US2772763A - Ratchet wrench - Google Patents

Description

W. J. JOHNSON RATCHET WRENCH Dec. 4, 1956 2 Sheets-Sheet 1 Filed Jan. 12, 1951 INVENTOR.

mwmmm Wdifer f Jvizizsm BY @402 W. J. JOHNSON RATCHET WRENCH Dec. 4, 1956 I 2 Sheets-Sheet 2 Filed Jan. '12, 1951 mm s I v RATCHET I Walter J. Johnson, Butfalo, N. Y., assignor to ,J. H. Willianls & Co., Buffalo, N. Y., a corporation of New York Application January 12, 1951, Serial No. 2 (l5 ,'6 2 d 4 Claims. (Cl. 19243.1)

My. present invention relates to ratchetrnechanis'ims and aims to provide certain improvcments'ther'ein. More particularly it relates to ratchet wrenches of the type in which a driving member carriedby a handle is opera-1 tively connected with a rotatable head or driven member by a. pawl and ratchet mechanism, externally, manually man pula'table means being provided for quickly effecting a reversing action for the wrench. v 4 I In'wrenches of the type set forth, the driving member usually comprises a handle which is formed with an enlarged hollow head having internal teeth, and the driven member comprises a work-engaging head having one qr in'o re pawls for coacting with the teeth in thedriving member whereby an oscillatory movement of the driving member operates to rotate the driven member in a clock: i f wl terc'l k b d r t d n r n. the set position of the pawl or pawls. In order to obtaina 'fine ratchet action with such wrenches the pitch of the teeth must be very small, thus necessitating the driving member being formed with a large number of intern al teeth, a construction which is not only costly to produce but one which renders the teeth weak because of their :small pitch.

, An object of the present invention is to provide a ratchet wrench of thegeneral type set forth wherein the adyan- :tages of a fine-toothed ratchet wrenchis obtained without reducing the pitch or increasing the number of the internal teeth in thedriving member. V v

A furthe r object of the invention is to provide a wrench oflthe character set forth wherein apositive mechanical. shift .of, the pawls is relied upon to manually reverse the .operation of the wrench. v

A further object of the invention is to providea ratchet wrench with a plurality of multiple-toothed pawls which :are so proportioned and correlated in relation tothe 'teeth on the driving member, to compensate for wear on. the. teeth and to obtain a fuller contact of the teeth under deflection of ,the power-applying head of the wrench and, under such deflection, to also provide partial engagement for the normally partially engaged pawl and? itherebyabs'orb part of the torsional load and thus reduce the stressesin the fully engaged pawl.

. A. still further object of the invention is .to generally improve and simplify the construction of ratchet wrenches :tolren'der. them more e'flicient in use. I

. The-foregoing and other objects of my invention notv zs'p'ecifically enumerated I accomplish by providing .a 'ratchet wrench, comprising a driving member having an internally toothed wall and a driven member, which car-. ries a plurality of oscillatable pawls, the teeth of which: :are. so formed and correlated to the'internal teeth inthe driving member that a multiple ratchet action will result, "i. .e., .a'ratchet action equivalent to that provided by a .multiple of .thenumber ofteeth in-the driving. member. Suchzmultiple ratch'eta'ction is preferably obtained-by em'-- ploying a..-pair of substantially diametrically opposed *mu'lti-toothed pawls pivotally mountediii the driven me'mbertfor coaction with the teeth in the driving member,

2,772,753 Patented Dec. 4, 1956 I h on'oneof the pawls being disposed for ith the'tleethon the driving member, while U ther pawl are offset substantially A N in re tion ito the teeth on the driving member; ;,me ns being provided for biasing the pawl te htoward engaging position with'the teeth in the d rivin "member. Theinvention as. a whole as well the va ous novel'elements and combinations will be better uh need frijrn the detailed description which f'o o when considered in connection with the ac.- cornpanylng idrawings'showing a preferred embodiment, d. whe n Figured is a top plan view of a ratchet wrench emy yj r 15 Fig. 23s sectlonal View taken along the plane of the qz z. a Fi -J.

