US3258248A - Ratchet plunger - Google Patents

Description

June 28, 1966 1... w. LERCH ETAL RATCHET PLUNGER 2 Sheets-Sheet 1 Filed June 22, 1964 INVENTORS LOREIV UV- LEPCH ALLAN E- El-DR/DGE BY HENRY 7..JAKU80WSK/ gm, @W,@u0 4*6 A TTORNEYS June 28, 1966 L. w. LERCH ETAL RATCHET PLUNGER 2 Sheets-Sheet 2 v -n 5 ..H 7. 4

Filed June 22, 1964 m m w m EN WLERCH AN E. ELD NRY 7: JAK

ATTORNEYS United States Patent 3,258,248 RATCHET PLUNGER Loren W. Lerch, Buffalo, Allan E. Eldridge, Williamsville,

and Henry T. Jakubowski, North Tonawanda, N.Y.,

assignors to Columbus McKinnon Corporation, Tonawanda, N.Y.

Filed June 22, 1964, Ser. No. 376,677 3 Claims. (Cl. 254-167) This invention relates to hoist or puller mechanisms and pertains in particular to certain improvements in pawl mechanisms therefor.

Light duty chain hoist or puller mechanisms which are manually actuated by means of a ratchet handle may be made of light weight, economical cost and relatively fool-proof design by employing a reaction member which forms part of a brake mechanism, the reaction member being in the form of a ratchet wheel which, when blocked by an associated pawl, will hold the load by maintaining the frictional grip of the brake mechanism. Because the aforesaid pawl which is associated 'with the reaction member or ratchet wheel must be withdrawn from operative engagement in order to allow the mechanism to be free running (as, for example, to take up chain slack), such pawl must be provided with some convenient mechanism for withdrawal and for locking it in such withdrawn position. conventionally, this is accomplished by simply extending the pawl to provide an external portion in the form of a knob, suitable locking means being provided to respond to withdrawal and turning of the knob. In operation of such devices, as the load is raised, the pawl is repeatedly reciprocated as the ratchet wheel is turned and, due to the aforesaid external exposure of the pawl, the mechanism is propensed to the introduction and build up of foreign material which may ultimately block the pawl from returning into engagement with the ratchet wheel. This, of course, presents a definite safety hazard since such a position of the paWl establishes the free running condition of the mechanism and will permit the load to be dropped suddenly and unexpectedly. It is, therefore, of primary concern in connection with this invention to provide an improved pawl mechanism for such assemblies which will substantially eliminate the possibility of pawl blockage as'aforesaid.

More specifically, it is an object of this invention to provide a pawl mechanism as aforesaid which is of two piece construction, comprising an inner portion acting directly upon and reciprocated by the ratchet wheel, and an external portion which remains motionless during such reciprocation of the inner portion; the outer portion serving to protect the assembly against the entrance of foreign material and to furnish means whereby the pawl assembly may be withdrawn and locked temporarily in the free running position.

Other objects and advantages of the invention will appear from the description hereinbelo-w and the accompanying drawing wherein:

FIG. 1 is a view, partly in section, illustrating a chain hoist mechanism having the improved pawl assembly according to the present invention associated therewith;

FIG. 2 is an enlarged transverse sectional view taken substantially along the plane of section line 2-2 in FIG. 1 and showing the reaction ratchet wheel and pawl assembly associated therewith;

FIG. 3 is a view similar to FIG. 2 but showing the pawl assembly in the withdrawn position;

FIG. 4 is a transverse sectional view taken substantially along the plane of section line 4-4 in FIG. 2;

FIG. 5 is a transverse sectional view taken substantially along the plane of section line 55 in FIG. 2;

FIG. 6 is a transverse sectional view taken substantially along the plane of section line 6-6 in FIG. 3;

FIG. 7 is an elevational view showing the pawl assembly-in the locked, withdrawn position;

FIG. 8 is a transverse sectional view taken substantially along the plane of section line 88 in FIG. 7; and

FIGS. 9 and 10 are perspective views of the outer and inner portions of the pawl assembly respectively.

