US2365486A - Set torque wrench - Google Patents

Description

De@ 19 1944- H. P. MORRIS 2,365,486

SET TORQUE WRENCH Filed Aug. 1'?, 1942 IN VN TOR.

H/i/e/eYRMmK/J,

BY uw Mr-ry.

Patented Dec. 19, 1944 UNITED STATES PATENT OFFICE SET TORQUE WRENCH Harry P. Morris, Coronado, Calif.

-ApplicationAugust 417, 1942, Serial No. 455,095 2 claims. l(icl. :s1- 53) This invention relates'to a-Wrench and particularly pertains to a set torque Wrench.

In various mechanical assembling-operations, and particularly inA ordnance and aircraft Work it is necessary to tighten bolts and nuts rapidly and at the same time to linsure Athat the parts have been screwed togetherto produce a desired holding action without applying an excessive degree of torque Avvhichwvould tend to weaken or fracture the threads of the parts being tightened. Various devices have been provided to foperatein connection with Wrencheswhereby the degree `of torque applied bythe Wrench is indicated either audibly or visibly. Devices of this character `tend to increase the co-"ordination` and efliciency of the operator andit has beeniound desirable to pro'- vide means Which'will indicateautomatically on the Wrench when thejselected amount of torque has been app1ied, this indication being imparted to the handle grip of the Wrench so that the operator Will be sensible ofthe `indication Without observing dials, needle,` or other indicating members. It isalso'desirable'to provide a'wrench which may beset to a'desired tensionsotha'tthe Wrench cannot exert -a pressure greatervthana predetermined sei-,pressure and so'that this maxi# mum set pressure may be indicated to the operator. 1

It is the principal object of the lpresent inven-` tion therefore to 'provide a torque Wrench tted with simple and effective means whereby the Wrench may `be set to a predetermined maximum torque and will' thereafter function to operate upon threaded members to be tightened-to that maximum torque only, and to indicate when the maximumtorquehas been reached.

.sembled Wrench with the cover'removed and the parts in a normal' position; i

Fig, 2 is a view in plan showing` the wrench with its cover removed and the parts insa maximum torqueposition'.v

Fig. `3 is avewin central 'longitudinal' 'section Fig. 2 and shows fthedetailsofconstruction of the Wrench.

Fig. 4 Vis a fragmentary `view :showingtheapplication of a demountablehead.

Fig. 5 is a fragmentary View in= elevationishowing the end 4portion of' the handle and the .micrometer calibrations.

Referring `more particularly to the drawing, .i0 indicates a Wrenchl body at one end ot Whicnisa hand grip Il. The Wrench' body is preferably madefof steel andincludes a caseItZ.` The case l 2 is formed With-a Wall alongitsperimeter. One end of the case has -a substantially semi-circular wall portion f|"3 and oppositeside Wall portions M and l5.4 4The side Wall portions taperwtoward each other and terminate in an endportion 1'6. 'Formed integral with the end portion 116 i's a tubular handle ll'l. The tubular handle .has `a central bore ITB vinternally threaded at its outer end as indicated 'at I9 and communicating with a bore 20?` `of -reduced diameter Whichlextends throughthe portion i6 andf into -thefcavity 21 formed by the walls -alongtheiperimeter 'of the case. The handle 4Il `and'theboresfll and Zilf'are 'in longitudinal alignment -and are centrally aligned 'with thelongitudinal -aXis `of vthe cavity A2l in the case.' The wall portion .I3 which is iat the 'opposite end of the' case from the bore 2D represents an arcuate length greater Vthan..180 for a purpose to be Ahereinafter described. The *case l2 has alcor2'2 onone side `thereof and is provided withia cover plate 23 on the opposite 'side thereof. The .floor andthe cover plate are .ormedaat fone end :with relatively .large `complementary openings A211 and.25 respectively, which openings are in axial alignment, the axis intersecting the longtudinalcenterfof thecase andbeing at right angles thereto. Formed through the end'ofthe arcuate Wallsection -l3 isanelon'gated slot'or opening 26, the median line of Whichis coincident lWith the longitudinalcenter line of the case. A similargopeningl-l Yisiforrned to the side -of thecase and Withitsmedian line substantially at -rightangles to that of theopeningZB, both o'f said median lines being.. radially -disposed with relation to the axis' of the openings "211 l"and 25. Mounted Within the openings 24 arrd2`5 is a rot-ary head 28. ThislheadA is formedwithoppol 'assembled body :structure l0. Intermediate the cylindrical portions 1291 and 3U is a substantially 'cylindrical lportion 3l of` larger `diameterlwhiclr.l is

