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Dec. 31, 1946.
A. L. ELLIS
2,413,301
I
'POWER mnsmIssxon
Filed Jan. 14. 1936
7 Sheets-Sheet 1
INVENTOR
AII'NUI L. ELus
BY
ATTORNEY
. Dec. 31, 1946.
I
A_ |___ E|_|_|5
I
2,413,301
POWER TRANSMISSION
Filed Jan. 14, 1936
37+
7 Sheets-Sheet 2
an
34-2
El: .'.2
INVENTOR
ARTHUP L. 81.0.15
ATTORNEY
. Dec. 31, 1946.
A. |_. ELLIS
2,413,301
'POWER TRANSMISSION
Filed Jan. 14, 1936
h
I
'7 Sheets-Sheet 3
'
83-6
lNVENTOR
ARTHUR L. ELLIE
ATTORNEY
Dec. 31, 1946.
A.‘ |_. ELLIS
2,413,301
‘
POWER TRANSMISSION
' Filed Jan. 14, 1936
7 Sheets-Sheet 4
l
INVENTOR
Anmurr L. ELLIS
BY
P_
1’. AM
1
ATTORNEY
‘
Dec. 31, 1946,
4 _
A. L. ELLIS
2,413,301
POWER TRANSMISS ION
Filed Jan. 14, 1936
> 7 Sheets-Sheet 5
INVENTOR
Am'uun L. ELL/s
- BMY z. TMJ
ATTORNEY
Dec. 31, 1946.
A. L. ELLIS
‘ , ~
2,413,301
POWER TRANSMI SSION
Filed Jan. 14, 1936
,
7 Sheets-Sheet 6
INVENTOR
ARTHUR L. ELL/5
BY
ATTORNEY
Dec. 31, 1946.
A_ |__ E|_|_|s
I
2,413,301
POWER TRANSMISS ION
Filed Jan. 14, 1936
7 Sheets-Sheet 'T
50
0
r
+8
3/6
3/4
3/2
INVENTOR
Anruw L. Enos
ATTORNEY '
2,413,301
Patented Dec. 31,1946
UNITED‘. STATES PATENT OFFICE‘
2,413,361
rowan rmnsmssron ’
Arthur L. Ellis, Deep River, Gonna assignor, by
mesne
ents, to Vlckers Incorporated,
Detroit, Mich, a corporation of Michigan
Application January 14, 193.6, Serial No. 59,072
16 Claims. (CI. 60-53)
1
,
This invention relates to power transmissions,
Fig. 4 is a
2
cross section on line
particularly to control devices for power trans
4-4 of Fig. 5‘ showing the control valves with
missions of the variable speed type for transmit
their operating mechanisms partly in‘elevation.
ting power from a
member to a driven
member at any speed ratio therebetween. With 5
power transmissions in which a positive and non
yielding drive is provided, such, for example, as
the well-known hydraulic type of transmission,
Fig. 5 is a cross section on line 5-5 of Fig. 4.
Fig. 6 is a cross section on line 6-5 oi’ Fig. 4.
Fig. 7 is a fragmentary perspective view of a
portion of the valve control mechanism.
‘ Fig. 8 is a top view partly in section‘ of the
the application of an excessive resisting load on
power transmission mechanism and a portion of
the driven member transmits an overload-to the 10 the control system.
I
prime mover which operates the driving mem
Fig. 9 is a fragmentary sectional view on line
ber unless some provision is; made for preventing
this. Should such an excessive load be imposed
9-9 of Fig. 8.
.
Fig. 10 is a fragmentary sectional view on line
on the driven member while the ratio of power Iii-i B of Fig. 8.
transmission is such that the driven member 15 Referring now to Fig. 8, there is illustrated a .
moves at a high speed relative to the driving mem
power transmission of the well-known “Water
ber, the mechanical advantage of the driving
bury” type comprising a variable displacement
member in overcoming this load is small, so that
pump or “A-end" I 0 and a ?xed displacement hy
the prime mover becomes easily overloaded under
draulic motor or “B-end” l2. Transmissions of
these conditions.
’
this character are fully described in the patents
Since the variable speed power- transmission in
to Williams 1,044,838 and to Janney 1,020,285, so
itself provides a means for increasing the me
that it is unnecessary to describe the construc
chanical advantage of the driving member over .
tion of the transmission itself in detail. For the ‘
the driven member, it is an object of the present
purpose of this speci?cation it may be stated that
invention to provide control means operative to 25 the “A-end” l0 comprises a drive shaft l4, rota.
change the ratio of power transmission upon the
tion of’ which causes ?uid to be pumped to the
occurrence of an excessive load on the driven
"B-end” l2. The displacement of the pump and
member in such a way that the power transmis.
consequently the quantity of ?uid pumped per
sion itself will act to prevent transmission of the
revolution of shaft l4 are regulated'by a tilting
overload to the driving member.
30 box I‘ which is shown in the neutral position.
A further object is to provide in a power trans- .
