US3163400A - Hoist - Google Patents

Description

G. A. SKERRY Dec. 29, 1964 HOIST z Sheets-Sheet 1 Filed Sept. 25. 1961 INVENTOR A RNEY G. A. SKERRY Dec. 29, 1964 HOIST 2 Sheets-Sheet 2 Filed Sept. 25, 1961 GEORGE A. SKERRY INVENTOR United States Patent 3,163,400 HGEST George A. Sherry, Worcester, Mass, assignor to Lincoin Precision Machining (10., North Grafton, Mass.,a corporation of Massachusetts Filed Eiept. 25, 196i, er. No. 1443,51 6 Claims. ((31. 254-167) This invention relates to a hoist and more particularly to apparatus arranged to exert forces and lift loads through the medium of a cable or the like.

In the construction of winch hoists making use of the pawl and ratchet principle, devices known in the past have provided not only for lifting a load but also for rearranging the pawls so that the load may be lowered. It is a relatively simple matter to arrange for moving the load upwardly either one tooth at a time or a plurality of teeth at one time. The lowering operation for more than one tooth at a time is somewhat more difficult; for that reason, it has been common practice'to manufacture hoists of this kind capable only of lowering a load one tooth at a time. This small lowering increment makes it difiicult to lower a load speedily. On the other hand,

it is desirable that it be possible to lower the load one tooth at a time for close adjustment of load position. These and other difi'iculties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a hoist which may be lowered in increments as large as the increments by which it may be raised.

Another object of this invention is the provision of a hoist which may be lowered in small increments of movement or selectively in multiples of such increments.

It is another object of the instant-invention to provide a winch-type hoist using a toothed ratchet in which the load may be lowered either one tooth at a time or in a multiple of one tooth at a time.

A still further object of the invention is the provision of a winch hoist using a ratchet and double pawls in which most of the apparatus is compact and there is little danger of the operator being hurt by protruding mechanism.

It is a still further object of the present invention to provide a winch hoist which is compact and clean in external appearance, which is simple in constructon, which may be readily manufactured from easily obtained materialsgwhich is relatively free of maintenance problems, which has an open construction which may be readily inspected for clogging by an accumulation of dirt, and which may be easilycleaued, if dirty, by use of simple cleanng materials. a

A further object of this invention is the provision of a winch hoist having ratchet teeth wherein lowering may take place in increments of more than one tooth at a time.

Another object of the invention is the provision of a winch hoist of open construction that may be easily mspected for wear wthout disassembly and, if repair or replacement of parts becomes necessary, may be disassembled and re-assembled with simple tools.

It is a further object of the invention to provide a cable-type winch hoist in which a load may be lowered in small increments or" large increments, the increments being selectively determined.

Another object of the invention is the provision of a cable-type hoist capable of selective operation in lifting ceveral teeth at a stroke or lowerng several teeth at a stroke and characterized by the fact that a cam operates in the lowering condition to carry a locking pawl over several teeth of the ratchet before the pawl is released to engage the ratchet, wherein means is provided making 3,163,499 Patented Dec; 29, 1964 ICC it impossible for the cam to operate in this manner during the lifting operation.

Another object of the invention is the provision of a cable hoist in which free release is possible Without the operator placng his finger in the mechanism, such free release permitting unimpeded rotation of the ratchet when completely free of load and, therefore, permitting the operator to wind or unwind cable from the drum at a rapid rate when securing a load or after completing a load operation.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in combination of parts set forth'in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings in which:

FIG. 1 is a sectional View of a hoist embodying the principles of the present invention taken on the line I-I of FIG. 2; and 1 FIG. 2 is a sectional view of the invention taken on the line TIII of FIG. 1.

Referring to the drawings, the hoist indicated generally by the reference numeral 16, consists ofa main frame 11 through which extends a main shaft 12 on which are mounted a locking pawl cam 13, an actuating handle 14, and a drum 15. Also, mounted on the frame is a locking pawl 16 while an actuating pawl 20 is mounted on the actuating handle 14. The upper portion of the main frame is provided with an aperture 17 by which it may be suspended from a support such as a structural member of a building, and at the lower end the frameis provided with an aperture 18 for attaching the end of the cable when using a block to permit use of the bight of the-cable with the block in a well-known manner to have the cranking fare while halving the lifting speed.

