US3253487A - Pliers having a rack and pawl coupling to produce greater force after the jaws closeabout the work - Google Patents

Description

y 1966 w. D. BENTLEY, JR 3,253,437

PLIERS HAVING A RACK AND PAWL COUPLING TO PRODUCE GREATER FORCE AFTER THE JAWS CLOSE ABOUT THE WORK Filed June 9, 1964 INVENTOR.

ma D. BEA/72.5), Lle. E/4m Mf r1 United States Patent PLIERS HAVING A RACK AND PAWL COUPLING This invention relates to hand tools and particularly to pliers adapted to exert very high clamping pressure on the work.

One known device of this character has been marketed for many years under the trade mark Vise Grip. This device includes a trapezoid linkage with two of the links being formed as parts or extensions of opposed jaw members and the other two links forming elements of a toggle. The maximum mechanical advantage occurs when the toggle links are in alignment, and this corresponds to adefinite relative angular position of the jaw links and, hence, a definite separation of the jaw members. But the size of the work determines the separation of the jaw members. Hence, unless the toggle linkage is adjustable, the toggle links will be out of alignment when the work is engaged. Accordingly, the effective length of one of the links is subject to adjustment, as by manipulation of a knurled screw. A manipulation is also required to break the toggle. These manipulations are tedious and time consuming.

It is thus the primary object of this invention to provide a hand tool of this character that need not be adjusted according to the size of the work, but which yet applies a uniformly high clamping pressure thereto. For this purpose a handle is pivotally connected to one of two pivotally connected jaw members and yieldingly held by light, return-spring at one relative angular position. A companion handle is formed as an extension of the other jaw member. The jaws are caused to engage the work by movement of the handles together; continued movement of the handle overpowers the light return spring. A high mechanical advantage linkage then automatically becomes operative between the pivoted handle and the jaw member joined to the opposite handle and high clamping pressure is exerted. When the grip on the handles is released, the coupling is disengaged.

Another object of this invention is to provide a simple tool of this character that can be economically manufactured.

V This invention possesses many other advantages, and

has other objects which may be made more clearly apparent from a consideration of one embodiment of the invention. For this purpose, there is shown a form in the drawings accompanying and forming a part of the present specification, and which drawings are true scale. This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a pictorial view of a hand-tool incorporating the present invention;

FIG. 2 is an enlarged fragmentary sectional view taken along a plane corresponding to line 22 of FIG. 1;

FIG. 3 is a front elevational view of the tool;

FIG. 4 is a fragmentary sectional view taken along a plane corresponding to line 4 -4 of FIG. 2; and

FIG. 5 is a fragmentary elevational view similar to FIG. 2 but illustrating the parts in a clamping position.

The tool shown in FIG. 1 comprises two mutually Patented May 31, 1966 pivoted plier elements. One of the elements made as a single part has ends with an intermediate pivot plate 12, a jaw member 13 at one end and a handle 14 at the other. The companion plier element has two main parts, a link 15 and a handle 16. The link 15 includes a pair of spaced parallel, flat, generally rectangular plates 17 and 18. These plates 17 and 18 are integrally joined at corresponding ends to the base of a jaw member 19 to form a yoke.

The plates 17 and 18 receive the circular pivot plate 12 of the companion plier element. A suitable pin 20 adjacent the base of both jaw members determines their path of relative angular movement. The pivot plate 12 extends well into the yoke formed by plates 17 and 18, the outer arcuate edge 12a of the pivot plate 12 extending approximately across the central area of the yoke plates 17 and 18.

The handle 16 has a flattened end 21 that fits into the outer end of the yoke well beyond the pivot plate 12. A pin 22 connects the handle 16 to the link 15 for movement about an axis parallel to the axis of movement of the jaw members.

The handle 16 and link 15 normally move in unison. For this purpose, an overrunning coupling is effected between the link 15 and the handle 16. Movement of the handle 16 in a clockwise direction about the axis of the pin is limited. The handle 16 is yieldingly held at this limited position illustrated in FIG. 2. When the handles 14 and 16 are moved together, the jaw members 13 and 19 close about the work.

