Through-bolt gripping pliers with adjustable opening width

The invention relates to gripping pliers with an upper extended handle 2 and a lower extended handle 1 which comprise a handle section 9, 7 and a jaw 8, 6 positioned opposite the handle section 9, 7, with the upper extended handle 2 and the lower extended handle 1 being hingeingly supported in relation to each other in a box joint and with the joint comprising an engagement position and an adjustment position, and furthermore with an adjustment element 11 manually displaceable against a spring 19 in the direction of the swivelling axis being provided for adjusting the engagement position and the adjustment position, with the lower extended handle 1 comprising a slot in the joint area and with the upper extended handle 2 being inserted through the lower extended handle 1 in the joint area.

BACKGROUND OF THE OF INVENTION
 The present invention relates to gripping pliers with the characteristics.
 Such gripping pliers are known from practical application and in particular
 from the printed publications DE-PS 805 265 as well as DE-92 18 069 U1. In
 the known gripping pliers the lower extended handle and the upper extended
 handle cross in a joint which comprises an elongated indexing hole. The
 handle which constitutes the upper extended handle when the pliers are in
 use, forms the lower jaw while the lower extended handle when the pliers
 are in use, forms the upper jaw of the pliers.
 A through-bolt which forms the bearing axis of the joint is star-shaped or
 round in cross section and in longitudinal direction of the elongated hole
 engages the indexing hole located in the lower extended handle with a
 positive fit. A leaf spring arranged without protection provides
 pretension to the through-bolt in its catch position, with the said leaf
 spring being located on the outside of the joint opposite the
 through-bolt. To adjust the opening width of the known gripping pliers,
 the through-bolt must be pushed into the joint of the pliers, against the
 force of the leaf spring so that its larger cross-section is pushed out of
 the indexing hole. Thereafter the lower extended handle can be adjusted to
 the desired extent in relation to the upper extended handle. As soon as
 the through-bolt is no longer held, the leaf spring pushes it into the
 engagement position in the indexing hole, and the intended opening width
 of the gripping pliers is fixed. With these gripping pliers the upper
 extended handle comprises a slot and the lower extended handle in the area
 of the joint is inserted through the upper extended handle. For reasons of
 stability the aim is to keep the dimension of the lower extended handle in
 the joint area to approximately half the entire thickness, so that the
 load bearing surfaces of the joint components resting against the indexing
 bolt are approximately the same for the lower extended handle as they are
 for the upper extended handle.
 In the case of the known gripping pliers it is therefore necessary in order
 to undo the indexing connection, to displace, transversely to the
 longitudinal plane of the pliers, the indexing bolt by an amount
 approximately corresponding to half the thickness of the pliers. It is
 thus seen as a disadvantage that this travel is relatively extensive and
 that the free activation end of the indexing bolt in its home position
 laterally protrudes significantly further out than the joint.
 SUMMARY OF THE INVENTION
 Starting from this it is the object of the invention to create gripping
 pliers with a shorter activation distance of the index bolt.
 Because the lower extended handle comprises a slot in the area of the joint
 and the upper extended handle is inserted through the lower extended
 handle in the area of the joint, the adjustment element in the lower
 extended handle incorporating the slot can be engaged in two places spaced
 apart from each other. This provides the option of providing two
 relatively narrow bearing surfaces in the lower extended handle comprising
 the slot, with the adjustment position of the adjustment element being
 attained by displacing said adjustment element by an amount equal to the
 width of a bearing surface transversely to the longitudinal plane of the
 pliers. The activation distance (travel) for adjusting gripping pliers
 with a joint region designed in this way is only about half of the
 activation distance of conventional gripping pliers.
 An adjustment element which is simple to produce results if it comprises an
 essentially rotationally symmetrical indexing pin. In its engagement
 position the indexing pin can at the same time constitute the bearing axis
 of the joint. Furthermore, good bearing support is provided if the
 indexing pin comprises a first area of smaller diameter, a second area of
 medium diameter and a third area of larger diameter.