Movement of the tilting box in a clockwise direc
mission of the character described a control
tion away from the neutral position produces for
means responsive to the application of a prede
ward rotation of the "B-end” and its driven mem
termined amount of torque to the driving mem
ber l8 (arrow A), while vmovement of the tilting
ber for increasing the mechanical advantage of 35 box counter-clockwise away from the neutral po
that member over the driven member.
sition causes rotation of .the driven member l8 in
A further object is to provide a novel control
the opposite direction. While the position of the
system of the character described including a
tilting box IE may be controlled in any suitable
?uid motor having a. di?erential piston and a
manner, in the form of the invention illustrated,
pair of control valves therefor, one of which is 40 a. control mechanism of- the type shown in the '
operable to determine the operativeness or non
patent to Janney 1,220,424 is utilized and in
operativeness of the piston and the other of which
cludes a non-rotati've rod 20 mounted for slid- .
is operable to determine its direction of move
ing movement in bearings 22 and 24 and having
ment.
a sliding and pivoting connection at 26 with a
-
Further objects and advantages of the present 45 stud 28 on the tilting box IS. A screw shaft 30
invention will be apparent from the following de
is connected .to the shaft 20 by a. swivel 32 and
_ scription, reference being had to the accompany-.
ing drawings wherein a preferred form of the
present invention is clearly shown.
In the drawings:
‘
'
sleeve ‘36 (see Fig. 9); The sleeve 36,is jour
50 nalled on bearings 38 and 40 and has a project-.
'
Fig. 1 is a diagrammatic illustration of a ?uid
.circuit embodying one form of the present in“
vention.
‘at its opposite end carries a splined head 34 which
is slidable but not rotatable relative to a slotted»
'
Figs. 2 and 3 are views corresponding to Fig.
1 showing the parts in di?’erent positions.
ring shaft 42 upon which is mounted a hand wheel
44 by which the screw shaft 30 may be rotated.
The screw shaft 30 is threaded into a rotatable
nut 48 rigidly secured in the hub 48 of a gear 50
which in turn is Journalled in a bearing 52 by
2,413,301
~
3
ment of the valve I26 to the right opens a con
which the nut and gear are held against axial
movement. The pitch of the threads of shaft 36 '
is su?iciently great as to make the thread re
nection between the port I34 and the port I86.
versible. That is, the shaft 36 may be threaded
into or out of nut 46 by pushing or pulling on the
shaft 20, the shaft 80 turning in swivel 32 and
in nut 46. Gear 50 meshes with a pinion 54 rigid
ly secured to the "B-end" driven shaft I8._ The
portion I88 which is adapted to connect a port
I48 with 8. port [42 in the position illustrated
The valve I26 is also provided with a reduced
and to close off the port I40 when valve.I26 "'
moves to the right sufllciently to open port I 88.
A closure I48 protects the spring I22 and seals
the end of bore I28.
left-hand end of the rod 20 carries a differential
Referring now to Fig.5, the directional con
' piston 68 operating in a-cylinder 58 by which the 10
trol valve 86 includes a valve member I44 slid
rod 20 and tilting box I8 may be operated di
rectlywith ?uid under pressure. .
able in a bore I46 formed in the valve block
‘
98 and having an end ‘closure I48 at its outer
An. “A-end” driving shaft I4 carries a double
end. The valve 'member I44 is operated from the
clutch 80 having a movable member 62 Splined to
the shaft I4 and slidable to engage either a clutch 15 arm 82 by means of the cam bar 84 having a cam
member 64 rigidly secured ‘to a shaft 66 or a _
portion I60 which cooperates with a pin I52
clutch member 68 rotatably mounted on the shaft
‘
I4. The shaft 68 may be that of any suitable
prime mover, for example an electric motor, not
shown,‘ and is used for normally driving the power 20
formed on a lever arm I64. The arm I64 is piv
transmission. The clutch member 68 carries a
sprocket 18 which is driven by a chain 12 from
a manual drive clutch unit 14 by which the “A I ‘
end" may be driven by hand from a hand crank
18 upon failure of-power. at the shaft 66.
25
Means for moving the tilting box toward neu
tral position upon occurrence of an overload is
provided and includes a housing 18 mounted on
top of the “A-end" directly over the upper trun
nion upon which the tilting box I6 is mounted.
Referring now to Fig. 4 the housing 18 carries a
removable bearing 80 within which a stub shaft
82 is mounted. The lower end of the shaft 82
is adapted to be coupled directly to the tilting
box by means of a keyway 84. Shaft 82 has 35
rigidly secured thereto an arm 86 carrying a
cam 88 for the purpose of controlling a constant
horsepower control valve generally designated at
80. Shaft 82 also carries an arm 82 having a lost
motion connection with a cam bar 84 for the
purpose of operating a directional control valve
generally designated at 86. The valves 90 and
86 are formed within a valve block 88 secured to
oted at I56 to a bracket I58 formed in the hous
ing 18 and carries an adiustable stop screw I60
:for determining the left-hand positionof the
valve I44.
The arm I54 also carries a pin I62
which projects through a slot I64 in'the bar 84
for the purpose of preventing the cam bar 64
from lifting away from the pin I62 and also for
positively moving the arm I64 to the left when
the cam bar 84 reaches the left-hand limit of
its-‘travel. The cam bar 84 is connected to the
arm 82 by means of a pin I86 carried by the cam
bar 84 and a slot I68 formed in the arm 82.
A spring I10 abuts against a pin I12 on the
arm 82 and a pin I14 on the cam bar 84 and
tends to keep pin I66 in the left-hand end of
slot I68. »
The mechanism is so arranged and adjusted
that in the position illustrated which corresponds
to neutral position of the tilting box I6 the valve
I44 is maintained in its left-hand position by
the spring I10 acting‘through the pin I14, cam
bar 94, the right-hand end of the slot I64, the
40 pin I62, and the lever I54. Movement of the
arm 92 away from the position illustrated in a
clockwise direction in Fig. 5 does not-move the
cam bar 84 but merely increases the tension in
the spring I10; the slot I68 permitting clock
one side of the housing 18. Valve block .88 also
includes a constant torque valve I00 (Fig. 5) 45 wise overtravel of the arm 82. Should the arm
92 move counter-clockwise away from the posi
which is operated from the clutch unit 14 shown
tion illustrated, the left-hand end of slot I68
in Fig. 8.
