US 2635496 A
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Description (OCR text may contain errors)
April 21, 1953 v. MARASCO 2,635,495
FINGERS WITH JAW LOCKING MEANS Filed Dec. 20, 1950 2 SHEETS-SHEET 1 W/vcE/vr MAE/1500,
April 21, 1953 v. MARASCO 2,635,496
PINCERS WITH JAW LOCKING MEANS Filed Dec. 20, 1950 2 snams smm :2
Patented Apr. 21, 1953 UNITED STATES PATENT OFFICE 8 Claims.
The present invention relates generally to hand tools like pliers or tongs with pivoted jaws for gripping and holding a piece of work, and more particularly to hand tools of this character provided with means for locking the jaws in any selected gripping position so that the gripping action of the jaws is maintained independently of further action by the operator.
Pincers, as pliers or tongs, and similar hand tools are old and well known and have been used widely for a long time without any means for holding the gripping jaws in any set position.
-machinist or mechanic could manually operate the pliers to grip the work piece, as for example a nut, and then set the pliers manually to maintain this grip. For another example, a welder 'desiring to weld together two pieces of metal could manually actuate the tongs to hold the two pieces in the desired position and then look them in this gripping position to free his hands for other work.
There have been various attempts to combine the advantages of both types of tools by providing locking devices for tools with movable jaws for gripping a piece of work. In order to obtain a locking action, known types of these tools have departed more or less from the conventional design of a pair of pincers having only a pair of pivotally interconnected lever members and have from necessity rather complicated mechanisms.
.The particular defect of known types of tools of this character is the fact that they are not self-adjusting so that the jaws can be locked in any position of expansion or movement relative to each other without some adjustment of the locking mechanism. Thus for any given adjustment of the locking mechanism, the lock may be applied only within a very narrow range of the jaw movement with the result that a person using this type of tool on work pieces of different sizes f must take the time to adjust the locking mechanism for each individual size of work piece gripped. This usually requires adjustment of the locking mechanism by trial and error, the work piece being released during each manipulation of the adjusting means until after one or more trial settings, sometimes several settings being required, the locking means is adjusted to grip -means intermediate their ends.
with the desired tightness for the particular jaw spacing required.
The big disadvantage of this type of tool is the time required to use it properly. Several seconds may be required to obtain the proper setting of the parts; and sometimes this time factor is considerably increased because of the fact that the work piece must be released between trial settings. Consequently, in a repair shop and the like where the tool is being used on different parts and upon work of different sizes continually, most of the advantage of the clamping action of the tool is lost and very little gain is made in either time or convenience over a conventional clamp, as for example a C-clamp.
Hence it becomes the general object of my invention to provide a hand tool like pliers or tongs which is provided with means for locking the jaws in any position to maintain gripping pressure upon the work piece.
It is a further object of my invention to make a tool of this character in which the locking mechanism can be operated at once in any position of the jaws and without adjustment of the locking means to render it operable at a particular jaw spacing.
A further object of my invention is to provide a self-adjusting locking mechanism for a hand tool such as a pair of pliers or tongs which may be manipulated in all respects without requiring that the jaws release the work piece.
Another object of my invention is to provide a tool of the character described in which the locking mechanism is adapted to increase the gripping pressure upon the work means when the locking mechanism is set in looking position. These objects are accomplished in a tool constructed according to my invention by applying suitable locking means to a pair of lever members which are pivotally interconnected by pivot On one side of the pivot means the lever members may have any suitable type of jaws for gripping the work while at the other side of the pivot means the levers are providedwith handles for manual bar and preferably is connected through the pivot means to the lever member other than the one carrying said abutment. At another position on the lock bar there is connected a link or actuating member by which the lock bar is manually moved into engagement with the arcuate surface on the abutment. The lock actuating means consists of two pivotally interconnected members one of which is connected to the lock bar, as just mentioned, and the other to the lever member other than the one carrying said abutment. These last two interconnected members form a toggle arrangement which can be manually moved over center to bring and hold the lock bar in firm engagement with the arcuate surface.