In the description of the elements it will be assumed that the hoist is suspended in the position shown in FIG. 1 with the aperture 13 at the upper portion. It will be understood that, although the hoist can be used in other positions, the expressions horizontal, vertical,"up, and down, and the like will be used to indicate these relationships with the hoist suspended from the aperture 18 and the load pulling downwardly.

Extending through an aperture 19 in the drum 15 is a cable 21 from the lower end of which is suspended the load. The drum T5 is provided at one side with a flange 22 and at the other side with a ratchet 23. The ratchet is provided with teeth 24 each of which is provided with a sloping rear surface and a sharp forward surface which is inclined slightly to the radial to give a rake. The main frame 11 is provided with two vertical sides 25 and 26. The handle 14 is generally'U-shaped and is provided with a bight 27 and two legs 28 and 29. The leg 29 is rotatably mounted on the main shaft 12 outside of the side 26 t of the main frame 11, while the leg 28 is rotatably mounted on the main shaft between the flange 22' of the drum 15 and the side 25 of the main frame. The locking pawl cam 13 is rotatably mounted on the main shaft between the ratchet 23 of the drum 15 and the side 26; Suitable snap rings 3]. and 32 hold the elements in assembly on the shaft. A suitable extension would, in practice, he provided for the actuating handle 14, but for the sake of simplicity, this has been omitted. The locking pawl 16 is'mounted on a shaft 33 extending between the sides 25 and 26 of the main flame. The shaft passes through the center portion of the pawl and the pawl is provided with a stop finger 34 extending in one direction and a pawlengaging finger 35 which extends in the other direction. A pin 36 extends from the center portion ofthe finger 35 and a pin. 37 extends from the inner surface of the side 26 of the main frame; both of these pins are grooved and are engaged by the opposite ends of a spring 38 which is formed of wire which has been suitably heat treated to give it spring quality. The spring is provided with a small loop 39 which surrounds the pin 36 and at the other end with a small loop 41 which surrounds the pin 37. In the center portion the spring is provided with a large, generally circular loop 42. Between the large loop 42 and the small loop 41 the spring is provided with a generally straight portion 43. As is evident in FIG. 1, the straight portion 43 forms a junction with the loop portion 42 in the general area of the pitch line of the teeth 24 of the ratchet 23.

The locking pawl cam 13 has a low portion 44 and a high portion 45 which can be rotated under the loop 42 of the spring 38 by rotating the cam about the main shaft 12. The cam is provided with an elongated finger 46 which may strike the lower portion of the main frame 11 on occasion and which is provided with a narrow rounded outer end 47 for a purpose to be explained hereinafter. When the low portion 44 of the locking pawl cam is adjacent the loop 42, it does not contact it. When the loop 42 of the spring 38 is approached by the high portion 45 of the cam 13, the spring rides up on the cam surface for the full length of the selected travel and exerts pressure toward discngement of the locking pawl 16.

As has been stated above, the actuating pawl is pivoted in the handle 14; this pivoting takes place on a shaft 48 which is locked in place in the U-shaped handle a 14 by snap rings or the like.

mounted on the shaft and is retained in place on one side with a snap ring 51., Sandwiched between the snap ring 51 and the leg 29 of the handle 14 is the selector lever 49, the actuating pawl 20, a collar 52, and a washer 53.