'e ional view taken along the plane of the "F gif W fractionaltopiplanview of the wrench head, part theregf being jbrolgen away to better illustrate the relationship of parts thereof.

l i g. is a 'sect'onal mew taken substantially alongthe 25 l ne g, t w'ls'b 'ng disposed in a position to elf e'ct kwise rotation 0 th driven :inemberr J H v I V v ilar to Fig. 6 .shoiving' the v pawls d spos'edinj neutral ppsition to permit the driving er to be freely rotated either clockwise or counterrelative to the driven member. v "Ref ring to the rawing's in the various figuresof same ref ence'characters are employed todesthereference numeral .1 0 is ihg diameters 1 14, lflq, 1 5 alndj 1 6 providing shoulders 40 11;p 18 andhl9 between the; bore';portions .13 and H i I M 4a and 15, ,and and 16,.respectively. The b'ore portion 13 is internally'threaded to provide s c rew threads 13 ar'1dj the bore portion-14a is formed .t .h1t. eet v Th 1 0, n-v the driving member of the ratchet ihgat its lower end a work-engaging head or shank 23 prpj'epting throughthebore portion 16 and having a socket 2 4 within .Which is usuallyv mounteda spring-impelled ball detent,(not shown); Therunner is formed with an axial recess 25 extending inwardlyfrom its top andwith a pair of drilled recesses 26 and 27,' t'he axes of which are disp' d the plane of a diameter of the runner and at equal radlal distances from the axis thereof. Also formed in thetop face of the'runner is a recess 28 for accommodatingrastop ball 29,-the'function of which will be'hereinafterexplained. The runner 'is also formed withsegmental slots 30 and 31' which intersect the recesses 25, 26 and 27, at right angles, which slots terminate in parallel ch'ordal walls which are equally spaced from a d'ia'rn'etrieal 'pIan leaving diametrically disposed portion 3 2aiid 33 in the nature of supports connecting theiipper and lower portions of the runner. The corners of said supporting members '3'2'and 33 whereat t hey intersect the cehtral'rcess 25 are'cha'mfered, as shown at 34, and the ir'inereiids' of said supports form parts of the wall of said" dle having a, hand-gripping axial recess 25. The gland 22 is formed with recesses 22a for accommodating a spanner.

Pivotally supported on shafts 35 and 36 mounted in the recesses 26 and 27, respectively, are a pair of substantially sector- shaped pawls 37 and 38, respectively, which are double ended and symmetrical with respect to their pivotal supports. Preferably the pawls are formed with a plurality of teeth at each end for coaction with the teeth 20 in the head, the teeth on the pawl 37 being designated 39, 39', and the teeth on the pawl 38 being designated 40, 40'. The inner end of each pawl is con: stituted by a generally flat central surface 41 and merging curved end surfaces 43. The pawls 37 and 38 are mounted in diametrically opposed relation and the teeth on the corresponding ends of the pawls are selectively normally urged or biased toward engaging position with the teeth in the driving member by spring-pressed means, hereinafter described, mounted in a shifter bolt 44.

The shifter bolt 44 has a lower cylindrical portion 44a of a diameter corresponding to the diameter of the axial recess 25 in the runner, said cylindrical portion being cut away along parallel chordal planes to provide opposite flat faces 44b, between which faces it is formed with a through transverse cylindrical opening 440 within which is disposed a helical spring 45 which presses a pair of balls 46 radially outward in opposite directions against the inner ends of the pawls 37 and 38. Above the cylindrical portion 44a the shifter bolt is formed with an annular flange 47 which rests on the top face of the runner 21 with which it is held in rotatable engagement by an overhanging central flange 48 on the gland 22, said flange 48 also serving to hold the ball 29 in its recess 28. The flange 47 is partially cut away along a chordal plane 49, as best shown in Fig. 5, for a purpose which will be presently explained. Directly above the flange 47 the shifter bolt has a portion 50 of reduced diameter which is also cut away along the same chordal plane 49. Projecting upwardly from the portion 50 the shifter bolt is of reduced diameter and formed with a left-hand screw-thread 51 which is engaged by a manually operable shifter 52, herein shown as being of cruciform shape to facilitate finger manipulation thereof. The shifter 52 is secured to the shifter bolt by a screw 53 having a right hand thread engaging in a tapped hole 54 in the top of the shifter bolt, said screw having an enlarged head 55 seating within a recess 56 in the shifter 52.

In order to obtain a fine ratchet action for the wrench without increasing the number of internal ratchet teeth 20 in the head 12, I preferably employ an odd number of teeth in the head and mount the pawls 37 and 3-8 in diametrically opposed relation so that when the teeth on one end of one of the pawls are in engagement with the ratchet teeth in the head, for example, when the teeth 39 on the pawl 37 (Fig. 6) are in substantial engagement with the teeth 20 in the head 12 of the driving member, the corresponding teeth 40 on the pawl 38 will be offset substantially one-half pitch in relation to the teeth on the driving member; and vice versa when the teeth 40 on the pawl (Fig. 7) are in substantial engagement with the ratchet teeth 20, the corresponding teeth 39' on the pawl 37 will be offset substantially one-half pitch in relation to the teeth 20. Accordingly, in the use of the wrench, when the handle is drawn back to again engage the teeth of the pawl after having rotated the driven member through an arbitrary angular distance, the teeth on the driven member may engage the teeth on either of the pawls 37 or 38 depending on whether the back angular stroke of the handle is stopped at a point of tooth engagement between the teeth 20 and the teeth on pawls 37 or 38. The same principle of operation can be accomplished by employing an even number of teeth on the driving head in conjunction with diametrically opposed unsymmetrical oscillating pawls the teeth of which on the corresponding ends of the pawls are staggered one-half pitch; or where more than two pawls are employed, by pivotally mounting them in substantially equal angular spaced relation on the driven member about the axis thereof, with the teeth on successive angularly spaced pawls progressively offset in relation to the teeth on the driving member an amount equal to the tooth pitch of the teeth on the driving member divided by the number of pawls.

