, actuation pin 513 (Figure 60 ing upon the direction of rotation of azimuth
motor 228.
5) on spider | I4 closes switch S5, passing cur
VThe gear reduction between compensator worm
rent from wire 24 to wire 25, which leads up the
wheel 245 and worm 21‘33 is the same as that be
column to relay L5. This causes the relay L5 to
break the current to armature Ai and the sleeve
tween column worm wheel 240 and driving worm
65 238, resulting in compensator` shaft 248 rotating
§20 ceases to operate.
one revolution for every revolution of column 208
As the turret retracts, non-rotatable head |26
rises with it.
The slightest upward movement
of head |26 allows >switch S5 (Figure 5) to con
nect wire l5 to wire 28, passing current to wire
28 which leads down the column to relay L3.
Energizing relay L6 breaks the current to arma
ture A2, preventing movement of the guns in
elevation during retraction, after retraction and
while extending, This provision insures against
injury of the turret if the controls are accidental~
and rotating in synchronism.
Rotatable column 208 is preferably made of
aluminum or magnesium to reduce weight. The
frame 2| 0 secured to the top of column 208 is
also preferably magnesium or aluminum and
may be made by casting. An opening 2H in the
frame 2|0 provides a place wherein the gunner
may position himself to operate the turret. The
guns 2 I2 are secured to a rotatable gun shaft 244
supported near each gun by frame brackets 213.
Gun shaft 244 is driven in elevation by a high
speed electrical motor 241 positioned within a
well 2139 in frame 2id. Motor 241 drives a motor
shaft 249 to which is secured worm 25D engaging
driving worm wheel 252 mounted on a drive shaft
254. Secured on the other end of drive shaft 254
is a driving Worm 254 engaging a worm wheel
sector 253 secured to gun shaft 254. The gun
shaft is rotated in either direction by reversing
elevation motor 241, elevating or depressing the
guns according to direction of rotation of motor
The elevation compensator drive is obtained
through abevel gear 252 secured to shaft 244, and
driving a matching bevel gear 264 which drives
elevation compensator shaft 266. Fastened to
compensator shaft 226 are limit cams 412, 414,
4| 6 and 4|8. Since the elevation movement of
from below locking upwardly. The cover plate
425 has an opening in front of fan 432, which is
covered with metal screen 468. The fan 432
blows air through the screened covered opening
to cool the motor and electrical contacts. The
pulley 434 on the other end of motor 43B, through
a belt 435, drives a pulley 433 connected to the
rotary cam shaft 444.
Lever 454 is shown in Figure 8 and adjusting
screw 462 is shown contacting double frustro
conical cam 454. A similar lever 413 for oper
ating the breaker .arm for the elevation motor is
also shown in Figures 9 and 11 pivotally mounted
on rod 4513. Lever 410 is similar in construction
to lever 454 and operates in the same manner.
It is positioned however by a rotary cam 412
mounted on a rotatable hollow shaft 414. This
structure is shown in detail in Figure 11, where
the elevation cam 412 appears in prof-lle. Shaft
the guns is about 90°, the ro-tation of compensa 20 414 rotates in a bushing 415 integrally formed
tor shaft 265 is multiplied about three times to
with cover plate 424. The outer end of shaft 414
increase sensitivity of the cam control.
is enlarged to form a housing 41S. Control
The control box 444 for the power` system of
handle 402 is rotatably secured to housing 418 by
the upper turret is shown in Figures 7, 8, 9, 10
a stem 43D. When the gunner pushes or pulls
and 11. Figure 7 shows a rear view of the con
on handle 492 transversely to the aXis of shaft
trol box showing a cover plate 426 to which the
414 he will cause the shaft to rotate, rotating cam
mechanism of the entire box is añixed so that
412 and changing the position of lever 410.
the whole unit may be removed from column 248
Secured to stem 486 of control handle 4t2 is
in one unit. Secured to plate 42S is a frame 428
a gear` segment 482 contacting a rack 484. The
which supports the inner ends of the control
double~frustro-conical azimuth cam 464 is se
mechanism. Secured to frame 428 is an electric
cured to rack 444 and the inner end of the rack
motor 438 having a fan 432 secured to one end
is positioned in a bushing 48S integrally formed
and a pulley 434 secured to the other. Through
in frame 423. Back 484 rotates with shaft 414
a drive which will be later explained, the motor
and consequently causes cam 454 to rotate. Since
434 causes a shaft 441) to rotate at a constant
cam 444 is circular, however, there is no effect on
speed. Mounted on shaft 44D are eccentric cams
the azimuth adjustment due to rotation of the
442 which strike breaker arms 444 pivoted to a
cam. When the gunner Wishes to change the
rod 445 and urged in a clockwise direction by a
speed of the azimuth motor he merely rotates
spring 448 secured to frame 423.
