US2662435A - Predetermined torque release wrench - Google Patents

Description

Dec. 15, 1953 O. B. HARMES PREDETERMINED TORQUE RELEASE WRENCH Filed April 9, 1951 Patented Dec. 15, 1953 PREDETERMINED TORQUE RELEASE WRENCH Oren B. Harmes, Algona, Iowa, assignor to Livingston Tool 00., Algcna, Iowa, a partnership Application April 9, 1951, SerialNo. 219,903

7 Claims.

This invention relates to torque wrenches. More particularly it relates to a torque wrench constructed to automatically release when the torque exerted thereon exceeds a predetermined torque so as to positively prevent the element being tightened by the wrench from being damaged by an excessive torque.

In various mechanical assembling operations and in various other operations such as in rolling or expanding tubing into ferrules, it is necessary to be able to rotate elements such as bolts, nuts, expanders etc. until and only until the resistance offered thereto reaches a predetermined .force and requires a torque in excess thereof to overcome the same. It is imperative that the torque applied to such elements never exceed a predetermined amount in order to insure that irrepairable damage is not done. My invention is directed toward providing a wrench which will positively prevent such damage.

It is a general object of my invention to provide a novel and improved torque wrench constructed to positively prevent tightening of an element therewith beyond a predetermined torque.

A more specific object is to provide a novel and improved torque wrench which will automatically release its element engaging member when the torque applied thereto exceeds a predetermined amount.

Another obiect is to provide an automatically releasing torque wrench which is reversible in nature to permit its use for rotating an element in either direction and for releasing such element from said turning action when a predetermined torque is exceeded.

Another object is to provide an automatically releasing torque wrench capable of ready adjustment to cause the same to release the element to be turned from turning action at various predetermined torques.

These and other objects and advantages of my invention will be more apparent from the following description made in connection with the accompanying drawings, wherein like reference characters refer to similar parts throughout the several views and in which:

Fig. 1 is a longitudinal sectional View of one embodiment of my invention.

Fig. 2 is a side elevational view of the same with the head member shown in longitudinal section taken in a plane at right angles to the plane shown in Fig. '1.

Fig. 3 is a top plan view of the head member with the top plate intact and of the interior shank portion of the handle.

Fig. 4 is a cross sectional view of the handle taken along line 4-4 in Fig. 1.

One embodiment of my invention may include as shown in Figs. 1-4 an interiorly tapped handie member indicated generally as H and having rigidly secured thereto at its outer end a head member 6. The head member 5 has a hollowed out (portion 7 formed therein, this hollowed area being somewhat elongated but approximately circular at its largest end portion 8. The shape of this hollowed out area i is best shown in Fig. 1. An opening ta is formed in the bottom wall of the hollowed out head mem er so that a passage extends transversely through the head member 6. This is best shown in Fig. 2. Mounted for rotation in the circular portion 8 is a rotatable body or socket 9. This socket *3 has an opening it extending therethrough of the proper size and shape to engage the element desired to be turned by the wrench. The socket it has a central circumferential rib H which provides a shoulder #32 to cooperate with a ring it to hold the socket from sliding outwardly from the head member ii. A plate i l is secured to the other side or" the head member by cap screws it, this plate it having an opening it therein or" sufiicient size to permit the outer edge portions of the socket to extend outwardly therethrough. Formed in the outer circumferential surface of the central rib H of the socket 9 is a recess or groove il' which extends parallel to the axis of rotation of the socket. Absent engaging element the socket 9 is free to rotate in the enlarged portion 8 or" the head member but is confined to that portion.

The handle H is comprised 01' a shank it which as shown in Fig. l is formed integrally with the head member 6. This shank it has a longitudinally extending bore ill which communicates with the hollowed out portion l of the head 6 and which extends throughout its entire length. The medial portion of the shank i3 is externally threaded as at 23 while the rearward or inward portion is reduced as at ii. The extreme inner end of the shank I3 is provided with a pair of inwardly extending shoulders 22 which are disposed opposite each other as best shown in Figs. 1 and 4. The shank it is graduated as at along the circumferential surface of its outer end portion.