The selector lever 49 is generally triangular shaped with the shaft 48 passing close to an apex; the other two apices lie on either side of the handle, and are provided with small horns 54 and 55, one or the other of which always engages an edge of the bight 27 of the handle. Midway between the horns 54 and 55 the selector lever is provided with a notch 56 which embraces a cantilever spring 57 one end of which is embedded in an abutment 58 formed in the handle. The free end of the spring 57 engages the collar 52 usually at one side or the other thereof. When the spring attempts to reside in the portion of the collar 52 which is closest to the abutment 58 the force of the spring against the collar is quite large so that there is a tendency for the spring to go over dead center and slide one side or the other of the collar. The portion of the actuating pawl 20 which extends from the opposite side of the shaft 48 from the tooth of the pawl is provided with semi-circular slots 59 and 61, the outer peripheries of which merge with horns 62 and 63, respectively. The side of the actuating pawl 20 which faces the collar 52 is provided with a boss 64 surrounding the shaft 48; this boss is partially cut away in the area of the horns 62 and 63 and the slots 59 and 61.. The actuating pawl 20, incidentally, is freely pivoted on the shaft 48, as is the selector lever 49.

A spring 65 is fastened to the cam 13 at one end and at the other end to the side 26 of the main housing; the spring tends to bias the cam to its position against the bottom of the main frame in the manner shown in FIG. 1.

The operation of the device will now be readily understood in view of the above description. In order to raise the load on the end of the .cable 21, it is necessary to rotate the drum 15 in a counter-clockwise direction, as shown in FIG. 1. in the position shown in FIG. 1 with the spring 65 holding it in such a way that only the low portion 44 of the cam is near the loop 42 of the spring 38. In this condition the loop holds the finger of the locking pawl 16 in position against the ratchet 23 and, as the drum is rotated, the pawl cams over the surfaces of the teeth 24. At the same time, the selector lever 49 is in the position A selector lever 49 is also For that purpose, the cam 13 remains shown in FIG. 1 with the horn 54 contacting the top of the bight 27 of the handle 14. The spring 57 extends through the notch 56 and the slot 59 of the actuating pawl and rests against the lower side of the collar 52 nesting against the end of the boss 64 which is adjacent the slot 59. In this condition of the mechanism the actuating pawl 20 is pressed against the ratchet, so that a downward or counter-clockwise movement of the handle 14 will, because of the engagement of the pawl with a tooth 24 of-the ratchet, cause the ratchet to rotate. During up strokes of the handle 14 the locking pawl 16 will press against a forward edge of the tooth 24 and will prevent clockwise rotation of the ratchet 23 while the pawl 20 is able to cam over the teeth one by one. In this way the drum may be raised one tooth or a plurality of teeth at a time depending on the arc subtended by the stroke of the handle. V

When it is desired to lower the load which is attached to the end of the cable 21, it is only necessary to press the selector lever 4 in the opposite direction so that the horn 55 rests against the lower edge of the bight 27 of the handle. The motion of the selector lever in thismanner causes the edges of the notch 56 to carry the spring 57 upwardly so that it passes over the position of the collar 52 which is closest to the abutment 58 and passes over dead center to the other side of the collar 52. When it does so, as it-passes over dead center it strikes the horn 63 and causes the pawl 20 to rotate slightly in a clockwise direction. The spring then rests in the slot 61 and on the top side of the collar 52. The operator then presses the outer end 47 of the can 13 to slide between the spring 57 and the upper surface of the pawl 20 in the area of the horn 63 and the slot 61. This locks the cam to the handle and causes it to move with the handle.

The finger may be moved'into position under the spring 57 either by moving the handle 14 downwardly until the spring 57 strikes the outer end 47 or the cam can be moved up and placed under the spring by the operator.

lowest position, the cam rotates and the low portion of the cam no longer lies adjacent-the loop 42 of the spring 38, but thehigh portion 45 comes into contact with it. This has the effect of relieving the spring bias on the locking pawl 16 and causing it to press away from the ratchet. However, as long as there is a load on the cable 21, the angle of the tooth. pressing against the finger 35 i of the locking pawl will hold the locking pawl in place,

