HAND TOOL FOR PULLING CABLES

Abstract: A hand tool composed of two articulately coupled jaws (10, 12). The tool is to be used when pulling cables and/or wires by means of a draw spring or similar implement, when it receives and grips the draw spring and serves as a handle by means of which a fitter can insert the spring into and pull it out of a duct, for example. The jaws, when pressed towards each other, form between them a longitudinally oriented space (16) fitting the spring. Those parts of the jaws which then grip the spring and retain it by pressing against it from opposed sides are located between the joint (22) and the area to which pressure is applied by the hand.

Description: Hand Tool for Pulling Cables The present invention is concerned with a hand tool composed of two articulately coupled jaws and designed to receive and grip a draw spring or similar device for pulling cables and/or wires and to serve as a handle by means of which a fitter can easily insert the spring into and pull it out of a narrow passage, such as a duct. It is e ry common to use a draw spring when pulling wires through ducts. Such a spring normally consists of a fairly rigid, flat metal band, rolled up when in its normal state, which is passed through the duct and attached at the other end to the wire in question - such as an electrical conductor - which can then be easily pulled through the duct as the draw spring is retracted. Often, however, both the insertion of the draw spring into the duct and also its retraction there- from can be troublesome operations. Moreover, due to the form of the spring - flat and comparati ely stiff - it is hard to get a proper grip of it with the hand, and injuries to the hand often result from trying to propel or pull the spring too vigorously. It is therefore usual to employ tongs - such as drawing tongs or cutting pliers - to get a better grip of the spring. However, tongs have a tendency to slip easily and can also cause damage to the draw spring in the form of burrs. These increase the risk of hand injuries in case of subsequent manual handling of the spring. The main object of the invention is to provide a hand tool specially designed for wire pulling as described in the ingress hereto. For this purpose the tool should be easily applied, so that it can grip the draw spring either by one end thereof or by some portion between the ends. A hand tool of the type described above is to be chiefly characterized, according to the invention, by the fact that the jaws, when pressed towards each other, form between them a longitudinally oriented space fitting the spring, and that those parts of the jaws which then grip the spring and re¬ tain it by pressing against it from opposed sides are locate 5 between the joint and the area to which pressure is applied by the hand. The jaws should preferably be detachably jointed, so tha the spring can be inserted between them irrespective of whether they are latched together or disengaged. It is ad- 10 visable to link the jaws to each other by means of a chain, so that the jaws, although separable, will still always hang together during handling. The invention will now be described in closer detail in the form of an embodiment presented as an example, with refe 15 rence to the figure in the drawing. The hand tool illustrated as an example in the drawing comprises two jaws 10 and 12. Jaw 10 comprises an elongated, relatively flat portion 14 which can be inserted in a groove 16 formed by the two. sides 18, 20 of jaw 12. The two jaws 10 20 12 can be articulately latched together at their forward end For this purpose a pin (22) is provided, passing through jaw 10 and with its two ends 24, 26 projecting from the sides thereof. The pin ends 24, 26 can be inserted radially into corresponding slots 28, 30 in the sides 18, 20 of jaw 12 and 25. the slots 28, 30 are so designed that the pin ends 24, 26 ar forced towards the forward extremities 32, 34 of the said slots when hand pressure is applied to the portion of the to - opposed to the latch end. The slots 28, 30 in the sides 18, 20 are paral 1 el " and , in a lateral view, slightly curved. Thu 30 the slots set out from the tops 36, 38 of the sides 18, 20 of jaw 12 towards the bottom piece 40 joining the sides, and then at points approximately midway between the said tops an the bottom piece 40 they curve upwards and forwards. When th assembled tool is compressed, the edge 42 of jaw 10 will be 35 forced towards the bottom 40 of jaw 12. A draw spring (not illustrated) or similar object inserted between the jaws 10, 12 will then be gripped effectively. Jaw 10, as indicated in the figure, has a T-shaped sec- I °- " V? . vV ' X tion for a considerable part of its length and jaw 12 has a U-shaped section, matching the T-shaped section, for at least part of its corresponding length to function as a guide for jaw 10. Both the jaws 10 and 12 can with advantage be made chiefly of nylon but the forward portion of jaw 12 should be reinforced with metal details - components 44 and 46 in the figure - so that the pin ends 24, 26 come to bear on metal at the forward extremities 32, 34 of the slots 28, 30. The metal components 44, 46 are preferably fixed by means of rivets 48, 50. The rivets 48, 50 pass through the metal com¬ ponents 44, 46 and also through the sides 18, 20 adjacent thereto . A linking chain 52 of metal is attached by its ends to the pin 22 and the rivet 48 respectively of jaws 10 and 12. By this means the jaws 10, 12 will always hang together during handling, although capable of being unlatched from each other. The length of the chain 52 is not critical but should be between approximately 5 cm and 20 cm. As appears from the drawing, the contact face 42 of jaw 10 has a somewhat curved profile. This profile has a smaller radius of curvature than the corresponding contact face 54 of jaw 12. This arrangement ensures the wanted effective bearing pressure on the draw spring. Thanks to the choice of material and the consequent elasticity of the jaws it will further be possible, by applying greater pressure to the ends of the jaws, to increase the length of face transmitting pressure to the draw spring. The contact faces 42, 54 may be comparatively smooth and, since the material of the jaws 10, 12 is softer than that of the draw spring, there is no risk of damage in the form of burrs or the like on the draw spring while the latter is gripped between the contact faces 42, 54. Inasmuch as the draw spring, in its normal state, tends to assume a curved form, the rigidity of the spring will tend to separate the jaws 10, 12, by pivoting them about the pin 22, when the compressing force on the ends of the jaws ceases to operate. Hence by relaxing somewhat the pressure. of his hand on the tool , the fitter can slide the tool back or forth along the draw spring, which will be gripped once again when the pressure is increased. When the draw spring is to be gripped by one end it is inserted between the jaws 10, 12 at the forward end of the tool. In this case the jaws 10, 12 are latched together with the ends 24, 26 of the pin at the forward extremitites 32, 34 of the slots 28, 30. If the draw spring is to be inserted into the hand tool at some point between the ends - of the spring, the jaws 10, 12 are unlatched from each other. The spring is then placed in the groove between the sides 18, 20 of jaw 12, whereafter jaw 10 is latched onto jaw 12 by inserting the pin ends 24, 26 into the slots 28, 30 respect¬ ively. The hand tool described above is naturally susceptible of modification within the terms of the claims. Thus, the mechanism for guiding and retaining the jaws with respect to each other may be varied in many ways. The pivot pin may instead be fixed to the jaw that is provided with sides, in which case a corresponding slot is provided in the other jaw. The form of the jaws may be modified as desired so as to provide a good grip for the. hand whenever the tool is grasped .

