AU694751B2

AU694751B2 - Cable clamping device for a cable loaded in tension

Info

Publication number: AU694751B2
Application number: AU13669/95A
Authority: AU
Inventors: Walter Dipl.-Ing. Schroder
Original assignee: Siemag Transplan GmbH
Current assignee: Siemag GmbH
Priority date: 1994-03-17
Filing date: 1995-03-08
Publication date: 1998-07-30
Anticipated expiration: 2015-03-08
Also published as: ZA952064B; GB9504305D0; GB2287447B; GB2287447A; AU1366995A; DE4409191C1

Description

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AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specificatit Lodged: Accepteu: Published: Priority 0900 O 00 i 40 Related Art: 4 I Name of Applicant: ccns\ a Cb MAN Gutchoffhungshuttc A C Actual Inventor(s): Walter Schrod"- S t Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: CABLE CLAMPING DEVICE FOR A CABLE LOADED IN TENSION Our Ref 397513 POF Code: 1308/1308 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- CABLE CLAMPING DEVICE FOR A CABLE LOADED IN TENSION The present invention relates to a cable clamping device for a cable loaded in tension.

Cable clamping devices are used for, inter alia, the detachable fastening of conveying cables to a conveying cage or the like in a shaft conveyor installation. Usually, gutter rings are used for this purpose, in which a wedge-shaped gutter ring core, 0o 0 around which the cable end is laid in a loop, is mounted to be displaceable in a gutter ring housing narrowing in wedge shape and 0000 00 *is clamped against the housing by the cable tension, for example as 10 illustrated in Lueger, "Lexikon der Technik", Volume 1, 1960, page S00 415, Figure 9. A cable gutter ring with circular gutter ring core, but which is not displaceable and has no clamping function, is known om i from DE 42 39 298 Al.

Gutter rings are expensive to manufacture, since the housing I *0 o 15 and the gutter ring core require precision production in order to ensure that the opening angle is maintained exactly. Production I errors impair the security of the cable clamping. A further disadvantage consists in that the cable is clamped in self-locking manner in the gutter ring under tension loading, so that release of the cable clamping is possible only with very high expenditure of force, frequently with the use of hydraulic piston-cylinder units.

Contamination and encrustation of the gutter ring, which can occur in dirty shafts, make the release process more difficult or even impossible.

i 2 A clamping device for the catching of a drill rod linkage, which can in theory also be used for the clamping of a stretched traction cable and which has a pivotable clamping body and a counterbearing member co-operable with the body, is known from DE 41 04 896. Similar types of cable clamps for clamping cables on sailing boats are known as Curry clamps. However, these known clamping devices serve for the catching or brief holding of the linkage or cable and are not suitable in this form for a permanent, operationally reliable and highly loadable connection of a cable with a load, such as a conveying cage, carried by a cable.

According to the invention there is provided a cable clamping device for clamping a cable loaded in tension, including a rotatably mounted clamping body S° and a rotatably mounted counterbearing, between which the cable is clamped in, I wherein the clamping body has a circumferential surface curved eccentrically with j 15 respect to its axis of rotation and the cable tension causes a rotation of the clamping body which generates an increased clamping pressure against the counterbearing, wherein in use the cable contacts the curved circumferential S, surface of the clamping body through an arc of at least 900.

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iL 1 ML- I i -3- Preferably, the clamping body is a round, eccentrically mounted clamping sheave. The angle of looping of the cable around the body is preferably at least 1800, for preference about 2700.

The direction of tension on the cable is preferably about oarallel to the direction of the contact pressure against the counterbearing member.

The eccentricity of the clamping sheave is preferably one quarter and one half the radius of the sheave. The member may have i a a shape concavely rounded out concentrically with the sheave, and m 10 is, for preference, mounted to be pivotable. The body itself is 0° preferably resiliently biassed, such as spring-loaded, in the a direction of pivotation reinforcing the pressure against the member.

l ,The device may further comprise a housing with two side walls, between which the member and the body are arranged. The housing can i 15 be provided with attachment means for a load to be carried by the cable.

