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Патент USA US3077974

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Feb. 19, 1963
D. J. KIRK
3,077,964
BOOM CONTROL DEVICES
Filed March 7. 1957
2 Sheets-Sheet 2
70
75
74
75
52
6/
73
21
55
62
INVENTOR
Oe/b 0')‘ J Kirk
ATTORNEY
"cc
3,077,964
Patented Feb. 19, 1953
2
boom is to be lowered under control of the hoist engine or
motor the ratchet clutch must be engaged before each
such lowering operation or this clutch may be contin
3,077,964
BOOM CQNTRGL DEVECES
Delbert 1. Kirk, Beacons?eld Road, Willernie, Minn.
Filed Mar. 7, 1957, Ser. No. 644,675
uously engaged. Obviously, in the interest of safety,
9 Claims. (Cl. 192—12)
this clutch should remain engaged at all times. How
This invention relates to an improvement in boom con
trol devices for cranes and deals particularly with an ap
ever, the dogs or pawls Within the ratchet clutch con
stantly ride over the ratchet teeth or stops and provide
a clattering sound which is extremely annoying to the op
paratus useful in increasing the safety of operation of
erator, particularly as this clutch is usually located close
Attempts have been made
to silence this clutch by enclosing it in a silencing band
but this band is not particularly effective. Accordingly,
the operator often prefers to disengage the ratchet clutch
10 to the head of the operator.
cranes of a certain type.
For many years cranes have been constructed having
boom raising and lowering lines which function by wind~
ing or unwinding the line from a boom hoisting drum.
Some cranes are constructed in such a manner that the
at all times except when the boom is to be lowered and
rotation of the boom hoist drum is always power actuated 15 at this time engages the clutch for the lowering opera
so that the speed of raising and lowering the boom may
tion. This operation not only requires two additional
be controlled only by variations in the driving speed of
movements on the part of the operator before and after
the apparatus. Other hoists have been produced in which
the boom lowering operation but also greatly increases
the hoisting drum is power driven to raise the boom while
the hazard of operating the crane for if the operator fails
the lowering of the boom is dependent upon brake control. 20 to engage the ratchet clutch before pulling back the lever
In other words, the lowering of the boom is effected by
the weight of the boom which tends to unwind the line
from the drum and the speed of this lowering operation
depends upon the operation of a manually controlled
which releases the brake and permits the boom to drop,
the boom will lower by gravity until the brake is again ap
plied. When the ratchet clutch is engaged, the release
of the brake will cause the boom to lower by gravity
brake. Certain other cranes such as those produced by 25 until the ratchet dogs of the ratchet clutch engage and
the Thew Shovel Company and known as “Thew Lorain
from this point the ratchet clutch cannot operate at a
Cranes” optionally incorporate a combination of both of
speed greater than the speed of the shaft on which it is
these systems. In other words, the boom may be raised
mounted. Thus, the brake lever can be fully released
or lowered under power, or may be raised by power
when the boom is lowered under power. Fully releasing
and lowered by manual brake operation. It is with this
type of crane that the present invention is involved,
Hoists which are provided with a precision boom lower
power will cause the boom to drop at a terri?c speed,
ing device as well as with a manually operable brake
and to personnel.
actuated lowering device often employ a boom cable
the brake when the boom is not being lowered under
creating the liability of accidents both to the equipment
This rather lengthy explanation is provided in order‘
drum which is driven through an idler gear from a gear
to give a better understanding of the reasons for pro
rotatably supported upon a constantly operating shaft.
A clutch is provided for connecting the shaft with the
ducing the present invention. The present invention com- '
prises a safety device which automatically engages the'
ratchet clutch while the boom is being raised and lowered,
gear and when this clutch is engaged the boom drum is
rotated in a direction to wind the hoisting cable upon
and automatically releases this clutch during the 're-_
the drum. A brake is usually provided encircling the 40 maining periods of operation. As a result, the ratchet
drum and controlling the operation of the gear on the
constantly rotating shaft for normally holding this gear
from rotation and accor ingly holding the hoisting drum
rom rotation. This brake is usually wrapped about the
brake drum forming a part of the clutch and is dead
ended at one end and spring loaded at the other end so‘
that rotation of the clutch in a direction to hoist the
boom can be effected Without releasing the brake. How
ever, rotation of the gear and brake drum in the oppo 50
site direction tends to wrap the brake band tightly about
the drum and hold the drum from rotation. Thus, the
lowering of the boom may be accomplished by releasing
the brake band upon the drum to permit a controlled
lowering of the boom.