 A particularly robust embodiment which is also insensitive to damage and
 dirt provides for the lower extended handle in the region of the joint to
 comprise two elongated indexing holes opposing each other transversely to
 the plane of the pliers, of which one indexing hole comprises a number of
 overlapping small indexing bore holes of a first bore hole diameter and of
 which the other indexing hole comprises a number of overlapping large
 indexing bore holes of a second, larger bore hole diameter; in each
 instance a bore hole of the first diameter and a bore hole of the second
 diameter are arranged coaxially in relation to each other. This embodiment
 is further improved in that the indexing pin in the engagement position
 with its second area of medium diameter engages a bore hole of the first
 indexing hole, and with its third area of large diameter engages a bore
 hole of the second indexing hole, so that the indexing pin is fixed with a
 positive fit in the plane of the pliers, and the indexing pin in the
 adjustment position with its first area of smaller diameter is
 longitudinally slidable so as to engage the first indexing hole, and with
 its second area of medium diameter is longitudinally slidable so as to
 engage the second indexing hole, so that the indexing pin is altogether
 slidable in the plane of the pliers in longitudinal direction of the
 indexing holes.
 Preferably, the spring is a helical spring which engages an axis-parallel
 bore hole of the indexing pin. By way of a buttress, in the area of the
 joint the upper extended handle supports a pin arranged transversely to
 the indexing pin, with the spring being supported by said pin which
 penetrates the indexing pin. With this pin the indexing pin is secured so
 that it cannot be lost.
 Finally it is advantageous if the indexing pin at its face adjacent to the
 first area comprises a closure which closes off the bore hole for the
 helical spring, to the outside.
 Below, one embodiment of the present invention is illustrated by means of a
 drawing, as follows:

DETAILED DESCRIPTION OF THE INVENTION
 FIG. 1 shows gripping pliers according to the invention with a lower
 extended handle 1 comprising a slot and a upper extended handle 2 inserted
 through. In its joint area 3 incorporating a slot, the lower extended
 handle 1 comprises an elongated indexing hole 4 which in this embodiment
 is made up of a total of 7 round bore holes 5. The bore holes 5 are
 aligned side-by-side in a straight line; they partly overlap. In addition,
 the lower extended handle 1 comprises an upper jaw 6 as well as a handle
 section 7 which during use is the lower handle section. By contrast the
 upper extended handle 2 comprises a lower jaw 8 as well as a handle
 section 9 which during use is the upper handle section. Support of the
 upper extended handle 2 in the lower extended handle 1 is provided by an
 indexing pin 11 which penetrates both the lower extended handle 1 and the
 upper extended handle 2 and which in its engaged position, in the indexing
 hole 4 forms a non-slidable bearing axis for the lower extended handle 1
 and the upper extended handle 2.
 FIG. 2 is a lateral view of the indexing pin 11. The indexing pin 11
 comprises an essentially rotationally symmetrical base 12 which comprises
 a first area 13 of smaller diameter, a second area 14 of medium diameter
 adjacent to the area 13, as well as an area 15 of large diameter adjacent
 to the area 14. Each of the areas 13 and 14 as well as 14 and 15 is joined
 to the other by means of a bevel 16. On the inside of the indexing bolt
 11, in the middle, there is an axial blind bore hole 17 which completely
 penetrates the areas 13 and 14. A cap 18 screwed or bonded to the base 12
 closes off the open end of the blind bore hole. A helical spring 19 is
 inserted into the blind bore hole 17. The base 12 of the indexing pin 11
 is penetrated by an elongated hole 20 in transverse direction i.e. in
 radial direction.