How the above objects and advantages of my invention, as well as others not specifically referred to herein, are attained will be more readily understood by reference to the following description and to the annexed drawings, in which:
Fig. 1 is a side elevation of a hand tool constructed according to my invention;
Fig. 2 is a section on line 2-2 of Fig. 1;
Fig. 3 is a side elevation of the hand tool of Fig. 1 with the jaws in a typical gripping position and the jaw locking means in looking position;
Fig. 4 is a side elevation of my improved hand tool with the parts in the same position as in Fig. 1 but viewed from the opposite side of the tool;
Fig. 5 is a fragmentary view showing the locking toggle and release handle detached from the remainder of the tool;
Fig. 6 is a side elevation of a modified form of my invention;
Fig. 7 is a view similar to Fig. 6 but with the tool jaws spread to grip a work piece and the jaw locking mechanism in looking position; and
Fig. 8 is a fragmentary elevation on line 8--8 of one of the work gripping jaws.
A preferred embodiment of my invention is illustrated in Figs. 1 to 5. In these drawings, the tool comprises a pair of principal lever members In and I2 which are pivotally interconnected intermediate their ends by means of pivot I4. At one end each lever I0 and I2 is provided with a work gripping jaw I5, the two jaws being located opposite each other and at the same side of pivot I4. At the opposite side of pivot I4 each of the principal lever members is shaped to provide a handle It by which the levers may be grasped by an operator for manual operation. These two lever members with their jaws and handles are essentially the same as a familiar pair of pliers and they may be modified as desired to provide any one of a large number of shapes of handles or jaws to adapt them to a particular job.
In order to hold the jaws in any selected position in which they are gripping the work, locking means are provided. The locking means comprises an abutment I8 on one of the primary levers, here shown as being lever i2, the abutment presenting an arcuate surface I9 which is circular and concentric with the axis of pivot I4. The other part of the locking means is looking bar 20 adjacent arcuate surface I9 and which is movable, as will be described, into engagement with the arcuate surface to hold the lever mem-- bers against relative pivotal movement. The engagement between abutment I8 and lock bar 20 is preferably a frictional one in order to obtain gripping engagement at any position on surface I8; and for this reason the character of the engagement between them may be improved by providing surface I9 with small serrations or teeth which serve to grip bar 20 more firmly. In order to resist wear and abrasion, abutment I8 is preferably case hardened. On the other hand,
bar 20 is preferably of softer material since two equally hard surfaces are inclined to slip one on the other.
It is obvious that a roughened or serrated surface may be provided on lock bar 20 instead of or in addition to teeth on surface I9. Likewise both the bar and abutment may have teeth providing a more positive engagement; but as the teeth increase in size the two members hecome properly engageable only at a series of spaced or stepped positions rather than at any position.
The forward end of lock bar 20 is held in a relatively fixed position by means of arm 22 which is pivotally connected to bar 20 at its forward end and is connected to lever I0, which is the other lever than the one carrying abutment I8, by means of pivot II. For reasons that will be more fully explained later, arm 22 is pivotally mounted on pivot pin I4 to move relative thereto and with respect to lever I0, though the amount of such movement is small. Although arm 22 may be made as a single member, it is preferably a double member (see Fig. 2) with one part on either side of bar 20 in order to hold the locking bar more firmly and evenly in engagement with abutment I8, as will be readily understood.
It is preferred to construct the arm to have a limited amount of movement, as will now be described. For this purpose, one side of arm 22 is extended at 22a beyond pivot I4. The outer end of extension 22a is connected by spring 25 to lever I0, one end of the spring being fastened to a fixed boss 26 on the lever member. Spring 25 is a tension spring and pulls the arm (in a counter-clockwise direction viewed in Fig. 1) around pivot I4, thus bringing extension 22a into engagement with an adjustable stop in the form of screw 21 which is threaded into boss 28 on primary lever I0. When the parts are in the released position of Fig. 1, extension 22a engages the end of adjusting screw 21 and the exact position of arm 22, and consequently pivot 24 and bar 20, can be adjusted by turning screw 21 in one direction or the other. At the same time, arm 22 is free to move a limited amount in a clock-wise direction against spring 26 under conditions which will be later described.