Referring now to Figs. 6 and 7, cam 88 is formed ' abuts pin I66 moving cam bar' 84 to the right.
Cam I50 thus moves the pin I62 downwardly
with a high portion I02 at its mid-part corre
sponding to neutral position of the tilting box 50 causing a clockwise movement of the arm I64
and moving valve I44 to the right. The con
I6 and curved portions I04 and I06 sloping away
struction is such that the complete travel .of
from the high part I02 symmetrically on either
valve I44 takes place in a very small angle of
side thereof. A roller cam follower I08 is'piv
movement of the arm 92 as compared with its
oted on a lever IIO, the latter being pivoted at
H2 in a bracket II4 formed on the valve block
88. The outer end of the lever IIO carries a link
II8 pivotally connected to a tension rod II8 hav
ing an adjustable spring plate I20 at its outer
end abutting a spring I22. The spring plate I20
is moved to the right in Fig. 6 whenever the
arm 86 moves away from the neutral position
total movement.
'
The bore I46 of the valve I44 has a port I18
at its left-hand end and a port I18 to the right
thereof. Valve I44 is formed with a reduced
portion I80 adapted‘ to connect the ports I16
and I18 when the valve is moved to the right. A
bore I82 is formed centrally of the member I44
and connects by means of a cross bore I84 the
illustrated. thus decreasing the compression of
right-hand end of the bore I46 with the inte
the spring I22. The left-hand end of spring I22
rior of the housing 18. In the position illustrated
abuts against a spool I24 which in turn abuts
against a valve member I26 slidably mounted 65 in Fig. 5, the port I18 is in communication with
the right-hand end of tne bore I48 by means of
within a bore I26 formed in the valve block 88.
a reduced portion I86 formed on the valve mem
The left-hand end of the valve member I26 is
ber I44 and is, therefore, in communication with
reduced in diameter at I30 to ?t a reduced por
the interior of the housing 18 when the valve is
tion I82 of the bore I28. There is thus pro
vided a small area against which ?uid pressure 70 in the position shown. This communication is
cut oil by the valve I44 being moved to the right.
may be exerted through a port I34 to counter
The constant torque valve I68 includes a valve
act the force of the spring I22 and to move the
member I88 slidably mounted within a bore I88.
valve I 26 to the right in Fig. 6. A port I36 is
The bore I80 is formed with a port I82 communi
provided leading to the bore I28 and is so posi
tioned that a predetermined amount of move 75 cating with the port I16 through a conduit I84
a
2,418,301,
5
.
and a port I96 communicating with the port I42
of valve 90 through a conduit I98. The valve
I88 is formed similarly to the valve I44 except that
when the valve 2I4 is moved to the limit in the
left-hand direction. An intermediate position is
provided in which the piston 56 is hydraulically
it is operated by means of a stem 200 project
locked against movement. The valve 2 I6 is oper
ing outwardly from the valve block 98 through a
ated in response to the constant horsepower valve
packing gland 202. A bracket 204 carries a lever
90 and the constant torque valve I00 to move the
206 having pivotal connection at 208 with the
piston56 and the tilting box I6 toward neutral
stem 200 and at 2I0 with an operating rod 2I2.
position irrespective of the position of valve 2I4
In the position illustrated in Fig. 5 the valve I88 ‘ or, when the-hand wheel 44 is being used for nor
closes off communication between ports I92 and 10 mal control, with su?lcient force to overcome the
I96 and connects port I96 to the interior of hous
greatest manual effort which can be applied to
wheel 44.
'
ing 18. When the valve is moved to the right,
the ports I92 and I96 are connected together
Fluid under pressure for operating the piston '
and port I96 is cut off from communication with
56. under the joint control of the valves 90, 96. '
15 I00, 2I4, and 2I6 is provided from two alternate
the housing 18.
sources: The ?rst is the power circuit of the hy
The clutch unit 14 illustrated in Fig. 8 includes,
draulic transmission itself the valve plate there
a main shaft 286 carried in bearings 268 and rig
of being indicated at 222. Conduits 224 and 226
idly secured to the crank 16. Shaft 286 carries
connect with each of the two valve ports 228vand
a hub 290 rigidly secured thereto which drives a
set of planetary pinions 292 cooperating with a 20 230, respectively, and lead to a shuttle valve 232
for the purpose of connecting a conduit 234 with
?xed ring gear 294 and a sun pinion 296. The
whichever of the conduits 224 and 226 has a high
sun pinion 296 is rigidly secured to a ?ywheel 298
er pressure at a given instant. The other source
. journalled on the shaft 286 by means of bearings
comprises an auxiliary pump 236, of any suitable
300. The hub 290 also carries a driving part 302
of a spring loaded friction clutch 304. The driv 25 construction, having an intake 238 leading from
the expansion tank,‘not shown, and having a re
en part of the clutch 304 comprises a hub mem
lief valve, not shown, which are customarily pro‘
her 306 freely rotatable on shaft 286. The hub
vided with hydraulic systems of this character.
member 306 has splined thereto a cam member
Pump 236 may be driven, for example, by an elec
300 (see Fig. 10) which is spring pressed to the
right by springs 3I0.‘ The cam member 300 has 30 tric motor 240'. Pump 236 has an outlet conduit
242 communicating with a shuttle valve 244 for
a projection 3| 2 engaging with a cam surface 3M.
the purpose of selectively delivering to a conduit
formed in the hub of a sprocket 3I6 which is
246 fluid from either conduit 234 or conduit 242.
mounted on the hub member 306 so asto be ro
depending upon which has a higher pressure at
tatable relative thereto. Cam member 308 has a
a given instant.
slot 3I8 formed therein for engagement with-a
The conduit 234 has a branch 248 leading to
fork 320 which is pivotedly mounted on a shaft
the port I34 of the constant horsepower valve 90
322. Shaft 322 has a lever 324 connected by
while the'conduit 242 has a branch 250 leading
means of a linkage 326 to the operating rod 2I2
. to the port 252 of the valve 2I4. Conduit m
for the constant torque valve I00.