handle 442 on stem 48!! causing gear segment 482
Current is grounded through breaker arm 444
to move the rack 454 in or out, and thereby
from relays which then act to interrupt the cur
moving cam 464.
rent as will be later- explained. Breaker arm
The outlines of the control levers 41€! and 454
444 breaks against a grounded Contact 450 held
are shown in Figure 9. It will be noted that lever
in a curved arm 452 also pivoted to rod 445.
454 has two screws 458 for positioning two con
Since the free stroke and the frequency of “ tact arms 452.
In all, there are four breaker
breaker arm 444 is a constant the duration of
arms 444 controlling four relays interrupting the
contact of breaker
444 and contact 45t is var»
current supply, as will be later explained.
ied by varying the position of contact 45t? with re«
The arrangement of the cams 442 on shaft 44K.`
spect to the stroke of arm 444. In this way the
is shown in Figure 10. Each cam is offset 180°
breaker arm 444 may touch contact 454 at an 50 from its mate, to obtain alternation in the relays
intermediate point in its cycle of movement and
operated by each breaker arm 444. Also shown
remains in contact until the cycle of movement
in Figure 10 are the levers 454 and 410.
again lifts it free. As shown in Figure '7, the con
The control box is shown diagrammatically in`
tact 454 is in the “neutral” position wherein
Figure 12 as applied to a simplified version of the
there is continuous contact with the b-reaker arm
contro-l system. The control box motor 430, the
causing the actuated relays to remain con
driving and driven pulleys 434 and 438 are shown
tinuously open so that no current flows to the
in dotted outline as well as the cam shaft 440 on
which cams 442 are mounted. During operation
The positioning of contact arm 452 is accom
the shaft 444 is continuously rotating causing the
plished by a lever 454 pivoted on a rod 456 and
breaker arms 444 to move regularly and to open
having an adjustable screw 453 touching arm
and make Contact when not in the neutral posi
tretched between contact arm 452 and
tion. rI‘he control handle 442 is also shown in
lere-r 454 is a spring 44@ holding the two parts
dotted outline and both rack 484 and shaft 414
constantly against each other. lever 454 is in
are shown diagrammatically by a single broken
turn positioned by an adjustment screw 462 con
line leading therefrom. The azimuth and eleva
tacting a double frustro-conical cam 454 which
ti-on cams 4&4 and 412 are also shown diagram
is axially movable to act as a cam. The axial
matically as eccentric cams on a shaft. The
position of cam 444 is controlled by the gunner
function of cams 434 and 412 already described,
land in this way the gunner controls the dura
that of varying the position of the grounded con
tion of the current shots to the azimuth motor. " tact 454 against which the breaker arms strike,
Between the lower end of lever 454 and frame 424
is also shown diagrammatically.
is a compression spring 4% urging adjustment
Current is supplied by the battery B2 to the
screw 442 in contact with cam 4&4.
The control box 40d is seen in vertical section
in Figure 8, which is a sectional View of the box `
wire 341 which leads up the column to a relay
L42. A branch wire 355 leads through relay L|2
to the main power switch Si I in the control han
dle 452. When the gunner grasiûs the control
handle §22 he closes switch SII grounding wires
SI5 and causing the relay LI?x te close, passing
current to the entire turret. Leading from relay
LIE is a wire SI5 which passes through the relay
box and back t0 the control box where it sup
plies power to the control box motor 430. Thus
neld in the azimuth and elevation motors.
is done by shunting around the armature resist
ances R2 and R4, and by opening normally closed
shunts around ñeld resistances R4 and R5,
Branching from wire BIS near resistance R2 is
a wire 835 leading to one contact of a relay L11.