At a position removed from pivot 24, preferably at or near the other or rear end of lock bar 20, there is connected manually operable lock actu ating means which is adapted to draw the lock bar firmly against arcuate surface I9. This lock actuating means comprises a pair of toggle members 30 and 3I which are pivotally connected together at one end of 32. The other end of the longer bar 3| is pivotally connected at 34 to lock bar 20. The other end of toggle bar 30 is pivotally connected at 35 to principal lever member Ill which is the other lever member than the one carrying abutment i8.
The lock actuating means as so far described is fully effective for its purpose, but it is preferred to add to it a release handle which not only facilitates release of the locking mechanism but also gives additional leverage for setting the lock mechanism. This handle consists of an angular member 38 which is pivotally mounted on the toggle bars at pivot 32. The grip portion of handle 38 extends rearwardly in the same general direction as handles I6 and is spaced at one side of them. This position is preferred so that an operator can grasp handle 38 and handles I 6 within the span of one hand. Handle 38 has a lateral extension 39 that is channel shaped in crosssection and lies over the top of bar 3|. Extension 39 is provided with a pair of spaced flanges 39a and 3% which engage either side of bar 3| in order to limit the angular motion of handle 38 about pivot 32. To facilitate the releasing operation, described later, stop pin 45 is mounted on principal lever member Iii in a position to be engaged by projection 3?) of handle 38.
Having described the construction of a preferred embodiment of my invention, I shall now describe briefly its operation. The parts are shown in Fig. 1 in what may be termed a released or free position. Here lock bar 28 is free of abutment l8 and the two lever members may be manipulated in the usual manner of a pair of pliers by an operator who grasps the handle E5 in one hand. Now assume that a work piece is placed between the two jaws |5 as in Fig. 3 and that the jaws are caused to grip the work piece firmly by pressure applied to handle l5 by the operator which brings the handles and the jaws toward each other. If it is desired to lock the jaws in this gripping position, all that is necessary is to move toggle members 3|! and 3| into the position of Fig. 3. It will be noticed that this is accomplished by moving pivot 32, interconnecting the two members of this lock actuating means,
forward toward jaws l5, until bars 35 and 3! reach and slightly pass a dead-center position in which the axis passing through pivots 32 and 34 is moved from the position of Fig. 1 through the position of Fig. 5 to slightly ahead of the axis of pivot 35 as in Fig. 3. Additional mechanical advantage may be obtained to move pivot 32 forward by using handle 38. Flange 39b engages the side of bar 3| to hold the handle against rotation on the pivot.
As the several members are moved forward into this position, the bar 38 acts as a crank or lever which, through the connection to the locking bar by means of member 3 i, pulls the locking bar in a clock-wise direction about pivotal connection 24. This rotation of the lock bar moves it into firm engagement with surface l9 of abutment i8 thus holding lever member |2 in a fixed position relative to the other lever member. As a result, it is no longer necessary for the operator to maintain pressure on handles in order to continue gripping the work piece between jaws l5.
In the locking operation, arm 22 rotates slightly about pivot l4, as may be seen by comparing Figs. 1 and 3. This motion is very slight but it is sufficient to disengage arm extension 22a from the forward end of stop 27. Because of this limited movement of arm 22, there is a tendency for jaws |5 to move somewhat closer together as the locking mechanism is set. There is little or no actual movement of the jaws unless the work piece is sufficiently elastic or flexible to permit such movement, but this feature is highly desirable since it increases the gripping pressure applied by the jaws when the locking mechanism is set.
In order to release the lock, pressure is applied on the outer end of handle 38 in the direction to move it counter-clockwise about pivot 32, as indicated by the arrow in Fig. 5. Engagement of handle extension 39 with stop 40 not only limits forward movement of bar 3| but provides a fulcrum about which this releasing pressure applied to the outer end of handle 38 acts to move pivot 32 rearwardly or counter-clockwise about pivot 35. As soon as the toggle members pass over dead center to the position of Fig. 5 moving rearwardly, gripping pressure is released on the work piece which is then free. The parts are now moved back to the position of Fig. 1.