It will be seen that the crank 16 is directly 40 communicates by means of a branch 264 with
the conduit I94 connecting ports I16 and I92 of
geared to the flywheel‘ 298 in a manner to cause
valves 96 and I00 respectively, and has a second
the flywheel to revolve at a greater rate of speed
branch 256 leading to a port 253 of the valve 2I6.
than the crank 16. The clutch 304 connecting
Valve 2 I6 is formed with a port 260 communicat
the shaft 286 to the rotatable hub 30s is ar-'
ing by means of a conduit 262 with the small end
ranged to slip when a predetermined amount of
of the cylinder 58 and, in the position of the valve
torque is applied thereto. The force of the
2I6 illustrated, the ports 250 andl260 are con
springs 3I0 is so proportioned relative to the
nected. When the valve 2 I6 is moved to the right
torque transmitted by the clutch 304 that the
by a spring 264, the port 260 is cut oil‘ from com
projection 3I2 may move substantially half the
munication with the port 258 and placed in com
length of the cam surface 3I4 before springs 3I0
‘ are compressed sufficiently to require a torque
munication with a port 266 communicating with -
the conduit 250.
greater than the maximum transmitted by clutch
The port I16 of valve 96 communicates by
304 for further travel of. the member 3I2 ‘along
means of a conduit'268 with a port 210 of the
the cam surface 3M. Thus, whenever the load
applied to the sprocket 3I6 is suf?ciently great 55 ‘valve 2I6. In the position illustrated in Fig‘. 1
the valve 2I6 is arranged ‘to connect the port
to cause clutch 304 to slip, the sprocket 3|6 must
210 with a port 212 leading by means of a con
duit 214 to the large end of the cylinder 5.8.
When the valve 2I6 is moved to the right as in
member 308 is transmitted through the slot 3I8, 60 Fig. 3, port 212 is cut oif from communication
with port- 210 and connected with a port 216
fork 320, shaft 322, lever 324, linkage 326, to
leading to a port 218 of the valve 2I4. Port 218
the operating rod 2I2 for the constant torque ‘
have moved relative to hub 306 an amount su?l
cient to move the cam member 308 to the'left a
predetermined amount. This movement of the
is connected with the port 252 by the valve 2I4
Referring now to Fig. 1, the hydraulic circuit
in the position illustrated in Fig. l. Whenvalve
for the control mechanism of the present inven 65 2I4 is moved to its mid-position, the port 218
is cut o? from communication with any port in
tion includes the mechanism above described, and
valve I00.
the valve 2I4. When moved to the limit of its
in addition, a pilot control valve 2I4 and a hy
draulically operated valve 2I6 both of which are
travel to the left, valve 2I4 connects port 218
with a port 280 leading to the expansion tank,
formed in a second valve block 2I8 formed in the
body of the cylinder 58 (see Fig. 8). The pilot 70 not shown. Conduits 26I and 203 connect the
opposite ends of the valve 2I4 to the expansion
control valve 2 I4 may be operated by a hand lever
tank to eliminate‘ trapping effects. ' The ports
220 or by any suitable automatic mechanism de- \
I36 and‘ I40 of valve 90 are connected together
sired, and is arranged to move the piston 56 and
by means of a conduit 282 leading to an oper
tilting box I6 to the right when in the position
illustrated,'and to move the same to the left 75 ating cylinder 284 at the right-hand end of valve
2,413,301
I
2 I8 for overcoming the force of the spring 284 and
moving the. valve 2" into the, position illustrated '
in Figures 1 and 2. '
_
In operation, the transmission being suitably
assembled with the shaft 88 connected to a prime
mover, preferably one of constant speed, and the
shaft I8 being connected to a load which it is de
8
missions of the type. described that the ?uid pres
sure in the working circuit of the transmission
itself varies in direct proportion to the torque
load imposed upon the “B-end" shaft I8. When
the shaft I8 is ‘turning in one direction, one of
the valve ports, for example 288, becomes the
pressuré port and the pressure existing in this
port is transmitted to the conduit 228 and the
sired to drive at variable speeds, the clutch 88
shuttle valve 282. On rotation in the opposite
is shifted to engage the clutch member 84. If it
is desired to operate the "B-end" shaft I8 and 10 direction the port 228 becomes the pressure port
and the pressure therein is transmitted to con
the load to a predetermined position, that is by
duit 224 and shuttle valve 282 which moves to the
"follow-up” control the hand wheel 44 is turned
position ‘opposite to that illustrated in Fig. 1. Any
causing the screw shaft 88 to move axially in, the
abnormal pressure rise that occurs ineither valve
nut 48 moving the tilting box out of neutral po
port 228 or 288 is thus transmitted through con
sition. Fluid is thus pumped from the "A-end"
duits 284 and 248 to port I84 of the constant
to the “B-end" and the latter operating as a ?uid
horsepower valve 88. When this pressure exceeds
motor turns the shaft I8 and the load. ~This
the value determined by the compression of the
movement of shaft I8 turns the nut 48 through
spring I22, the valve member I28 moves to the
the gears 88 and 84 in a direction tending to move
the screw shaft 88 back into the position corre 20 right opening port I88 and permitting the ?uid
to pass through conduit 282 to the power cylin
sponding to neutral position of the tilting box in
der 284 of the valve 2I8. The opening of port
the manner more fully described in the Janney
I38 to pressure ?uid from port I84 initiates a
Patent 1,220,424. So long as handwheel 44v is
sequence ‘of operations immediately causing a ra~ '
turned the "B-end" shaft I8 will continue to
turn at a corresponding speed and direction.