The other contact of relay LI1 is connected to a
wire 336 connected to wire SIS. Thus when relay
when the gunner closes switch SI I he causes cur
LH is energized a shunt circuit around resist
rent to ilow to motor ¿itil and the cams 442 start
10 ance R2 is formed by wires $35 and 636. It will
to rotate.
be noted that when relay LI 1 closes its movement
Branching from wire 8l@ near the cam 442 is a
opens a normally closed switch SIS one end of
wire SI1 leading to a double relay LIS. Leading
which is connected t0 a wire 831 passing down
from relay LI3 is a wire SIB which passes down
the column and out the brushes to connect to wire
the central column to a resistance R2. The
other side of resistance R2 is connected to a wire 15 830 near resistance R5. The other terminal of
switch SI5 is connected to a wire 838 which like
8I9 leading down the column out through the
wise leads down the column and connects to wire
brushes and to armature A3 of the azimuth mo
829 near resistance R5. It is thus apparent that
tor 228. Also branching from wire SI5 near the
when relay LIii is energized, not only is a shunt
cams 442 is a wire 320 leading to a second double
relay LI4. Leading from relay Llíl is a wire B2i 20 formed around armature resistance R2, but a
normally closed shunt around field resistance R5
which leads upwardly to a resistance R3 the other
is opened, decreasing the ñeld current.
side of which is connected to a wire 822 leading
to armature A4 of the elevation motor 225.
Referring to Figure l2, the iields of the eleva
tion and azimuth motors are also connected to
In the elevation motor wiring, branching from
wire 821 near resistance R3 is a wire 839 lead
ing to one contact of a relay LIB, the other con
tact of which is connected to a wire 84B leading t0
armature wire 322. When relay LIB is closed a
shunt is formed around resistance R3 through
wires S39 and Sfiû. The movement of closing re
F4 of the elevation motor 241, the other side of 30 lay LIB opens a normally closed switch SI1 one
terminal oi which is connected to a wire 8M lead
which is connected to a wire 825 leading to a re
ing to a wire 826 near resistance RII. The other
sistance R4. A wire 826 connects the other end
terminal oi switch SI1 is connected to a wire
of resistance R4 to the other finger of relay LI5.
852 leading to wire 825 near resistance Ril. En
Branching downwardly from wire SI5 near the
ergizing relay LI S therefore closes a shunt around
center column is a wire 821 leading down the
resistance R3 and opens a normally closed shunt
column and out brush box to a- field reverse relay
around resistance RG, decreasing the field cur
LIB for reversing the azimuth motor 223. Lead
ing from one finger of relay LIB is a wire 828
Referring to Figure 12, azimuth speed change
which connects to a ñeld F3 of the azimuth motor
228. The other end of field F3 is connected to a 40 relay LI1 is operated by the extreme movement
of azimuth control cam 451i and elevation speed
resistance R5 and a wire 83!) connects the other
Change relay LI5 is operated by the extreme
end of resistance R5 to the other linger of relay
movement of elevation cam 412. It will be noted
Referring to the control box in Figure 12 it will
that both calm 45d and ¿i12 have projections
be noted that when the breaker arms 4M close
designating the extreme position of movement.
on contact 450 that a current through the arma
When rotated to either extreme position the pro
power wire SIB. Branching upwardly from wire
SI5 near the center column is a wire 823 leading
to a field reverse relay LIE. Connected to one
finger of relay LI5 is a wire B24 leading to a field
ture relays-LIS and Lili is grounded operating
the relays. The ground currents consist of four
branches from wire BIS, wires BSI and 832 passing
through relay LIS and connected to the azimuth 50
breaker arms MA and wires 833 and 83@ passing
through relay Lili and connected to the elevation
breaker arms 444.
Since each cam 442 of a pair
jections on azimuth cam 454 causes it to close
a switch SIS one terminal of which is connected
by a wire i353 to power wire 8 I 6 and the other ter
minal of which is connected to a wire 844 leading
down the column to relay L! 1. Thus when either
projection on cam 55H, corresponding to the ex
treme position of the cam, come into register at
is rotated 180° with respect to the other, the gen
the top it will close switch SIB causing the speed
eral tendency is for the two contact members of
control relay LIT to function. Although cam 465i
relays L3 and LI4 to be alternating in breaking
is shown schematically in Figure 12 as a rotary
contact. Depending upon the position of the
cam, actually it moves axially to effect its con
contacts 45B with relation to the breaker arms
trol iunction. However, the switch unit actually
444, the contact members of the relays may both
used (but not shown) in place of the schematic
be opened or closed at any one instant.
If vary
snowing of Figure 12 is a switch having a mova
ing the position of contact 45D, the normal flow 60 ble member axially arranged and having two high
of current may be interrupted varying amounts
points thereon to be contacted by the cam at
until it is completely stopped, thus giving speed
either extreme of axial movement to close the
control through a large range from a few R. P. M.
switch SIB.
of the motor up to several thousand.