With reference at this time more particularly to FIG. 1, the chain hoist or puller mechanism shown therein will be seen to include a frame or body 10 provided with a hook 12 or other suitable means for anchoring or mounting the assemblage. The body 10 is provided with aligned bushings or bearings 14 and 16 for journalling a lift wheel shaft therewithin, the portion 1'8 of the shaft being received in the bushing 14 and the portion 20 of the lift wheel shaft being received in the bushing 16. Between these two portions 18 and 20 of the shaft is provided a lift wheel 22 of conventional form which is preferably formed integrally with the shaft mechanism itself and which, as is conventional, presents a plurality of chain link pockets within which the links of the load chain indicated generally by the reference character 24 are adapted to be received for controlled raising and lowering of the associated load. The shaft is also provided with an integral brake plate portion 26 and an extension 28 provided with a retaining nut 30 thereon which serves as an abutment member .for the cam block 32 which is suitably [fixed for rotation with the shaft extension 28 as by a key 34 or the like. Disposed adjacent the cam block 32 is the brake plate portion 36 of a motion-transmitting ratchet wheel 38. The ratchet wheel 38 is provided with a central opening by means of which it is journalled on the cam block 3-2 and the contiguous faces of the brake plate 36 and the cam block 32 are angled in a direction axially with respect to the shaft extension 28 as indicated by the parting face portions 40 and 42 so that relative rotation between the ratchet wheel 38, and consequently the brake plate 36, and the cam block 32 will shift the motion-transmitting ratchet wheel assembly and its brake plate 36 axially of the shaft 28. In response to such axial shifting of the motion-transmitting ratchet wheel mechanism, a reaction ratchet wheel 44 is sandwiched between the brake plates 26 and 36, intervening friction plates 46 and 48 being provided to enhance the frictional engagement so that, in effect, the reaction ratchet wheel 44 will be locked with the shaft 28. Normally, however, the reaction ratchet wheel 44- is mounted so as to be freely rotatable on the shaft portion 28, as for example by the provision of hearing means 50 as shown.

The above mechanism is entirely conventional and is identical with the mechanism shown for example in Patent 2,608,107 issued August 26, 1952. In the operation of the device, the motion-transmitting handle 52 operates to rotate the motion-transmitting ratchet wheel 38 in stepby-step fashion through the action of the pawl 54 carried thereby. If, for example, the load is being raised, the handle 52 will be manipulated in a direction opposite to the direction in which the load chain 24 reacts against the lift wheel shaft and, as a consequence, the cam surfaces of the members 36 and 32 maintain the frictional grip on the reaction member 44 to rotate with the shaft 28 to a new position wherein it is held by its associated pawl assembly, hereinafter described. When the load is being lowered, the pawl 54 of the handle mechanism 52 is reversed so as to permit rotation of the motion-transmitting ratchet wheel 38 in the opposite direction from load lifting direction and as soon as the handle 52 is manipulated, the camming action between the entities 32 and 36 is instantaneously overcome'so as to loosen the grip of the mechanism on the reaction ratchet wheel 44 to thus permit the load wheel shaft to rotate a slight amount cor responding to the angular movement of the handle 52 and consequently lower the load. Thus, when the load is being lowered, theshaft 28 continually catches up with the brake plate36 and particularly the cam surface thereof to re-establish the frictional grip on the reaction ratchet wheel 44. Thus, during either raising or lowering, it is the reaction ratchet wheel 44 which holds the load in any given position when the handle 52 is not being manipulated. However, there are times at which it would be desirable to permit the load 'chain 24 to be free running as for example when slack is to be taken up and, in order to do this, the pawl mechanism associated with the reaction ratchet wheel 44 must be withdrawn from its engagement therewith so as to permit free wheeling of the lift wheel shaft assembly. For this reason, the plunger which is associated with the reaction ratchet wheel 44 must be provided some external means for manipulating such pawl to a withdrawn position relative to the reaction ratchet Wheel 44. However, as has been stated hereinabove, such requirement has, heretofore, necessitated that the pawl assembly associated with the reaction ratchet wheel 44 be exposed to the introduction of foreign material which may ultimately impair its operation and create a safety hazard in connection with the device since it is this pawl which is responsible for holding the position of the reac tion ratchet wheel 44 and thereby preventing sudden release of the load.