55
A pinion engages the gear attached to the boom cable
drum and a ratchet clutch is mounted upon a second
clutch is always engaged during the lifting and lowering
of the boom but is always disengaged at other times so"
that the noise caused by the ratchet dogs is eliminated
during most of the operating time of the crane.
A feature of the present invention lies in the provision ,
of a ?uid actuated cylinder connected to the ratchet clutch
operating arm and in the provision of a valve for coni~
trolling the operation of the cylinder. This valve is op
erated automatically through operation of the boom con
trol lever which controls the raising and lowering of the
boom and acts to engage the clutch automatically each
time the boom control lever is moved in either direction
from its neutral central position. I
A further feature of the present invention resides in the
provision of a cylinder which includes means for nor
constantly rotating shaft which is normally the shaft on
mally biasing the ratchet clutch operating lever to ‘dis
clutch. When the ratchet clutch is disengaged, operation
ratchet clutch operating arm into operating position.
These and other objects and novel features of the pres
ent invention will be more clearly and fully set forth in the
engaged position. When the control lever for operating‘
which the hoisting drums are located. This ratchet clutch
is connected to the gear engaging the boom drum gear, 60 the boom drum in either direction is actuated, a valve
is simultaneously actuated, controlling the‘ ?ow of ?uid
by a suitable chain. Thus, rotation of the boom drum
to or' from the ?uid actuated cylinder and moving the
causes a corresponding motion of a part of the ratchet
of the boom drum merely causes free rotation of a por
tion of the clutch. However, when the clutch is engaged,
rotation of the boom drum in a direction to lower the
boom causes automatic engagement of the ratchets or
pawls and as a result the boom cannot be lowered at a
speed greater than the speed of the constantly operating
shaft on which the ratchet clutch is mounted.
In the drawings forming a part of the speci?cation:
FIGURE 1 is a diagrammatic side elevational view of
a portion of the drive mechanism of a crane showing the
70 general arrangement of parts.
FIGURE 2 is a diagrammatic view of the added parts
If the
which form the automatic operator.
While this device functions very effectively for its in
tended purpose, certain difficulties are involved.
following speci?cation and claims.
3,077,984
3
4
FIGURE 3 is a diagrammatic view of the ratchet
clutch.
FIGURE 4 is a diagrammatic sectional View through
acting to raise the boom 5?. It will be understood that
the line 49 passes through suitable sheaves such as 41
and extends to the boom through any of a series of line
connections which usually involve a several part line
in order to reduce the necessary pulling force to raise
the boom.
‘
the ratchet clutch showing the general arrangement of
parts.
FIGURE 5 is a diagrammatic view of a safety pawl
which must be released before the boom may be lowered.
FIGURE 6 is a view similar to FIGURE 5 showing the
A brake drum 42 is connected to the clutch 33 to rotate
in unison therewith. A brake band 43 is dead ended at
pawl in released position.
44 and extends around the drum 42 in a clockwise direc
FIGURE 7 is a diagrammatic view of a crane of a 10 tion as viewed in FIGURE 1. A pull rod 45 is connected
type which may employ my mechanism.
to the end of the brake band 423, this rod 45 extending
In view of the fact that the crane construction is
through a fixed support 46. A spring 47 is interposed
well known and is on the market, only portions of the
between the fixed support 46 and a bearing plate 49 at the
mechanism which are important to the operation of the
end of the rod which is adjustably held in place by nuts
present device have been disclosed. Furthermore, in view 15 56. The spring 47 applies a force to the brake band
of the complexity of the apparatus, the structure illus
tending to hold it wrapped about the drum 42. When
trated is for the most part shown diagrammatically in
the brake drum 42 rotates in a counter-clockwise direc
order to avoid complicating the drawing and description.
tion, the friction of the drum against the band 43 acts
In general, FIGURE 1 illustrates diagrammatically the
against the spring 4-7 and permits the drum to slip within
?oor of a crane cab A upon which the hoist mechanism 20 the brake band without undue friction. However, rota
is mounted. The ?oor is illustrated in general by the
tion of the .drum 42 in a clockwise direction acts to wrap
numeral 16 and it includes a pivotal support 11 for a
the band 43 tightly about the drum and to hold the drum
boom hoist drum operating lever 12. An arcuate seg
ment 13 is provided adjacent to the lever 12 and is
provided with a central notch 14. The lever 12 supports
a vertically slidable rod 15 which supports a lug or bolt
16 which is engageable in the notch 14. A push button
17 is provided at the top of the handle lever 12 and by
£59m rotation unless the band is manually released.