Elevation cam £12 operates in a manner similar
In addition to the speed change by varying the 65
to azimuth cam ¿554 t0 close a switch SIS. One
duration of the interruptions of current to the
terminal is connected to a wire 8fi5 branching
azimuth and elevation motors, there is a stage
from power wire SIS. The other terminal of the
speed control after the shots have been made so
switch is connected to a wire BIS leading to relay
long in duration that the current is as continuous
as possible. This second stage of high speed op 70 LIB. Thus whenever the projections on cam 4112
register, switch SIS is closed and the elevation
eration is effected automatically as the gunner
speed change is thus effected. Cam 1312 is shown
moves the handle A82 to an extreme position in
in its actual embodiment herein in Figure l2 as
either direction of both azimuth and elevation
a rotary cam. The exact construction however
movement. This high speed is obtained by in
creasing the armature current and decreasing the
was not shown previously to keep mechanical
features of the control box separate from the
electrical features.
The field reverse relays Llö and Lili are oper
ated also by the elevation control cam 472 and the
azimuth control cam 464 respectively. It will be
noted that each cam in Figure 12 has a relieved
portion on the bottom. rI‘his portion represents
the travel of the cam in traversing the speed
current. Increasing the armature current and
decreasing the held current causes the armature
A4 of the elevation motor 241 to rotate at a very
high speed.
The reversal of the azimuth and elevation mo
tors is also effected by manual operation of the
control cams 45t and 4W. Each cam is recessed
on the bottom for a space corresponding to full
range from zero to one extreme. When the cams
movement of the cam from zero to one extreme.
464 and 4l? are moved from zero to the other 10 When the cams are rotated in the other direction
extreme they actuate switches S20 and SEI re
spectively. Switch S23 takes current from power
line BIS and passes it to a wire 241 leading down
the column and out the b-rushes to ñeld reverse
relay Lit. Energizing relay Llä causes it to re
verse the direction of current through azimuth
ñeld F3 from that shown reversing the motor 223.
from the zero point they close switches control
ling the field reverse relays Ll 5 and Ll E. Moving
azimuth cam été', past the center point and away
from the recessed portion closes switch S23 pass
ing current to wire t4? which actuates relay LIB,
reversing the field current from the direction
shown. Likewise, movement of cam 412 past the
When elevation cam 412 passes the zero or neutral
center point closes switch SZl passing current to
position the direction away from its relieved por
wire Bilt which actuates relay L55 reversing the
tion it causes a switch S2! to open which takes 20 field of elevation motor 24T.
current from. wire 816 and passes it to a wire 84S
The complete electrical power system is shown
leading to field reverse relay Lib. Actuating re
in Figure 13. The complete system differs from
lay Ll3 causes current to pass through field F2
the simplified system of Figure l2 by the addi
in a direction opposite from that shown, thus
tion of a dynamic brake and controls to make the
reversing the elevation motor |46.
25 lower limit of elevation of the guns dependent
The operation of the simplified circuit shown
upon the position of the guns and azimuth. The
in Figure 12 is as follows. Current flows from
provision of a dynamic brake causes the stopping
battery B2 to relay LIZ. When the gunner grasps
motors by causing them to act as gen
control handle 4132 he closes switch Si l actuating
erators. This dynamic braking is eiîective in
relay L|2and passing current to power wire SI5 30 both elevation and azimuth motors when a given
leading to azimuth relay L13 and elevation relay
limit of movement is reached, and for a short
LII! and to control box motor 430. Motor 435i
interval after the gunner releases his grasp on
causes cams 442 to rotate rocking vbreaker' arms
the control handle. The varying lower limits of
444 so that they intermittently are grounded at
the guns in elevation are provided to roughly con
contact 45@ causing the connected part of the
form the lower limit to the shape of the airplane
relays L53 or Llll to break contact for the dura
structure in which the gun is mounted.
tion of the ground at contact 45S. The position
The parts of the circuit identified in Figure 12
of the contacts 450 are varied by manual control
are readily recognizable in Figure 13. In the
of elevation cam 41.2 and azimuth cam 464. By
wire 8l9 to the azimuth armature A3 however a
changing the duration of the ground at contact 40 relay L59 is inserted to cause the azimuth motor
450 the duration of the current interruption at
to act as a dynamic brake. The wire 8l9 there
relays Lit and Lili is varied, thus giving a speed
fore leads to dynamic brake relay Li 9 and a wire
control for the azimuth and elevation motors.