25 tio of transmission to be established which will
be safe for the particular overload imposed on
Alternatively the transmission may be operated
the “B-end" shaft I8. That is, the mechanical
under normal control of the pilot valve 2| 4 in
advantage of the “A-end” shaft I4 over the “B
stead of under the controlof handwheel 44, if it is
end” shaft I8 is increased to the point where
desired to drive the load continuously at a given
rate of speed for considerable intervals. Thus, 30 the prime mover is not overloaded..- The opera
tion for this purpose is as follows:
during normal operation, when there is no tend- '
Assuming that the tilting box is standing in a
ency to overload the prime mover, which is il
position for forward drive the piston 88 will be
lustrated in Fig. 3, the valve 2I8 lies in its right
standing to the right of the mid-point of its travel
hand position, in which the small end of the cyl
as illustrated in Fig. l. The directional control
inder 88 is constantly supplied with ?uid under
valve 88 will also be in the position illustrated in
pressure through the conduit 282, ports 288 and
Fig. 1 in which ?uid ?ow is cut‘ oil between the
288, conduits 288 and 242, and pump 288. The
ports I18 and I18 and the port I18 is connected
large end of the cylinder 88 under these condi
tothe interior of the housing 18 which‘is 'main
tions is subject to , control by the valve 2I4
through the conduit 214, and ports 212 and 218. 40 tained at atmospheric pressure by a connection
to the expansion tank, not shown. The valve
Thus with the valve 2“ in the position shown
2I8 having moved to the left,v as illustrated, by
the port 218 is blocked and piston 88 is held sta
the ?uid pressure admitted to the power cylin~
tionary. With the valve 2I4 moved to the right,
der 284 by valve 88, connects the large end of
port 218 is'connected with conduit 282 for ad
mission of ?uid under pressure from the auxiliary 45 control cylinder 88 to the tank through the con
duit 214, port 212, port 218, conduit 288, port
pump 288 to the large end of the cylinder 88 caus~
I18, and bore I82. Thesmall endof the cylinder
' ing piston 88 to move to the right and thus mov
88 is supplied with ?uid under pressure either
ing the tilting box in‘ a clockwise direction in
from the main power circuit of the transmission
Fig. 8, and increasing the speed of the “B-end”
in a forward direction.
When the valve 2“ is 50 or from the auxiliary pump 288. depending upon
moved fully to the left. the port 218 is connected
to port 288, thus exhausting ?uid from the large
end of the cylinder 88 causing the piston 88 to
the position of the shuttle valve'244. The circuit
for this ?uid is from the shuttle valve 244 through
conduit 288, port 288, valve 2I8, port 288, and
conduit 282 to cylinder 88. The piston 88 thus
supplied to the small end of the cylinder 88.. The 55 moves to the left until the ratio of transmission
is such that the prime mover 88 may handle the
speed of the “B-end” in a forward direction will
move to the left under the constant pressure
therefore be reduced, or if the tilting box has been i
moved to the left past neutral position the speed '
overload without danger.
'
The compression of the spring I22 is varied‘by
the cam 88 in accordance with the-position of
in the opposite direction will be‘ increased. Dur
ing operation under normal control of ‘valve 2“ 80 the tilting box I8 and the shape of the cam is
such that the horsepower required at the shaft
the handwheel 44 is free totum with the "B-end"
88 when valve 88 opens is constant for all ratios
shaft I8. That is, with the pump "on stroke” in
of transmission. Since the horsepower trans
any given position, the member 28 and tilting
mitted by the hydraulic transmission is propor
box I8 will remain stationary while the gear 84
will rotate the gear 88 and nut 48 and carry along 65 tional to the product of the ?uid .pressure ex
isting in the transmission and the speed of the
with them in their rotation- the screw shaft 88,
“Bend” shaft, the cam 88 may be so shaped
the head 84, the sleeve 38, and the handwheel 44.
that the compression of the spring I22 will be
as a unit, without imparting longitudinal move
maintained at the proper value for any speed
ment to the member 28.
Should an excessive resisting load be imposed 70 ratio of transmission. Thus when the “B-end”
shaft I8 is revolving slowly, the pressure which
upon the shaft I8 such that the prime mover
may be built up without exceeding the limiting
connected to the shaft 88 would be overloaded.
horsepower is high. Since the position of the
the constant horsepower valve 88 operates to
tilting box I8 is determinative of the speed of
move the tilting box I8 toward neutral posi
tion. It is a characteristic of hydraulic trans 75 the shaft I 8, it will be seen that when the tilt
2,413,301
9
,
10
ing box I6 is near the neutral position the cam
as just described, bringing with it the shaft 80.