' In order to release the brake band, an adjustable pro—
jection 51 is provided on the rod 45. A lever 52 is pivot~
ally supported at 53 and includes a forked end 54 which
engages the projection 51. The lever 52 is connected to
the link 37 so that movement of the control lever 12 in
a clockwise direction from center exerts a pull upon the
from the notch 14 which normally holds the lever in a 30 link 37 swinging the lever 52 in a clockwise direction
depressing the button 17, the lug 16 may be disengaged
central neutral position. When the lug 16 is disengaged,
and urging the forked end 54» against the projection 51
the lever 12 may be either swung forwardly which acts
to raise the boom or may be swung rearwardly which acts
to release a brake and to permit the boom 9 to lower.
to relieve the pull upon the brake band 43 and to permit
this brake band to slip relative to the drum 42.
As is diagrammatically illustrated in FIGURES 5 and
The motor or engine of the hoist or crane drives a 35 6 of the drawings, the brake drum and clutch support a
drive gear 19 which meshes with a gear 20 mounted
series of ratchet teeth 55 which are engaged by a pawl
upon a transverse hoist shaft 21 and also engages a sec
or dog 56 pivotally supported upon a transverse pivot 57
ond gear 22 which is mounted upon a swing shaft 23.
Hoisting drums such as 24 are mounted upon the hoist
shaft 21 and are provided with suitable brakes and
clutches by means of which they may be either engaged
for rotation with the hoist shaft 21 or may operate inde
pendently thereof. The hoist shaft operates continually
in‘ a counter-clockwise direction as viewed in FIGURE 1.
which may also serve as the anchor for the dead end of
the brake band and may comprise the dead end point
44. An arm 5h is also pivotally supported upon the
pivot 57 and includes a hook portion 6% which is engage
able with a pin 61 projecting from the dog 56. The arm
59 is provided with a weighted end 62 which, in the posi
tion shown in FIGURE 5, holds the dog 56 against the
Swing drums 25 are mounted upon the swing shaft 23 45 ratchet teeth. When the arm 59 is swung in a clockwise
and are also suitably controlled by clutches and may
direction as viewed in FIGURE 6, the weighted end 62
rotate in unison with the swing shaft 23 which operates
passes over the pivot 57 and the weight of the arm tends
continuously in a counter-clockwise direction as viewed
to disengage the pawl from the ratchet teeth 55 as shown
in FIGURE 6.
inFIGURE 1. The rotation of the crane cab A about
The weighted arm 5h is in a position where it may
a. vertical axis is controlled by suitable mechanism actu 50
ated by the swing drums.
be swung from one extreme position to the other by the
foot of the operator. The purpose of the arm 59 is to
A boom hoist shaft 26 extends transversely of the cab
provide a safety ratchet to prevent accidental lowering
and ‘supports a boom drum 27 to which is attached a
of the boom. When the arm 59 is in the position shown
driving gear 29. An idler pinion 30 is mounted on a
stub shaft 31 and engages the teeth of the gear 29. The 55 in FIGURE 5, the gear 32 attached to the clutch 33 and
brake drum 42 cannot rotate in a clockwise direction and
idler pinion 36 also engages gear teeth of a gear 32
as this gear 32 is in constant mesh with the idler gear 30
mounted upon the swing shaft 23 and which is engage
which in turn is in mesh with the boom drum gear 29,
able and disengageable therefrom by means of a clutch
the unwinding of the line 4% from this drum cannot take
33,v the detail of which is not disclosed. The clutch 33
is ‘actuated'by a clutch shift lever 34 which is pivotally 60 place when the ratchet .dog 56 is engaged.
