US3885309A

US3885309A - Cable cutters

Info

Publication number: US3885309A
Application number: US442229A
Authority: US
Inventors: Alfred Ernest Lund; Kenneth Harry Holbrook
Original assignee: Post Office
Current assignee: Post Office
Priority date: 1973-02-19
Filing date: 1974-02-13
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27
Also published as: ES200623Y; JPS5344707Y2; AU6560174A; ES200623U; DE7405768U; JPS49126183U; GB1408703A; CA984601A

Abstract

A manually operable tool for cutting cables and the like has first and second crossed levers formed with co-operating cutting jaws. A handle pivotable on the first lever has a spring biassed plunger mounted within it which bears against a toothed fulcrum member integral with the second lever. Closure of the jaws is effected by a ratchet action on pivoting the handle; the plunger drives the jaws together during the forward stoke and a retaining pawl locks the jaws in their relative positions during the return stroke. Means are included to effect simultaneous release of the plunger and the retaining pawl from the toothed fulcrum member to enable rapid opening or closure of the jaws.

Description

United States Patent Lund et al. 1 1 May 27, 1975 1 CABLE CUTTERS 3,243,880 4/1966 Weller 30/250 {75] Inventors: Alfred Ernest Lund, Reading;

Kenneth Harry flommok Primary Examzner-Al Lawrence Smith Aldermason both of England Assistant Examiner-J. C. Peters 4 Attorney, Agent, or Firm-Kemon, Palmer &

[73] Assignee: The Post Office, London, England Estabrook {22] Filed: Feb. 13, 1974 App]. No.: 442,229

1 1 ABSTRACT A manually operable tool for cutting cables and the like has first and second crossed levers formed with co-operating cutting jaws. A handle pivotable on the first lever has a spring biassed plunger mounted within it which bears against a toothed fulcrum member integral with the second lever. Closure of the jaws is effected by a ratchet action on pivoting the handle; the plunger drives the jaws together during the forward stoke and a retaining pawl locks the jaws in their relative positions during the return stroke. Means are included to effect simultaneous release of the plunger and the retaining pawl from the toothed fulcrum member to enable rapid opening or closure of the jaws,

15 Claims, 6 Drawing Figures PATENTLU 3.885.309

SHEET OlUF 5 PATENTEDWZWYB 3,885,309

SHEET 614 OF 5 PATENTED 3.885309 SHEET USBF S CABLE CUTTERS BACKGROUND OF THE INVENTION This invention relates to apparatus for cutting cables and the like.

Cutters are known in which a toothed rack forms one arm of a bell crank lever whose other arm is formed with a cutting jaw, the bell crank lever being pivotably mounted on a first handle formed with a second cutting jaw. A pawl and ratchet mechanism operable by movement of a second handle, acts through an intermediate geared pinion rotatably mounted on the first handle to drive the toothed rack to close the jaws.

Rapid opening of the cutting jaws, for example, after termination ofa cutting operation, is obtained by disengaging a retaining pawl from the pinion, thus freeing the pinion and allowing the bell-crank lever to pivot under the action of a tension spring extending between the lever and first handle. Such cutters suffer from the disadvantage that, during rapid opening, the toothed rack moves rapidly and uncontrollably laterally across the tool and may cause injury, especially ifa retaining pawl trip mechanism is actuated inadvertently. Such cutters also have no means for quickly tightening the cutting jaws onto a cable or bar prior to commencing at cutting operation.

It is a primary object of the invention to provide apparatus for cutting cables and the like which utilises a compound lever system which can provide appreciable mechanical advantage.

By the invention, it is also sought to provide apparatus for cutting cables and the like, the apparatus being readily convertible from a compound lever system to a simple lever system to enable a pair of cutting jaws of the apparatus to be rapidly and controllably opened or closed.

According to the invention there is provided appara tus for severing cables and the like comprising first and second co-operating severing jaws formed respectively at one end of each of first and second pivotally connected first-order levers, said first first-order lever hav ing integral therewith a fulcrum member having a number of fulcrum defining positions each of which is directly engageable by one end of a second-order lever, said second-order lever being pivotally mounted relative to said first-order lever at a point spaced from the end of said second-order lever to provide a drive transfer pivot at said point, and retaining means selectively interengageable between said second first-order lever and a first of the fulcrum defining positions on said fulcrum member to prevent the jaws from opening while said one end of the second-order lever is transferred between adjacent fulcrum defining positions. Preferably said second-order lever is resiliently biassed towards engagement with the fulcrum member so that while normally the end of the second-order lever is maintained in contact with the fulcrum member, movement of said second-order lever away from the fulcrum member is permitted.