and it cannot move radially outwardly of the ratchet wheel and cannot release the ratchet wheel, despite the fact that not only is there no spring tension in the spring 38 to cause the pawl to move inwardly toward the ratchet, but there is actually a positive pressure to move it away from the teeth. The actuating pawl 20, of course, has been moved and held by the spring 57 in a position outside of the circle of the teeth 24 of the ratchet; therefore, it does not engage any of the teeth. However, as the handle is moved to its lowest position, the actuating pawl eventually comes into contact with the straight portion 43 i of the spring 38. This straight portion acts as a cam to ,pull the pawl downwardly toward the teeth; at the same time, the spring is compressed. Eventually, then, the actuating pawl will contact the leading edge of one of the teeth 24, will take over the load from the locking pawl 16, and will draw the ratchet teeth away from the locking pawl 16. The angle on the leading edge of the tooth no longer presses against the locking pawl to prevent it from moving outwardly so that it then rotates clockwise. The clockwise motion carries it outside of the outer circle of the teeth, but the motion is limited by the stop finger 34 striking the pin 37. The handle is then raised, carrying the ratchet clockwise and lowering the load. The locking pawl 16 remains out of the tooth circle until the handle 14 reaches a high enough position for the loop 42 of the spring 38 to move off the high portion 45 of the cam and move into the low portion 44, at which time the spring is free to draw the locking pawl inwardly again. Eventually, then, the leading edge of a tooth will strike the finger 35 of the locking pawl and relieve the actuating pawl 29 of the load. However, the number of degrees subtended by the high portion 45 is selected to give the lowering action a motion of four teeth or some similar large number.

If it seems to be desirable to lower the load one tooth at a time, as in positioning a load during its final stages of lowering, it is possible to do this by moving the selector lever $9 in the manner described so that the horn 55 contacts the lower edge of the bight 27 of the handle. This carries the spring 57 over to its position on the upper side of the collar 52, as has been described. However, the cam 13 is left in its normal position as shown in FIG. 1 and is not connected to the handle. The spring 57 holds the actuating pawl 26 away from the teeth, however, so that it is possible to move the handle through most of the stroke without engaging any teeth. However, eventually, in moving toward the low position of the handle the actuating pawl 28 strikes the portion 43 of the spring 35 and this will not only have the etfect of bringing the pawl downwardly for engagement with the forward edge of the tooth but will also compress the spring 38 in such a way that the spring pressure will tend to make the locking pawl 16 move away from the teeth when the actuating pawl 29 strikes a tooth and takes over the load. The locking pawl 16 will then be free to move away from the teeth, and it does so. Then, the handle is raised under load to carry the loaded ratchet and drum 15 with it. However, very slight movement of the handle in this clockwise direction causes the actuating pawl to move away from the straight portion 43 of the spring 38 so that the spring again acts to draw the locking pawl in toward the ratchet. However, at that time the leading edge of a tooth is not immediately available for contact with the finger 35 of the locking pawl. Before very long, however, as the handle with the actuating pawl moves an angular distance of about one tooth, the finger 35 of the locking pawl does contact the forward edge of a tooth 24 and prevents further action. The instant that the load is owed by the locking pawl 16 in this way a slight further motion of the handle 14 causes the actuating pawl to be relieved of the forward edge of its tooth. This is because it was only held in position against the teeth by the angle on the forward edge of the tooth, and because it had left the straight portion of the spring behind and that straight portion was the only element which held the actuating pawl inwardly. Therefore, the minute the locking pawl takes over the load, the actuating pawl moves away from the forward edge of its tooth and is no longer restrained against the outward motion in which it tends to take part because of the pressure of the spring 57. Operation in this way, therefore, will cause the lowering to take place one tooth at a time.

Several advantages of this hoist should be noted. For instance, when the selector lever 42* is in the lifting position (as shown in FIG. 1) it is impossible for the spring 57 to engage and lock the locking pawl cam 13 to the handle 14. This means that the cam cannot possibly hold the locking pawl 16 out of engagement with the ratchet during the raising operation. This, of course, contributes to safe operation. Another advantage of this hoist is that it is capable of so-called free release without it being necessary for the operator :to place his fingers in the mechanism. This is done by placing the handle at a position midway between the top and bottom of its stroke and also placing the selector lever in the rapid lowering position with the horn 55 contacting the bight 27 of the handle; in this condition of the mechanism, the drum is free to rotate in either direction, since both pawls are disengaged from the ratchet wheel. This can,

of course, place only when the cable and drum are free of load, since otherwise, one of the pawls would be locked by the rake or the ratchet teeth.