An idler gear 63 is mounted upon a transverse stub .
supported at 35 and extends through the cab ?oor 10.
shaft 64 and meshes with the gear 29 on the ‘boom drum.
This clutch lever 34 is actuated through a transversely
The gear 63 is a combination gear and sprocket. The
extending lever 36 which connects the shift lever 34 to a
sprocket portion of the gear 63 is connected to the ratchet
link 37 connected to the lower projecting end 39 of the
control lever 12. Movement of the lever 12 in a for 65 clutch 65 by means of a chain 66. Thus, the rotatable
portion of the ratchet clutch rotates in unison with the
ward direction transmits motion through the link 37 and
boom drum during any movement thereof.
the lever 36 to the clutch shifting lever 34 to engage this
With reference now to FIGURE 4 of the drawings, the
clutch. When engaged, the gear 32 rotates in unison
ratchet clutch is diagrammatically disclosed and is
with the swing shaft 23. Counter-clockwise movement of
the gear 32 with the shaft 23 causes rotation of the idler
mounted upon the hoist shaft 21. A hub or sleeve 68
gear 30 in a clockwise direction and this in turn rotates
is mounted upon the end of the shaft 21 and is secured
the gear 29 and the boom drum 27 in a counterclockwise
for rotation in unison therewith by a suitable key or spline
direction. When moving in this direction, the cable or
67. A ?ange 69 is provided at one end of the hub 68
line 40 which is anchored to the drum 27 is wound upon
to support a cylindrical ?ange 70 having ratchet teeth
the drum exerting a pulling force upon the_ line 40 and 75 or ratchet pockets 71 in its inner surface. 'A bushing 72
5
3,077,964
encircles the hub 68 and rotatably supports a sleeve 73.
The sleeve 73 is provided with a peripheral ?ange 74
which is toothed on its outer surface to provide sprocket
6
the safety ratchet lock shown in FIGURES 5 and 6 is dis
engaged. However, when the clutch 65 is disengaged, the
speed of lowering of the boom is controlled solely by the
teeth 75.
brake band 43.
The sleeve 73 is also provided with a series of angularly
spaced outwardly projecting ears 76. Ratchet arms 77
are mounted upon pivot pins 79 extending through the
In order to automatically operate the clutch 65, so that
the clutch 65 is engaged only when the boom is being
raised or lowered, I provide the arrangement diagram
matically illustrated in FIGURES 1 and 2. of the drawings.
A cylinder 92 is provided pivotally attached at one end
?ange 74 and the ears 76. The ratchet arms are pinned
to the pins 79 as indicated at 86.
A clutch sleeve 81 is mounted for axial slidable move 10 at 93 to a supporting bracket 94 which in turn is secured
ment upon the sleeve 73 and includes camming surfaces
to a brace 95 forming a par-t of the frame of the crane
82 which engage cooperable surfaces 83 on the heads 54
by means of U-bolts 96 or other suitable means. The
of the pivot pins 79. When the sleeve 81 is moved to the
cylinder 92 includes a piston 97 mounted upon a piston
left from the position illustrated in FIGURE 4, the cam
rod 99 which is pivotally connected at 100 to a link 101
ming surfaces 82 engage the heads 84 of the pivot pin 79 15 which extends through the operating lever 87 and which
and swing the ratchet arms 77 into inoperative position.
is secured in place by nuts 103 or other suitable means.’
As is indicated in FIGURE 3 of the drawings, the
A spring 1114 is provided Within the cylinder 92 urging
ratchet arms 77 include terminal rollers 85 which engage
the piston 97 to the right as viewed in FIGURE 2 which
into the ratchet pockets or teeth 71. Springs 86 swing
tends to retract the piston rod 99 and to draw the oper
the roller bearing end of the arms 77 outwardly. Thus, 20 ating lever 87 rearwardly as viewed in FIGURE 1 so as
when the clutch 65 is engaged, the rollers 35 are urged
to disengage the clutch 65. The end of the cylinder 92
toward the pockets '71. When ‘the sleeve 81 shown in
opposite the end through which the piston rod 99 extends
FIGURE 4 is moved to the left in order to disengage the
may be vented as indicated at 105 so that the piston 97
clutch, the various roller bearing ends of the arms 77 are
may move to the right without compressing air in the
swung inwardly by action of the pivot pins 79 so that the
ratchet arms do not engage in the teeth and the inner
portion of the clutch may rotate freely relatively to the
outer portion thereof.