Preferably the apparatus includes actuating means operable to move the second-order lever between first and second positions in which said one end of said second-order lever is respectively engaged with and disengaged from said fulcrum member. In the engaged condition, the apparatus may be used in a cutting operation utilising the full mechanical advantage attainable with the apparatus, whereas in the disengaged position,

a simple lever system results and the cutters can be quickly closed onto an object, for example, a cable, prior to cutting. Preferably releasing means are in cluded interjacent said second-order lever and said retaining means whereby movement of said second-order lever from said first to said second position disengages said retaining means from said fulcrum member to allow free pivotal motion between said first-order levers.

Preferably said one end of said second-order lever is, in use, engageable with successive notches of a row of notches formed on said fulcrum member to provide successive fulcrums for the second-order lever.

In one embodiment of the invention both of the jaws are formed with cutting edges. In another embodiment of the invention one of the jaws has a cutting edge and a shear block is mounted on the other jaw. In the former embodiment use of the apparatus results in the cut potions of an object having V-shaped or convex end formations, particularly useful in cutting multiconductor cables, whereas in the latter embodiment. the cut portions have flat end formations.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view from one side of cutting apparatus according to the invention having a pair of cutting jaws receiving a cable prior to a cutting operation:

FIG. 2 is an elevational view similar to FIG. 1 but from the other sidev FIG. 3 is a sectional view of the apparatus after com pletion of a cutting operation;

FIG. 4 is a scrap sectional view showing details of a pawl and ratchet mechanism adjusted for use in a cutting operation;

FIG. 5 is a scrap sectional view similar to FIG. 4 but showing the pawl and ratchet mechanism adjusted for rapid opening or closure of the cutting jaws; and

FIG. 6 is an elevational view of the apparatus in schematic form to show the apparatus in a fully open condition and to indicate the mechanical advantage attainable with the apparatus.

Referring firstly to FIG. I, a cutter is shown having a pair of first-order levers l and 2 pivoted with respect to one another at 3. The lever 2 has a fulcrum member 4 formed integral with it. The fulcrum member is a curved arm having one edge formed with teeth 5 lo cated along an arc of a circle centred at the pivot 3. The levers l and 2 are each formed at their lower ends with

co-operatingjaws

6 and 7. Demountable tempered steel cutting blades 9 and 10 are rigidly attached by set screws to the

jaws

6 and 7, the jaws and the blades each having one of their edges of bevelled configuration to provide cutting edges.

As shown in FIG. 2, a web 10' extends from a lower edge of the jaw 7 and a flange 11 extends upwardly from the web. The upstanding flange ll acts as a keeper for the jaw 6 and its attached blade 9 and prevents the cutting jaws from springing apart perpendicularly to the blades during a cutting operation.

A peg l2, projecting from an upper potion of the lever l, pivotally supports a retaining pawl 13 which is engageable with the fulcrum member 4. As shown in FIGS. 4 and 5 the retaining pawl 13 is spring-loaded by a tension coil spring 14 having its remote end attached to the lever 1.

Referring to FIG. 2, a generally rectangular block 15, integral with the lower end of a tubular handle 16, is

pivotally mounted on a cross-bolt 17 projecting from the upper portion of the lever 1. A cover plate 18 extends between and is secured at the cross-bolt 17 and the pivot 3 as shown in H6. 1.

Referring to the sectional views of FIGS. 3 to 5, an elongate cylindrical plunger 19, slidably housed within the tubular handle 16 and having a lower portion slidably received in a cylindrical bore 20 in the block 15, terminates in an operating dog 21 which is engageable in notches 22 between the teeth 5. The plunger 19 and the dog 21 are biassed towards the fulcrum member 4 by a compression spring 23 housed in an upper end portion of the handle 16. The dog 21 is formed with oppositely disposed

faces

24 and 25 together defining a chisel-shaped working edge 26. The face 24 is generally flat and adapted to slide in plane parallel relationship across alternate faces of the teeth as the dog is moved between successive operating positions. The opposite face 25 is radiussed to provide working clearance between the apices of the teeth 5 and the dog 21 during the operating stroke of the too].

An arm 27 integral with the plunger 19 as shown in FIG. 3, is located in an L-shaped slot 28 cut in the wall of the handle 16. The plunger 19 may be moved longitudinally within the handle 16 between upper and lower limiting positions determined by the location of the arm 27 in the slot 28.

The dog 21 is normally retained in engagement in a notch 22 on the fulcrum member 4 with the arm 27 at the lower end of the longitudinal part of the slot 28. Upon operator controlled movement of the arm 27 upwardly in the slot, the dog 21 may be disengaged from the fulcrum member 4 and may be held disengaged therefrom by angular movement of the arm 27 into the transverse section of the slot 28.

