US 2264012 A
Description (OCR text may contain errors)
Now-25,1941. R. B. wAssoN 2,264,012
' POWER WRENCH Filed March 20, 1940 alumn /1144a? JW/ Patented Nov. 25, 1941 UNITED STATES PATE POWER WRENCH Robert B. Wasson, Cranford, N. J., asslgnor to General Motors Corporation, Detroit, Mich, a
- corporation of Delaware Application March 20, 1940, Serial No. 324,898 3 Claims. (CI. 81-54) The invention relates to improvements in power operated wrenches, and may in general be considered as an improvement on that disclosed in Ernest H. Shafi Patent No. 2,119,968 issued June 7, 1938. This Shaft patent discloses a wrench embodying a socket at one end which is rotated by a power actuated pawl, engageable with a circular series of ratchet teeth on the socket periphery. Though this wrench has met with marked success, it has one definite limitation, namely, that it can be applied only endwise of a nut, bolt or the like, which is to be turned. In other words, it cannot be moved laterally into engagement with the member to be turned, in the manner of a so-called open end wrench. Furthermore; merely cutting an entrance opening or throat in the side of the socket, to make it an open end type, will not solve the problem. for then the series of ratchet teeth would be interrupted by the entrance opening and the device rendered inoperative as soon as the driving pawl came into registry with the opening. Accordingly, one aim of the present invention is to provide a power driven wrench having the attributes of ruggedness and simplicity characteristic of the wrench of the Shafi patent, but embodying a novel power driving arrangement for rotating a socket having an entrance opening in one side so that it can be applied to a part, which is to be turned, in the manner of an open end wrench.
Another object is to provide a power wrench having a rotatable socket, with an entrance opening in its side and a peripheral series of ratchet teeth interrupted at the opening, together with a plurality of pawls, power driven in timed relation, and arranged to insure a positive drive for the socket in all rotary positions of the latter.
Another object is to provide means to split the power impulse driving the rotatable socket into vectors of opposite direction so that the power thrust will be converted to a torque couple;
This is desirable because manufacturers of power wrenches have in the past, devised wrenches in which the power vector was in one direction. They proved impractical in use because the supporting members with their necessarily limited bearing surface rapidly wore under this one direction load.
The invention also resides in various structural improvements and combinations of parts by means of which simplicity and low cost of production are combined with effectiveness and versatility of operation and use.
Further objects and advantages-of the invention will become apparent as the following descriptlon proceeds, taken in connection with the accompanying drawing in which:
Figure 1 is a general perspective view illustrating the use of a power wrench embodying the invention; Figure 2 is an enlarged partial plan view of the wrench shown in Figure 1; Figure 3 is a longitudinal sectional view substantially along the line 3-3 in Figure 2; Figures 4, 5 and 6 are a series of fragmentary stop motion views showing successive positions of the pawls and ratchet teeth during rotation of the socket; and Figure 7 is a partial longitudinal sectional view similar to Figure 3, of a modified form of power wrench embodying the invention.
While the invention is susceptible of various modifications and alternative constructions, I
have shown in the drawing and will herein de scribe in detail the preferred embodiment, but it is to be understood that. I do notthereby in-' tend to limit the invention to the specific form disclosed, but intend to cover all-modifications and alternative constructions falling within the spirit and scope of they invention as expressed in the appended claims.
In the first embodiment of the invention selected for illustration (Figure l) the wrench shown includes a cylindrical-socket l0 rotatably journaled in the yoke shaped jaw ends of a pair of thin side plates H. ,The shank portions of these side plates receive between them a spacer web or septum I2 projecting from the nose of a cylindrical housing l3, to the outer end of which is screwed the casing l4 of a power unit I5 (Figure 3). The unit l5 embodies a suitable power means such as a pneumatic motor, power being supplied from this motor, through the medium,
of a novel drive mechanism described more par,- i
ticularly below, for rotating the socket I 0.
It will be observed that the socket ID has a longitudinal entrance opening I6 (Figure 3) in its side. A so-called open end is thus formed for the wrench through which a device to be turned, such as the coupling I! in Figure 1, may be inserted. vantageous ere the device to be turned is such that the socket cannot be engaged with it by movement longitudinally of the member. For example, the coupling I! in Figure 1 is threaded at its opposite ends on rods I 8 so that only an open end type of wrench can be applied to it. The present wrench thus has the versatility peculiar to a. hand operated wrench of the open end type and yet has all of the advantages of a full power operated device. The interior of the socket ID has been shown as being of hexagonal This is, of course, particularly adconfiguration and the usual adaptors (not shown) may be inserted in it to'accommodate nuts or the like of diilerent diameters or shapes.