During operation of the ‘hoist, the hoist shaft 21 oper
a-tes in a counter-clockwise direction and therefore carries
the housing ?ange 70 in a clockwise direction. During
this operation the rollers 85 successively roll over the
teeth 71 and form a clattering noise which is very audible
end of the cylinder.
A valve 1% is mounted upon the operating lever 12
by means of a suitable bracket 1117 which is attached to
the lever 12 by any suitable means such as U-bolts 109.
In the diagrammatic view, the valve is shown forwardly
of the operating lever but in actual practice it is usually
located rearwardly of the lever due to restrictions of
the operator’s cab. Furthermore, the size of the valve
disengaged by means of an operating lever 87 which is
pivoted to the frame 89 of the crane by a vertical pivot
91). The lever 87 includes a loop portion 91 which en
closes the sleeve 81. The sleeve 81 is provided with a
peripheral groove 88 in its outer surface and pins 91’
upon the loop portion 91 of the lever 87 engage in the
is exaggerated in order to better illustrate the construc
tion.
The valve 1116 includes a valve cylinder 110 which
slidably supports a sleeve 111 having a ?anged end 112
which limits the slidable movement of the sleeve into the
body of the valve. A valve stem 113 extends through the
sleeve 111 and is provided with a valve head 114 which
is engageable against the end of the sleeve 111 to form
groove 83. Thus, by pivotal movement of the lever 37
a seal.
to the crane operator.
The clutch may be engaged or
in a rearward direction as viewed in FIGURE 1, that is,
away from the reader, the ratchet clutch is disengaged
by the pivot pin 79. When this lever 87 is pulled out
wardly toward the viewer in FIGURE 1, the ratchet clutch
is engaged as the sleeve 81 is withdrawn from engage
ment with the heads of the pivot pins 79.
Thus, it will be seen that when the ratchet clutch 65
is engaged, the various ratchet arms continually pass over
the ratchet teeth both while the hoist drum 27 is station—
ary and also when this hoist drum is being rotated in a
direction to raise the boom through engagement of the
clutch 33. However, in the event the boom is lowered,
the weight of the boom acts through the cable line 41}
A passage 115 is provided at the base of the cylinder
1113 and this passage 115 is connected by a ?exible con
duit 116 to the interior of the cylinder 92 forwardly of
the piston 97. A second passage 117 extends into the
valve body at right angles to the cylindrical chamber 110,
and this passage 117 is open to a point slightly above the
lower end of the sleeve 111. When the head 114 of
the valve stem engages the bottom of the sleeve 111,
and lifts this sleeve, the passage into the interior of the
valve is opened. Normally, the sleeve 111 closes this
opening.
The passage 117 is connected to a ?exible conduit 119
leading to a source of partial vacuum such as the mani
to rotate the boom drum 27 in a clockwise direction. 55 fold of the internal combustion engine driving the crane.
This action causes rotation of the gear and sprocket 63
A valve 12% is provided in the conduit 11!! so that the
in a counter-clockwise direction and causes corresponding
vacuum supply may be cut off in the event the operator
counter-clockwise rotation of the clutch sleeve 73 of the
desires to lower the boom under control of the brake
ratchet clutch. Rotation of the ratchet sleeve 73 in a
only. In certain speci?c operations, the lowering of the
counter-clockwise direction at a speed greater than the 60 boom by gravity is advantageous because of its speed.
speed of rotation of the shaft 21 causes the roller bearing
A bracket 121 is connected to the outer surface of the
ends 85 of the ratchet arm 77 to engage in the ratchet
valve 1116 and a lever 122 is pivotally supported on the
bracket 121 by a pivot 123. The lever 122 is provided
with a forked end 124 which straddles the upwardly pro
mit-ted to drop faster than is allowed by the speed of
rotation of the hoist drum shaft 21. Stated otherwise, 65 jecting extremity 125 of the valve rod 113. A spring
126 encircles this projecting portion 125 of the valve rod
the clutch housing 71} may rotate only as fast as the sup
and the spring extends between the forked end 124
porting shaft 21 and the engagement of the ratchet arms
of the lever and adjusting nuts 127.
into the pockets 71 prevents rotation of the other portion
The lever 122 is loosely pivoted at 129 to a clamp 130
of the clutch at a greater speed. As a result, the speed
70 which is secured by a set screw 131 or other suitable
of lowering of the boom is de?nitely controlled.
teeth or pockets 71 and as a result the boom is not per
It will be seen that when the ratchet clutch 65 is en
gaged, the boom will lower at a controlled speed as soon
as the control lever 12 is moved rearwardly in order to
means to the operating rod 15 on the lever 12.