As shown in FIGS. 4 and 5, a stepped bore 29 of cylindrical section extending through the block laterally of the bore 20, houses a solid cylindrical pin 30 having

hemispherical ends

31 and 32. The pin 30 is slidable along the bore 29 and has an annular flange 33 extending therearound. A compression spring 34 encir cling part of the pin 30 has one end acting against the flange 33 and its distal end acting against the step of the bore 29. The pin 30 is thereby biassed against a ramp 35 formed integrally with the plunger 19 and located in a channel shaped housing 36, within the block 15.

Operation of the cutters is achieved by pivoting the handle 16 to and fro about the cross-bolt 17 while a second handle 37 integral with the lever 2 is held in a stationary position. The handle 16 and the plunger 19 act as a second-order lever, the engagement of the dog 21 in a notch 22 of the fulcrum member 4 providing a fulcrum for the second order lever and drive being transferred to the lever 1 at the cross-bolt 17. Each complete ratchet stroke of the handle 16 moves the levers l and 2 through a relative angular rotation equal to the angle substended at the pivot 3 by one of the teeth 5.

As the handle 16 is forced towards the handle 37, it pivots about the cross-bolt 17 and the working edge 26 of the dog 21 is held under pressure of the spring 23 in engagement with the base of a notch 22 to drive the fulcrum member 4 and the lever 2 in a clockwise direction about the pivot 3, the retaining pawl 13 simultaneously riding under the bias of spring 14 over one of the teeth 5 to drop into engagement with the next adjacent notch 22. During the driving movement of the dog 21, the

plunger 19 is moved slightly longitudinally within the handle 16 against the bias of the spring 23, but the working edge 26 remains in engagement with the base of the notch 22 between adjacent teeth 5.

Upon subsequent pivotal movement of the handle 16 away from the handle 37, the pawl 13 is held under spring bias in engagement with a notch 22 to retain the fulcrum member 4 and the lever 2 against anticlockwise rotation relative to the lever 1; simultaneously, the working edge 26 of the dog 21 slides up the face of the following tooth 5 until it reaches the apex thereof. Further slight opening movement of the

handles

16 and 37 carry the working edge 26 over the apex of the tooth whereupon the spring 23 acts to move the plunger 19 so that the dog 21 slides down over the following tooth face and the working edge 26 engages in the next adjacent notch 22. ln this reversion of the plunger 19 to its lower position, the flat face 24 of the dog 21 slides in parallel relationship with the adjacent face of the adjoining tooth 5 so that wear on the apices of the teeth 5 is minimised.

Each stroke of handle 16 extends between limiting positions governed by a pair of

shoulder portions

38 and 39 on the lever 1 as shown in FIG. 2. In these limiting positions, respective faces of a lateral protrusion 40 on the block 15 abut faces of the

shoulder portions

38 and 39.

When it is desired to open the

cutter jaws

6 and 7, or to close the jaws without utilising the pawl and ratchet mechanism, e.g., for a rapid action, the plunger 19 is pulled upwardly within the tubular handle 16 by moving the arm 27 to the upper limiting position in the slot 28, where it may be retained in the transverse section of the slot. As shown in FIG. 5, the dog 21 is thereby disengaged from the fulcrum member 4 such move ment of the plunger 19 simultaneously causing the ramp 35 to act against the hemispherical end 31 of the pin 30 to bias the pin to the right.

To open the jaws, the handle 16 is now moved away from the handle 37 to the limiting position shown in FIG. 5. The hemispherical end 32 of the pin 29 is thereby brought into engagement with a surface 41 of the retaining pawl 13, which pawl is thereby rocked anti-clockwise against the bias of the spring 14 and is unlatched from a notch 22.

With the retaining pawl 13 and the dog 21 disengaged from the notches 22, the lever 16 is forced further away from the lever 37 until a limiting position is reached in which a face of the protrusion 40 abuts the shoulder portion 39 (FIG. 2). Further movement of the handle 16 away from the handle 37 opens the cutter jaws. A cable to be cut may then be readily inserted between the

jaws

6 and 7.

By maintaining the plunger 19 in its upper position, the cutter may be operated to enable rapid closure of the jaws, for instance, onto a cable prior to a cutting operation, by forcing the handle 16 towards the handle 37. Thus, after reaching a limiting position in which a face of the protrusion 40 abuts the shoulder portion 38, subsequent movement of the handle 16 towards the handle 37 brings about closure of the

jaws

6 and 7, since the pawl 13 is unlatched and rides freely over the teeth 5. The block 15 is dimensioned to prevent closure of the

handles

16 and 37 beyond a predetermined position in which the handles are sufficiently spaced to allow them to be gripped by the tool operator.

