US2553400A

US2553400A - Plier-type, toggle actuated wrench

Info

Publication number: US2553400A
Application number: US654065A
Authority: US
Inventors: John A Blair
Original assignee: KATHRYN K BLAIR
Current assignee: KATHRYN K BLAIR
Priority date: 1946-03-13
Filing date: 1946-03-13
Publication date: 1951-05-15
Anticipated expiration: 1968-05-15

Description

May 15, 1951 J, BLA|R 2,553,400

PLIER-TYPE, TOGGLE ACTUATED WRENCH Filed March 15, 1946 2 Sheets-Sheet l INVENTOR.

May 15, 1951 J. A. BLAIR PLIER-TYPE, TOGGLE ACTUATED WRENCH 2 Sheets-Sheet 2 Filed March 13, 1946 INVENTOR.

fif 5142/.

Patented May 15, 1951 "BIKER-TYPE, TOGGLE ACTUAT-ED WRENCH ,l'ohn A. Blair, Pleasant Ridge, Mich., assignor to lKa'thryn K.'Blair, Pleasant Ridge, Mich.

App'lication'March .13, 1946, Serial'No. 654,065

12 .Claims.

The :present invention melates to an automat- :ically adjustable awrench :having parallel jaws and is a .continuation-in-gpartof .my copending application on Wrench, :Serial .No. 640,047, filed JanuaryS, 1946,. now abandoned.

The jaws of an wrench used-on nuts and the like must present fiat parallel .faces and must closely fit thenut -,to.-;avoid;a destructive concentration of load at the corners of the nut when it :is turned. InSthat-connection, the load applied at each .of two corners =ofa hexagonal .nut for a five-eighths inch bolt by a fifty pound pull at the end of a ten inch wrench riS approximaely twelve hundred pounds. Higher loads are frequently exerted .in :actual practice. Such loads .not :be made to .fit the corresponding nut with suflicient accuracy to avoid objectionable concentration of the twisting load at two corner of the :nut for the reasonthat -'a-close fit would make their application to the nut difficult. To make -;application practical, substantial clearance is specified in the United Statesfitandard for open end .wrenches (.006" for .a nut). This necessary clearance is so high that socket wrenches which distribute the lead .over all corners :of the nut are preferred to openend wrenches where it is possible to use .them. With either type 'a separate wrench is required for each size nut, which is 1 exceedingl inconvenient.

Many attempts have been made towdevisea satisfactory adjustable wrench in order to avoid .the necessity of carrying and selecting the proper .one of a multiplicity of wrenches in assembling and repairing machinery. The most widely used adjustable wrenches have a sliding jja-w whichis adjusted relative to the other jaw by a .screw. FI-hese may be opened up for easy application and then tightened on the nut .before the nut is turned. However, distortions and unavoidable play between the relatively :sliding parts permit the gja-wsto open-slightly under load and even a deflection of a few 'thousandth's of an inch is ob- ;jectionable. :In addition, the necessary :manipw :lations of the adjusting screw are troublesome, particularly when the wrench must be used in places which are not within the range :of vision of the mechanic. .a :result of these defec 2 fixed wrenches :of the :socket or open :end type are used very extensively in preference to ad- .justablewrenches.

Many other forms of adjustable wrenches have been devised. Some have been automaticall adjustable but are usable onl as pipe wrenches because they do not maintain the jaws in ;parallelism.

Parallel jaw .pliers have (been proposed but these generally rely:on hand-gripping pressure to resist the forces exerted against the jaws. If sufficient force multiplying mechanism is provided for this purpose, as, for example, by a toggle mechanism, the movement of the jaws .is'insufficient to permit use on :more than one size of nu" un ess an auxiliary adjustment of some kind is also provided. Prior ;paral:el jaw toggle pliers have, moreover, employed parallel linkages which are subject to :bending stresses and excessive distortion.

Many oftheproposed automatically adjustable wrenches have employed some form of ratchet mechanism 'for locking the Jews in any oneof a plurality :of positions. Most of these have been defective :because no provision was made for fit- .tingtnut :s'izes intermediate the possible positions of adjustment of the ratchet. Inaddition, all such wrenches .herefiofore :propo ed have been -peculiarly subject to spreading, distortion and misalignment or non-parallelism of the jaws under load. Moreoven'no prior ratchet type constructions have embodied a ratchet mechanism capable of withstanding the high .s'resses encountered in the normal usesofaa-wrenoh. .In that connection, it should be noted that in order to carry heavy loads, engagement Of a substantial tooth .tareais required. .No -:one ratchet tooth can carry sufiicient load unless .it :is :so large that the increments :of adjustment rof the wrench are excessive. All prior attempts to distribute the load over .a plurali y of 'teeth have :involved iIXIBChfinismswhich did not insure engagement to the full tooth depth and -.'distribution of the load on all teeth. "Consequently, there is serious danger of stripping or mangling the teeth.

Accordingly, it .is one :object of the presentinventionto providea wrench which'will automatically grip :a'range of different sizenutswith less angularity between the laws and the .nut faces than'is encountered :in standard fixed wrenches.

Another object of the present invention is to provide an adjustable parallel jaw wrench which "may by a single convenient manipulation be closed .on any .size nut within a relatively wide :range :oI sizes and thereafter :bring into action anism in which a load carrying engagement to.

the full depth of the teeth and over a substantial tooth area is positively insured and in which the teeth are of a form which provides maximum strength.