Thus,
when the rod 15 is pressed downwardly to disengage the
lever 12 from its central position, the lever arm 122 is
relieve the pressure on the brake band 43, assuming that 75 swung in a clockwise direction, compressing the spring
126 and raising the valve head 114 against the lower end
3,077,984
8
of the sleeve 111, and then raising the sleeve 111 with the
valve rod 113.
In normal position, the source of partial vacuum is cut
off through the passage 117 by the sleeve 111. The valve
scribed the principles of construction and operation of
my boom control devices for cranes, and while I have
endeavored to set forth the best embodiments thereof, I
desire to have it understood that changes may be made
within the scope of the following claims without depart
head 114, which is of smaller diameter than the sleeve
ing from the spirit of my invention.
111, is unseated below the lower end of the sleeve 111.
The valve rod 113 is externally grooved or ?ts loosely
I claim:
1. A safety device for a crane having a boom, a drum
within the sleeve 111, so that atmospheric air may enter
the valve body through the sleeve 13.1 and about the
rotatable in two directions, a power shaft, :1 pair of shafts
valve head, replacing air withdrawn by the suction line 10 driven by said power shaft, clutch engageable with one
119 and equalizing air pressure on opposite sides of the
of said shafts to rotate said drum in one direction, brake
piston 97. The piston 97 is accordingly normally held
means associated with said ?rst clutch and releasable to
permit rotation of said drum in the opposite direction,
in retracted position by the spring 164. ‘In this position,
a second clutch engageable with the other of said shafts
the ratchet clutch 65 is disengaged.
When the push button 17 is depressed, urging the operat 15 and connected to said drum to control rotation thereof
ing rod downwardly to disengage the lug 16 from the
in said opposite direction, a manually operable control
lever connected to said ?rst named clutch means and
notch 14 preparatory to raising or lowering the boom,
the lever arm 122 is pivoted in a clockwise direction from
said brake means and movable from a neutral position
the position illustrated.
This action acts through the
into position to selectively control the operation thereof,
spring 126 to raise the valve stem 113 until the valve
head 11-’!- seats against the lower end of the sleeve 111.
This action closes the vent passage about the stem 1E3.
an operating lever connected to said second clutch to 0p~
from the valve body, the conduit 116, and the portion
of cylinder 92 to the left of the piston 97. The greater
named means comprises a fluid actuated means.
air pressure on the right of the piston 97 then moves the
named means comprises a ‘fluid actuated means connected
crate the same, means releasably holding said control
lever in neutral position and means operable upon release
of said holding means for said control lever to engage
Further upward movement of the stem 113 moves the
sleeve 111 upwardly, opening the passage 117 leading to
said second clutch.
2. The structure of claim 1 and in which said last
the source of partial vacuum. Air is then withdrawn 25
3. The structure of claim 1 and in which said last
piston to the left, compressing the spring 104. Move
to said operating lever and a valve controlling the ?uid
ment of the piston 97 acts through the rod 99 and link 30 supply thereto, said valve being actuated by release of
said holding means for said control lever.
101 to shift the clutch operating lever 87 into position
4. The structure of claim 1 and in which said last
to engage the clutch 65.
named means includes a vacuum cylinder connected to
While the movement of several elements are involved,
said operating lever to actuate the same and a valve
in actual practice the action takes place almost instan
taneously. By the time the push button is fully de 35 acutated by release of said holding means for said con
trol lever connected to said cylinder to control the ?ow
pressed, the clutch lever is shifted. This is important, as
of ?uid therefrom.
it is essential that the clutch be engaged before the oper
ating lever is swung into boo-m lowering position. The
5. A safety device for a crane having a boom, a drum
spring 104 is only strong enough to overcome the effect
rotatable in two directions, a power shaft, a pair of shafts
of friction, as instantaneous release of the clutch 65 is 40 driven by said power shaft, a first clutch means engage
unessential. The suction lines are purposely large, so
able with one of said shafts to rotate said drum in one
that quick action is obtained. During the time the operat
direction, brake means associated with said clutch and
ing lever is out of neutral position, the valve is held open
to the suction supply by the engagement of the lug 16
with the segment 13.