Due to the combination of a cable clamping with a looping angle of the cable borne in front thereof, a part of the cable tension is taken up through looping friction directly by the clamping body, so that only the remaining part of the tension force has to be taken up the actual clamping of the cable between the body and the member. The clamping device can therefore be loaded with very high forces; in which case absorption of the force takes place not only locally at the clamping location, but over the entire looping region of the cable, so that the cable is not overly stressed. By contrast to cable gutter rings, the cable looped -4around the body can, apart from the region of the member, be exposed towards the side in the clamping device, so that the cable can easily be inspected at any time. In addition, no unventilated cl amp ing zones are present, in which, for example, zones of corrosion can form. When the cable is not loaded, the clamping device is easily releasable, for example by tension at the cable free end.

Embodiments of the present invention will now be more o particularly described by way of example with reference to the 10 accompanying drawings, in which: Fig. 1 is a schematic side elevation of a first cable clamping device embodying the invention; Fig. 2 is a schematic side elevation of a second cable clamping device embodying the invention; and Fig. 3 is a cross-section, to enlarged scale, along the line A-A of Fig. 2.

4 Referring now to the drawings in Fig. 1 there is shown a cable clamping device in which a fixedly located counterbearing member 2 is mounted at a housing 1, which in the simplest case can be a flat plate. A circular clamping sheave 3 is mounted eccentrically, so as to be rotatable about a bearing pin 4, at the housing or plate 1 The eccentricity, i.e. the spacing between the axis of the bearing pin 4 and thle cen'tre axis M of the sheave 3, is preferably between 1/4 and 1/2 the radius of the sheave. A cable S to be fastened is clamped between the circumference of the sheave and the counterbearing 2 and then so laid around the circumference of the i..rra clamping sheave 3 that a looping angle oC of about 2700 is present between the first point of contact A of the cable S with the sheave 3 and the counterbearing 2. A tension force K acting on the cable 2 exerts a turning moment of the sheave 3 in such a manner that the clamping of the cable between the sheave and the counterbearing is reinforced. However, an appreciable part of the tension force K need not be taken up by the clamping force at the counterbearing, but is transmitted to the sheave through friction in the region of the cable looping angle. The formula 0 K K' eP oooo o o 0 o o 00o oooo according to Eytelwein applies, wherein K is the tension force of the cable, K' the clamping force at the counterbearing 2, P the coefficient of friction between the cable and the circumference of oo oo a 0 the clamping sheave 3 and oc the looping angle.

15 In the case of the embodiment illustrated in Figs. 2 and 3, the housing of the clamping device consists of two side plates 6 and 7 (only plate 6 is shown in Fig. between which the counterbearing 2 is mounted to be pivotable on a strong rotary pin 9. The clamping sheave 3 is mounted to be rotatable'between the side plates 6 and 7 on a further rotary pin 11, and in particular eccentrically of 'the centre axis M of the sheave 3. The cable S is laid around the sheave 3 in such a manner that its end S E is clamped between the sheave 3 and the counterbearing 2 and a looping angle of about 270° is present between the first point of contact A of the -6 cable S on the sheave 3 and the centre of the counterbearing 2.

This has the additional advantage that the direction of tension of the cable S is ait least approximately parallel to the direction of the clamping force exerted on the counterbearing by the sheave via cable end S E' The end face 2a, which faces the clamping shave 3, of the counterbearing 2 is concavely rounded concentrically with the sheave, so that the clamping force can distribute itself asubstantially over the entire width of the counterbearing. Due to 00 10 the rotatability of the counterbearing 2 about the pin 9, the 0 0counterbearing can bear uniformly against the cable end SE over its 0 a entire width.

00:":The clamping device according to Fig. 2 further comprises a receptacle 13a for attachment of a load, for example the conveying cage of a shaft conveyor, to be carried by the cable. This load receptacle 13 consists, in the illustrated embodiment, of a 00projection at at least one of the side plates 6 and 7 and an opening 13a, which is formed in the projection and through which, for example, a pin can be inserted for fastening thereto of the load to be suspended. The load receptacle is so arranged that it aligns itself with the axis of the tension-loaded cable S.