Another object of the present imvention is to provide a wrench having a ratchet adjusting mechanism in combination with means for automatically compensating for the inherent incremental characteristic of the ratchet mechanism so that the wrench will close on and clamp any 'size nut;

Another object of the invention is to provide a wrench in the form of a pair of toggle acting pliers in which a normal squeezing of the handles toward each other automatically closes the jaws 'on any size nut and applies a final toggle clamping action. 7

Another object of the invention is to provide a toggleplier wrench of the type mentioned in which the jaws are maintained in substantial parallelism Another object of the invention is to provide a toggle plier wrench in which'the final position of the free ends of the handles remains approximately the same regardless of variations in the size of the nut to which it is applied.

Another object of the invention is to provide a wrench of the type mentioned which, by a simple manipulation, may either have self-locking or automatic releasing characteristics.

Other objects, which include the provision of a wrench of the type mentioned which is simple and rugged in construction, will become apparent from the following specification, the accompanying drawings and the appended claims.

In the drawings:

7 Figure 1 is a side elevation'of the preferred form of the invention, with parts broken away and showing the wrench in fully open position;

I Figure 2 is a side elevation showing the wrench in its fully closed position;

Figure 3 is a transverse section taken on the line 3-3 of Figure 1; I

Figure 4 is a transverse section taken on the linedi of Figure 1;

Figure 5 is a transverse section taken on the line 5 "5 of Figure 1;

Figure 6 is a transverse section taken on the line 66 of Figure 1;

Figure 7 is a fragmentary enlarged longitudinal section taken on the line 1-"! of Figure 6; Figure 8' is a greatly enlarged fragmentary, longitudinal section similar to Figure 7 showing the manner in which the ratchet teeth approach clamping the jaws on a nut after they have engaged the nut and after the ratchet mechanism has engaged. This clamping mechanism is capable of giving the jaws a small additional closing movement sufiicient to cover the gap between the increments of adjustment of the ratchet mechanism, and has sufficient force multiplying capacity to apply the required jaw gripping force in response to ordinary hand pressure. In order to accomplish that result, the ratchet teeth are made quite small and the load is distributed over a plurality of teeth. Since this provides small increments of adjustment of the ratchet, the clamping mechanism need not transmit any appreciable movement and hence may have the requisite force multiplication. The wrench is so constructed that by a single hand movement in one direction, the'normally open jaws are closed on a, nut and thereafter the clamping force applied. The ratchet mechanism becomes effective automatically in response to engagement of the nut by the jaws, and the clamping mechanism becomes effective after the ratchet mechanism engages.

In the preferred form of the invention shown in the drawings, the wrench resembles a pair of pliers and the clamping mechanism is a tog gle linkage. Thus, as best shown in Figures 1 and 2, the Wrench comprises a pair of

handles

1 and 2 which are positioned relative to each other in the manner of the handles of a pair of pliers. The handle 2 is preferably formed as a unitary forging with an integrally fixed jaw 3. The handle forging has a centrally located web portion 4 which extends the full length of the handle and a Wider flange portion 5, which also extends the full length of the handle 2 and termi nates in a U-shaped section 6, shown best in Figure 3. The web portion 4 is providedinter mediate its ends with a generally triangular opening I, which is made of substantial size in order to lighten the tool and which also serves an additional purpose hereinafter mentioned. At the rear of opening 1, the web is further reduced in thickness at 8. The web is also provided with an opening 9 located forwardly of the opening 1 and separated from the latter by an intermediate web portion H]. The forward wall of the opening 9 is formed with a series of ratchet teeth ll and the opening is generally in the form of an elongated slot extending approximately perpendicular to the face of jaw 3.

Positioned within the opening 9 is a ratchet pawl I2 having a plurality of teeth l3 adapted to mesh with the previously mentioned teeth II. The pawl I2 is press fitted or otherwise fixedly secured to a pin l4 having a flattened portion l5 adapted to prevent rotation of the pawl relative to the pin.

lines at It in Figure 7, adapted to co-operate with the fiat surface [5 on the pin M to limit rotation of the pin within the openings in the side plates. The space between the fiat surfaces [8 of the openings in the side plates I! and flat IS on the pin I4 is sufficient only to permit the minute rocking movement of the pawl I2 necessary to maintain full contact between the teeth H and I3 during the limited pivotal movement of the jaw l6 relative to the axis .of pin 14 inch dent to .operation of the toggle mechanism hereina-fter described in greater detail.

The jaw [6 may be made up in any desired manner but, as illustrated, comprises an integral element of generally channel shape with the side plates connected by a web, the inner surface of which i curved in the manner indicated in dotted lines in Figure 1, and merges with the jaw face 19.

The rear end of the web of jaw 16 projects beyond the rear edges of the side plates .11, as best shown in dotted lines at 2.0 in Figure 1, and is provided with a transverse opening to receive a pivot pin 2|. The handle :1 is *formed as a stamping having a generally U-shaped cross section providing relatively deep side wall .portions 22 which embrace the projecting portion 20 of the jaw l6 and also a substantial portion of the web 4 of the handle 2. The side plates 22 are provided with suitable openings to receive pivot pin 21. The handle comprises one link of a toggle linkage including an additional link 23, which is pivoted between the side wall members 22 .of the handle I by means :of a pin 24 at one end, and is pivoted within the U-shaped terminus .6 vof the handle -2 at the other end by means of a pivot pin .25. Asa result of this construction, separation of the handles l and ,2 tends to break the ggle linkage and thereby swing the jaw 1.6 about the pin I 4 in a clockwise direction, and squeezing of the handles together effects a reverse rotation of the jaw I .6 about the pivot pin 1-4.

