Hand-grip cutting tools

A hand-grip tool for cutting, crimping, swaging or gripping is disclosed, having a multi-stroke action provided by a ratchet and pawl operating arrangement whereby sufficient mechanical advantage to permit one-handed performance of heavy duty tasks can be achieved.

This invention relates to hand-grip tools. In particular, but not 
exclusively, it relates to tools suitable for one-handed performance of 
heavy duty cutting, crimping, swaging and gripping tasks. 
A wide variety of hand-grip tools having single-stroke operation are known, 
i.e. having co-operating work members which are moved from fully open to 
fully closed during a single stroke of the handles. However, when such 
single-stroke tools are intended for heavy duty tasks the necessary 
mechanical advantage can only be obtained by extending the handles to 
increase the leverage effect. Such long handled tools, bolt croppers for 
example, have a handle span which is too great for a man's single hand, 
thus necessitating the use of both hands with the attendant disadvantage 
that the second hand is no longer available to perform other functions 
often related to the task. Furthermore the large operating arc of such 
long handled tools makes them unsuitable for use in confined spaces. 
It is an object of the present invention to provide a tool suitable for 
cutting, crimping, swaging or gripping which can be operated with one 
hand, having a multiple-stroke action to provide sufficient mechanical 
advantage for the performance of heavy duty tasks. 
According to the present invention, a hand-grip tool includes two coactive 
work members, a cam means arranged to urge a first one of the work members 
towards the second, a ratchet drive means arranged to rotate the cam 
means, and an operating lever arranged to rotate the ratchet drive means, 
all being operatively mounted upon a common support member. 
The first and second work members may comprise a pivotable cutting blade 
and a fixed anvil respectively, which anvil may consist of a single plate 
having a cutting edge arranged to coact in shearing action with a cutting 
edge of the cutting blade or preferably may consist of a pair of parallel 
plates arranged on one either side of the pivoted cutting blade, one plate 
providing a cutting edge coactable with the cutting edge of the cutting 
blade and the other providing anti-twist support for the blade as well as 
serving to locate securely the object to be cut. 
Alternatively, the first and second work members may comprise crimping, 
swaging or gripping anvils. 
The ratchet drive means may comprise a toothed wheel axially coupled with 
the cam means, rotatably mounted on the support member and driveable by a 
drive pawl operatively connected to the operating lever, which lever may 
be pivotally attached to the support member. The toothed wheel may be 
additionally engaged by a non-return mechanism secured to the second work 
member or to the support member. In operation, full closure of the 
operating lever with the support member advances the toothed wheel by one 
tooth thereby rotating the cam means through an equivalent angle and 
closing the first work member towards the second work member by an amount 
dependent upon the contours of the cam means. The non-return mechanism 
simultaneously engages a next succeeding tooth of the wheel thereby 
retaining the wheel in its advanced position and permitting the drive pawl 
to be withdrawn from the wheel to re-engage a next succeeding tooth when 
the operating lever is returned to its fully open position in readiness 
for the next stroke. The first work member is thus progressively advanced 
towards the second work member by successive closures of the operating 
lever with the support member. 
The toothed wheel may have as many teeth as are necessary to secure the 
mechanical advantage required for a particular task. The greater the 
number of teeth, the greater will be the mechanical advantage and the 
greater will be the number of operating strokes required to achieve full 
closure of the two work members.