B49 leads therefrom to armature A3. In normal
Current passes through wire BFS connected to
position relay Lia connects wire SIS to wire 849
relay Ll3 leading down the column to resistance 45 allowing normal operation of armature A3.
R3, to wire 8l!) and out the brushes to the azi
When relay Lig is energized, however, it grounds
muth motor, armature A3. Current passes
wire 549 allo-wing a large current to ñow through
through wire 82l leading up from relay LI4 to
wire 84d to ground thus imposing the greatest
resistance R3
to wire i322 and to the elevation
possible load cn the azimuth motor 228 when
motor armature A3.
50 acting as a dynamic brake. The circuit for ac
If a greater speed is desired than is obtainable
tuating dynamic brake relay L19 will later be
at the position of the control cams when current
is flowing uninterruptedly to the motor arma
It will be noted that the movement of relay
tures, the control handle is moved to the extreme
Lili actuates a switch S29 which closes during
position for both azimuth and -elevation in either 55 dynamic braking to shunt out resistance R5 from
direction, This movement causes the projections
the azimuth held circuit. Switch SZû is con
on azimuth cam 464 to close switch SIS which
nected to wire 332i which is one part of the speed
passes current to wire 844 energizing relay Ll?,
change shunt and the other terminal of switch
Relay Ll'l then closes shunting current around
Sie is connected to a wire 85e connected to wire
resistance R2 and thereby increasing the arma 60 83? the other part of the speed change shunt.
ture current. The movement of relay Ll'l opens
Thus a shunt circuit is formed around held re
normally closed switch Slß thereby breaking a
sistance R5 through wires 838, switch 52€! and
shunt around the field resistance R5, and decreas
wire 859 and wire 523i which is operative during
ing the held current. This decrease of field cur
dynamic braking to produce the greatest possi
rent together with an increase in armature cur 65 ble held in motor 228.
rent causes azimuth motor to operate at an ex
Referring to Figure 13, a dynamic braking re
tremely high speed.
lay L28 is provided for the elevation armature
Likewise movement of elevation cam 412 to
circuit also. Relay L23 is connected to arma
either extreme position causes its projection to
ture wire B22 and a wire 85! leads therefrom to
close switch SiS. passing current to wire 845 70 elevation armature A4. Relay L2?? also operates
energizinfr relay LIS which then closes to shunt
a iield shunt switch SE2d. One terminal of
out armature resistance R3 increasing armature
switch S22@ is connected to wire 842 and the
current. The movement of relay Llß causes
other terminal is connected to a wire 855 which
normally closed switch Sil to open, breaking a
connects to wire 84 i . Thus when elevation brake
shunt around iield resistance R4, decreasing field 75 relay L20 is actuated, the armature A4 is ground
ed and the resistance Ré in the ñeld circuit is
shunted. This produces the maximum load on
the armature Ad and greater strength in field F4.
'I‘hese two limit cams operate in combination
with elevation cam dit corresponding with the
elevation position of the gun. IThe three cams
Each cam is recessed. on the bottom for a space
operate switches in a circuit which will now be
described and only when the elevation cam and
an azimuth cam act together is there an appli
corresponding to full movement of the cam from
zero to one extreme,
Several additions to the electrical circuit to ac
cation of the dynamic brakes.
Still referring to Figure 13, branching from
commodate the» dynamic braises are also shown
in Figure 13. 1t will be noted that the operation
of power relay Liz operates three switches S22,
and Sîfl. When power relay L52 is ener
gized it closes normally open switch S22 and
opens normally closed switches S23 and S24.
Switch S22 is connected to a wire Sts leading to
a time delay relay Lîé which has the characterisn 15
tic of maintaining its energizat -n for a short
timeafter the energizing current has been cut off.
Relay- L2i is connectedy on one side to a branch
from main power wire iiíii and on the other side
is connected to a wire E352 which is connected at
the central column to the elevation held wire 823
and to the azimuth held wire EN.
Thus ener
wire 339 near the azimuth field resistance R5
is a wire 855 leading around to a switch S25
actuated by counterclockwise limit cam 484. Wire
83d is at a high potential only when the relay
Llc is in the position shown in Figure 13, oper
ating the turret in a counterclockwise direction.
When the turret reaches its counterclockwise
limit, cam ¿idd closes switch S25 passing current
to a wire 356 leading around to the column and
up the column to elevation switch cam M4.