It is obvious that minor changes may be made in the a locking pawl pivotally mounted on the main frame in position to engage and hold the ratchet wheel, a spring normally maintaining the locking pawl in engagement with the ratchet, an actuating pawl pivotally mounted on the actuating handle in position to engage and rotate the ratchet wheel, and a cam engaging the locking pawl spring for lifting the locking pawl during part of the letdown motion of said handle, thereby permitting the ratchet wheel to be automatically rotated selectively in increments of a fixed plurality of teeth in lowering a load.

2. A hoist, comprising a main frame, a drum rotatably mounted on the frame, a ratchet fixed to the drum, a handle pivotally mounted on the main shaft, a locking pawl pivotally mounted on the main frame in position to engage and hold the ratchet, a loop spring normally maintaining the locking pawl in engagement with the ratchet, an actuating pawl pivotally mounted on the handle in position to engage and rotate the ratchet, an overcenter spring associated with the actuating pawl capable of occupying either of two positions, the latter spring in one position biasing the actuating pawl toward engagement with the ratchet and in the other position away from engagement with the ratchet, and a cam engaging the loop of the locking pawl spring and moving the locking pawl away from engagement with the ratchet to permit the ratchet wheel to be automatically rotated selectively in increments of a plurality of teeth in lowering the load, the cam having an engaging finger that may be attached on occasion to the handle for rotative movement therewith.

3. A hoist, comprising a main frame, a drum rotatably mounted on the frame, a ratchet having teeth with rake fixed to the drum, a handle pivotally mounted on the main shaft, a locking pawl pivotally mounted on the main frame in position to engage and hold the ratchet, a loop spring normally maintaining the locking pawl in engagement with the ratchet, and the actuating pawl pivotally mounted on the handle in position to engage and rotate the ratchet, a cantilever spring associated with the actuating pawl capable of occupying either of two positions, the latter spring in one position biasing the actuating pawl toward engagement with the ratchet, and in the other position away from engagement with the ratchet, and a cam selectively rotatable with the handle engaging the loop of the locking pawl spring and moving the locking pawl away from engagement with the ratchet to permit the ratchet to be automatically rotated in increments of a plurality of teeth in lowering a load, the cam having an elongated finger that may be attached on occasion to the handle for the rotative movement of the cam with the handle, the locking pawl spring having a portion adapted to force the actuatingpawl inwardly into engagement with the ratchet in spite of the cantilever spring being in the said other position.

4. A hoist, comprising a main frame, a drum rotatably mounted on the frame, a ratchet having teeth with rake fixed to the drum, a U-shaped actuating handle having the free ends of its legs pivotally mounted on the main shaft, a locking pawl pivotally mounted on the main frame in position to engage and hold the ratchet, a loop spring normally maintaining the locking pawl in engagement with the ratchet wheel, an actuating pawl pivotally mounted on the shaft of the actuating handle in position to engage and rotate the ratchet, a shaft on which the actuating pawl is mounted extending from leg to leg of the handle, a cantilever spring fixed at one end to the handle and pressing at the free end on a collar mounted on the actuating pawl shaft, the latter spring residing in a small angle to the last-named shaft and pressing against the collar, the spring in one position biasing the actuating pawl toward engagement with the ratchet and in the other position away from engagement with the ratchet, and a cam compressing the loop of the locking pawl spring and biasing the locking pawl toward movement away from engagement with the ratchet to permit the ratchet to be automatically rotated in increments of a fixed plurality of teeth in lowering a load, the cam having an elongated finger that may be inserted on occasion between the actuating pawl spring and the actuating pawl for rotative movement of the cam with the handle, the locking pawl spring having a portion adapted to force the actuating pawl inwardly into engagement with the ratchet wheel in spite of the cantilever spring being in the said other position.