:Suitable means are provided to break the toggle linkage and thus maintain the handles and .2 in a separated position. In the preferred form of the invention illustrated, this means comprises a link 26, which is pivoted by means .of .a pin 2.1 between the .side walls 22 of the handle I and .a helical spring 28, one end of which is secured in an opening 29 in the extremity .of the handle 1 and the other in an opening 3!! in the link 26. Thearrangement is such that the spring .28 normally tends to swing the link 26 in a counterclockwise direction about the

2,1,,as viewedin Figure 1, thus tending to .break the toggle linkage. The link is provided with a pair of grooves 13.1 .in order to provide clearance between the link ,and the side walls 22 for the end of the spring .23.

The toggle breaking movement effected by the spring .28 and link 26 is limited .to a relatively small angle by means of an abutment surface 32 formed .on the left-hand extremityof the link 23 and adapted to abut the underside of the top wall of the handle I when .the parts are in their fully opened position,,i1lustrated in Figure 1. ,In that position, a flattened end portion .33 on the link 25 bears against the top surface of the ,link 23. This flattenedsurface is so arranged that the link extends at a small angle from a normal to the top surface of the link 23. This-angle slightly exceeds the angle of repose for the materials of the link 26 and lever 23, with the result that upon application of a closing force to the handle .I, the end of the link 26 will tend to slide to the left, as viewed in Figure 1, along the topsurface of lever 23. The spring 28 is a relatively light spring which resists this movement. The arrangement is such that an appreciable closing force must be applied to the handles before the link v26 will slip to the left, but as soon as such movement is started, .the link .25 will swing to the position shown in Figure 2 and the resistance to closure of the handles induced by the spring .28 will .be reduced toanegligible value byreason of.

tp le linkage.

the tact that the line of force exerted by the spring approaches closely to the axisof pin 21. In the fully straightened toggle position illustrated in Figure 2, a nose 3.4 on the link .26 engages the underside of the top wall of the handle I to limit the toggle straightening action.

If, as is preferred in the operation of a wrench, it is-desired to have the jaws release automatically when the pressure on the handles is relieved, the nose 34 is so constructed that it stops the toggle straightening movement just short of the fully straightened position.

The wrench also incorporates means to swing the upper jaw in a counterclockwise direction about pin 2| to a limited extent sufficient to effect disengagement of the teeth H and 13. In addition, means are provided to urge the upper jaw l 6 upwardly, as viewed in Figure ,1, inorder to main! tain the jaws in a normally open position.

In the preferred form of the invention illustrated, both of these functions are performed by a single mechanism comprising a lever 35 .anda helical spring 35, best shown in Figure 1. One end of the lever 35 is pivoted on a pin 3 carried by :a pair of cars 38 formed on the flange .5 of the handle portion 2, as best shown in Figures 1 and .5. The opposite-extremity of the lever .35 is twistedat 39 throughan angle of 90 with respect to the plane of the lever and is provided with a pair of oppositely projecting lugs 41!) which project into slots AI formed in the side plates J1 of the upper jaw I6, in the manner best shown in Fig ure .2, The slots Al extend at an angle of approximately with resp ct to the plane ef the jaw iaces and, consequently, the force exerted upon the top walls of the slots 41 by the lugs 40 is in a direction to not only separate the laws but to cause a rotation of the upper jaw in .a counterclockwise direction about the pin 2| when the lever 35 is urged in a clockwise direction about its pivotpin31. :Qne end of the spring 36 isfixed in an opening 42 in the thinner web section -8 and the'opposite end in an opening 43 formed in the lever .35 adjacent its outer extremity, thus tending to swing the lever 35 in a direction to separate the jaws and at the same time to separate theteeth H and 13.

As a result of the above described mechanism, the wrench normallyoccupies the fully open position illustrated in Figure 1, with the toggle linkage broken to the full extent permitted by the limiting abutment 32. When it is desired to clamp the wrenchon a nut, the jaws are placed over the nut in the usual manner and the handles l and .2 squeezed together :byasingle hand pressure. The arrangement of the

levers

26 and 35 and the springs 28 and is such that a pres.- sure applied by the hand to the handles suflicient to overcome the force exerted by lever 35 will close the jaws of the wrench on the nut without overcoming the tendency of the lever 26 and spring 28 to maintain the toggle linkage in its fully broken position. As a result, the toggle linkage, comprising the link '23, andthe hand-1e pivot bodily about the pin 25 to close the jaws on a nut.

During such movement, the force exerted by the lugs 46 of lever 35-onthe upper jaw I36 holds the pawl l2 out of contact with the teeth I l and the pawl rides along the smooth back wall Jlllrof the opening 9 without any straightening of the .As soon as the jaw L6 engages thenut, .its bodily movementtcward the jaw 3 will be'arrested and continued pressure on the handles "will tend to move the pivot pin 2| downwardly while the jaw fulcrums to a limited extent about its point of contact with the nut. This rocks the jaw in a clockwise direction about pin 2| simultaneously with the downward movement of the pin 2|, thereby moving the pawl I2 downward and to the left, as viewed in Figures 1 and 2, until the teeth I3 engage the teeth II. After the teeth have engaged, pin 2I can no longer move downwardly and, consequently, application of further presure to the handles will cause link 25 to slip to the left along the top surface of lever 23 and the toggle links will be straightened. This straightening action will rock jaw IS in a counterclockwise direction about pin I4 to a limited extent, and thusapply a strong clamping action to the nut located between the jaws.