The pawl assembly according to the present invention can be seen more clearly in FIG. 2. In this figure, it will be seen that the pawl assembly according to the present invention includes an inner portion 60 and an external portion 62, mutually cooperating with each other so as to minimize the danger of accidental blockage of the pawl mechanism as set forth hereinabove. The frame or body 10 is provided with a boss portion 64 having a bore 66 therethrough within which the inner portion 60 of the pawl mechanism is reciprocably received. The boss 64 is also provided with a counterbore 68 slidably receiving the shank portion 70 of the external portion 62 of the pawl mechanism and it will be seen that this shank portion 70 as well as the head portion 72 of the external portion 62 are provided with a bore which is, in effect, a continuation of the bore 66 of the boss 64 and which bore in the external portion 62 also reciprocably receives the inner portion 60 of the pawl assembly. The knob or head portion 72-of the external portion 62 is provided with a counterbore 74 which provides clearance for the inner portion 60 so that the same may reciprocate Within the external portion 62 as the reaction ratchet wheel 44 is rotated without imparting any motion to the external portion 62.

The boss 64 is provided with diametrically opposed lugs 75 carrying a cross pin member 76 which extends through elongate side wall slots 78 .in the inner portion 60 and in the stemportions 80 of L-shaped slots in the external portion 62, see particularly FIG. 9. The external portion 62 is provided with notches 77 which normally receive the lugs 75 allowing the latter to cover the stem portions 80 of the L-shaped slots so as to prevent the entry of foreign material as aforesaid. The outer 'end of the portion 60 is provided with a flange 82 adapted to be engaged by the shoulder 84- provided for by the counterbore 74 in the knob portion 62 so that if the external portion 62 is withdrawn to the position shown in FIG. 3, the inner portion 60 will likewise be withdrawn to a position clearing the reaction ratchet wheel 44 substantially as is shown. A suitable compression spring 86 is seated in the bottom of a recess 88- in the inner portion 60 and against the cross pin 76 to normally urge the inner portion 60 into engagement with the reaction wheel 44 substantially as is shown in FIG. 2. When, however, the external portion 62 is withdrawn as shown in FIG. 5, a slight turning of this external portion will cause the leg portion 90 of the L-sha-ped slots to receive the cross pin 76 and the lugs 75 to turn clear of the notches 77 thus locking the pawl assembly in the position of FIG. 3 to establish the load lift mechanism in the free running condition. The locked position of the component parts is illustrated in FIG. 7.

Preferably, the shank 7 0 of the external portion 62 is grooved and provided with an O-ring or other suitable compressible ring as indicated by the reference character 92 which not only seals off the assembly from the entrance of foreign material at this point but also serves to provide a cleaning action as will be evident. In prior art constructions, the entire plunger is reciprocated as the reaction ratchet wheel 44 is rotated so that the region 96 and the stem portions of the L-shaped slots, see particularly FIG. 3, are frequently and periodically exposed to the introduction of and accumulation or build up of foreign material which might ultimately cause the plunger mechanism to be blocked or maintained in the withdrawn position, .thus creating a safety hazard as has been set forth hereinabove, However, with the mechanism according to this invention, the external portion 62 is not reciprocated as the ratchet wheel 44 is rotated and as a consequence the region 96 and the slot portions 80 are only infrequently exposed and only at such times as the external portion is Withdrawn as shown in FIGS. 3 and 7.

It is to be understood that certain changes and modifications as illustrated and described may be made without departing from the spirit of the invention or the scope of the following claims.