of a thickness representingthe space between the inner faces of the floor 22 and the plate 23 respectively. This prevents the rotating head 28 from becoming displaced, At one side of the rotating head 28 and formed integral with the cylindrical portion 3I are lugs 32 and 33 between which a radial seat 34 is formed. This seat extends in the general direction of the longitudinal axis of the body structure III and toward the handle II. Mounted within the cavity 2l is a lever 35 and a link 36. The lever 35 is secured upon a pivot pin 31 which extends through the cover plate 23 and is threaded into the floor 22 the axis of the pin being parallel to the ro-tating axis of the head 28 and lying in a plane in the longitudinal center of the body I. At lone end of the lever 35 is a finger 38 which extends into the seat 34 on the rotating head 23. The end of the finger is rounded so that as the head 28 rotates the finger may swing around the axis 31 without binding. The opposite end of the lever 35 is formed with an extension 39 of reduced thickness. This extension projects into the forked end of the link 36. A connecting pin 40 extends through the forked end of the link 36 and the extension 39 yof the lever 35 to connect the lever and the link pivotally. The opposite end of the link 36 is similarly constructed and receives an extension 4I of a piston rod 42. The rod 42 reciprocates within the *bore 26 of the body of the structure and is pivoted to the link 36 by a pin 43. The end of the rod 42 opposite the extension 4I has an enlarged collar 44 which ts within the bore I8 of the handle and limits the movement Vof the rod 42 through the bore 26. A pin 45 extends longitudinally of the end of the rod 42 and into the bore I8. Positioned within the bore I8 is a helical tension spring 46 which rests against the end of the piston rod 42 at one end and against a plug 41 at the opposite end. The plug 41 is tted with a pin 48. The pins 45 and 48 extend into the opposite ends of the spring 46 and center it. The plug 41 is formed at its outer end with a concaved ball seat 48 to receive a ball 49. The plug extends into a threaded adjusting cap 56 which is threaded into the bore I9 of the `handle II. A concaved seat 5I is formed within the bore adjusting cap and between the seats 48' and 5I a ball 49 is held. The cap 50 projects beyond theend of the tubular handle II and is fitted with a squared head 52 by which the cap may be rotated.

For purposes to be hereinafter set forth a stop screw 53 is threaded through the side wall I5 of the body I of the wrench and limits the swinging movement of the lever 35 as shown in Fig. 2 of the drawing. The rotary head 28 of the wrench is provided with a central opening 54 which is here shown as being square. This opening is to accommodate the head of a nut or bolt. It is to be understood that the opening may be of any desired or necessary configuration. Formed through the side wall of the rotary head are slots 55 and 56. These slots are in the plane of the slots 26 and 21 of the, body of the wrench 'and may receive the shank 51 of interchangeable wrench heads 58.

In order to properly adjust the tension of the spring 46 suitable graduations 59 are formed around the circumferential end face of the handle II and cooperate with a pointer mark 60 upon the cap 50. Formed through the side walls of the handle II are slotted openings 6I. A pin 62 extends through these openings and the plunger 41.