To drive the socket III, a pair of motor driven pawls i9 and 20 are arranged to engage a series of ratchet teeth 2| (Figure 3) rigid with the periphery of the socket. The series of ratchet teeth is c-shaped, rather than annular, because of the interruption in them necessitated bythe entrance opening IS in the socket. In general, the pawls l9 and 20 are reciprocated in opposite vectors to each other and in timed relation by the power unit l5 and are engageable with the ratchet'teeth at points spaced apart circumferentially of the socket a greater distance than the width of the entrance opening it so that the teeth are engaged by at least one pawl in all rotational positions of the socket (see Figures 4, 5 and 6).
The lower pawl i9 is of the pusher type while the upper pawl 29 is of the puller type, being provided with a hook shaped end for engaging the ratchet teeth 2|. These pawls are longitudinally reciprocable in corresponding grooves defined between the side plates ii at the lower and upper edges, respectively, of the central web [2. The pusher pawl I9 is yieldably urged upward into engagement with the ratchet teeth by a leaf spring 22 screwed to the housing l3. Similarly, the puller pawl is yieldably urged into engagement with the ratchet teeth by a second leaf spring 23 hearing against it and mounted on a U-shaped bracket 24 which is fixed to and embraces the inner ends of the side plates H (see Figure 1).
To connect the pusher pawl l9 in driven relation with the motor in the power unit i5, an open face barrel cam 25 is provided, which is rigid with the end of the motor shaft 26, the latter being joumaied in suitable anti-friction bearings 21 in the inner end of the casing i 4 (Figure 3). Coacting with this cam 25 is a cam follower roller 28 journaled on a pin 29 in the bifurcated inner end of the pusher pawl l9. It will be observed that the inner end of the pin 29 extends laterally from the pawl and has fixed on it a projection 30 receiving the end of a helical compression spring 3|. The latter is located in a longitudinal bored recess 32 in the housing l3 and yieldably urges the pin 29, to the right (as viewed in Figure 3) to retain the cam follower roller in engagement with the cam. As the motor shaft 29 rotates the pawl I9 is pushed longitudinally outward as the roller 28 rides up on the lobes or high points of the cam 25. and the pawl is then reciprocated inward in the opposite direction by the compression spring 3| as the roller rides into the low points on the cam. Since the inner portion of the pawl I9 is held loosely in position by the leaf spring 22 its necessary downward tilting or pivotal motion is permitted so that the pawl nose can pass over the ratchet teeth 2| during the return motions of the pawl.
The other, or puller pawl 29 is driven from, and in timed relation with, the pusher pawl l9.
For this purpose a rocker 33 is pivoted in a transverse opening 34 in the housing web l2 on a transverse'pin 35. Incidentally, this latter pin, as well as a second transverse pin 36 serve-to secure the side plates II in place. The rounded ends of the rocker 33 are received respectively in slots 31 and 33 in the pawls i9 and 20.
As the pusher pawl I9 is thrust outward by the cam 25 the puller pawl is simultaneously drawn inward by the rocker 33, so that the two pawls act simultaneously to advance the ratchet 2| a distance of slightly more than one tooth for each reciprocation of the pawls.
By using pusher and puller pawls, as distinguished from, say, two pusher pawls, it is possible to assure positive actuation of both pawls during their power strokes even though they are driven from an open faced cam and are spring returned. Thus the pusher pawl I9 is positively thrust outward by the cam, during its power stroke, and simultaneously the puller pawl 29 is positively drawn inward. It is only during their return strokes, when no torque is applied to the ratchet, that the spring 3| moves the pawls.
To prevent inadvertent reverse rotation of the series of ratchet teeth 2|, a back-up pawl 39 is utilized. This pawl is block shaped in form and is longitudinally slidable between the side plates II. A pair of compression springs 40, located in parallel bores in the outer end of the housing web i2, yieldably urge the back-up pawl into engagement with the ratchet teeth 2|. Two abutments or teeth 4| and 42 are provided on the back-up pawl. The upper tooth 4| is of rectangular configuration and the lower tooth 42 triangular so that they will conform to the angular positions of the ratchet teeth faces presented to them in the manner shown. The pawl teeth 4| and 42 are spaced apart a distance slightly greater than the width of the entrance opening IS in the socket l0 so that even when the socket is rotated to present this opening toward the back-up pawl 39', at least one of the latters teeth will always be in engagement with the ratchet teeth. By looking the socket against reverse rotation with such a back-up pawl, the device can be used effectually as a hand wrench when the motor is idle.