88 holds the tension rod “8 to the left, as shown
In order to move, the shaft 30 must at least slow '
in Fig. 6, applying a relatively high force to the
down relative to the "B-end" and may even stop
valve member I26. A relatively high pressure
or reverse. In any event the rotation of shaft
is therefore required to move the valve member 5 30 must be algebraically less than the rotation of
I26 to the right under these conditions.
the “B-end” shaft I8 and nut 46 in order to cau‘sev
Conversely when the "B-end” shaft I8 is re
a difference in speeds which is made up by the
volving at a high speed, much lower pressure in
translatory movement of shaft 38.
the system will produce an overload on the prime
The control mechanism‘ thus far described also
mover so that with the tilting box in a high speed 10 operates to limit the horsepower which may be
position, as shown in Fig. 1, the cam 88 applies
transmitted back through the transmission from
a smaller force to‘ the valve member I26 permit_
the “B-end” shaft I8 to the "A-end” shaft 88.
ting it to open on a much lower pressure. Thus ' In other Words, should'the load tend to drive
the full horsepower of the prime mover may be
the prime mover, the horsepower which may be
utilized at low “Beend” speeds without danger of 15 transmitted backward through the transmission
overloading the prime mover at high “B-end”
is limited to the same value that may be trans~
speed.
.
mitted therethrough in the normal direction.
When the tilting box is in position for rotation
Operation under these conditions is identical '
of the “B-end” shaft I8 in the reverse direction,
to that previously described, the only difference
the parts take up the position illustrated in Fig. 20 being that if the port 230, for example, be the
2 wherein the piston '56 lies to the left of the
pressure port when power is transmitted normal
mid-point of its travel and upon the occurrence
1y through the transmission for a given direction
of an overload it-_is necessary to move the piston
of rotation of the shaft I8, then the port 228
to the right rather than to the left as previously
becomes the- pressure port when the load' tends
described. The directional control valve 96 moves 25 to feed power back to the prime mover. Since
to the right during the ?rst small increment of
the occurrence of an abnormal pressure rise in
travel of the tilting box away from neutral posi
either port causes movement of the tilting box
tion in a counter-clockwise direction in Fig. 1
I6 toward neutral position, it will be seen that an
and Fig. 8, and thereupon connects the port 210
excessive amount of power feed-back will reduce
of the valve 2 I 6 with the shuttle valve 244 through 30 the mechanical advantage of the “B-end" shaft
the conduits 268, I94 and 254. Fluid under'pres
I8 upon the “A-end” shaft,_thus slowing down the
sure is thus admitted from either the main power
“B-end” shaft and reducing the horsepower
circuit or from the auxiliary pump 236 to the .
transmitted back to the “A-end" shaft;
. large end of the cylinder 58 from port 212
When the transmission is operated manually
through conduit 214. Thus, whenever the "B 35 by the crank 16, as when a failure of the prime
end” shaft is rotating reversely and an overload
occurs, the movement of valves 90 and 2I6 to the
right and left respectively, admits ?uid under
' pressure to both ends of the cylinder 58. Since
mover occurs, the horsepower which may be
‘transmitted through the transmission is limited
by the constant torque valve I00. ‘Rotation of
the crank 16 drives the shaft 286 which drives
40 the ?ywheel 298 at a higher rate of speed through
the area of the piston 56 exposed to the left
hand end of the cylinder 58 is greater than the
the planetary gearing 292, 294, 296 for steadying
area exposed in the right-hand end, the resultant
the speed of operation of the shaft 286, and also
force tends to move the piston to the right toward
drives the sprocket 3I6 through the clutch 304
neutral position until the mechanical advantage
and through the spring-loaded cam mechanism
of the “A-end” shaft over the “B-end” shaft is 45 3I2, 3I4. Upon the occurrence of an overload
increased su?iciently so that the prime mover
sufficient to require an excessive torque upon the
may handle the overload imposed.
crank ‘I6, the sprocket 3I6 slips relativeto the
During operation with normal control exer
hub 366 causing the projection 3| 2 to travel along
cised through valve 2I4, the operation of valve 98
the cam surface 3I4 compressing the springs 3I0.
causes this normal control to be temporarily in
50 As soon as the projection 3E2 has travelled along
terrupted since valve 2I6, in the position shown
the cam surface 3I4 a predetermined distance, the
in Fig. 1, cuts off communication between conduit
torque required for further travel exceeds the,
218 and port 212. The cylinder 58 is thus cut off
torque which the clutch 304 is capable of trans
from any control in?uence by valve 2I4 until the . mission and thereafter the clutch 304 slips until
valve 90 closes permitting valve 2I6 to move to 55 the torque required falls off to a safe value.
the right into the position shown in Fig. 3. When
The movement of the cam member 398 to the
normal control is exercised through valve 2I4,
left caused by the cam 3I4 actuates the fork 320
the handwheel 44 is free to turn with the “B
to pull the operating rod 2| 2 to the left in Figs.
enfd"'shaft I8; the shaft 30 and nut 46 turning
1 and 8, thus moving the valve member I88 to
together as a single unit at each particular set 60 the right and connecting port I96 to port I92
ting of the control piston 56. When piston 56
instead of to the tank. Fluid under pressure is
moves, of course, the handwheel 44 speeds up or
thus admitted from the shuttle valve 244 through
slows down relative to the "B-end” shaft I8 so
the ports I92 and I96, conduit I98, ports I42 and
long as piston 58 continues to push or pull the
I 40 and the conduit 282 to the power cylinder 284,
threaded shaft 30 into or out of the nut 46. Dur-, 65 moving valve 2I6 to the left-hand position illus
ing operation with normal control exercised
trated in Fig, l. The piston 56 is thus caused to
through handwheel 44 instead of through valve
move toward neutral position in the manner pre
2| 4, that is during operation with follow-up con
yiously described in connection with the constant
trol, the valve 90 takes control away from hand
horsepower valve 99.