The other section of the handle H is internally threaded as at Tel to cooperate with the external threads 28 of the shank 8 as best shown in Fig. 1. This section has an interior bore extending inwardly from its outer end and of suificient diameter to accommodate the shank it.

The bore is of sufficient length to also accommodate a relatively strong spring 25 which is maintained at its inner end in central position with respect to the bore by a plug 26 having a reduced head 2'? adapted to be inserted within the spring. Also formed in this section of the handle is reading hole 28 and an internally threaded aperture 29 adapted to receive a set screw 26.

Mounted for limiting sliding movement within the shank it of the handle H is a rod 3| as best shown in Fig. 1. The inner end of this rod is externally threaded as at 32 to threadedly receive the nut 33 of external diameter equal to the spacing between the opposed shoulders 22. As best shown in Fig. 1 this rod 3i is of suificient length so that its inner end extends inwardly beyond the shank i8 and the nut to be received in the outer end of the spring 25 and is of sufficient length so that its outer end 3% extends into the hollowed out area 7 of the head member 6.

The outer end of the rod 3! is flattened and reduced as at 35 to receive the inwardly extending bracket arms of a toggle member indicated generally as T. The bracket arms (iii are spaced from each other to accommodate the flattened portions 35 therebetween and have apertures formed therein to accommodate a pivot pin 3: which extends through each of the arms 38 and the flattened portion 35. This pivot pin 37 is arranged to extend transversely with respect to the rod SI and on an axis substantially parallel to the axis of rotation of the socket member 9.

The toggle member T is provided with an out wardly extending circumferential shoulder 38 and is further provided at its outer end portions with a cylindrically shaped key 39. This key 39 extends transversely with respect to the rod ti and substantially parallel to the pivot pin 3'3. The key 39 is so shaped as to complement and snugly set into the groove ll formed in the socket member 9. A relatively weak spring 46 is carried by the outer end 35. of the rod 3! and by the inner end of the toggle member T. This spring abuts against the shoulder 33 and against the wall of the head member 6 which defines the hollowed area The walls of the hollowed area i are sufficiently spaced from the toggle member T so that the latter may swing sufficiently far to either side of the longitudinal center of the rod 3! to cause the key as to become completely disengaged from the socket member 9.

When the wrench is assembled for use, the respective parts are in relation to each other as best shown in Fig. 1. By referring to Fig. 1 it can be seen that the section of the handle which receives the shank portion I8 is threaded onto the shank sumciently far to exert the desired compression on the spring 25. When this has been done, the set screw 36 is tightened and thereafter the socket 9 will be prevented from turning by the toggle T until a sufficient torque has been exerted thereon to cause the toggle T to cam over, thereby compressing the spring 25. It can be readily seen that in normal position the toggle T extends diagonally with respect to the rod 3! and is constantly urged toward engaging relation with respect to the socket 9. At the same time the spring 25 constantly urges outwardly against the nut 33 to tend to prevent the rod 35 from being moved inwardly.

In operation the wrench is arranged so that the socket 9 will engage the bolt, nut, pin or other element desired to be rotated. The necessary torque is then applied to the handle H to rotate the element. So long as the resistance offered by the element being turned does not exceed a predetermined torque arrived at by the amount of compression placed upon the spring 25, the wrench will continue to tighten the element. However. when this predetermined torque is exceeded the toggle '1 will cam over to the opposite side and in so doing will compel the rod (ii to move inwardly, overcoming the outward thrust of the spring 25. By camming over, the toggle T automatically, for all practical purposes, releases the socket 9 since a much lower torque will be required to cause the key 39 to slide out of the groove ll, thus permitting the socket 9 to rotate freely relatively to the handle I-i. Thus it can be seen that it becomes impossible with this wrench regardless of carelessness or abuse in the use of the wrench, to tighten a given element beyond a predetermined torque for the socket 9 will automatically be released as soon as that predetermined torque is exceeded.