In the operation of the ratchet wrench let it be assumed that it is desired to apply a rotative force to the driven member in a clockwise direction. To do this the shifter 52 is manually turned in a counterclockwise direction until the chordal surface 49 engages the stop ball 29, as shown in Fig. 5. This action rotates the shifter bolt 44 in a counterclockwise direction in the course of which the lateral flat faces 44b of the shifter bolt engage and move the pawls about their pivot shafts 35, 36 while the springpressed balls 46 exert a radial outward force again-st the inner end surfaces 41 and 43 to urge the teeth on one end of one of the pawls into engagement with the teeth inthe driving head and the corresponding teeth on the other pawl toward the teeth on the driving head, but only into partial engagement with said teeth because of the one-half pitch offset between said teeth on said latter pawl and the driv-. ing member. When it is desired to reverse the operation of the wrench, the shifter is moved in a clockwise direction until such movement is stopped by engagement of the chordal surface 49 with the stop ball 29, as shown in phantom in Fig. 5. In view of the symmetrical form of the pawls and the absence of teeth between the toothed ends thereof, it will be apparent that when the shifter is in an intermediate position between its stop limits, the teeth on neither end of the pawls will be in engagement with the teeth in the driving head and, under said condition the driving head may be freely rotated in either direction relative to the driven member without imparting rotation to the latter.

The formation of the teeth on each pawl end are so proportioned to compensate for wear and thereby obtain fuller contact under deflection of the driving member head, runner and shafts; also under deflection and wear, the partially engaged pawl teeth 40 in Fig. 6 and 39' in Fig. 7 more fully engage the teeth in the head and absorb part of the primary torsional load which reduces the stresses in the fully engaged members. The tooth formation on the pawl-s and their disposition whereby under deflection and wear they will more fully engage the teeth in the driving head, follows the teaching with respect to said parts as disclosed in United States patent to Kress, No. 1,957,462, May 8, 1934. Under normal stress, the back face of the inoperative sides of the pawl'does not contact the body of the driven member .but is spaced slightly therefrom as will be apparent from an inspection of Figs. 6 and 7. Under such condition the direction of shear in the pawl shaft is substantially parallel to the flat faces on the parts 32 or 33 of the driven member. Under severe stress and deflection of the pawl, the back face of the inoperative sides of the pawl abuts the fiat faces on the parts 32 or 33 which then prohibits the pawl from further rotation on its shaft axis. In this position all additional forces tending to rotate the pawl are absorbed by bending of the pawl, a change in direction of shear in the pawl shaft and a compressive stress in the body of the driven member by contact therewith of the end at the back face of the inoperative side of the pawl. It will also be seen from Figs. 1, 5, 6 and 7 that the internal teeth in the driving head are eccentrically disposed in said head so that the thickness of the head is smallest at the end of the center line of the handle and progressively increases toward the juncture of the head with the handle, a construction which also contributes toward influencing the engagement of the teeth on the pawl and in the head caused by flexing of the handle in use. Also, the gland 22 is recessed at 22b, 22c to form a bearing for the driven member 21, which bearing, in addition to maintaining axial alignment of the driven member separate from the body (which is distorted under stress) serves as a reinfOICiQment of the upper flange of the driven member to.

interrupt and reduce the expanding forces of the flange at the pawl shaft journals, which forces otherwise would be transmitted directly to the unsupported mouth of the cup-shaped head 12.

From the foregoing detailed description it will be understood that I have provided a ratchet wrench which accomplishes the various objects of my invention as set forth in the opening part of this specification and, although I have specifically illustrated and described a single embodiment of my invention, the same is to be considered as merely exemplary and not in a limitative sense, since changes therein may be made within the scope of mechanical and engineering skill without departing from the spirit of my invention as defined in the appended claims.