The support member of the cutting tool illustrated in FIGS. 1 and 2 is 
constituted by a support handle 1 which is bifurcated at one end into 
twin, parallel support checks 2a and 2b. Two anvil plates 3a and 3b 
comprising the aforesaid second work member, are rigidly mounted between 
the support cheeks 2a and 2b and held in parallel separation by four 
cylindrical spacers 4, 5, 6 and 7. The anvil plates 3a and 3b are 
respectively provided with a cutting edge 8 and a locating edge 9, and a 
coacting blade 10 comprising the aforesaid first work member and having a 
cutting edge 11 is rotatably attached between the two anvil plates at a 
pivot 12, the blade 10 being a sliding fit between the two plates. 
The cutting edge 11 of the blade 10 can be advanced and retracted with 
respect to the cutting edge 8 of the anvil plate 3a, in a direction which 
is transverse to the inclination of these edges as is described below, 
with respect to FIG. 7, by the rotation of a cam 13 interjacent and 
angularly interlocked with two ratchet wheels 14, all being rotatably 
mounted between the twin support cheeks 2 upon a common axial shaft 15, 
which shaft protrudes normally through and is supported by the support 
cheeks 2a and 2b. Cutting edge 8 is angled transversely normal to the 
direction of closure of the cutting edge 11. The blade 10 is held against 
the cam 13 by the pressure of a leaf spring 16 captively located at one of 
its ends within a slot 17 of the blade 10 and slideable at the other end 
against the spacer 5. 
An operating handle 18, comprising the operating lever, is rotatably 
attached at one of its ends to the shaft 15 and angularly located with 
respect to the support handle 1 by means of a compression spring 19. 
A pawl 20, engageable with the two ratchet wheels 14, is rotatably attached 
to the operating handle 18 at a pivot 21 and maintained in contact with 
the ratchet wheel by a torsion spring 22 axially located at the pivot 21 
and angularly constrained by the operating handle 18. 
In operation, the operating handle 18 is closed towards the support handle 
1 thereby driving the pawl 20 against the ratchet wheels 14 to rotate them 
and to turn the interlocked cam 13 against the blade 10, thus causing the 
cutting edge 11 to be rotated towards the cutting edge 8 of the anvil 
plate 3a. A bifurcated leave spring 23 is attached at its divided end to 
the anvil plates 3a and 3b, the other end coacting with the ratchet wheels 
14 to maintain them in their advanced position at the end of each complete 
stroke of the operating handle, thus providing a non-return mechanism 
which permits the handles to be reopened for the next stroke without loss 
of blade closure already gained. 
The cam 13 of this example is shaped to provide full closure of the cutting 
edge 11 with the cutting edge 8 at each 180.degree. of revolution, 
whereupon the next turn of the cam resulting from a further operating 
stroke permits the blade 10 to return to the fully retracted position. It 
will be apparent that a variety of other cam shapes may be employed giving 
full closure at various sub-divisions or multiples of a complete 
revolution, and providing variously graded amounts of blade closure for 
successive operating strokes. 
Interchangeable ratchet wheels 14 having differing numbers of teeth can 
also be provided, any of which may be fitted to give the tool a range of 
mechanical advantage suitable to meet various cutting requirements. The 
wheels are changed by axially withdrawing the shaft 15 from the tool and 
reassembling the cam 13 with a selected ratchet wheel pair, angular 
interlock between the cam and the wheels being ensured by the provision of 
locating pins 24. Obviously the cam 13 may also be replaced by differently 
contoured cams in like manner. Alternatively, complete sub-assemblies of 
ratchet wheel pairs and cam may be provided, the three components being 
permanently interconnected, by rivets for example. 
The edges 8 and 9 of the anvil plates 3, together with the cutting edge 11 
of the blade 10 are shaped in this example to permit cutting of both steel 
wire and steel tape, a semi-circular notch (not shown) being provided in 
the anvil plate 3b adjacent the pivot end of the locating edge 9 to 
prevent cylindrical objects from sliding out from the cutting edges. 
Referring to FIG. 7 when tape 35 is being cut it is positioned against the 
edges 8 and 9 of the anvil plates 3a and 3b respectively, an angled lead 
9a of the locating edge 9 being provided to prevent twisting and wedging 
of the tape 35. The cutting edge 11 of the blade 10 is chamfered back 
transversely to the direction of closure at two distinct angles, the first 
angled portion 11a providing the cutting angle and the second angled 
portion 11b providing a tape clearance slot with respect to the angled 
shoulder of the locating edge 9. 
A second embodiment of the invention, illustrated in FIGS. 3 and 4, is 
arranged for crimping and differs from the first embodiment only in its 
two work members, which comprise crimping anvils instead of cutting 
blades. Two anvil holders 25a and 25b are rigidly mounted between the 
support cheeks 2a and 2b and support between themselves a fixed first 
anvil 26 and a second anvil 29 which is rotatable about the pivot 12. The 
two anvils 26 and 29 have coacting faces 27 and 30, respectively provided 
with a female crimping die 28 and a male crimping die 31. 
Operation of the rotatable anvil 29 is as described for the rotatable blade 
10 of the first embodiment, the cam 13 being so disposed that once the 
anvils have reached full closure, the anvil 29 is retracted by the next 
following operating stroke. Because the ratchet drive operates in one 
direction only, the dies cannot be re-opened to permit removal of a 
workpiece before full closure has been achieved, with the advantage that 
the tool cannot be defeated by an operator, i.e. the pre-selected crimping 
pressure must always be fully applied. 
Variants of the two anvils 26 and 29 adapted for swaging and for gripping 
are illustrated in FIGS. 5 and 6 respectively, the coacting faces 27 and 
30 of the anvils being provided with swages 32 or serrations 33. 
It will be apparent to those skilled in the art that many other 
arrangements according to the present invention are possible. For example, 
the operative components may be variously disposed upon a suitable support 
member so as to permit operation at any convenient work angle, and the 
work members may be of various configurations adapted to suit specific 
tasks. 
The fixed anvil of the crimping and swaging heads may be additionally 
provided with position adjustment means to permit variation of the 
pressure achievable and also to allow for wear. The movable anvil may also 
be arranged to slide instead of rotating towards the fixed anvil under the 
action of the cam. 
Further, support plates or jaws may be fitted for locating or holding 
ancillary items such as ferrules, terminals, sleeving etc.