It is desirable to limit the force required to effect a closure of the jaws on a nut and, consequently, the lever 35 and spring 36 are so constructed that they exert the minimum jaw opening force necessary. Moreover, the arrangement of the spring 36 and the lever 35 is such that as the spring is stretched incident to closure of the jaws, the lever arm through which the spring force acts upon lever 35 decreases, with the result that the torque applied to the lever 35 is substantially constant in all positions of the lever. Lever 26 and spring 28 are then so constructed that they will maintain the toggle linkage broken when subject to a force sufficient to close the jaws, but will permit toggle straightening action on a slight increase in that pressure.

The construction, location and arrangement of the ratchet holding mechanism is such as to provide maximum holding strength and maintenance of the jaws of the wrench so nearly parallel at all times that the minute departures from true parallelism, which result from the limited swinging movements of the jaw I6, are more than compensated for by the toggle clamping action of the jaw on a nut. These results flow from a number of specific features of the wrench construction. Thus, in the preferred construction the teeth II and I3 are made as small as it is possible to manufacture them practically and still maintain a high degree of accuracy in tooth form and spacing. As a specific example, for a, wrench of high quality and accuracy, the tooth spacing may be made as small as twenty-five one thousandths of an inch. As a result of the small size of the teeth, it is necessary to distribute the very high loads which they must carry over a relatively large number of teeth, as indicated on an enlarged scale in Figure '7. Moreover, it is necessary that all of the teeth on the pawl I2 make full depth engagement with the teeth II in order .to properly and accurately distribute the load.

through the pawl I2 to the teeth I I passes through teeth of pawl I2 intermediate the ends of the toothed surface of the pawl, as indicated by the dotted line arow 45 in Figure '7. The direction of this force is such that the pawl will swing automatically about the axis of pin I 4 until all of the teeth I3 on the pawl I2 seat squarely against the teeth II.

It will be noted that the direction of the resultant force applied to the ratchet teeth, as indicated by the line 45, is an angle of approximately 45 to the faces of the jaws. This results from the relative positions of the axes of pins I4 and 2| relative to the face of jaw I6. Thus,

7 tial contact exactly with the points of teeth II.

as shown in Figure 2, when the wrench is clamped upon an object, the toggle linkage will exert a force indicated by the dotted line arrow 46 on the jaw I6, while the object which is clamped will exert a vertically acting force on the face of the jaw I6. The location of this latter force may b at any point along the length of the jaw face but, under the worst condition that may arise, will be concentrated at the innermost portion of the face, as indicated by dotted arrow 41. Since the distance from the innermost portion of the face of jaw I5 to the line connecting the axes of pins I4 and 2I is approximately equal to the distance betweenthe axes of pins I4 and 2|, the resultant of the forces indicated by

arrows

46 and 41 extends at an angle of 45 to the jaw faces, as indicated by dotted line arrow 45. If the load applied to the jaw I6 is located further out on the jaw, the resultant of

forces

46 and 4! will extend at an angle slightly less than 45 with respect to the jaw faces but will not depart from the 45 angle by an amount sufiicient to cause cocking'of the pawl I2.

By so locating the points of application of the forces on the upper jaw that the resultant force on the pivot pin I4 extends at an angle of approximately 45" to the faces of the jaws, it is possible to construct the teeth II with side faces which make an angle of 45 with respect to the jaw faces and which, consequently, make an angle of 90 with each other, as shown in Figure 8. That form of. tooth may be used without ,danger of slippage between the pawl and the teeth I I by reason of the fact that the direction of the force 45 is approximately normal to the under sides of the teeth 5| under the worst possible conditions. A major advantage of teeth so formed is that they provide the maximum strengthbecause the loads applied to them are pure compression loads, thus eliminating all bending and shearing stresses on the teeth.

In order to utilize the full load carrying capacity of teeth I I and I3, it is not only necessary to provide the automatic self-aligning pawl construction previously .described, but it is also necessary to insure that teeth I3 engage to the full depth of the teeth II at all times. Such full depth engagement is positively insured in the i1.- lustrated embodiment of the invention by reason of the fact that the path of movement of the points of the teeth I3, as they approach the teeth II, is in such a direction that initial contact between the teeth II and I3 will occur at the upper sides of the teeth I I, while in the final po sition the load is taken by the lower sides of the teeth i I. As a result, straightening of the toggle linkage causes the teeth I3 to slide up the upper surfaces of teeth II into full depth engagement. Initial engagement at the upper sides of teeth II always occurs because pins I4 and 2i are moving downwardly during the limited rocking move- 'ment of the jaw I6, which occurs after it engages an object located between the jaws. and before the toggle linkage is straightened. Thus the points of the teeth I3 have a resultant movement parallel to the path indicated by dotted line 7 48 in Figure 9.