Although connection 32 is described as moving forward to set the locking mechanism my invention is not limited necessarily to motion in this direction which is preferred for convenience. For example the toggle may be rearranged to bring about looking action when joint 32 is moved rearwardly.
It is a characteristic of the construction shown that the engagement between members [8 and 20 is of a ratchet type. For any spacing of jaws l5, they are held against movement separating them further; but they may be moved closer together when the locking mechanism is set withoutreleasing the locking means. This is possible because by pivoting arm 22 at [4, the linkage consisting of elements 22, 20, and 3| can change shape slightly by pivoting about points l4 and 32 when pivot 24 is moved rearwardly but the same linkage is rigid to resist movement of pivot 24 forward.
There is shown in Figs. 6, 7 and 8 a modified form of my invention which is the same in prin ciple as the form already described except that the locking mechanism is applied to what may be termed a pair of tongs rather than pliers. In this form of the invention, primary levers 4| and 42 are relatively longer than in the form previously described, and are pivotally interconnected at a point intermediate therein by pivot 43. At one end, levers 4| and 42 are provided with handles 45 and at the other end with jaws 46 which are pivotally connected at 41, one jaw to each of the levers. Jaw members 46 are designed to have their gripping faces maintained parallel to one another throughout their entire range of movement and for this purpose a pair of positioning bars 48 are provided. Bars 48 are pivotally interconnected at 49 at one-end, while the other end of each bar is pivotally connected at 50 to one of jaws 45. Pivot 49 is spaced from pivot 43 by a short rigid bar 52. Two tension springs 53 are fastened one to each of levers 4| and 42 and at the other end both to pivot 49 so that the equal pull of the two springs 53 keeps pivot 49 midway between the two primary lever members. Consequently link 52 is maintained substantially on the bisector of the angle between handles 45, regardless of the degree to which the handles are spread or brought together. As a consequence, each of positioning bars 48 is maintained parallel to the associated one of the primary levers 4| and 42. The positioning bars in turn maintain jaws 46 with their opposed gripping faces parallel to each other at all times, as may be seen by comparison of Figs. 6 and '7. In the latter figure the jaws are spread wide apart to grip a piece f work between them.
The locking means comprises abutment 55 attached rigidly to lever 42 and provided with arcuate surface 56v which is concentric with primary pivot 43. Lock bar 58 is positioned adjacent the arcuate surface in order to engage the same.
Lock bar 58 is pivotally connected at 59 to arm 6|] which is also attached to pivot 43. Pivot 43 is a means for connecting arm 60 to lever 4|, the lever other than the one carrying abutment 55. Arm 6|] extends beyond the pivot to provide for attachment to the link of one end of tension spring 6|, the other end ofspring 6| being attached to the other primary lever member 4|, that is the one not carrying abutment 55, by means of connecting strap 62.
The lock actuating means for drawing lock bar 58 against the arcuate surface is a toggle mech! anism as before described. It consists of two bars 65 and 66 which are pivotally interconnected at 61. Bar 65 is connected to lever 4| at pivot 68 while the other or longer bar 66 is pivotally connected at 69 to the rear end of lock bar 58.
When the locking mechanism is released and the jaws are free to move, the parts occupy the relative position shown in Fig. 6. Since there is no engagement between abutment 55 and lock bar 58, the tongs may be manipulated freely without regard to the locking mechanism. If the jaws are spread apart and then grip a work piece as shown in Fig. 7, the locking mechanism may be set to hold the tongs in adjusted position by manually pushing toggle pivot 61 forwardly in a direction clockwise about pivot 68 to the position shown in Fig. 7. At this position, the axis of bar 66 has moved ahead of pivot 68 and is in contact with a bend in strap 62 to limit such forward movement. held in the forward position in which look bar 58 has been rotated about pivot 56 to bring the bar into engagement with arcuate surface 51 of abutment 55, which will be understood from the foregoing description. The locking mechanism can be released by reversing the direction of movement of toggle joint 61, thus restoring the parts to the released position of Fig. 6.