In some instances a shallow notch may be formed in
the segment 13 to hold the operating lever 12 in an ex
treme' position. The depth of this added notch, however,
is insuihcient to permit the closing of the passage 117 by
releasable to permit rotation of said drum in the oppssite
direction, a second clutch engageable with the other of
said shafts and connected to said drum to control rotation
thereof in said opposite direction, a manually operable
control lever connected to said ?rst named clutch means
and said brake means and movable fro-m a neutral posi
tion into position to selectively control the operation
50 thereof, an operating lever connected to said second
clutch to operate the same, lever latching means on said
When the operating lever 12 is returned to central
the sleeve 111.
position, the lug 16 engages the notch 14, swinging the
control lever locking said control lever in neutral posi
lever 122 into normal position. The sleeve 111 slides
downwardly to close the passage 117 to the partial
lluid line controlled by said valve, and a ?uid actuated
vacuum source.
The valve stem 113 then disengages
the valve head 114- from its seat against the lower end
of the sleeve 111, and air is drawn into the valve about
the stem 113, ?owing into the cylinder 92 to equalize
pressure on opposite sides of the piston 97. The spring
104 then returns the piston 97 to normal position, dis
tion, a valve connected to said lever latching means, a
means connected to said fluid line and attached to said
operating lever to move said operating lever and to en
gage said second clutch upon release of said lever latching
means.
6. The structure of claim 5 and in which said ?uid
60 line is connected to a source of partial vacuum when
engaging clutch 65.
said valve is opened.
Thus, it will be seen that as long as the boom is being
raised or lowered, the clutch 65 will be engaged. As
soon as the operating lever 12 is returned to its central
7. The structure of claim 5 and including resilient
means normally biasing said operating lever toward clutch
disengaging position.
8. The structure of claim 5 including a source of par
position, the clutch 65 will be disengaged. Thus, the 65
tial vacuum connected to said ?uid line when said valve
objectional clatter caused by the ratchet clutch is
is opened, an air inlet open to atmosphere into said valve
when said valve is open, said valve closing said air inlet
upon actuation of said lever latching means.
by vacuum as a source of partial vacuum is usually ac
9. In a crane, a power-driven hoist shaft, a rotary
cessible, it is obvious that air pressure or hydraulic pres 70
cable drum adapted to be driven by said shaft, a brake to
sure could be employed in a very similar manner. The
control the rotation of said drum, a clutch upon said
main feature of the invention lies in the automatic control
eliminated.
While I have described the system as being operated
hoist shaft operable to couple said hoist shaft and said
of the ratchet clutch when the operating handle 12 is
drum, a lever hinged at one end to a stationary support
moved.
In accordance with the patent statutes, I have de 75 on said crane, and secured to the clutch at a point re-’
3,077,964
moved from the hinged end thereof, spring means posi
tioned between ‘the lever and a stationary part of the
crane and acting upon the lever to maintain the clutch
in disengaged position, a cylinder mounted upon a sta
tionary part oi the crane and including a piston-rod
therein, said rod extending axially of the cylinder into
contact with the lever at a right angle thereto, a ?uid
line leading to the cylinder to supply ?uid under pressure
to push the rod outwardly against said lever, a manual
brake control, a normally closed valve in said ?uid line, 10
a valve control means mounted upon the manual brake
control operable to open said valve to pass ?uid through
10
the ?uid line to engage the clutch and to maintain the
said valve open during the operation of the brake.
References Cited in the ?le of this patent
UNITED STATES PATENTS
1,460,813
Harris ________________ __ July 3, 1923
1,579,903
Yungling _____________ __ Apr. 6, 1926
2,445,116
2,501,198
2,681,205
2,914,303
Huston ______________ __ July
Wagner et a1. ________ __ Mar.
Bannister et a1. _______ __ June
Holmes _____________ _- Nov.
13,
21,
15,
24,
1948
1950
1954
1959
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