5. A cable hoist, comprising a main frame, a drum rotatably mounted onthe frame, a ratchet having teeth with rake fixed to the drum, a handle pivotally mounted on the main shaft, a locking pawl pivotally mounted on the main frame in position to engage and hold the ratchet, a spring normally maintaining the locking pawl inengagement with the ratchet, an actuating pawl pivotally mounted on the handle in position to engage and rotate the ratchet wheel, a shaft on the handle on which the actuating pawl is mounted, a cantilever spring fixed at one end to'the handle and pressing at the other end on a member mounted on the actuating pawl shaft, the latter-spring residing at a small angle to the last-named shaft and pressing against the member, the latter spring in one position pressing the actuating pawl toward engagement with ratchet wheel and in another position away from engagement with the ratchet wheel, and a cam rotatably mounted on the main shaft and compressing the locking pawl spring for moving the locking pawl away from engagement with the ratchet when said locking pawl 0 i3 is relieved of its load to permit the ratchet to be automatically rotated in increments of a fixed plurality of teeth in lowering a load, the cam having a member fastenable to the handle on occasion for rotative movement of the cam with the handle, the locking pawl spring having a portion adapted to force the actuating pawl inwardly into engagement with the ratchet in spite of the cantilever spring being in the said other position.

6. In a rapid lowering winch adapted to move a load comprising a supporting frame, a cable drum, a ratchet 1 wheel rotatable with said drum and having a plurality of ratchet teeth, an operating lever associated with said drum, a lever pawl pivotally secured to said lever, a lever pawl spring for biasing said lever pawl in a chosen direction, a holding pawl pivotally secured to said frame, a holding pawl spring biasing said holding pawl into normal ratchet engaging position, said holding pawl spring, ratchet teeth and the free end of said lever pawl being arranged in alignment, said holding pawl spring being adapted to be acted upon by said lever pawl to bias said holding pawl away from its normal ratchet engaging position, and restraining means for rapid lowering associated with said holding pawl to prevent said holding pawl from being again normally biased by said holding pawl spring for a predetermined limited rotation under load of said ratchet wheel of at least two of said ratchet teeth thereby to restain said holding pawl from its normal ratchet engaging position for said predetermined rotation of at least two of said ratchet teeth.

References Cited in the file of this patent UNITED STATES PATENTS 475,376 Appleby May 24, 1892 1,340,322 Brown May 18, 1920 1,435,176 Pecker Nov. 14, 1922 2,407,397 Carhart Sept. 10, 1946 2,633,328 Wallace Mar. 31, 1953 2,645,106 Lambach July 14, 1953 2,741,927 Hollander Apr. 17, 1956 2,793,535 Stump May 28, 1957 2,913,224 Uhlig Nov. 17, 1959 2,967,046 Ratclitf Jan. 3, 1961 2,978,224 Moseley et a1. Apr. 4, 1961

Claims (1)

1. A HOIST, COMPRISING A MAIN FRAME, A DRUM ROTATABLY MOUNTED ON THE FRAME, A RATCHET WHEEL FIXED TO THE DRUM, AN ACTUATING HANDLE PIVOTALLY MOUNTED ON THE MAIN SHAFT, A LOCKING PAWL PIVOTALLY MOUNTED ON THE MAIN FRAME IN POSITION TO ENGAGE AND HOLD THE RATCHET WHEEL, A SPRING NORMALLY MAINTAINING THE LOCKING PAWL IN ENGAGEMENT WITH THE RATCHET, AN ACTUATING PAWL PIVOTALLY MOUNTED ON THE ACTUATING HANDLE IN POSITION TO ENGAGE AND ROTATE THE RATCHET WHEEL, AND A CAM ENGAGING THE LOCKING PAWL SPRING FOR LIFTING THE LOCKING PAWL DURING PART OF THE LETDOWN MOTION OF SAID HANDLE, THEREBY PERMITTING THE RATCHET WHEEL TO BE AUTOMATICALLY ROTATED SELECTIVELY IN INCREMENTS OF A FIXED PLURALITY OF TEETH IN LOWERING A LOAD.

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