II/I2XISII4 In a preferred embodiment of the invention the distances are:

mm 19 mm 162 mm 85 mm II ll Thus a mechanical advantage of about 56 is obtained clearly by changing the dimensions of l, to while limiting the dimensions to such a range that the apparatus can be operated manually, the mechanical advantage can be altered. Mechanical advantages in the range 40 70 have been found most useful in cable cutting.

The apparatus may be used to cut multiconductor cables in general use in the telecommunications field. The conductors are typically copper or aluminium, insulated with plastic or paper, the whole being sheathed in lead or plastic or a combination of both.

The handle 37 serves when held to provide a stationary reference towards and away from which the handle 16 may be pivoted. It will be apparent that such a stationary reference could, for example, take the form of a handle rigidly attached to the lever I, or even a flat plate integral with the keeper web upon which the cutter operator could stand.

The embodiment described shows a cutter particularly suitable for cutting muIti-conductor cables, since with bevelled cutting jaws 6 and 7 a V-section or rounded cable end results. This type of cut is preferred since the end of individual conductors of the cable are sufficiently spaced for them not to come into electrical contact in spite of the ends being turned over by the passage of the blades during a cutting operation. This is especially important where a conductor identifcation procedure is to follow the cutting operation.

In an alternative embodiment (not shown), only one of the jaws has a bevelled blade attached, a blade having a flat unbevelled edge being mounted on the other jaw to act as a shearing block. A cutting operation using this embodiment results in the two parts of the cut cable having flat ends.

What is claimed is:

1. Apparatus for severing cables and the like comprising first and second co-operating severing jaws formed respectively at one end of each of first and second pivotally connected first-order levers, said first first-order lever having integral therewith a fulcrum member having notches directly engageable by one end of a second-order lever, said second-order lever being pivotally mounted relative to said second first-order lever at a point spaced from the end of said secondorder lever to provide a drive transfer pivot at said point, and wherein said notches provide successive fulcrums for said second-order lever during oscillatory movement thereof so that during pivotal movement in a first direction of said second order lever, relative rotation is effected between said first-order levers in a jaw closing direction and during pivotal movement of the second-order lever in the opposite direction, retaining means interengageable between said second first-order lever and said fulcrum member prevents relative rotation of the first-order levers in a jaw opening direction and actuating means associated with the second-order lever effects relocation of the end of the second-order lever in the next adjacent notch.

2. Apparatus for severing cables and the like comprising first and second co-operating severing jaws formed respectively at one end of each of first and second pivotally connected first-order levers, said first first-order lever having integral therewith a fulcrum member having a number of fulcrum defining positions each of which is directly engageable by one end of a second-order lever, said second-order lever being resiliently biased into engagement with said fulcrum member and being pivotally mounted relative to said second first-order lever at a point spaced from. the end of said second-order lever to provide a drive transfer pivot at that point, and retaining means selectively interengageable between said second first-order lever and a first of the fulcrum defining positions on said fulcrum member, to prevent the jaws from opening while said one end of the second-order lever is transferred between adjacent fulcrum defining positions.

3. Apparatus according to claim 2 including actuating means operable to move the resiliently-biassed second-order lever between first and second positions in which said one end of said second-order lever is respectively engaged with and disengaged from said fulcrum member.

4. Apparatus according to claim 3 wherein releasing means are included interjacent said second-order lever and said retaining means whereby movement of said second-order lever from said first to said second position disengages said retaining means from said fulcrum member to allow free pivotal motion between said firstorder levers.

5. Apparatus according to claim 2 wherein said one end of said second-order lever is, in use, engageable with successive notches of a row of notches formed on said fulcrum member, which notches provide said fulcrum defining positions.

6. Apparatus according to claim 5 wherein said notches are located on an arc centred at the pivotal connection between said first-order levers.

7. Apparatus according to claim 2 wherein said second-order lever comprises a handle and an elongate plunger having its lower end directly engageable with said fulcrum member, said elongate plunger being slidably mounted within a hollow section of the handle which is pivotally connected to said second first-order lever.

8. Apparatus according to claim 7 wherein a spring means located within said handle biasses an end of the plunger into engagement with an adjacent notch of a row of notches formed in said fulcrum member, which notches provide said fulcrum defining positions.

9. Apparatus according to claim 8 including an actuating arm operable to move the plunger between first and second positions in which said one end of said 7 plunger is respectively engaged with and disengaged from said fulcrum member.