After the toggle T has cammed over, the wrench is immediately ready for re-use on the next element to be tightened, by merely turning the wrench over and applying the other end of the socket 9 to the element to be tightened. The toggle need not be returned to its original position and the wrench will operate equally as ethciently from either side. Thus a substantial saving in time is efiected in addition to the positive prevention of damage to the element to be tightened.

The torque required to cause the toggle T to cam over may be predetermined at various degrees of compression exerted on the spring 25 and the same may be indicated on the shank i3 by graduating the shank as indicated in Fig. 3. Thus the user may readily adjust the compression exerted on the spring 35 by tightening or loosening the portion of the handle carrying the set screw with respect to the shank l8. When the handle has been adjusted so that the desired torque will be required to cause the toggle T to cam over, that fact will be indicated and the user will be appraised thereof through reference to the reading hole 28 as shown in Fig. 2. Thus it is possible to adjust the wrench readily to cam over at various predetermined torques.

It should be noted that my wrench is also adjustable to compensate for changes which may take place over a period of time in the resistance which the spring 25 offers to compression. By adjusting the nut 33 on the thread end of the rod 31, the amount of compression can be changed even though the two sections of the handle remain in the same position with respect to each other.

Thus it can be seen that I have provided a torque wrench constructed to automatically release when the torque exerted thereon is such as to exceed a predetermined torque. This positively prevents the element being tightened by the wrench from being damaged. It is highly important in aircraft assembling operations and in the expanding of ferrules that exact predetermined torques be exerted on the element to be rotated. My wrench provides a ready and efilcient means for accomplishing this function.

It should be noted that in addition to the fact that my wrench automatically releases itself when the torque applied thereto exceeds a predetermined amount, it is also reversible in nature so that no time is lost in its use when moving from one element which has just been tightened to the next element to be tightened, It should also be noted that my wrench is .capable of ready adjustment to various predetermined torques.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of my invention.

What I hereby claim is:

1. An automatically releasing torque wrench comprising an at least partially hollow head member, a rotatable body mounted for free rotation in said head member and adapted to engagingly receive the element to be turned by the wrench, said body having engagement means on its circumferential surface, a handle secured to said head member and having a central bore, a rod mounted within said bore for limited. sliding movement longitudinally of the handle, resilient means constantly urging said rod toward said rotatable body, and toggle mechanism connected to the outer end of said rod and normally extending diagonally with respect thereto and adapted to cooperate with said engaging means to engage said rotatable body, said toggle mechanism, being swingably mounted on said rod and disposed with respect to said head member to permit the toggle mechanism to swing to the opposite side of the longitudinal center of said rod sufficiently far to permit the same, when a sufficiently strong torque is exerted on said rotatable body, to force said rod inwardly despite said resilient means, to disengage said rotatable body to permit the latter to thereafter turn freely in the direction of that torque without being re-engaged by said toggle mechanism.

2. An automatically releasing torque wrench comprising an at least partially hollow head member, a rotatable body mounted for free rotation in said head member and adapted to engagingly receive the element to be turned by the wrench, said body having a recess formed in its circumferential surface, a handle secured to said head member and having a central longitudinal bore, a rod mounted within the bore of said handle for limited sliding movement longitudinally of the handle, resilient means constantly urging said rod outwardly from said handle and toward said rotatable body, and toggle means connected to the outer end of said rod and normally extending diagonally with respect thereto and engaging said rotatable body within said recess, said toggle means, when a sufficiently strong torque is exerted on said rotatable body to force said rod inwardly despite said resilient means, being swingably mounted and disposed to permit the same to move to the opposite side of the longitudinal center of said rod sumciently far to permit the same to disengage the recess of said rotatable body to permit the latter to thereafter turn freely in the direction or" that torque without being re-engaged by said toggle mechanism.

