GB2340577A - Chain coupling - Google Patents

Abstract

A chain coupling for high-tensile steel chains has two identical yokes 1 that can be fitted together. A stud 5 is arranged at one yoke end 3 and has a coupling formation with a projection 6. At the other yoke end 4 there is a complementary coupling formation which matches the stud 5, and has a socket 9 with an undercut section 10 corresponding to the stud projection 6. One yoke end 3 and the inside back 8 of the stud 6 form an inner yoke curve that supports the inserted chain link in the event of tensile loading. A centre web 12 is formed on the longitudinal arm 2 and has a hooked lug 13, and underneath has an undercut groove 14 corresponding to the lug 13.

Description

077 23405 Chain lock for high-tensile steel chains The invention relates

to a chain lock for high-tensile steel chains, consisting of two identical yokes which can 5 be fitted together.

Chain locks of this kind are known from German Offenlegungsschrift, DE 23 54 0 28 Al and from German Gebrauchsmuster DE GM 74 35 053. As a result of positive locking elements at the yoke ends, that is the shape of the stud and locator pockets provided there, chain locks of this kind have the advantage of automatically locking when tensile strains occur with the result that the crosssections of the yoke ends have to be adapted to the forces which are to be taken up. This applies both to the core area of the stud at one yoke end and to the wall area of the locator pocket at the other yoke end, and it concerns in particular those cross-sections which lie in the main load direction, namely the longitudinal direction of the chain lock. The greater the stud length in this direction on one side and the wall length in the area of the locator pocket on the other side, the greater the tensile forces which can be transferred through the chain lock.

However in the event of strain those forces which act in the transverse direction of the lock are smaller. This is the transverse direction which lies in the plane which is spanned by the chain lock. In this transverse direction the positive locking members at the ends of the yoke 30 produce a lock which prevents the two lock halves which are formed by the yokes from being drawn or broken apart. Nevertheless the so-called underengagement by which the projection on the stud at the end of one yoke engages under the undercut section of the locator pocket at the 35 end of the second yoke must be large enough to take up the P2425.P3 22 June 1999 transverse forces which arise. In practice an interfitting grid is formed in the area of the coupling faces on the positive locking members since chain locks of the kind mentioned above are generally provided for those high5 tensile steel chains which are used in underground mining. Under these conditions here a chain lock must be capable of easy fitting and dismantling, and dismantling can be made considerably more difficult through the appearance of an interfitting grid. Often those chain locks can only be opened by brute force. In underground mining the use of a hammer is quite common for this purpose. Excessive impact forces however deform -the chain locks so that often dismantling is made even harder.

The object of the invention is therefore to provide a chain lock of the kind already mentioned wherein the coupling faces in the area of engagement between the stud projections and the undercut sections of the locator pockets are made smaller without overall reducing the longitudinal and more particularly the transverse strength of the chain lock.

According to the invention there is provided a chain lock for hightensile steel chains, comprising two identical 25 yokes which can be fitted together in a longitudinal direction and which are rotationally symmetric relative to each other, and each has, to match with the associated chain links, a longitudinal arm with two curved ends, a stud arranged at one yoke end and having a coupling side 30 with a projection pointing outwards in the longitudinal direction, a coupling side at the other yoke end matching the coupling side of the stud and having a locator socket with an undercut section corresponding to the stud projection, wherein the one yoke end forms with the inside 35 back of the stud an inner yoke curve which is biased by an P2425.P3 22 June 1999 inserted chain link in the event of tensile load, and wherein an inwardly projecting centre web is formed on the longitudinal arm the centre web having a hooked region at the end of the arm with the hook portion projecting in the fitting direction, and beneath the hook portion has a groove corresponding to the hook portion and adapted to receive the hook portion of a mating yoke.

Basically chain locks for high tensile chains are known 10 with centre webs, but such locks are however as a rule divided in the area of the longitudinal webs and when fitting these locks together the centre web is inserted as a bridge. It serves here solely as a support between the two longitudinal webs of the chain lock in order to stop is this from cutting in in the event of tensile strain in the centre area.

It is however essential for the invention to provide in addition to the centre webs which can hook together when joining the chain lock also further positive locking faces which only require a slight underengagement of the hooked web on the centre web of the one yoke into the hook-in groove on the centre web of the second yoke. The smaller the underengagement at the positive locking connecting points of the chain lock, so the smaller the interfitting grid which can be formed there, and thus the easier the chain lock can be re-opened. The same likewise applies for the coupling faces on the positive locking elements in the area of the end-side studs and locator pockets which can be reduced as a result of the additional positive locking at the studded centre webs of the chain lock. BY way of example with a common size it is possible to provide in practice between the hook webs of the yoke in the centre of the lock and the studs and locator pockets at the ends of the yoke an underengagement which only P2425.P3 22 June 1999 amounts to about 4 mm in the longitudinal direction of the lock at the largest point. As a rule the coupling faces between the stud projections and the undercut sections of the pockets are sickle-shaped and taper from the place of the largest width towards the ends. Also here it is possible to manage with about 4 mm at the point of the maximum underengagement, which can be compensated in that in the area of the centre webs the underengagement runs over the entire thickness of the longitudinal arms, which presupposes that the width of the centre webs is equal to the thickness of the longitudinal arms of the lock yoke. Moreover the centre webs of the lock yoke which are to be hooked with each other take up forces in the main load direction, namely the longitudinal direction of the chain is lock which is indeed therefore necessary because owing to the centre webs which are to be hooked the length of the chain lock cannot be increased and consequently at the yoke ends in the area of the studs and pockets only smaller wall and stud lengths can be provided in the longitudinal direction of the lock. Nevertheless the new chain lock can be subjected to very heavy loads and even after longer use can still always be opened satisfactorily for which it is only necessary to slide the two yokes towards each other over the reduced underengagement length.

