US3831468A - Impact wrench - Google Patents

Abstract

An impact wrench for use in tightening or loosening threaded parts, the wrench including a spindle adapted to engage a nut or bolt, a moment arm porjecting transversely of the spindle, a semicircular brace disposed radially of the spindle and interconnected at its ends to the ends of the moment arm, and a breaker bar pivotally secured on the spindle and adapted to impart a force substantially simultaneously to the moment arm at both ends thereof thus applying a uniform and balanced application of torque to the workpiece.

Description

United States Patent 1191 Miller Aug 27, 1974 IMPACT WRENCH [76] Inventor: Robert G. Miller, 311 w. Prairie sr, Examme-'j?mes Jones Camp Point, L 62320 Attorney, Agent, or Firm-Henderson & Strom [22] Filed: July 13, 1972 57 A S C I [21] Appl. No.: 271,505 An impact wrench for use in tightening or loosening threaded parts, the wrench including a spindle [52] U S C] 81/52 3 adapted to engage a nut or bolt, a moment arm por- [511 In} .0 19/60 j g transversely of the Spindle, a semicircular I brace disposed radially of the spindle and intercom [58] Field of Search 81/523, 173/93 nected at its ends to the ends of the moment arm, and a breaker bar pivotally secured on the spindle and [56] gFXF Sg adaptedto impart a force substantially simultaneously to the moment arm at both ends thereof thus applying 1i; gaird a uniform and balanced application of torque to the arnson 3,145,593 8/1964 Humphrey 173 93 workpece' 3,158,050 11/1964 Shandez 81/523 x 1 Claim, 6 Drawing Figures IMPACT WRENCH BACKGROUND OF THE INVENTION The loosening or tightening of screw threadedparts may either be accomplished by applying a constant twisting force, or by applying an instantaneous impact force. The advantage of applying an impact force isreadily manifest in the separation of screw threaded parts which will not yield to an instant torque and in situations where the torque requirements are greater than can normally be applied. In many instances threaded parts are assembled with power assisted tools or freeze because of rust or other foreign material imbedded between the threads of the corresponding parts. Furthermore, many such parts must be assembled or reassembled to a high torque to assure safe operation ofthe parts in their subsequent use. often the necessary power tools are unavailable or excessively expensive.

A number of impact wrenches have been manufactured, however, they are not effective in use. One such wrench has a spindle adapted to receive a socket and having an arm projecting radially thereof. A bar is rotatably mounted on the spindle and projects radially thereof and a weight is disposed on the free end of the bar. An arm also is secured to the bar and also projects radially thereof, wherein, upon grasping the weight and imparting a force thereto the bar strikes the arm and provides a torque to the socket through the spindle. Unfortunately not only is a torque applied but also a resultant force is applied, which is generally angularly disposed to the axis of the socket. This resultant force can and does strip the faces of the bolt or nut, leaving the operator in a position wherein the bolt or nut must be cut from its mating part.

One wrench, U.S. Pat. No. 3,158,050, attempted to provide an arm which projected radially from both sides of the spindle and a bar which projected beyond ,both ends of the arm. Lugs were secured to the arm wherein rotation of the bar coacted with both lugs to eliminate the resultant force discussed hereinabove. Warping of the bar or damage to one of the lugs, however, defeats the object thereof and a resultant force will occur. Again that wrench having a securing device mounted to the spindle outwardly of the socket to provide stability to the spindle for lessening the possibility of causing a resultant force when the bar strikes the lugs. It will be obvious that care must be taken to pre vent damage to the lugs or the breaker bar. Furthermore, as the bar projects radially outwardly of the spindle considerablly more space is required to effectively use the wrench.

SUMMARY OF THE INVENTION This invention relates to an impact wrench and more particularly to a manually operated tool wherein the inertia of a weighted pivotally mounted breaker bar in combination with a moment arm secured to a spindle is utilized to loosen or tighten threaded parts, and wherein the inertia of the bar is converted into a torque which coacts on opposed sides of the spindle through a brace element interconnected between both ends of the moment arm, thus substantially eliminating any resultant forces.

The impact wrench includes a spindle adapted to axially receive a socket on one end thereof and having a handle joumalled to the other end thereof. Secured, intermediate the ends of the spindle, is a radially projecting trough shaped moment an'n which extends outwardly an equal distance on opposed sidesof the spindle. Disposed in each end of the trough is a boss which projects normally thereto. A semicircular brace interconnects the ends of the arm-on the side opposite the bosses. An arcuate shaped brace is secured to the arm inside the semicircular brace and vertically disposed links interconnect the braces to the arm intermediate their respective ends. A second substantially semicircular offset holding unit is secured to the sides of the ends of the arm and projects oppositely to the braces and includes holding spurs for additional sockets. Pivotally connected to the spindle in the plane of the'braces is a weighted breaker arm which will pivot about the spindle to contact the bosses.