Claims: CLA I MS 1. A hand tool composed of two articulately coupled jaws (10, 12) and designed to receive and grip a draw spring or similar device for pulling cables and/or wires and to serve as a handle by means of which a fitter can easily insert the spring into and pull it out of a narrow passage, such as a duct; the tool being characterized in that the jaws (10, 12) , when pressed together, form between them a longitudinally oriented space (16) fitting the spring, and that those parts of the jaws which then grip the spring and retain it by pressing against it from opposed sides are located between the joint (22) and the area to which pressure is applied by the hand. 2. Hand tool per Claim 1 , characterized in that the jaws (10, 12) are detachably coupled together so that the spring can be inserted between them whether they are latched together or disengaged. 3. Hand tool per Claim 1 or 2, characterized in that the latch comprises a pin (22) passing transversely through the jaws (10, 12) at one end of the tool . 4. Hand tool per Claim 3 (when dependent on Claim 2) , characterized in that the pin (22) is fixed in one jaw (10) and that the ends (24, 26) thereof can be inserted radially into corresponding guide slots (28, 30) in the other jaw (12), in order to latch the jaws together. 5. Hand tool per any of Claims 1 to 3, characterized in that the face (42) of at least one of the portions of the jaws pressing on the spring has a curved profile. 6. Hand tool per Claim 4, characterized in that the face (42) of at least one of the portions of the jaws pressing on the spring has a curved profile, and that the slots (28, 30) are so formed that the pin (22) is forced towards the forward extremities (32, 34) thereof as the jaws (10, 12) are pressed together . 7. Hand tool per any of Claims 1 to 6, characterized in that the jaws (10, 12) are arranged to guide each other when pressed together. 8. Hand tool per Claim 7, characterized in that one jaw (10) has a T-shaped section for part of its length and that the other jaw (12) is provided with a U-shaped section, matching the T-shaped section, for. at least part of its corresponding length to function as a guide for the first jaw. 9. Hand tool per any of Claims 5 to 8, characterized in that at least one of the jaws (10, 12) is somewhat yielding, so that the exertion of greater pressure on the jaws results in an increased length of face acting on the spring. AMENDED CLAIMS (received by the International Bureau on 25 June 1979 (25.06.79)) 1. A hand tool composed of two articulately coupled jaws (10, 12) and designed to receive and grip a draw spring or similar device for pulling cables and/or wires and to serve as a handle by means of which an electrican can easily insert the spring into and pull it out of, respectively, a narrow, passage, such as a pipe, a space (16) fitting the spring being defined between the jaws (10, 12) in the longi¬ tudinal direction thereof when they are pressed together, characterized in that said jaws (10, 12) which are detach- ably interconnected to enable the insertion of the draw spring either when they are interconnected or when they are separated, include contact surfaces (42, 54) , facing each other and extending along the greater part of the length of the tool , one contacting surface (42) having a smaller radius of curvature than the other surface (54) , and that at least one of the jaws (10, 12) is made from a resilient material , so that an increasing pressing of the jaws together means that a corresponding, greater length of the contacting surfaces of the tool is applied to the draw spring. 2. Hand tool according to claim 1 , characte ized in that the articulated coupling comprises a pin (22) passing transversely through the jaws (10, 12) at one end of the tool . 3. Hand tool according to claim 3, characterized in that the pin (22) is fixed in one jaw (10) and that the ends (24, 26) thereof can be inserted radially into corresponding guide slots (28, 30) in the other jaw (12), in order to latch the jaws together. 4. Hand tool according to claim 1 or 2, characteri zed in that the face (42) of at least one of the portions of the jaws pressing on the spring has a curved profile. 5. Hand tool according to claim 3, characterized in that the face (42) of at least one of the portions of the jaws pressing on the spring has a curved profile, and that the slots (28, 30) are so formed that the pin (22) is for¬ ced towards the bottoms (32, 34) thereof as the jaws (10, 12) are pressed together. 6. Hand tool according to any of claims 1 to 6, characterized in that the jaws (10, 12) are arranged to guide. . each other when pressed together. 7. Hand tool according to claim 6, characterized in that one jaw (10) has a T-shaped section for part of its length and that the other jaw (12) is provided with a U- shaped section, matching the T-shaped section, for at least part of its corresponding length to function as a guide for the first jaw.

Inventors: LARSSON K
Applicants: LARSSON K
Application year: 1979
Main classification: H02G1
IPC codes: H02G1