Having shown and described a preferred form of my invention, and indicated various possible modifications thereof, it will be evident that various other changes may be made without departing from the spirit and scope of my invention. Consequently, I wish it understood that the foregoing description is considered to be illustrative of, rather than limitative upon, the appended claims.
1. In a hand tool of the character described,
the combination comprising: a pair of lever memi bers pivotally interconnected by pivot means intermediate their ends, the lever members being provided with work gripping means at one side of the pivot and handle means at the other side; locking means comprising an abutment on one lever member providing an arcuate surface concentric with said pivot means, and a lock bar movable into engagement with the arcuate surface to hold the lever members against relative pivotal movement; an arm pivotally connected to the lock bar and pivoted relative to the lever members; and manually operable lock actuating means connected to the lock bar and to said other lever member to draw the lock bar firmly against the arcuate surface.
2. A hand tool as in claim 1 in which the lock actuating means includes a toggle having two pivotally interconnected members connected one to the other end of the lock bar and the other to the other one of the lever members.
3. A hand tool as in claim 2 in which the lock actuating means also includes a release handle pivotally mounted on the pivot interconnecting the two members of the toggle and engageable with a fixed stop on said other lever member to move the toggle to non-locking position.
4. A hand tool as in claim 1 in which the work gripping means includes a pair of jaws pivoted one to each lever member, and which also includes a pair of positioning bars pivotally interconnected at one end and at the other end each pivoted to one of said jaws, and spring means connected to each lever member and to the positioning bars to maintain the jaws in parallel mari a p si In this way the toggle is 5. In a hand tool of the character described, the combination comprising: a pair of lever members pivotally interconnected by pivot means intermediate their ends, the lever members being provided with work gripping means at one side of the pivot and handle means at the other side; locking means comprising an abutment on one lever member providing an arcuate surface concentric with said pivot means, and a lock bar movable into engagement with the arcuate surface to hold the lever members against relative pivotal movement; an arm pivotally connected to the said pivot means and pivotally connected to the lock bar; and manually operable lock actuating means connected to the lock bar at a point spaced from said arm to draw the lock bar firmly against the arcuate surface.
6. In a hand tool of the character described, the combination comprising: a pair of lever members pivotally interconnected by pivot means intermediate their ends, the lever members being provided with worl: gripping means at one side of the pivot and handle means at the other side; loci-ting means comprising an abutment on one lever member providing an arcuate surface, and a lock bar frictionally engageable with the arcusurface; an arm extending generally transversely of the lever members, the arm being pivotally connected to said pivot means and pivotally connected to the lock bar near one end thereof; and lock actuating means spaced from the pivot toward the handle end of the lever members, said means including a pair of rigid members pivotally interconnected at one end, one member being pivotally connected at the other end to the lock bar at a position spaced from the arm and the other me...!-er being pivotally connected at the other end to said other lever member.
7. In a hand tool of the character described, the combination comprising: a pair of lever members pivotally interconnected by pivot means intermediate their ends, the l ver members being provided with work gripping means at one side of the pivot and handle means at the other side; locking means comprising an abutment on one lever member providing an arcuate surface, and a lock bar frictionally engageable with the arcuate surface; an arm extending generally trans versely of the lever members and connected intermediate its ends to said pivot means, the arm being pivotally connected near one end to the lock bar and connected by a resilient member near the other end to the other lever member to bias the arm toward a fixed position; and manually operable lock actuating means connected to the lock bar and spaced from the arm to draw the lock bar firmly against the arcuate surface.
8. A hand tool as in claim 7 that also includes an adjustable stop mounted on said other lever member and engaging the arm to limit the movement thereof under the influence of the resilient member.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 673,605 Jacques May 7, 1901 767,237 Plank et al. Aug. 9, 1904 1,276,815 Ruthven Aug. 27, 1918 1,294,689 Mellum Feb. 18, 1919 2,439,785 Feitl et al. Apr. 13, 1948