,
wheel 44 whenever safe loads are exceeded. This
Thus, assuming that the crank ‘I6 is operated
comes about from the fact that the effort ex
erted by piston 56 when valve 90 opens is greater
at a substantially constant speed, the occurrence
of an excessive load at the “A-end” shaft I4
tends to increase the mechanical advantage of
'. the “A-end” shaft l4 over the '“B-end" shaft is
than any effort which can be manually applied
to handwheel 44. Accordingly when valve 90
Opens, piston 56 moves toward neutral position 75 until the ratio of power transmission is such that
2,418,801
'
11
the overload may be safely handled at the crank
18. Since the power delivered-to the crank 18 is
ordinarily less than that of the prime mover,
the constant horsepower valve 80 will not operate
for limiting loads which are excessive when the
transmission is driven from the crank 16. In
other words, it is desirable that the settings of
driven member and including means forming a
source of pressure ?uid, a member movable in
either direction away from a neutral position for
varying the speed and direction of the driven
member relative to that of the driving member,
means including a di?erential piston and cylinder
' for operating said movable'member, a valve for
the operating mechanism for the constant horse
power valve Sll and the operating mechanism for
controlling the admission of ?uid from said
torque valve is subject to the directional control
through the neutral position.
source to both ends of said cylinder and a sec
the torque limiting valve lilll be such that the 10 ond valve for cutting of! ?uid from the large’
end of the cylinder in cooperation with the ?rst
valve lllli comes into operation at a mugh lower
mentioned valve and means for operating the
load on the shaft l8 than does the constant horse
second valve as the movable member passes
power valve 90. The operation of the constant
valve 85 in the same manner as is the constant
horsepower valve SI. Thus, whenever the tilting
4. In a power transmission device the combina
tion oi’ a driving shaft, a driven member, a re
versible variable speed power transmission for
delivering power from the driving shaft to the
position in Fig. 8, valve 98 will lie to the right in
driven member, a member movable in either’
Fig. l and connect the large end of cylinder 58
to pressure ?uid whenever valve Iii is moved to 20 direction away from a neutral position for vary
ing the speed and direction of the driven mem
the left by pressure ?uid from valve III. This
ber relative to that of the driving member,
circuit is through conduit 25!, port i‘li, valve SI,
means including a dl?'erential piston and cylinder
port I18, conduit 2", port 21!, valve ZIG, port
for operating said movable member, a valve
212 and conduit 214. The greater area of the
large end of cylinder BI is thus predominant over 25 selectively operable to cause the ?ow of pressure
?uid to move said piston and-a second valve
the area at the small end and piston 56 is thereby
operable to selectively determine the direction or
moved to the right toward neutral position.
movement of the piston under the in?uence of
It will thus be seen that the present invention
?rst mentioned valve, and means for operating
provides a control device for a variable speed
transmission whereby the transmission itself will 30 the second valve as the movable member passes
through the neutral position, said last named
automatically prevent the overloading of its prime
means including a cam operable by said movable
mover regardless of the resisting load applied to
member to actuate the valve through its‘ full
the driven member of the transmission.
stroke by a slight movement of the movable
While the form of embodiment of the inven
member.
'
tion as herein disclosed, constitutes a preferred
5. In a, power transmission device the combina-'
form, it is to be understoodtthat other forms
tion of a driving shaft, a driven member, a re
might be adopted, all coming within the scope
versible variable speed power transmission for
of the claims which follow.
delivering power from the driving shaft to the
What is claimed is as follows:
driven
member, a member movable in either
40
1. In a ‘power transmission device the com
direction away from a neutral position for vary
bination of a driving,shaft, a driven member, a
ing the speed and direction of the driven mem
variable speed hydraulic transmission for deliv
relative to that of the driving member, means in
ering power from the driving shaft to the driven.
cluding a differential piston and cylinder for op
member, a member movable to vary the vmechanical advantage of the driving shaft upon 45 erating said movable member. a valve foricon
trolling the admission of ?uid to both ends of
the driven member, follow-up control means for
said cylinder, 9, second valve for cutting oi! ?uid
normally determining the position of said mem-_.
from the large end of the cylinder in cooperation
ber, ?uid pressure operated means for moving
with the first mentioned valve, means for op-.
said movable member, a valve responsive to ex
cessive ?uid pressure in' the hydraulic transmis 50 erating the second'valve as ,the movable member '
passes through the neutral position, said last
sion for controlling the ?uid pressure operated
named means including a cam operable by said
means, and means for increasing the pressure
movable member to actuate the valve through
response of said valve in accordance with changes
its full stroke by a slight movement of the mov
in the position of the movable member tending
55 able member, and a lost motion connection be
toward increased mechanical advantage.
tween the cam and the movable member.
2. In a- power transmission device the combina
box lies on the counter-clockwise side of neutral
tion of a driving shaft, a driven member, a vari
6. In a power transmission device the combina
able speed hydraulic transmission for delivering
tion of a driving shaft, a driven member, a revers
advantage of the driving shaft upon the driven
member, control means for normally determin
ing the position of said .member, ?uid pressure
operated means for moving said ‘movable mem
ber to increase said mechanical advantage upon
excessive pressure being developed within the
hydraulic transmission, and means for operat
member, a member movable in either direction
away from a neutral position for varying the speed
and direction of the driven member relative to
that of the driving member, means including a
?uid motor for operating said member, a valve
selectively operable to cause ?ow of pressure ?uid
to move said motor, a second valve in series with
driven member velocity.
able member passes through neutral position.