A bracket 23, welded as at 24 across the yoke, mounts a spring 25 that urges the handle to the FIG. 2 position. The bracket 23 has an offset end defining, at the side edges of the yoke, a space in which one end of the spring 25 is held. The outer free end of the spring 25 engages the outer end of a lug 26.

The lug 26 which is accommodated between the yoke plates 17 and 18 is pivotally connected to the handle end 21. Thus the lug has a rounded inner end that seats in a semi-circular recess 27 located at the edge of the handle end 21. One side of the recess or seat 27 is adjoined by an extended flat wall 28 that limits angular movement of the lug 26 in a counterclockwise direction, while the other side of the semi-circular seat or recess 27 is adjoined by a curved wall 29 that permits clockwise movement of the lug.

The leaf spring 25 acts upon a flat end surface 26a of the lug 26 that is accessible at the side of the yoke. The surface 26a extends at an angle of approximately 30 to a radial line from the lug axis x. Accordingly, the force exerted by the spring 25 on the lug 26 has a small component that tends to rotate the lug in a clockwise direction about the recess axis. A guide pin 30 extending through the yoke between the handle end 21 and the pivot plate edge 12a engages the side of the lug 26 and limits clockwise angular movement. The spring 25 thus keeps the lug against the pin 30. The force imposed by the spring 26 upon the flat surface 26a, however, also has a large radial component directed toward the axis of the recess 27. This component tends to rotate the handle 16 in a clockwise direction about its pin 22. The manner in which these force components act upon the handle 16 may be explained with reference to FIG. 5. In this position, the lug 26 is seated in the recess 27 but spaced from the fiat side surface 28 thereof. The spring 25 holds the lug against the guide pin 30. Absent restraining torque on the handle 16, the spring 25 acting through the lug 26 will rotate the handle 16 in a clockwise direction about the pin 22. As the handle 16 rotates in this direction, the guide pin 30 prevents the lug 26 from rotating therewith. Accordingly, the lug is caused to rotate about the axis of the recess 27. Ultimately the flat side surface 28 is engaged and the parts assume the position illustrated in FIG. 2. Should the link 15 be restrained and a counterclockwise torque exerted upon the handle 16 with the parts in the position of FIG. 2, the pawl 26 will be cranked outwardly toward the pivot plate 12 due to the location of the guide pin 30. This cranking movement of the lug 26 is used for the purpose of coupling the handle 16 to the opposite jaw member 13 for the imposition of substantial torque thereon.

Thus when the handles 14 and 16 are moved together with the handle 16 at its limited position, the jaw members 13 and 19 first close about the work W. Continued torque on the handle 16 causes the handle to move angularly in a counterclockwise direction about the pin 22. The lug 26 then moves to the position of FIG. and its corner 31 engages teeth 32 formed in the edge 12a of the pivot plate 12. Since the crank has a relatively short lever arm about the axis of the pin 22, the mechanical advantage is substantial, and a clamping pressure of high magnitude is imposed upon the work.

The teeth 32 formed in the edge of the pivot plate 12 extend along an extended are centered at the pin 20. Accordingly, at whatever point the jaws 13 and 19 first engage the work, one of the teeth 32 is in position to be engaged by the corner 31 of the lug 26.

As soon as the grip on the handles 14 and 16 is released, the spring 25 returns the handle 16 to the position illustrated in FIG. 2 and the work may be removed.

The inventor claims:

1. In a hand tool cooperable with a workpiece: a pair of jaw members; handles for the jaw members respectively; means operative independently of the workpiece and carried by the jaw members to confine the jaw members for movement in a fixed path; movement of said jaw members in opposite directions in said fixed path causing opening and closing movement of said jaw members; means forming an overrunning connection between one of the handles and its jaw member; yielding spring means normally holding the handle against overrunning movement whereby said one handle and its jaw member move as a unit relative to said other jaw member and its handle until relative movement of the jaw members is restrained by contact with the work, whereupon said one handle member begins its overrunning movement and causes energy to be stored in said spring means; and a releasable coupling between said one handle and the opposite jaw member for applying a closing force between the jaw members, said coupling being established upon overrunning movement of said one handle substantially independently of the relative position of said jaw members.

