US2491325A - Releasable screw driver - Google Patents

Description

Dec. 13, 1949 v G. E. McvEY 2,491,325

RELESBLE SCREW DRIVER I Filed Jan. 22, 1945 I ,20v ,JN

Patented Dec. 13, 1949 UNITED STATES PATENT CFFICE RELEASABLE SCREW DRIVER Gerald McVey, Columbus, liio Application January 22, 1945, Serial No. 573,843

4 Claims. l

This invention relates to screw drivers and has for its object to provide a novel type of screw driver in which the shank of the screwengaging bit element is rotatably mounted in. the receiving socket therefor provided in the handle member, there being a spring-pressed clutch device. arranged between the bit element and one of the walls of the handle member socket operative upon the application of a predetermined rotating force to the handle member to release the bit element to preclude rotation thereof until such rotating force is diminished.

In the ordinary screw driver, the shank of the bit element is iixed to the handle member to rotate in unison therewith under all conditions. Under certain conditions of screw driver usage, this conventional Vconstruction is undesirable'. Often, when too great a rotating force is applied to a screw driver when threading a screw into an applied position, the force so eX- ercised results in damaging the work into which the screw is being driven. Therefore, the present invention provides a screw driver in which the bit element thereof is-formed with a bore adapted for the reception ci a springmressed ball, a portion of the latter being normally seated in a socket or depression provided in the handle member of the tool, the spring-pressed ball acting as a slip clutch in uniting the bit element with the handle member, in that when rotating forces are applied to the handle member below a given value, the bit element will rotate in unison with said handle member, but when such forces reach or exceed said value, the clutch-like ball is displaced from its normally seated position, allowing the handle member Vto turn freely with respect to the bit element and thereby interrupting rotation of the latter.

For an undersanding of other objects and advantages of the invention, reference is to be had to the following description and accompanying drawings, wherein:

socket l, in which is tightly driven a metallic sleeve t, one end of the latter being closed as at Q while the other end thereof is formed with an annular outwardly extending ange i9, the outer face of the latter being formed with a substantially semicircular depression i l.

The bit element provides a shank IZ, the outer portion of which terminates in a screw-engaging extremity I3 shaped to enter the head slots of standard or special type screws. The lshank l2, intermediately of its length, is provided with an enlarged head it, which is annularly` flanged as at i5 for engagement with the flange Il) of the socket l, and beyond thek head ifi the bit element includes a cylindrical extension i6 which is received in the bore of the sleeve 8, the end of the extension I6 preferably engaging with an anti-friction thrust bearing il confined in the sleeve 3 adjacent to the closed 9' thereof. The bit element is held in connection with the handle member by providing the latter with a .errule in, thek latter having one end thereof formed with an inturned circular flange ES which receives and confines the `fia-nge it oli-.hc bit ele-i nient head Hi. The ferrule is non-rotatablysecured tothe flange portion it' of thesleeve il' by means of one or more set screws, shown at To rotatably unite the handle `ir-.er-.iber 5 with the bit element iso that the same normally rotate together,but to permit the handlernembei to rotate independenti?,-7 of the bit element when predeterminedtorque eiort is applied thereto, the head M of the bit element is lfoi ed with a diagonally extending bore El intersecting the longitudinal axis thereof. Adapted to be. re ceived in the, inner end ci this bore is a mica-'- able clutch ball 22. A part of this ball is normaily seated in the` depression H of the sleeve iiange Ell. and to maintain the ball thus seated.

se is made of an expansion type coil spring 23, the latter being positioned in the bore 2i, with one end engaging the ball 22 and the oppcsite end in contact with a slidabie plunger 2li. One or more set screws 2% are threaded irthe outer end of the bore 2i, and through adjustment of these screws, the desired degree of spring pressure may be exerted on the ball 22.

From the foregoing, it will be seen that the.

present invention provides a torque-type screw driver which is adapted for use in the same manner as a conventional screw driver having the bit element and handle members immovably united. However, with the screw driver formed as above described, it will be evident that when a predetermined amount of rotating energy is. imparted to the handle member, the ball 22,

that the principles thereof are applicable to` tools driven by electric motors or the like.

Having thus described my invention, I claim: 1. A safety slip clutch comprising a driving member formed at one end with an axially disposed socket, a sleeve stationarily positioned in said socket, said sleeve being closed at one end and having its opposite end formed with a laterally directed annular flange, a driven element having ashank extension rotatably received within said sleeve, a thrust bearing positioned between one end of said extension and the closed end of said sleeve, said driven element being formed intermediately of its length with a flanged head enlargement, the flange of said eniargement being disposed for engagement with the iianged end of said sleeve, a ferrule removably secured to said sleeve and cooperative with the flange of said driven element enlargement to retain said element in connection with said driving member, said enlargement being formed with a bore diagonally intersecting the longitudinal axis of the enlargement, a ball device positioned in one end of said bore for engagement with a, depression provided in the anged end of said sleeve, an eX- pansion spring positioned in said bore for maintaining said ball device normally in engagement with said depression, and threaded means positioned in said bore for regulating the force exercised by said spring on said ball device.

2. A safety slip clutch comprising a driving member formed at one end with an axially disposed socket, a driven element having a shank extension rotatably received Within said socket, said driven element intermediately of its ends being formed with a head enlargement having a bore diagonally intersecting in its length the longitudinal axis of the driven element, a ball device positioned in said bore for engagement with a depression provided in said driving member to cause rotation of the driven element in unison with said driving member upon predetermined torque conditions, a spring positioned in said bore in engagement with said ball device, threaded means positioned in said bore for varying the force exercised by said spring on said ball device, and a ball-type ythrust bearing arranged between said shank extension and the closed end of said driving member socket, said bearing relieving said ball device of thrust loads.

3. A safety slip clutch comprising a driving member formed at one end with an axially disposed socket, a driven element having a shank extension rotatably received Within said socket, said driven element intermediately of its ends being formed with a head enlargement having a bore diagonally intersecting in its length the longitudinal axis of the driven element, a ball device positioned in said bore for engagement with a depression provided in said member to cause rotation of the driven element in unison with said driving member under determined torque conditions, a spring positioned in said bore in engagement with said ball device, and threaded means positioned in said bore for varying the force exercised by said spring on said ball device.

4. A safety slip clutch comprising a driving member formed at one end With an axially disposed socket, a sleeve stationarily positioned in said socket, said sleeve being closed at one end and open at its other, the open end of said sleeve being provided with an annular flange, a driven element having a shank extension rotatably received within said sleeve, an antifriction thrust bearing positioned between one end of said extension and the closed end of said sleeve, said driven element being formed intermediately of its length with a flanged head-forming enlargement, the latter being provided With a bore which in the length thereof diagonally intersects the longitudinal axis of the enlargement, a detent positioned in one end of said bore for engagement with a depression provided in the flanged end of said sleeve, a spring means positioned in said bore for maintaining said detent normally in engagement with said depression, and threaded means positioned in said bore cooperative with said spring means for regulating the force exercised by the latter on said detent.

GERALD E. MCVEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 998,615 Haneke July 25, 1911 1,246,554 Cotterman et al. Nov. 13, 1917 1,328,087 LeChot Jan. 13, 1920 1,394,795 Sauve Oct. 25, 1921 1,456,148 Sands Aug. 28, 1923 1,684,345 Centeno Sept. 11, 1928 1,829,421 Roe Oct. 27, 1931

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