It is an object of this invention to provide an impact wrench which will apply a torque to a socket but which does not provide any angularly disposed resultant force.

Another object of this invention is the provision of an impact wrench having a breakerbar which is pivotally connected at one end to the spindle but which applies a substantially equal force to opposed sides of the spindle through a brace secured to opposite ends of a moment arm which is secured transversely to the spindle.

A further object of the inventionis to provide an impact wrench which has a holding unit for sockets, thus eliminating separate storage units for parts.

Yet another object of this invention is the provision of an impact wrench which is durable of construction, extremely effective in operation and uncomplicated in manufacture.

These objects and other featuresandiadvantages be come more readily apparent upon reference to the'following description when taken in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the impact wrench of this invention in combination with a wheel and its component lugs or nuts, thus showing one area of its operation;

FIG. 2 is a top plan view thereof;

FIG. 3 is a side elevational view thereof, wherein the opposite side is a mirror image thereof;

' DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, the impact wrench of this invention is indicated generally at 10 in FIGS. 1 6, and is depicted in use in a typical application. The wrench 10 (FIG. 1) is operably mounted on a lug or nut 11 which secures a wheel 12, having a tire 13 mounted thereon, to an axle (not shown) or the like. The lug or nut 11 is threadably mated with a corresponding threaded part (not shown) and although this description specifically discloses an application related to the removal of a wheel from an axle it is not intended to so limit same as its application is universally applicable to dle 14, a handle 18 journalled to the other end 18 of the spindle 14, a moment arm 19 secured to the spindle 14 intermediate its ends and projecting transversely thereto, a brace unit 21 secured at its ends to the ends of the moment arm 19, a breaker bar 22 pivotally secured to the spindle 14 at the intersection of the spindle 14 and the arm 19, and a holding unit 23 secured to the arm 19 opposite the brace unit 21 for holding additional sockets 16 in storage.

Referring now to FIGS. 2 and 3, the spindle 14 is depicted as an elongated rod which has a turned down section 24 intermediate its ends 17 and 18. Detachably mounted on the one end 17 is a socket 16 adapted to engage the head of a lug or bolt, or a nut in mating relationship.

Journalled to the other end 18 in a conventional manner is a handle 17, thus permitting an operator to securely hold the handle to support the wrench in a proper plane against the work piece, nut or lug, when the spindle rotates.

The moment arm 19 (FIGS. 2 and 6) is formed from an elongated member which is trough shaped 26 in cross section. Upstanding bosses 27 and 28 are integrally disposed in each end, 29 and 31, respectively, of the trough 26 and a cutout 32 is formed in the trough 26 intermediate its ends. The moment arm 19 is secured to the spindle proximate the turned section 24 with section 24 disposed in the trough 26 over the cutout 32, with the opposed ends 29 and 31 projecting radially of the spindle l9.

Secured to and depending from the moment arm 19 is the brace unit 21 (FIGS. and 6). The brace unit 21 comprises a semicircular brace 33 connected at its end 34 and 36 to the underside of the trough 26 opposite the bosses 27 and 28. Proximate the spindle cutout 32 are parallel links 37 and 38 which interconnects the trough 26 to the semicircular brace 32 thus preventing the latter from turning or twisting from a plane normal to the axis of the spindle 29 and trough 26. Disposed between the trough 26 and the semicircular brace 33 is an arcuate shaped brace 39 which is secured at its ends 41 and 42 to the trough 26 inwardly of the ends 34 and 36 and to the links 37 and 38 at its intersection therewith. The arcuate brace 39 also assists in preventing the semicircular brace 33 from twisting or turning.

Pivotally secured to the spindle 19 at the turned section 24 (FIGS. 3 and 5) and within the trough 26 is the breaker bar 22. The bar one end 41 is journalled on the turned section 24 and a weight 41 is integrally mounted on the bar other end 42. It will be noted in FIG. 5 that the bar contacts the moment arm 19 only at the bosses 27 and 28 when it is swung either to the right or left.