3. An automatically releasing torque wrench comprising an at least partially hollow head member, a rotatable body mounted for free rotation in the hollow portion of said head member and adapted to engagingly receive the element to be turned by the wrench, a handle member rigidly secured to said head member and having a central longitudinally extending bore adjacent to and communicating with said hollow portion of said head member, a rod mounted within said bore for limited sliding movement longitudinally of the handle, the outer end of said rod extending into said hollow portion of said head member,

resilient means adjacent the inner end of said rod constantly urging said rod toward said rotatable body, toggle mechanism swingably mounted on the outer end of said rod and having an engaging element on the outer end portion of the same, the outer circumferential surface of said rotatable body being adapted to cooperate with said engagement element to permit releasable interconnection between said rotatable body and said toggle mechanism, said toggle mechanism being spaced sufficiently far from the walls of said head member defining said hollow portion to permit the same to be swung sufficiently far to either side of the longitudinal center of said rod to disengage said engaging element from said rotatable body, and resilient means adjacent tne outer end of said rod constantly urging said engaging element into engaging relation with respect to said rotatable body, said toggle mechanism being normally disposed diagonally with respect to said rod and functioning to swing to the opposite side of the longi tudinal center of said red when a suihciently strong torque is applied to said body to cause said rod to move away from said body to thereafter permit said body to turn freely in the direction of that torque and thereafter remaining in engag ing position with respect to said rotatable body to engage the same in the event the direction of the torque is reverse i. [in automatically releasing torque wrench comprising an at least partially hollow head ieniher, a rotatable body mounted for free rotation in the hollow p rtion of said head member and adapted to engagingly receive the element to be turned by the wrench, said body having a re cess formed in its outer circumferential extending substantially parallel to the rotation of said body, a handle ri idly secui ed to said head member and having a central longitudinal bore communicating a hollow portion of said head member, a mounted hin r longitudinally of the handle, the outer end portion of said rod extending into i of said head member, relatively strong s ring carried with n said bore and constantly i 'ng said rod outwardly toward rotatable body with a predetermined force, a toggle member adapted to be engage,

in said recess of said body wardly extending shoulder thereon, a relatively weak spring carried by the outer end portion or said rod and arranged to constantly abut against said shoulder and urge toggle member toward longitudinal alignment with said rod where mod in by said key element is constantly contact with said rotatable bO' gle member being normally disposed diagon 1y ith respect to said rod and being spaced suiiiciently 1-' far from the walls of said head member defining said hollow portion to permit the same to swing sufficiently far to either side of the longitudinal center of said rod to disengage said key element from said recess whereby after a suiiiciently strong torque has been exerted on said rotatable body to force said rod inwardly and. to cause said toggle member to swing over to the opposite side of the longitudinal center of said rod, it becomes impossible to tighten an element beyond such a predetermined torque.

5. An automatically releasing torque wrench comprising a handle having a central longitudinal bore, extending inwardly from its outer end, a head member rigidly secured to the outer end portion of said handle and having an opening formed therethrough extending transversely to said handle and communicating with said bore, an open ended socket mounted for rotation within said opening on the longitudinal axis of the opening and adapted to engagingly receive in either of its ends the element to be turned, a rod mounted with said bore for limited sliding movement longitudinally of the handle and extending into said opening to a point adjacent said socket, a spring element carried within said bore and engaging the inner end portion of said rod and constantly urging the same toward said socket, a toggle member swingably mounted on the outer end portion of said rod in a plane substantially parallel to the plane of rotation of said socket, said toggle member having a key element on its outer end, and normally extending diagonally with respect to said rod, said socket having a recess formed in its outer circumferential surface to receive said key element in engaging relation, and means for resiliently urging said toggle member toward longitudinal alignment with said rod whereby said key element will be maintainec i abutting relation with respect to said socket, said spring element being under a predetermined copression whereby when a predetermined torque is exerted on said socket said rod may be forced inwardly despite said spring element and whereby said toggle ember may swing over to the opposite side of the longitudinal centeror" said rod to thereafter permit said socket to turn relatively freely in the direction of that torque and thereby prevent the element being turned by the wrench from being tightened excessively and thereby simultaneously becoming adapted for instant use for tightening a similar element by merely turning the wrench over, said toggle member being spaced suiliciently far from the walls defining said opening to permit the same to swing to either side or the longitudinal center of the rod sufiiciently far to cause said key element to be dis-en'- gaged from said recess.