Graduations 63 are made upon the body of the handle II along the slotted openings 6I so that an index groove 64 in the end o f the pin 62 may be brought to register therewith and will indicate spring tension imposed upon the spring 46 by the cap 56. f

In operation of the present invention the wrench is assembled as shown in the drawing, after which the adjusting cap 56 is tightened until the index mark 60 is brought to register with the graduations 59 representing the number of inch pounds of torque. This also forces the plunger 41 down so that the graduation rmark 64 on the pin 62 will register with the graduation 63 disposed along the slot 6I in the handle. This will indicate the number of hundred inch pounds torque adjustment which have been made. Thus the registration of the index mark 66 with a particular calibration 59 will indicate the maximum number of inch pounds to which the wrench is to be pressed. The wrench is then applied to the element which is to be turned and the torque force is delivered in the direction of the arrow a as indicated in both Figs. l and 2. In the normal position of the wrench parts as shown in Fig. l of the drawing, the head 28 is disposed so that its radial seat 34 will be at an angle to the longitudinal center of the wrench in the direction of the application of torque, and that the lever 35 will be disposed angularly of the longitudinal center of the wrench oppositely from that of the radial seat. It will also be noted that link 36 is disposed 'off center to connect the piston rod 42 and the free end of the lever 35. So long as the member seated within the rotary head 28 and to be rotated does rotater all of the parts of the wrench will remain in the position shown in Fig. l, since the response to torque force will be less than that required to compress the spring 46.

When, however, the rotated part, such for example as the nut, is screwed on to the threads of a complementary member to a point where the parts are sufficiently tightened to resist the torque force applied by the wrench, the rotating head 28 will tend to stand stationary and the wrench will swing around the axis of the rotating head, with the result that the lever 35 will swing around the fulcrum pin 31 and cause the link 36 to tend to swing to a position of longitudinal alignment with the lever. It will be recognized that the lever and the link have a toggle joint action with relation to each other, and as they strain they will force the piston rod 42 longitudinallyl against the action of the spring 46 and thus will cause a condition of lost motion in the application of torque force by the handle. This will continue until the free end of the lever arm 35 strikes the stop screw 53. It will thus be evident that by this arrangement it will be possible for the operator of the wrench to be advised instantly when a torque force is applied to the wrench which is resisted by the element which is engaged and is being tightened by the rotary head 28. It is to be understood that when desired an interchange of removable heads 58 may be made, asshown in Fig. 4 of the drawing. It willalso'be recognized that by the use of the structure here disclosed the tension of the spring 46 may be instantly changed to produce any set amount of torque, and that the mechanism is rugged and strong and cannot be easily broken, even though the operator does not heed the warning signal produced by the movement of the toggle jointin the wrench when a maximumset torque has been reached.

While I haveshown the preferredform of invention as now known to me, it is to be understood that various changes may be made in the combination, construction, and arrangement of parts by those skilled in the art, without departing from the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A set torque wrench, comprising a housing having a cavity at one end thereof and being formed with a cylindrical handle at the opposite end thereof disposed in longitudinal alignment with the cavity, said cavity being closed at opposite sides by flat parallel wall sections spaced from each other and through which aligned annular openings occur, a Wrench head disposed between said walls and having cylindrical bosses extending oppositely and outwardly through said openings to rotate relative thereto, said head being formed with a central passageway of a clonguration to receive an object to be rotated, a pair of spaced radial lugs projecting from the side face of the head within -the cavity and forming an intermediate seat normally disposed in the plane of the longitudinal axis of the wrench structure, a lever pvotecl between said side wall sections upon an axis normal to the longitudinal axis of the Wrench and lying along the plane of the center line of the wrench` said lever being formed at one end with an operating ringer extending into the seat, a link pivotally connected to the opposite end of said lever, whereby the link and lever will form a toggle joint, a pressure rod longitudinally slidable within the handle of the wrench and pivotally connected to the link, 1a, compression spring mounted within the handle and bearing against the end of the pressure rod, a plug resting upon the outer end of said spring, and an adjustable cap threaded into the end of the handle, whereby thetension upon the spring may be varied, said toggle structure being normally held with its elements in angular relation to each other by compression of said spring to hold the wrench head with its lugs and seat disposed at an angle to the longitudinal center of the wrench, whereby a torque force exerted against the handle of a magnitude greater than the set compression of the spring will tend to straighten the toggle and permit relative rotation of the wrench body and handle with relation to the wrench head.

2,. The structure of claim 1 including an adjustable stop against which the toggle structure may swing to limit the relative rotation of the Wrench body and its head.

HARRY P. MORRIS.

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