 FIG. 3 shows the joint area of the gripping pliers according to FIG. 1
 approximately in a cross-section along the line III--III in FIG. 1. In
 this area the lower extended handle 1 comprises an upper cheek 21 as well
 as a lower cheek 22. The upper cheek 21 bears the indexing hole 4 with its
 overlapping bore holes 5, while the lower cheek 22 comprises a
 corresponding indexing hole 24 as well as overlapping bore holes 25. In
 this joint area the upper extended handle 2 passes between the two cheeks
 21 and 22 of the lower extended handle 1. In addition, the upper extended
 handle 2 comprises a round through bore hole 26 which at one end comprises
 an associated pin 27 aligned transversely over the bore hole 26.
 The indexing hole 4 with its overlapping bore holes 5 is designed in such a
 way that the diameter of each bore hole 5 corresponds to the interior
 diameter of the bore hole 26 of the upper extended handle 2, while in the
 overlap area of every two adjacent bore holes 5 the clear diameter of the
 indexing hole 2 is narrowed. This design of an indexing hole is generally
 known from adjustable water pump pliers. However, the inside diameter of
 the indexing hole 24 of the lower cheek 22 is larger. Here the inside
 diameter of the overlap area between each two bore holes 25 is the same as
 the bore hole diameter of the bore holes 5 and 26 while the actual bore
 diameter of the bore holes 25 is larger than this.
 FIG. 4 shows the indexing pin according to FIG. 2 (rotated on its axis by
 90.degree.), inserted in the joint area according to FIG. 3. The same
 reference numbers are used for elements already described. In the
 engagement position shown, the indexing pin 12 with its area 13 of smaller
 diameter is positioned outside the joint of the pliers, while the area 14
 of medium diameter penetrates an indexing hole 5 as well as the bore hole
 26 of the upper extended handle 2. By contrast, the area 15 is positioned
 in a bore hole 25 of the lower extended handle 1. The pin 27 penetrates
 the elongated hole 20 of the indexing bolt 11 so that one end of the
 helical spring 19 can rest against the pin 27 while the other end can rest
 against the head 18. In this way the helical spring 19 pre-tensions the
 indexing bolt 11 in the joint to this engagement position.
 To adjust the opening width of the gripping pliers shown, axial pressure is
 exerted onto the head 18 of the indexing bolt 11 so that the indexing bolt
 11 is displaced against the tension of the helical spring. Consequently
 the area 15 of larger diameter leaves the bore hole 25, the area 14 of
 medium diameter is displaced from the bore hole 5 into the bore hole 25
 while it remains positioned in the bore hole 26 of the upper extended
 handle. The area 13 of smaller diameter enters the bore hole 5 instead of
 the area 14. Since now the next-smaller areas 14 or 15 instead of the
 areas 15 or 14 are resting in the indexing holes 4 or 24, the indexing
 bolt can be displaced in longitudinal direction of the indexing holes 4,
 24 in order to be brought into the desired position in this way. If the
 pressure on the head 18 of the indexing bolt 11 is reduced, then the
 helical spring 19 pre-tensions the indexing bolt again into its engagement
 position, with the areas 14 and 15 engaging the selected bore holes 5 and
 25 of the indexing holes 4 and 24. When the bore hole axes are not exactly
 covered, the bevels 16 facilitate insertion of the indexing bolt into the
 respective bore holes. In the engagement position, the joint is now
 secured in the direction of the indexing holes 4 and 24 so that it cannot
 slide.
 Furthermore this embodiment shows that displacement of the indexing bolt in
 axial direction by the amount equal to the thickness of a cheek 21 or 22
 is sufficient to completely unlock the joint of the pliers. If the joint
 of the pliers is dimensioned such that equal areas are carrying equal
 loads, then the width of each cheek 21 or 22 can be kept smaller than the
 joint area of the upper extended handle. For example each cheek 21 and 22
 can amount to a quarter of the entire thickness of the joint, while the
 thickness of the upper extended handle in this area amounts to half. With
 this configuration it is thus possible to define the height of the area 13
 to be a quarter of the entire thickness of the joint in this area, so that
 the axial displacement for unlocking also only needs to be a quarter of
 the thickness. With the known gripping pliers with adjustable locking
 opening, the required activation travel of the indexing element is twice
 as much.