What I claim is:

1. In a ratchet mechanism, the combination of a driving member having an internally toothed wall, a driven member rotatively mounted in the driving member, two double-ended, multi-toothed pawls journaled on shafts substantially diametrically opposite each other mounted in the driven member and parallel to the axis thereof for selective coaction with the teeth on the driving member, the teeth on one end of one of the pawls being normally in engagement with the teeth on the driving member while the teeth on the corresponding end of the other pawl are offset one-half tooth pitch in relation to the teeth on the driving member, resilient means biasing the pawls to the aforementioned positions, a shifter bolt rotatably and coaxially mounted in the driven member and supporting the resilient biasing means, manually operable means for rotating the shifter bolt to selectively engage the teeth on one end of the pawl with the teeth in the driving member and the teeth on the corresponding end of the other pawl into offset relation, the shifter bolt having integral abutments for mechanically engaging and moving the pawls about their shafts, for reversing the operation of the wrench, when the shifter bolt is manually rotated, the driven member having a hub formed with segmental slots therein to provide pairs of flanges within which the shafts of the pawls are journaled, and a recessed gland mounted in the top of the driving member providing a bearing for the driven member and serving as a reinforcement for the upper flanges to interrupt and retard the expansive forces of the upper flanges at the pawl-shaft journals, which forces otherwise would be transmitted directly to the driving member.

2. In a ratchet mechanism, the combination of a driving member having a bore the wall of which is formed with axially extending teeth, a driven member having a hub rotatably mounted in the bore of the driving member, said hub having segmental slots formed therein perpendicularly to the axis, said slots terminating in chordal walls, a double-ended, multi-toothed pawl in each of said slots journaled on a shaft parallel to the axis of the driven member with the axes of said shafts disposed in equal angular spaced relation at the same radius from the axis of the driven member, said pawl-s being mounted for selective coaction with the teeth on the driving member, resilient means biasing the corresponding ends of the pawls toward engaging position with the teeth on the driving member, one end of at least one of the pawls under normal stress being in engagement with the teeth on the driving member while the back face of the inoperative end of said pawl is slightly spaced from the chordal wall of the slot, and wherein under severe stress and deflection of said pawl, the back face of the inoperative end of said pawl will abut said chordal Wall of the slot, whereby all additional forces tending to rotate the pawl will be absorbed by bending of the pawl, a change in direction of the shear in the pawl shaft, and a compressive stress in the body of the driven member by the contact therewith of the back face of said inoperative end of said pawl with the driven member.

3. A ratchet mechanism according toclaim 2 wherein the driven member has two segmental slots each somewhat smaller than a semi-circle with the chordal walls of the slots parallel and equally spaced from a diametrical plane passing through a wall provided between the chordal wall surfaces and perpendicular to a diametrical plane passing through the pawl shafts.

4. In a ratchet mechanism, the combination of a driving member having an internally toothed wall, a driven member rotatively mounted in the driving member, two double ended, multi-toothed pawls journaled on shafts substantially diametrically opposite each other mounted in the driven member and parallel to the axis thereof for selective coaction with the teeth on the driving member, resilient means biasing the pawls to urge the corresponding ends thereof into engagement with the teeth on the driving member, a shifter bolt rotatably and coaxially mounted in the driven member and supporting the resilient biasing means, manually operable means for rotating the shifter bolt to selectively engage the teeth on the corresponding ends of the bolts with the teeth in the driving member, the shifter bolt having integral abutments for mechanically engaging and moving the pawls about their shafts for reversing the operation of the wrench when the shifter bolt is manually rotated, the driven member having a hub formed with segmental slots therein to provide pairs of flanges within which the shafts of the pawls are journaled, and a recessed gland mounted in the top of the driving member providing a bearing for the driven member and serving as a reinforcement for the upper flanges to interrupt and retard the expansible forces of the upper flanges at the pawl-shaft journals, which forces otherwise would be transmitted directly to the driving member.

References Cited in the file of this patent UNITED STATES PATENTS 1,307,485 Cunha June 24, 1919 1,957,462 Kress May 8, 1934 2,013,765 Richardson Sept. 10, 1935 2,020,883 Gagne Nov. 12, 1935 2,103,556 Rueb Dec. 28, 1937 2,126,843 Tintera et a1 Aug. 16, 1938 2,188,846 Rueb Jan. 30, 1940 2,395,681 Odlum et a1 Feb. 26, 1946 2,537,175 Viets Jan. 9, 1951 2,543,509 Sandberg Feb. 27, 1951 2,544,795 Knudsen Mar. 13, 1951 2,571,939 Pfauser Oct. 16, 1951 2,591,993 Aijala Apr. 8, 1952 FOREIGN PATENTS 729 Great Britain Feb. 19, 1881

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