The location of the line 48 extending between any pair of engaging teeth will depend upon the thickness of the object engaged by the jaws. For certain thicknesses of objects, it is theoretically possible to have the points of teeth I3 make ini- That condition, which is illustrated in Figure 8,

is the worst condition that can arise because in such case the final engagement may occur onehalf a tooth space above or below the point of initial contact for a negligible variation in the size of the object clamped. This variation in position of the dog is compensated for by the swinging of jaw It about pin I4 incident to operation of the toggle linkage, However, to obtain maximum mechanical advantage and minimum .departure from parallelism, this swinging movement should be as small as possible and, therefore, the teeth should be as small as practicable. Even where initial engagement of the teeth occurs point to point, final engagement will be to full tooth depth because if the points of the teeth catch during movement of teeth 5 3 along the line 48, the subsequent change in the direction of the forces caused by straightening the toggle links will cause the points of teeth l3 to slide inwardly on the upper sides of teeth I l.

Another factor affecting the degree to which the jaws remain parallel in clamping position and the amount of movement which the toggle linkage must transmit to pin 2| is the width of the opening 9 as compared with the size or" the pawl l2. The clearance between the pawl and wall 44 in Figure 7 determines the extent of swinging movement of the jaw It about the pin 2!. This clearance should be as small as possible. However, it must be sufiicient to permit complete disengagement of the teeth H and I3 and also permit such further separation as is necessary to prevent engagement of the point of pawl I2 with the teeth H due to the limited possible cocking movement of the pawl during separation of the jaws. The tooth depth determines the amount of movement required for separation, and the tooth spacing determines the amount of swinging movement of the jaw l6 which is nec essary to effect clamping of an object whose di mensions do not correspond to any possible adjustment of the pawl l2 along the teeth I l. Consequently, if, as is preferred, the teeth are made quite small, very little swinging movement of the jaw about pin [4 is necessary to clamp tightly on any size object and, therefore, very little piv otal movement of the pawl 12 with reference to the side plates I7 is required to insure distribution of the load over all of the teeth 13-. It is for that reason that the flat surfaces It of the openings in the side plates H are designed to limit swinging movement of the pawl i2 with respect to the side plates.

It will be noted that the maintenance of par allelism of the jaws during adjustments of the wrench results from the form and location of teeth i3 with respect to the toggle linkage. So long as the paths of movement of the pins l4 and 2! are in substantially the same line or are in substantially parallel lines, the faces of the laws will remain substantially parallel. In the preferred construction, the points of the teeth I l, instead of lying in a flat plane, lie in a plane which is curved with a radius equal to the length of the toggle linkage made up of handle I and link 23; and the center of this radius is located at the point indicated by the numeral 49, which isthe same distance from the axis of pin 25 as the distance separatin the axes of pins l4 and 2!. The back wall of the opening 9' is also preferably curved about the same center and the points of the teeth [3 on the pawl I2 are located on a similar convex curve so that they will properly mate with the teeth II. To further minimize deviations from parallelism, the face of jaw 16 should extend at such an angle that 'it is" iii arallel to the face ofj-aw a when the toggle linkage is fully broken and the pointsof the teeth it on pawl I2 have advanced until they are in the same plane as the points of the teeth ll. as the pawlteeth I3 complete their inward meshing movement, the jaw t5 willswing open slightly and the subsequent toggle straightening operation will tend to return them to the closedparall'el position.

The wrench mechanism described above will automatically release upon relief of the handlesqueezing pressure, and the jaws will open to permit ratcheting of the wrench about the nut for a gripi For some purposes, however, it desirable tohave a wrench which will act as a clamp and hold itself in locked position upon object. Accordingly, Figures 9 and i0 is illustratedamodified form of the invention incorporating means for that purpose. The wrench illustrated fragment'arily in Figures 9* and 1 0 is identical in constructionand mode of operation to the preferred embodiment previously de scribed except that the lever 50, which corresponds tothe lever 26 of the previous embodi ment, has anose portion 5| which will permit the toggle linkage to swing slightly past its dead center or straightened position when the heel of the lever is engaging the top surface of thelever 23. As a result, the wrench will maintain itself in a clamped condition on any object until a 1 positive separating force is applied to the handles. I

A relatively thin sheet metal sleeve 52' surrounds and is slidable upon the lever 23. When it is desired to use the tool in the usual manner as a wrench which will release automatically, the sleeve 52 is slid into the position illustrated in Figure 9, in which it is interposed between the heel of lever 50 and the top surface of lever 23. The thickness of the sleeve 52 is sufficient to prevent complete straightening of the toggle linkage and, consequently, upon release of the handles, the wrench will automatically open. Sleeve 52 may be slid to the right, as viewed in Figure 9', to a position in which it does not contact the lever 50, in which event the tool is self-locking".

It will be observed that there is provided, in accordance with the present invention, an auto"! matically adjustable parallel jaw wrench which, by a single squeezing movement of the handles, will close freely on any size object and then apply a clamping force having exceedingly high mechanical advantage, regardless of the size of the object clamped. The initial adjusting movement prior to engagement of the object is made without any mechanical advantage and, consequently, the force multiplying mechanism need only operate through the small final clamping movement. The construction is such that the force multiplying mechanism makes no appreciable movement until after the jaws have closed on the object. As a result, an exceedingly high degree of force multiplication may be provided without limitin the overall range of adjustment.

While the wrench employs a ratchet holding mechanism, that mechanism is of such construction that an effective clamping action is achieved on objects the size of which fall intermediate the increments of the ratchet mechanism. Consequently, the wrench is, in effect, adjustable to any infinitesimal variation in the size of the workpiece. Moreover, by making. the ratchet teeth exceedingly small, the final clamping action may be effected without any appreciable departure of the jaws from absolute parallelism. In fact, due

to'th'eheavy clamping of the jaws on the object, aslight departure from parallelism which may exist in certain cases will produce less angle between the faces of the jaws and the faces of a nut than will the normal clearance provided in prior fixed wrenches.