When the cable is loaded in tension, the friction of the cable at the clamping sheave 3 produces a turning moment at the sheave, which is directed counterclockwise in Fig. 2 and acts in the sense of an increased contact pressure between the sheave and the counterbearing. In order to achieve an initial clamping force, a -7 biassing spring 15 can be provided, which produces a turning moment in the same direction independently *of the tension force of the Icable. To release the cable clamping whe the cable is relieved of tension, it is only necessary to exert a turning moment in opposite direction, i.e. clockwise in Fig. 2, on the clamping sheave 3. This can be effected, for example, through tension at the cable end SE As illustrated, the housing of the clamping device consists only of the two side plates 6 and 7, which are connected by the pins 9 and 11, but has no end side walls. Consequently, the cable laid 10 around the clamping sheave is freely visible and is accessible from all sides with the exception of the portion clamped below the counterbearing 2. The cable is therefore able to be inspected all round and checked at any time, and it has full air access so that no corrosion zones can form. The manufacture of the clamping deivce is extremely simple. The side plates 6 and 7 need no machining apart from for the bores for the pins 9 and 11 and the bores 13a for the load pin. The clamping sheave 3 is a turned part and and therefore able to be manufactured cheaply and accurately. The entire clamping force, i.e. the maximum tension loading of the fastening device, is higher than for conventional gutter rings.

Changes in and refinements of the described embodiments are possible within the scope of the invention as defined in the appended claims. Thus, although a circular shape of the clamping body or sheave is preferred, it is not the only possible shape. The clamping body can also be oval or can have the shape of a semicircle or a sector with a circumferential surface curved eccentrically to -8the rotational axis 11 over only the angular region against which the cable lies. The looping angle of the cable around the body need not be 2700, but can be smaller, for example 1800 or g 0 Additional measures can be provided to increase operational reliability; for example, a locking of the clamping sheave 3 can be provided so that no undesired loosening of the cable clamping arises in the case of the cable being relieved of tension, i.e. if cable is slack.

In a further modification of the embodiment, the cable S can be laid with more than one loop around the cable sheave 3, for *example with a looping angle of 5400 or 720'. In this case, t~he clamping sheave is to be constructed to be correspondingly thicker, so that at least two cable turns can find space one beside the other. However, the counterbearing 2 acts on only one of the cable turns, namely that with the cable free end. The appropriate constructional form of the clamping device will be apparent to the expert.

Claims

1. A cable clamping device for clamping a cable loaded in tension, including a rotatably mounted clamping body and a rotatably mounted counterbearing, between which the cable is clamped, wherein the clamping body has a circumferential surface curved eccentrically with respect to its axis of rotation and the cable tension causes a rotation of the clamping body which generates an increased clamping pressure against the counterbearing, wherein in use the cable contacts the curved circumferential surface of the clamping body through an arc of at least

2. A device according to claim 1, wherein the clamping body is a circular, eccentrically mounted clamping sheave.

3. A device according to claim 1 or claim 2, wherein the one is greater than

1800. A device according to any one of the preceding claims, wherein the arc is

2700. 5. A device according to any one of the preceding claims, wherein the loading of the cable is in a direction substantially parallel to a direction of contact pressure against the counterbearing. i 25 6. A device according to claim 2, wherein the eccentricity of the circular Sclamping sheave is between 1/4 and 1/2 of the radius of the clamping sheave. 7. A device according to any one of the preceding claims, wherein the counterbearing has a concave rounded shape which is concentric with the clamping body. C:WINWORD\MEUSSA\BRAD\ODELETE'SPECJ3898-95.DOC i L. Y 3 i i. -IL- 8. A device according to any one of the claims 1 to 7, wherein the clamping body is resiliently biased in a direction of rotation which increases the pressure against the counterbearing. 9. A device according to any one of the claims 1 to 8, including a housing with two lateral walls, between which the counterbearing and the clamping sheave are provided. A device according to claim 9, wherein the housing has an attachment point for a load to be carried by the cable. 11. A cable clamping device substantially as herein before described with reference to any one of the embodiments illustrated in the accompanying drawings. DATED: 2 April 1998 PHILLIPS ORMONDE FITZPATRICK Attorneys for: MAN GUTEHOFFNUNGSHUTTE AG I t t I I /1 L e* *r I *04 I I S OS I 5 t W, L a 12 ABSTRACT OF THE INVENTION CABLE CLAMPING DEVICE FOR A CABLE LOADED IN TENSION A cable-clamping device for a cable loaded in tension comprises a clamping sheave which is mounted to be pivotable about an axis offset from the sheave centre axis and a counterbearing between which a cable is clamped in. The S 5 cable is laid around the circumference of the sheave in such a manner that a looping angle of at least 900, preferably about 2700, a4 o0 is present between the first point of contact of the cable with the clamping sheave and the counterbearing o a Fig. 1 0 04