10. Apparatus according to claim 9 wherein said ac tuating arm extends from the plunger through a slot in a side wall of the handle at a location remote from the end of the plunger and said location being adjacent a hand grip position of the operator.

11. Apparatus according to claim 10 wherein said retaining means is a pawl pivotally mounted on the second first-order lever, the pawl having an end which is spring-loaded into engagement with the notch which is coincident with the end of the pawl.

12. Apparatus according to claim ll wherein said retaining means is disengaged by releasing means acting on said pawl whereby when the end of the said plunger is disengaged from a notch on said fulcrum member by operation of said arm of the actuating means, movement of the handle in a direction to open said jaws disengages the pawl from the coincident notch and retains it in the disengaged position so that the jaws open freely.

13. Apparatus according to claim 12 wherein said rcleasing means includes a ramp integral with said plunger and an elongate member constrained to longitudinal movement and spring-biassed into engagement with the ramp whereby on movement of said plunger from said first to said second position said ramp moves the elongate member into contact with the pawl to rotate the pawl out of engagement with the notches fulcrum member.

14. Apparatus according to claim 2, wherein said first first-order lever and said second-order lever are adapted to be gripped at their outer ends and whereby on oscillatory movement of said second-order lever about successive fulcrum defining positions, said jaws are closed.

15. Apparatus according to claim 14 whereby on pivotal movement of said seeond order lever about a ful crum defining position in a direction to close said first first-order lever and said second-order lever a mechani cal advantage in the range from 40 to is attained at said jaws.

Claims

1. Apparatus for severing cables and the like comprising first and second co-operating severing jaws formed respectively at one end of each of first and second pivotally connected first-order levers, said first first-order lever having integral therewith a fulcrum member having notches directly engageable by one end of a second-order lever, said second-order lever being pivotally mounted relative to said second first-order lever at a point spaced from the end of said second-order lever to provide a drive transfer pivot at said point, and wherein said notches provide successive fulcrums for said second-order lever during oscillatory movement thereof so that during pivotal movement in a first direction of said second order lever, relative rotation is effected between said first-order levers in a jaw closing direction and during pivotal movement of the second-order lever in the opposite direction, retaining means interengageable between said second first-order lever and said fulcrum member prevents relative rotation of the first-order levers in a jaw opening direction and actuating means associated with the secondorder lever effects relocation of the end of the second-order lever in the next adjacent notch.

2. Apparatus for severing cables and the like comprising first and second co-operating severing jaws formed respectively at one end of each of first and second pivotally connected first-order levers, said first first-order lever having integral therewith a fulcrum member having a number of fulcrum defining positions each of which is directly engageable by one end of a second-order lever, said second-order lever being resiliently biased into engagement with said fulcrum member and being pivotally mounted relative to said second first-order lever at a point spaced from the end of said second-order lever to provide a drive transfer pivot at that point, and retaining means selectively inter-engageable between said second first-order lever and a first of the fulcrum defining positions on said fulcrum member, to prevent the jaws from opening while said one end of the second-order lever is transferred between adjacent fulcrum defining positions.

4. Apparatus according to claim 3 wherein releasing means are included interjacent said second-order lever aNd said retaining means whereby movement of said second-order lever from said first to said second position disengages said retaining means from said fulcrum member to allow free pivotal motion between said first-order levers.

9. Apparatus according to claim 8 including an actuating arm operable to move the plunger between first and second positions in which said one end of said plunger is respectively engaged with and disengaged from said fulcrum member.

10. Apparatus according to claim 9 wherein said actuating arm extends from the plunger through a slot in a side wall of the handle at a location remote from the end of the plunger and said location being adjacent a hand grip position of the operator.

12. Apparatus according to claim 11 wherein said retaining means is disengaged by releasing means acting on said pawl whereby when the end of the said plunger is disengaged from a notch on said fulcrum member by operation of said arm of the actuating means, movement of the handle in a direction to open said jaws disengages the pawl from the coincident notch and retains it in the disengaged position so that the jaws open freely.

13. Apparatus according to claim 12 wherein said releasing means includes a ramp integral with said plunger and an elongate member constrained to longitudinal movement and spring-biassed into engagement with the ramp whereby on movement of said plunger from said first to said second position said ramp moves the elongate member into contact with the pawl to rotate the pawl out of engagement with the notches fulcrum member.

15. Apparatus according to claim 14 whereby on pivotal movement of said second-order lever about a fulcrum defining position in a direction to close said first first-order lever and said second-order lever a mechanical advantage in the range from 40 to 70 is attained at said jaws.