Another important feature of the wrench resides in the fact that all of the heavy stresses to which the various elements of the wrench are subject are directly applied tension or compression stresses, with the result that distortion and fiexure, which would otherwise be encountered ifany'of the elements were subject to bending stresses, are avoided. Moreover, since the toggle mechanism pre-loads the wrench by clamping the nut, no spreading or distortion of the wrench jaws will occur on twisting a nut until the force at the nut corners due to the twisting action exceeds the clamping force. The ratchet mechanism is peculiarly designed to provide maximum load capacity. Moreover,- the construction is such that there is no danger of stripping the teeth of the ratchet mechanism; and, since during idle adjusting movements the ratchet teeth are held out of engagement by spring 36 and lever 35, there is no possibility of the points of theteeth being worn away or rounding 01f by relative sliding engagement.

1 Another feature of the wrench resides in the fact that the adjustment for diiferent sizes of nuts is efiected by bodily swinging movements of the toggle linkage including the handle pl about the pivot 25 at the rear end of handle 2. Consefluently, such adjustments do not have any appreciable effect upon the spacing of the rear ends of the handles and it is thus possible to space the handles at the optimum distance for a normal hand grip.

It will be apparent that variations in the design and construction may be indulged in without departing from the spirit of the invention. Thus the size of the teeth II and i3 may be varied, depending upon the degree of parallelism required in the wrench. Moreover, since the lengthof the opening 9 is relatively short compared to the length of the toggle linkage, the 'points of the teeth I I may lie in a flat plane parallel to the direction of movement of the movable jaw Without serious departure from parallelism of the. jaws. The particular wrench illustrated is so constructed that the jaws will not close into contact with each other and hence is adapted for use on a range of nut sizes, from a maximum size which will fit the spacing of the jaws illustrated in Figure 1 to a minimum size which will fit the spacing illustrated in Figure 2. If so desired, the wrench may be so constructed by simply altering the shape of the jaws that the jaw faces contact each other when the remaining parts are in the position shown in Figure 2. Such a wrench would then operate on smaller range of sizes.

While the use of combined levers and springs for maintaining the toggle broken, the jaws open and the ratchet teeth out of contact provide optimum performance, it will be apparent that the jaws may be maintained broken by a single leaf spring and the jaw movements controlled by either one or two springs without using either of the

levers

26 and 35.

Other variations in the design and construction will be obvious to those skilled in the art and may be indulged in without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

'1..A wrench having a pair of handles adapted to be gripped in one hand, a jaw carried by one of said handles, an element mounted for sliding movement with respect to said jaw in a direction approximately at right angles to the face of said jaw, a second jaw pivoted on said element, a pair of interconnected links forming a toggle linkage one of which links is pivoted to the second jaw and the other to said one handle, resilient means connected to the toggle linkage and normally acting to break the toggle linkage, the other handle being connected to the toggle linkage with the result that a squeezing of said handles together tends to bring the toggle linkage pivots into alignment and to swing said linkage bodily about its connection to the first handle in a direction to close the jaws, the location of the points of connection of said toggle linkage 'to said second jaw and said one handle being such that the faces of said jaws remain substantially parallel as said element slides with respect to said one jaw, said one jaw having a plurality of teeth fixed thereto and extending alongside the path of movement of said element, cooperating ratchet teeth on said element, a second resilient means connected to the second jaw and normally urging said teeth out of engagement by limited pivotal movement of the second jaw about its connection to the toggle linkage, the teeth on said one jaw and the face on the other jaw facing in the same direction around the axis of the pivotal connection between the toggle linkage and the other jaw, with the result that engagement by the second jaw with an object located between the jaws when said handles are squeezed together will swing said second jaw about its connection to the toggle linkage in a direction to cause engagement of said teeth and against the force exerted by the second resilient means, and the strength of said first resilient means relative to the strength of said second resilient means being such that squeezing of said handles together will cause engagement of said ratchet teeth before the toggle linkage begins to straighten.

2. A wrench having a fixed jaw, a movable jaw connected to the fixed jaw for pivotal and slidable movement with respect thereto, a toggle linkage connecting the movable jaw to the fixed jaw and extending at approximate right angles to the direction of relative sliding movement between said jaws, said toggle linkage including a handle member the major hand-engaging portion of which is positioned between the points of connection of the linkage to the two jaws with the result that hand pressure applied to the handle tends to slide the jaws toward each other, means for holding said jaws against relative sliding movement in any one of a plurality of positions of adjustment to permit clamping of an object by straightening of said toggle linkage and pivotal movement of the movable jaw, and resilient means for resisting straightening of said toggle linkage in order to permit pressure exerted on said handle to slide the movable jaw toward the fixed jaw prior to engagement of an object between said jaws without straightening of said to gle linka e.