We claim:

1. In a load lift mechanism having a body, a shaft journalled in said body and having a lift wheel thereon, a brake plate fixed to said shaft, a motion-transmitting ratchet wheel rotatably and slidably received on said shaft, a reaction ratchet wheel journalled on said shaft between said brake plate and said motion-transmitting ratchet wheel, cam means acting between said shaft and said motion-transmitting ratchet wheel to shift said motion-transmitting ratchet wheel along the shaft to frictionally lock the brake plate, the reaction ratchet wheel and the motion-transmitting ratchet wheel together in response to relative rotation between the shaft and said motion-transmitting ratchet wheel, handle means including a pawl for imparing step-by-step rotation of said motion-transmitting rat-chetwheel, and a pawl assembly carried by said body and engageable with said reaction ratchet wheel,

said pawl assembly being of two piece construction, an

inner portion engageable with said reaction ratchet wheel and adapted to be reciprocated thereby, and an external knob portion within which said inner portion is reciprocable, said portions having abutment surfaces whereby the outer portion may be partially withdrawn to free the inner portion from engagement with said reaction ratchet wheel.

2. In a ratchet hoist mechanism,

a frame provided with anchoring means,

a lift wheel shaft journalled in said frame and having a lift wheel thereon,

a ratchet wheel adapted to turn with said lift wheel shaft,

and a pawl assembly reciprocably mounted in said frame for engagement with said ratchet wheel, said pawl assembly including an external knob having a hollow head and a hollow shank defining a bushing, and an inner portion reciprocable within said bushing and having a nose engaging said ratchet wheel.

3. In a ratchet hoist mechanism,

a frame provided with anchoring means,

a lift Wheel shaft journalled in said frame and having a lift wheel thereon,

a ratchet wheel adapted to turn with said lift wheel shaft,

5 6 and a pawl assembly mounted in said frame, said pawl References Cited by the Examiner assembly including an inner portion engageable with YUNITED STATES PATENTS said ratchet wheel and adapted to be reciprocated 5 thereby, and an external knob portion within which 117811936 11/1990 swehzlen said inner portion is reciprocable, said portions hav- 5 2,519,400 8/1950 Robins 254-167 ing abutment surfaces whereby the outer portion may I be partially withdrawn to free the inner portion from EVON BLUNK Exammer' engagement with said reaction ratchet wheel. H. C. HORNSBY, Assistant Examiner.

Claims (1)

1. IN A LOAD LIFT MECHANISM HAVING A BODY, A SHAFT JOURNALLED IN SAID BODY AND HAVING A LIFT WHEEL THEREON, A BRAKE PLATE FIXED TO SAID SHAFT, A MOTION-TRANSMITTING RATCHET WHEEL ROTATABLY AND SLIDABLY RECEIVED ON SAID SHAFT, A REACTION RATCHET WHEEL JOURNALLED ON SAID SHAFT BETWEEN SAID BRAKE PLATE AND SAID MOTION-TRANSMITTING RATCHET WHEEL, CAM MEANS ACTING BETWEEN SAID SHAFT AND SAID MOTION-TRANSMITTING RATCHET WHEEL TO SHIFT SAID MOTION-TRANSMITTING RATCHET WHEEL ALONG THE SHAFT TO FRICTIONALLY LOCK THE BRAKE PLATE, THE REACTION RATCHET WHEEL AND THE MOTION-TRANSMITTING RATCHET WHEEL TOGETHER IN RESPONSE TO RELATIVE ROTATION BETWEEN THE SHAFT AND SAID MOTION-TRANSMITTING RATCHET WHEEL, HANDLE MEANS INCLUDING A PAWL FOR IMPARING STEP-BY-STEP ROTATION OF SAID MOTION-TRANSMITTING RATCHET WHEEL, AND A PAWL ASSEMBLY CARRIED BY SAID BODY AND ENGAGEABLE WITH SAID REACTION RATCHET WHEEL, SAID PAWL ASSEMBLY BEING OF TWO PIECE CONSTRUCTION, AN INNER PORTION ENGAGEABLE WITH SAID REACTION RATCHET WHEEL AND ADAPTED TO BE RECIPROCATED THEREBY, AND AN EXTERNAL KNOB PORTION WITHIN WHICH SAID INNER PORTION IS RECIPROCABLE, SAID PORTIONS HAVING ABUTMENT SURFACES WHEREBY THE OUTER PORTION MAY BE PARTIALLY WITHDRAWN TO FREE THE INNER PORTION FROM ENGAGEMENT WITH SAID REACTION RATCHET WHEEL.

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