In the operation of the power wrench described the socket III is initially located with its entrance opening I6 in registry with the corresponding openings in the ends of the side plates II (as shown in Figure 3) so that the socket can readily be slipped over a device to be turned, such as the coupling I! (Figure 1). Having engaged the wrench socket with the coupling, the operator starts the motor of the power unit l5 thus starting rotation of the motor outlet shaft 29. The resultant rotation of the cam 25 reciprocates the pusher pawl I9, as heretofore described, and at the same time the puller pawl 23 is reciprocated in the opposite direction, through the medium of the connecting rocker 33. In this way a strong torque is applied to the socket III at generally diametrically opposite points about its periphery. Even when the socket entrance opening I3 is in registry with one or the other of the pawls 9 and 20 (Figures 5 and 6) the other pawl is always in engagement with the ratchet teeth so that the drive is not interrupted nor seriously impaired and a continuous rotation of the socket is insured.
In Figure 7 a modified form of power wrench has been shown which is in general very similar to that of Figures 1 to 6, inclusive, except that a somewhat different arrangement has been provided for reciprocating the pawls. In the present instance both of them are driven directly from the cam instead of using an intermediate connection from one pawl to the second, and in addition, the pawls are positively returned by the cam rather than by a spring means. The same reference numerals have been used for identical parts and, accordingly, their description need not again be detailed.
In this modified construction, the pawls l9 and 20 correspond to the pawls l9 and 20 in Figure 3 and are similar in construction to them except that there is no cross linkage but, instead, each pawl is provided with a cam follower 28 rotatable on a pin fixed to the inner end of its pawl. These cam follower rollers are received in the peripheral groove of a barrel cam 25. Consequently, as this cam is rotated by the power unit- [5, the pawls l9 and 20 are positively advanced and retracted in timed relation.
The supporting structure is much the same as that previously described, with changes as are necessary to accommodate the differently shaped cam, cam followers, etc. A cylindrical housing l3 is threaded on the end of the motor casing M, as before, and the barrel cam 25- is received in the interior of this housing. A thin shank or projection l2 on the housing has fixed to its opposite sides the side plates II, by pins 35 and 36, and the socket I0 is rotatably journaled in the yoke shaped ends of these side plates. The pusher and puller pawls I9 and 20 are yieldably retained in position in the grooves defined on the opposite sides of the supporting structure shank by leaf springs 22* and 23*. In this instance, both of these leaf springs are screwed directly to the housing l3 and overlie the respective pawls.
From the foregoing, it will be seen that wrenches embodying the present invention afford the extreme flexibility of use and applicationheretofore peculiar to hand operated open end wrenches, and yet, have all of the advantages of positive power actuation.
1. A power wrench of the open end type comprising, in combination, an elongated body struc- V ture having a transversely extending socket rotatablysupported on one end thereof, said socket having 'a longitudinal opening in one side, an
annular series of ratchet teeth on the socketperiphery interrupted at the side vopening in the socket to leave the same unobstructed, elongated pusher and puller pawls longitudinally reciprocable on said body structure and engageable at their outer ends with said ratchet teethat generally diametrically opposite points, a cam follower on the inner end of said pusher pawl, a rotatable cam engageable with said follower, a power unit on said body structure for rotating said cam, a spring yieldably urging said pusher pawl longitudinally away from said teeth and into engagement with the cam, and means including a transverse rocker link pivoted intermediate its ends on said body structure and engaged at its opposite ends with said pawls for actuating said puller pawl in timed relation with the reciprocation of said pusher pawl.
2. A power operated wrench including a power actuated motor, a forwardly projecting shank fixed at one end to the motor, a rotatable socket mounted in the opposite end of the shank and provided with an annular series of ratchet teeth, a pusher rod slidable in a guide slot in one face of the shank and engageable at one end with said ratchet teeth and drive connected at its other end with said motor, a puller rod slidable in a guide slot in the opposite face of the shank and engageable at one end with said ratchet teeth, and a rock lever pivoted within, a transverse slot in the shank and engageable at opposite ends with intermediate portions of the two rods.
3. In a power hand wrench, a power motor having a forwardly projecting shank and an open end socket rotatable in the nose of the shank and provided with peripheral ratchet teeth, a pair of ratchet tooth engaging rods slidably guided on opposite faces of the shank, and arranged to engage ratchet teeth spaced apart a distance greater than the width of the socket opening, drive means between the motor and one of said rods and a rock lever pivotally mounted in the shank and engaged at opposite ends with said rods for transmitting motion from the motor driven rod to the other rod.
ROBERT B. WASSON'.