When the guns are at a substantially horizontal
position the switch cam liiêl will make contact
passing current to a wire ßäl which leads part
way down the column until it connects with wire
i353. It will be remembered that wire 853 con
gizing the power relay L52 closes switch S22
which energizes time delay relay L21 causingv cur
trols the azimuth dynamic brake relay Lie.
Branching from wire 8d? near azimuth íìeld
rent to iiow to the azimuth and elevation motor 25
ñelds. After power relay LEZ is deenergized,
relay Lid is a wire 858 leading around to a
delay relay Lâl continues to pass current to the
switch S25 actuated by clockwise limit cam 406.
motor field for dynamic braking because of its
Wire ¿lill is the wire energizing neld reverse re
time delay characteristic,
lay L55 and when energized, the turret rotates
Switch S22 is connected to held supply wire 85E 30 clockwise. When the turret rotates to its clock
on one side and on the other side is connected to
wise limit, switch S25 will close also passing cur
a wire 353 leading down the control column and
rent to wire tät. If switch cam @i4 is in the
out. the brush box to energize dynamic brake re
proper position current will ñow to wire 851,
lay L-i 8. Switch Sid is likewise connected on one
thence to wire 853 and actuate the azimuth
dynamic brake.
side to wire i552 and the other side is connected
to a wire 85d lead" -g up the column to energize
The limits of movement of the upper turret
elevation dynamic brake relay LZÉ. Thus when
in azimuth have now been- described, and the
power relay L52 is energized no current passes to
the dynamic brake relays because switches S22
and Sie are open, but for a short time after de
energization cf the power relay LIZ (at which
time switches
are closed) current
passes to the dynamic brake relays because time
delay relay L2# continues to pass current to wire
The purpose of? the dynamic brake circuits just
remaining limits are limits on the elevation
movements of the turret. When the guns are
40 pointing aft or toward the rear, the fuselage
of the airplane will permit them to be depressed
to a horizontal position.
When the guns are
pointing toward the front or fore position and
the sides, the shape of the airplane stops them
short of the horizontal position upon depres
sion. The upper limit of elevation is the same
for all positions of the turret in azimuth and is
described is to provide a “dead-man” control 'for
the zenith or straight upward position.
dynamic braking. If the gunner were moving
Referring to Figure 13, the upper elevation limit
the guns rapidly at the instant he was shot, there
is regulated by azimuth cam 412. Current is
might be a possibility that the guns would travel
supplied by tapping elevation field reverse re
through their normal limit control and damage
lay wire Sliß, which is energized only when the
the turret or the airplane. Thus the instant the
gunner relaxes his grip because of injury, and
current is in a direction to cause elevation of
the guns, the tap being wire 852i leading to a
the main power is cut off at power relay LIZ, the
dynamic brakes are applied to stop the movement 55 switch S2? actuated by the limit cam M2. When
the guns are elevated to the zenith positionv the
of the guns. The dynamic braking is possible
cam M2 permits switch S21 to closepassing cur
only by maintaining a ñeld in the elevation and
rent to a wire 85E) connected to the elevation dy
azimuth motors and this purpose is served by
time delay relay SEE. The actual application of
namic brake wire Stil. Thus whenever the guns
the dynamic brakes is by means of relays Llâ 60 approach the zenith the elevation dynamic brake
is applied.
and L25 operated by switches S23 and S24 re
The lower elevation limits for the aft- position
are actuated by the combination of azimuth
The circuits for operating the dynamic brake
switch cam die and elevation switch cam ME.
relays Lie and Lìíâ at the limits will now be ex
plained. It will be remembered that the only
Branching from elevation ñeld wire 92d is a wire
limit Íor moving the guns in azimuth is when the
Bât leading down the central column and around
guns are near 9d" elevation and pointing toward
to azimuth switch cams 453 and ¿23. Field wire
the rear. 11” it is then desired to swing the guns
826i is at a high potential only when the guns
clockwise or .counter-clockwise in azimuth the
are being depressed. When the turret is point
guns. would strike the fuselage of.“ the airplane
ing aft in azimuth the switch cam ¿Sill closes
in which the turret is mounted. These two posi
and passesY current to a wire 862 leading around
tions are represented in azimuth movement by
to the column and up the column to switch cam
cam ¿lii‘l which has a notch corresponding to the
dit. 1f the guns should now be depressed une
counterclockwise limit and cam ¿ißt which has a
til they approach horizontal, the switch cam M6
notch corresponding tov the clockwise limit.
willmake contact and pass current to the wire
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