6. An automatically releasing torque wrench comprising an at least partially hollow head member, a rotatable body mounted for free rotation in the hollow portion of said head member and adapted to engagingly receive the element to be turned by the wrench, a handle member rigidly secured to said head member and having a central longitudinally extending bore adjacent to and communicating with said hollow portion of said head member, a rod mounted within said bore for limited sliding movement longitudinally of the handle, the outer end of said rod extending into said hollow portion of said head member, resilient means adjacent the inner end of said rod constantly urging said rod toward said rotatable body, toggle mechanism swingably mounted on the outer end of said rod and having an engaging element on the outer end portion of the same, the outer circumferential surface of said rotatable body being adap-tecl to cooperate with said engagement element to permit releasable interconnection between said rotatable body and said toggle mechanism, said toggle mechanism being spaced sufficiently far from the walls of said head member defining said hollow portion to permit the same to be swung sufficiently far to either side of the longitudinal center of said rod to disengage said, engaging element from said rotatable body, and resilient means adjacent the outer end of said rod constantly urging said engaging element into engagin relation with respect to said rotatable body, said toggle mechanism being normally disposed diagonally with respect to said rod, said first mentioned resilient means being of substantially greater strength than said second mentioned resilient means whereby when a sufficiently strong torque is exerted on said rotatable body to force said rod inwardly despite said resilient means, said toggle mechanism will swing to the opposite side of the longitudinal center of said rod to thereafter permit said rotatable body to turn relatively freely in the direction of that torque and will remain in engaging position with respect to said rotatable body to engage the same in the event the direction of the torque is reversed.

7. An automatically releasing torque wrench comprising a head member, a rotatable body mounted for free rotation on said head member and adapted to be connected to the element to be turned by the wrench, a handle member rigidly secured to said head member and having a central longitudinally extending bore, a rod mounted within said bore for limited sliding movement longitudinally of the handle and extending to a point adjacent said rotatable body, resilient means constantly urging said rod toward said rotatable body, toggle mechanism swingably mounted on the outer end of said rod and hating an engaging element on the outer end portion of the same, a portion of said rotatable body being adapted to cooperate with said engagement element to permit releasible interconnection between said rotatable body and said toggle mechanism, said toggle mechanism being free to swing sufficiently far to either side of the longitudinal center of said rod to disengage said engaging element from said rotatable body, and resilient means adjacent the outer end of said rod constantly urging said engaging element into engaging relation with respect to rotatable body and toward alignment with said rod and being weaker than said first mentioned resilient means, said toggle mechanism being normally disposed diagonally with respect to said rod, and functioning when a sufficiently strong torque is exerted on said rotatable body to force said rod inwardly despit said resilient means, to swing to the opposite side of the longitudinal center of said rod permitting said rotatable body to turn freely in the direction of that torque and at the same time remaining in engaging position with respect to said rotatable body to engage the same in the event the direction of the torque is reversed.

OREN B. HARMES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,303,595 Rifilard May 13, 1919 2,179,855 Latimer Nov. 14, 1939 2,332,971 Johnson Oct. 26, 1943 2,556,587 Keen June 12, 1951 FOREIGN PATENTS Number Country Date 109,874 Australia Feb. 20, 1940 774,185 France Sept. 17, 1934

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