The holding unit 23 (FIGS. 1 and 5) comprises a semicircular element 43 connected intermediate its ends 47 and 48 to one end 44 of a leg 46 and at its ends 47 and 48 to the semicircular brace ends 34 and 36 and the moment arm ends. Approximately intermediate the leg 46 and the element ends 47 and 48 are a pair of opposed socket holding arms 49 and 51. Each arm has its free end threaded to receive a wing nut 52. Slidably disposed on the holding arms 49 and 51 are sockets 16 (FIG. I). The other end 53 of the leg 46 is secured to the spindle 14 adjacent to and outside the moment arm 19, thus it will be seen that the plane of the element 43 is offset from the plane of the brace unit 21.

In operation a socket having the appropriate inside dimensions is selected from the supply of same on the holding arms 49 and 51 and mounted on the spindle one end 17. The socket then is disposed over the lug or nut 16 which is to be loosened or tightened. The spindle is grasped at the handle 17 with the axis of the spindle aligned with the axis of the nut or lug. The weight is grasped and thrown to the right or left (FIG. 5) to tighten or loosen the nut. The impact of the bar 22 against the boss 28 will be transmitted through the moment arm to the spindle and through the semicircular brace 33 to the other end of the moment arm and then to the spindle thus applying opposed forces to the spindle, and providing an impact torque to the nut or lug. As the handle is journalled to the spindle a minimum effort is required to hold the wrench in proper alignment even when the breaker bar is pivoted in either direction. The extra sockets are always available thus eliminating the need for extra storage equipment. But more importantly the impact torque will have no resultant force to cause the socket to damage the head of the lug or the faces of the nut.

I claim:

1. An impact wrench for tightening and loosening screw threaded parts, the wrench comprising:

a spindle having a socket mounted on one end thereof and a handle journalled to the other end thereof in axial alignment with the spindle;

a moment arm secured at its midpoint to said spindle and projecting transversely thereof, said moment arm being an elongated member which is trough shaped in cross section and having a boss integrally disposed on each end thereof which projects upwardly into the trough; first semicircular bar-shaped brace secured at its ends to said moment arm ends and lying in a plane normal to the axis of said spindle; breaker bar means pivotally mounted on one end to said spindle and having an integral weight secured to its other end, for applying an impact force to said moment arm, said breaker bar being disposed radially of said spindle and operable in the plane of said brace;

a second semicircular bar-shaped holding unit brace secured at its ends to said moment arm ends, said second semicircular brace lying in a plane which is different from the plane in which the first semicircular brace lies;

two inwardly projecting socket holding means for detachably holding a socket which is not being used, said two socket holding means being symmetrically disposed on said second semicircular brace wherein each socket holding means includes mating threaded members;

a third arcuate bar-shaped brace having its ends secured to said moment arm and lying in the same plane as said first semicircular brace;

a first link member extending from one side of said moment arm to an intermediate portion of said first semicircular brace and connected to said third arcuate brace; I

a second link member extending from the other side of said moment arm to an intermediate portion of said first semicircular brace and connected to said third arcuate brace; and

a third link member extending from the middle of said moment arm to the midpoint of said second semicircular brace.

Claims (1)

1. An impact wrench for tighTening and loosening screw threaded parts, the wrench comprising: a spindle having a socket mounted on one end thereof and a handle journalled to the other end thereof in axial alignment with the spindle; a moment arm secured at its midpoint to said spindle and projecting transversely thereof, said moment arm being an elongated member which is trough shaped in cross section and having a boss integrally disposed on each end thereof which projects upwardly into the trough; a first semicircular bar-shaped brace secured at its ends to said moment arm ends and lying in a plane normal to the axis of said spindle; a breaker bar means pivotally mounted on one end to said spindle and having an integral weight secured to its other end, for applying an impact force to said moment arm, said breaker bar being disposed radially of said spindle and operable in the plane of said brace; a second semicircular bar-shaped holding unit brace secured at its ends to said moment arm ends, said second semicircular brace lying in a plane which is different from the plane in which the first semicircular brace lies; two inwardly projecting socket holding means for detachably holding a socket which is not being used, said two socket holding means being symmetrically disposed on said second semicircular brace wherein each socket holding means includes mating threaded members; a third arcuate bar-shaped brace having its ends secured to said moment arm and lying in the same plane as said first semicircular brace; a first link member extending from one side of said moment arm to an intermediate portion of said first semicircular brace and connected to said third arcuate brace; a second link member extending from the other side of said moment arm to an intermediate portion of said first semicircular brace and connected to said third arcuate brace; and a third link member extending from the middle of said moment arm to the midpoint of said second semicircular brace.

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