, 3. A wrench having a pair of handles adapted to be gripped by one hand, a jaw fixed to one handle, a second jaw pivotally connected to the other handle, a link pivotally connected at one end to said one handle at a fixed point thereon and'at the other end to the second handle inter- 7 5 mediate its ends and forming with said other ascend ii'ii'die a toggieimkage; anew-neat connected to one handle for sliding movement in a, dime-- intersecting theplafie of the face of the first j swam in a path lying approximately on an arc of a circle having a radius equal tothel'ength of the straightened togglelinkage and having its center paced from said fixed point by a distance'e'qiial to' the distance between the pivotal connections between the second jaw and said other handle and said element, and a pivotal connection be"- twen the element and'the' second jaw, said one handle and said element having intereng'a'gin surfac s thereon ior'holding said element in" any one' of a plurality" of positions with respect to said one handle.

4. A wrench having a pair of jaws, an element connected to one jaw for sliding movement relative to said jaw in a path approximately at right angles to the plane of the jaw face; a pivotal connection between said element and the other jaw, a series of teeth on said one jaw which ex'-' tend alongside the path of movement of saidelement, said teeth pointing toward said element, co-operatin'g' teeth on said element adapted to mesh with said first series of teeth, and a link mechanism pivotally connected to and between said jaws" and extending approximately at right angles to the path of sliding movement of said element and co-operating with said element to guide said other jaw for movement toward and from the one jaw and maintain the" jaw faces substantially parallel, the pivotal connection be tween said link mechanism and said other jaw being spaced from the pivotal connection between said element and said other jaw, the teeth on said one jaw and the face on the' other jaw fz icing in the same direction around the axis of the" pivotal connection between said other jaw and said link mechanism so' that a force applied perpendicularly to the face of said other jaw will swing said other jaw about its pivotal connection to said link mechanism in a direction to cause" meshing of said teeth on the element with those on" said one j aw.

5. A wrench having a pair of jaws, an element connected to one jaw for sliding movement relative to said jaw in a path approximately at right angles to the planes of the jaw face, a pivotal eonnection between said element and the other jaw, a series of teeth on said one jaw which ek tendalongside the path of movement of said ele'-' ment, said teeth pointing toward said element, o=operating teeth on said element adapted to mesh with said first series of teeth, a link mecha pivotally connected to and between said jaws and extending approximately at right angles to the path of sliding movement of said element and co-operating with said element to guide said other jaw for movement toward and from the one jaw and maintain the jaw faces substantially parallel, the pivotal connection between said link mechanism and said other jaw being spaced from the pivotal connection be tween said element and said other jaw, the teeth on said one jaw and the face on the other jaw facing in the same direction around the axis of the pivotal connection between said other jaw and said link mechanism so that a force applied perpendicularly to the face of said other jaw will swing said other jaw about its pivotal connection to said link mechanism in a direction to cause meshing of saidteeth on the element with those on said one jaw, and a single resilient constantly urging" said otherjav'v in a dii'e'c'tion to Separate Said jaws and also rotate 1 4 said? other jaw abcut its" pivotal connection to said link mechanism in a direction to cause sep'' aration of said ratchet teeth so that engagement between said teeth will not occur until a force isapplied tothe'face o'f saidother jaw.

6. A wrench" having a pair of jaws, an element connected to-one jaw for sliding movement relativeto said jaw in a path approximately'at right angles to the planes of the jaw face, a pivotal connection between said element and the other jaw', a' series of teeth on said one jaw which ex= tend alongside thepath'of movement of said ele-- ment, said teeth pointing toward said element, co-op'e'r'ating teeth on said element adapted to" mesh with said first series of teeth; a link mecha pivo-tally connected to and between said jawsand extending approximately at right angles to the path of sliding movement of said element and cd-operating with said element to guide said other jaw for movement toward and from the one" jaw and maintain the jaw faces substantially parallel, the teeth on said one jaw and the face on the other jaw facing in the same direc' tion around the axis of the pivotal connection between said other jaw and said link mechanism so that a force applied perpendicularly to the face of said other jaw will swing said other jaw about its pivotal connection to said link macha nism in a direction to cause meshing of said teeth on the element with those on said one jaw, and resilient means constantly urging said element out of contact with said teeth so that engag'ement between said teeth will not occur until after a; force is" applied to the face of said other jaw, said link mechanism including means for pivoting said other jaw about its pivotal connection to said element to apply a clamping force" to an object between said jaws after said teeth have engaged.

'7. A wrei'ach having a pair of handles adapted to begripp'ed in one hand, a jaw carried by one" of said handles, an element mounted for sliding movement with respect to' said jaw in a direction approximately at right angles to the faceof said jaw, a second jaw pivoted on said element, a pair of interconnected links forming a toggle linkage one of which links is pivoted to the second jaw and the other to said one handle, resilient means norfnally acting tob'r'eak the toggle linkage to a limited degree s6 that: the linkage will swing as a unit about the pivctal connection to the handle, the other handle being associated with the toggle linkage in such a manner that a squeezing of said handles together tends to bring the toggle linkage pivots into alignment and to swing said linkage bodily about its connection to the first handle in a direction to close the jaws, the location of the points of connection of said toggle linkage to said secondjaw and said one handle being such that thefacs of said-jaws remain substantially parallel said element slides with respect to said one jaw, said one jaw having a plurality of teeth fixed thereto and extending alongside the path of movement of said element, co-operating teeth on said element, a second resilient means normally urging said teeth out of engagement by limited pivotal movement of the second jaw about its connection to the toggle linkage, the teeth on said one jaw and the face on the other jaw facing in the same direction around the axis of the pivotal connection between the toggle linkage and the other jaw, with the result that engagement by the second jaw with an object located between the jaws when said handles are squeezed together will swing said second jaw about its connection to ange n the toggle linkage in a direction to cause engage! ment of said teeth and against the force exerted by the second resilient means, and the strength of said first resilient means relative to the strength of said second resilient means being such that squeezing of said handles together will cause engagement of said teeth before the pivots of said toggle linkage are aligned.