2. In a hand tool: a first tool part having a central pivot plate, said first tool part having a jaw member and a handle at opposite ends of the pivot plate; a second tool part having a yoke, and a jaw member extending from the base of the yoke, said second tool part having a handle, one end of the handle being received in and pivoted to the outer end of the yoke; said pivot plate being received in the yoke in inwardly spaced relationship to said pivoted handle; a pin connecting the pivot plate to the yoke; said pivot plate having an edge extending arcuately about said pin and opposed to said pivoted handle end; there being ratchet type teeth formed in said arcuate edge; a pawl having a rounded end; said lever end having a recess receiving the rounded pawl end, said recess extending inwardly of the edge of said lever end; said recess having one side extended to limit angular movement of the pawl about the axis of the recess; a stop pin carried by the yoke and engaging the pawl to limit angular movement of the handle; a leaf spring engaging the pawl and urging the pawl to seat in its recess and to move the pivoted lever to a limited position determined by said extended side and said stop pin; said pawl being cranked outwardly to engage said toothed edge upon angular movement of the lever away from its limited position whereby clamping torque is applied by movement of said pivoted handle.

3. The combination as set forth in claim 1 in which said means operative to confine the jaw members in a fixed path comprises a pivot pin carried by one of the jaw members cooperable with an aperture formed in the other of the jaw members, the aperture having a configuration operative to confine the jaw members for relative arcuate movement about said pivot pin as an axis.

References Cited by the Examiner UNITED STATES PATENTS 1,207,947 12/1916 Litchfield 81-314 2,413,178 12/1946 Feltman 81-314 X 2,720,900 10/1955 Quist 81-364 X 3,169,307 2/1965 Langwell 81-314 X FOREIGN PATENTS 80,545 5/1934 Sweden.

WILLIAM FELDMAN, Primary Examiner.

MILTON S. MEHR, Examiner.

Claims (1)

1. IN A HAND TOOL COOPERABLE WITH A WORKPIECE: A PAIR OF JAW MEMBERS; HANDLES FOR THE JAW MEMBERS RESPECTIVELY; MEANS OPERATIVE INDEPENDENTLY OF THE WORKPIECE AND CARRIED BY THE JAW MEMBES TO CONFINE THE JAW MEMBERS FOR MOVEMENT IN A FIXED PATH; MOVEMENT OF SAID JAW MEMBES IN OPPOSITE DIRECTIONS IN SAID FIXED PATH CAUSING OPENING AND CLOSING MOVEMENT OF SAID JAW MEMBERS; MEANS FORMING AN OVERRUNNING CONNECTION BETWEEN ONE OF THE HANDLES AND ITS JAW MEMBER; YIELDING SPRING MEANS NORMALLY HOLDING THE HANDLE AGAINST OVERRUNNING MOVEMENT WHEREBY SAID ONE HANDLE AND ITS JAW MEMBER MOVE AS A UNIT RELATIVE TO SAID OTHER JAW MEMBER AND ITS HANDLE UNTIL RELATIVE MOVEMENT OF THE JAW MEMBERS IS RESTRAINED BY CONTACT WITH THE WORK, WHEREUPON SAID ONE HANDLE MEMBER BEGINS ITS OVERRUNNING MOVEMENT AND CAUSES ENERGY TO BE STORED IN SAID SPRING MEANS; AND A RELEASABLE COUPLING BETWEEN SAID ONE HANDLE AND THE OPPOSITE JAW MEMBER FOR APPLYING A CLOSING FORCE BETWEEN THE JAW MEMBERS, SAID COUPLING BEING ESTABLISHED UPON OVERRUNNING MOVEMENT OF SAID ONE HANDLE SUBSTANTIALLY INDEPENDENTLY OF THE RELATIVE POSITION OF SAID JAW MEMBERS.

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