3. In a power transmission device the combina
tion of a driving shaft, a driven member,'a re
tion of a, driving shaft, a driven member, a
power from the driving shaft to the driven mem- ' iblevariable speed power transmission for deliver
her, a member movable to vary the mechanical 60 ing power from the driving shaft to the driven
the ?rst valve for selectively determining the
ing the ?rst mentioned means in response to
direction of ?uid ?ow to or from the motor, and
pressure so as to maintain a predetermined maxi
mum value for the product of ?uid pressure and 70 means for shifting the second valve as the mov
versible‘ variable speed power transmission for
delivering power from the driving shaft to the
7. In a power transmission device'the combina
variable speed hydraulic transmission for de
', livering power from the driving shaft to the driven
2,413,301
13
member, a member movable to vary the me
chanical advantage of the driving shaft upon the
driven member, means responsive to the pressure
in said transmission for moving said member,
and means movable with said member for in
creasing the pressure response of said means as
the member is moved toward the position of maxi
i4
erable manual means for controlling the ?ow of
fluid from the pump to the motor, additional
means for controlling the flow of ?uid from the
pump to the motor and including a servo-motor
and a pilot control valve therefor, and protec
tive means including a valve connected to exer
cise control over said servo-motor during over
mum mechanical advantage.
load independently of the other controlling
8. In a variable speed ?uid power transmission
means, and means for operating said valve in
device the combination of a variable displacement 10 response to pressure so as to maintain a'prede
pump, a ?uid motor driven by the pump, means
termined maximum value for the product of ?uid
'for driving the pump, means for regulating the
pressure and driven member velocity.
pump displacement’ in response to pressure
13. In a power transmission device the combi
changes produced at the ?uid motor and means
nation of a driving shaft, a‘driven member, a
for increasing the response of the regulating 15 variable speed hydraulic transmission for deliv
means in accordance with decreases in the dis
ering power from the driving shaft to the driven
placement of the pump.
member, a member movable to vary the me
chanical advantage of the driving shaft upon the
9. In a power transmission device the combina
tion of a driving shaft, a dri"en member, at
driven member, control means for normally de
variable speed hydraulic transmission for deliver 20 termining the position of said member, means
for moving said movable member to increase said
ing power from the driving shaft to the driven
mechanical advantage upon excessive pressure
member, a member movable to vary the mechan
being developed within the hydraulic transmis
cal advantage of the driving shaft upon the driven
sion and including means for disconnecting said
member, control means for normally determining
normal control means.
the position of said member, means for moving
14. In a power transmission device the combi
said movable member to increase said mechanical
nation of a driving shaft, a driven member, a
advantage upon excessive pressure being de
variable speed hydraulic transmission for deliv
veloped within the hydraulic transmission, said
ering power from the driving shaft to the driven
means responding to higher pressures at lower
speeds of the driven member.
30 member, a member movable to vary the mechan
ical advantage of the driving shaft upon the
10. In a power transmission system the com
binatlon of a driving shaft, a driven member, a
variable speed power transmission including a
driven member, control means for normally de
termining the position of said member, means
for moving said movable member to increase said
pump operable from the driving shaft, 9, motor
operable by ?uid delivered by the pump and con 35 mechanical advantage upon excessive pressure
being developed within the hydraulic transmis
nected to actuate the driven member, locally op
sion and including means for disconnecting said
erable manual means for controlling the flow of
normal control means, and means for increasing
?uid from the pump to the motor,‘ additional
the pressure response of the second mentioned
means for controlling the flow of ?uid from the
pump to the motor and including a servo-motor 40 means in accordance with decreases in the speed
of the driven member.
and a pilot control valve therefor, protective
means including a, valve connected to exercise
control over said servo-motor during overload in
dependently of the other controlling means, and
torque responsive means for operating said valve.
15. In a power transmission device the combi
nation of a driving shaft, a driven member, a
variable speed hydraulic transmission for deliv
ering power from the driving shaft to the driven
member, a member movable to vary the mechan
ical advantage of the driving shaft upon the
driven member, control means normally con
nected to operate said member and means re
pump operable from the driving shaft, a motor
operable by ?uid delivered by the pump and con 60 sponsive to the pressure in said transmission
for moving said member and including means for
nected to actuate the driven member, locally op
disconnecting said normal control means.
erable manual means for controlling the flow of
16. ‘In a power transmission device the combi
fluid from the pump to the motor, additional
nation of a driving shaft, a driven member, a
means for controlling the ?ow of ?uid from the
pump to the motor and including a servo-motor, 55 variable speed hydraulic transmission for deliv
ering power from the driving shaft to the driven
and a pilot control valve therefor, and protective
means including a valve connected to exercise
member, a member movable to vary the mechan
11. In a power transmission system the combi
nation of a driving shaft, a driven member, a
variable speed power transmission including a
‘control over said servo-motor during overload
independently of the other controlling means,
ical advantage of the driving shaft upon the
driven member, control means normally con
and pressure responsive means for operating said 60 nected to operate said member and means re
valve.
'
sponsive to the pressure in said transmission for
12. In a power transmission system the combi
moving said member, and including means for
disconnecting said normal control means, and
variable speed power transmission including a
means movable with said member for varying the
pump operable from the driving shaft, a motor 05 pressure response of said means._
operable by ?uid delivered by the pump and con
nected to actuate the driven member, locally op
ARTHUR L. ELLIS.
I nation of a driving shaft, a driven member, a
"s
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