8. A wrench having a pair of handles, a wrench jaw fixed on one handle at one extremity thereof with its jaw face extending approximately parallel to the length of the handle, a link pivotally connected at one end of the other handle and at its opposite end to the opposite extremity of said one handle and forming with said handle a toggle linkage, a member connected to said jaw for movement relative thereto in a direction approximately at right angles to the plane of the face of said jaw, a second jaw pivotally connected at spaced points to said other handle and said member whereby bodily pivotal movement of said toggle linkage about the axis of its connection to the first handle and toward the first handle will cause said jaws toapproach each other, resilient means tending to separate said jaws, means to lock said member against movement relative 'to said first jaw, and means to resist relative pivotal movement between said handle and link in order to induce said bodily pivotal movement of said toggle linkage when one handle is forced toward the other.

9. A wrench having a fixed jaw, a movable jaw connected to the fixed jaw for pivotal and slidable movement with respect thereto, a toggle linkage connecting the movable'jaw to the fixed jaw and extending at approximate right angles to the direction of relative sliding movement between said jaws, said toggle linkage including a handle mem-' ber the major hand-engaging portion of which is positioned between the points of connection of the linkage to the two jaws with the result that hand pressure applied to the handle tends to slide the jaws toward each other, means for holding said jaws against relative sliding movement in any one of a plurality of positions of adjustment to permit clamping of an object by straightening of said toggle linkage and pivotal movement of the movable jaw, and resilient means for resisting straightening of said toggle linkage in order to permit pressure exerted on said handle to slide the movable jaw toward the fixed jaw prior to engagement of an object between said jaws without straightening of said toggle linkage, said last mentioned means including a lever pivoted on one of the links and having a sliding engagement with the other link and acting as a strut to resist movement of the pivot point toward the other link, the line between the axis of the lever pivot and the point of contact between the lever and said other link lying at an acute angle tothe contacted link surface which decreases when the lever slides along said other link incident to straightening of the toggle linkage, and a spring acting between the lever and one of said links for exerting a force tending to rotate said lever in a direction to increase said angle.

10. A wrench having a fixed jaw, a movable jaw connected to the fixed jaw for pivotal and slidable movement with respect thereto, a toggle linkage connecting the movable jaw to the fixed jaw and extending at approximate right angles to the direction of relative sliding movement between said jaws, said toggle linkage including a handle member the major hand-engaging portion of which is positioned between the points of connection of the linkage to the two jaws with the result that hand pressure applied to the handle tends to slide the jaws toward each other, means for holding said jaws against relative sliding movement in any one of a plurality of positions of adjustment to permit clamping of an object by straightening of said toggle linkage and pivotal movement of the movable jaw, and resilient means for resisting straightening of said toggle linkage in Orderto permit pressure exerted on said handle to slide the movable jaw to-' ward the fixed jaw prior to engagement of an object between said jaws without straightening of said toggle linkage, said last mentioned means including a lever pivoted on one of the links and having a sliding engagement with the other link and acting as a strut to resist movement of the pivot point toward the other link, the line between the axis of the lever pivot and the point of contact between the lever and said other link ly ing at an acute angle to the contacted link surface whi-ch decreases when the lever slidesalong said other link incident to straightening of the toggle linkage, and a spring acting between the lever and one of said links for exerting a force tending to rotate said lever in a direction to increase said angle, the angle between the line of force exerted by the spring on the lever and said line between the lever pivot and point of contact being such that the effective lever arm of the spring force on the lever reduces as the toggle linkage is straightened, said lever having a portion which acts as a positive abutment between said handle and other link to prevent said toggle linkage from breaking in one direction.

11. A wrench having a pair of generally parallel handles adapted to be gripped by one hand, a jaw fixed on the forward end of one handle, a second jaw mounted for sliding movement relative to the first jaw in'a direction approximately at right angles to said handles, a pivotal connection between the forward end of the other handle and the second jaw with the result that when the forward ends of said handles are squeezed toward each other the jaws are caused to approach and when the rearward ends of the handles are moved toward each other the other handle pivots around its connection to the second jaw, automatic means operable in response to engagement of said jaws on an object for holding said jaws against relative sliding movement, yielding means connected to the other handle for resisting movement of the rear ends of the handles toward each other, separate yielding means connected to the jaws for separating the jaws, and force multiplying means connected to said other handle and operable when the rear ends of said handles are moved toward each other to force, said jaws toward each other while the reaction force is sustained by said automatic means.

12. A wrench having a fixed jaw, a movable jaw connected thereto, a pair of handles connected to said jaws for moving the jaws toward each other, a lever pivoted to one jaw and engaging the other, and a spring connected to the lever and to said one jaw and exerting a force tending to swing said lever in a direction to separate said jaws, the angle between the line of the force exerted by the spring on the lever and a line through the point of connection between the spring and lever and the pivotal axis of the lever being an acute angle which increases as the lever. swings in a direction to separate the jaws with 1 7 the result that the effective lever arm of the spring force on the lever reduces in approximate proportion to the increase in the force applied by the spring to the lever as the jaws move toward each other.

' JOHN A. BLAIR.

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

Number 1,445,280