The invention will now be explained in further detail with reference to the embodiment shown in the drawings in which:

Figure 1 is a perspective view of two lock yokes which are identical and can be fitted together; P2425.P3 22 June 1999 Figure 2 shows a perspective view of the lock yokes which are combined into a chain lock; Figure 3 shows the side view of a lock yoke and Figure 4 shows the plan view of the lock yoke.

The drawings show in detail two identical lock yokes 1 which each have a longitudinal web 2 and at both ends yoke ends 3 and 4 which are bent towards the longitudinal centre of the lock which is to be f ormed. Thus in the area of the yoke ends 3 and 4 the chain lock seen in its entirety is divided in the main load direction, the longitudinal direction, and the longitudinal arms 2 of the is yoke 1 are accordingly formed continuous.

Each yoke 1 has at its one yoke end 2 studs 5 protruding crosswise in relation to the imaginary dividing plane and having at the upper ends projections 6 projecting outwards away from the transverse centre of the lock. Recesses 7 are formed accordingly underneath these projections 6 on the studs 5 and the outer faces of the recesses are likewise rounded semi-cylindrical like those of the projections 6 on the studs 5. A sickle-shaped coupling face is thereby formed between each stud projection 6 and recess 7 and lies in the f itting direction of the two yokes 1 to be engaged by a counter face which will be explained in further detail below.

The studs 5 have a stud back 8 which forms the inner chain lock arc which is adjoined by the inner arc of the chain link hung from the relevant side in the chain lock.

At the other yoke end 4 is a locator pocket 9 which opens both inwards towards the centre of the lock and towards P2425.P3 22 June 1999 the dividing plane of the chain lock. The pocket 9 is adapted to the stud 5 so that two of the yokes 1 can be fitted together in a transversely off- set arrangement relative to each other until the surrounding faces 15 of the studs 5 at one yoke end 3 lying parallel with the dividing plane lie on the end faces 16 at the other yoke end 4 of the second yoke 1 parallel to the dividing plane, whereupon the two yokes are pushed in the longitudinal direction against each other whereby the relevant stud 5 projects into the locator pocket 9. The stud projections 6 hereby engage underneath a undercut section 10 in the area of the pockets 9 whereby a keyed engagement is produced in the transverse direction of the lock to prevent the chain lock from drawing apart or breaking apart in the event of load. The two yokes 1 can be secured relative to each other in the longitudinal or fitting direction by pins, splints or the like which can be inserted in suitable bores 11 in the yoke ends 3 and 4.

The identical yokes 1 furthermore have centre webs 12 protruding on the insides of their longitudinal webs 2 to engage with positive locking in each other during the described coupling of the two yokes 1. The centre webs 12 have across the lock plane a width which corresponds to the thickness of the longitudinal webs 2 of the yoke 1. Hooked webs 13 projecting on one side of the centre webs 12 extend over the entire width and project in the same direction as the hooked projections 6 on the studs 5. The hooked webs 13 are located on the upper ends of the centre webs 12, and underneath towards each longitudinal arm 2 of the yoke 1 is a recessed hook-in groove 14 which can hold with keyed engagement the hooked web 13 on the relevant second yoke in the assembled arrangement of the chain lock as shown in Figure 2.

P2425.P3 22 June 1999 7 Consequently when joining the two yokes 1 in the longitudinal direction of the chain lock a hooking of the two centre webs 12 corresponding with each other takes place whereby here the depth of the underengagement of the relevant hooked web 13 in the fitting direction during projection into the hook-in groove 14 is the same as that of the stud projections 6 in the area of the undercut sections 10 of the locator pockets 9. The centre webs 12 have at the top end slide and support faces 18 which come to adjoin the counter faces 17 in the fitting direction before the foot of the centre webs 12. The ability to join the two yokes 1 is made easier on the one hand by a relatively small underengagement of the hooked webs 13 and the stud projections 6, and on the other it helps that the studs 5 taper in the fitting direction in cross section, which can be seen particularly clearly on those studs 5 shown in Figure 1 on the lef t in the case of the yoke 1 shown at the bottom.

However the same also applies for the hooked webs 13 and the hook-in grooves 14, which is shown particularly in Figures 3 and 4. The hooked web 13 tapers towards its overhang over the centre web 12 over its entire length which corresponds to the thickness of the longitudinal webs 2. Thus the edge 19 has a clear rounded area 19 between the head-side support and slide face 18 on the centre web 12 and the projecting hooked web 13. This matches a rounded area 20 which is located at the transition between the base of the hook-in groove and the slide and support face 17 in front thereof. In the area of the ledge between the hooked web 13 protruding on the centre web 12 and the recessed hook-in groove 14 there is an inclined face 21 which adjoins at an obtuse angle the front side of the hooked web 13 as well as the bottom of 35 the hook-in groove 14. Overall the hooked web 13 has, P2425.P3 22 June 1999 8 seen in cross section, a clear wedge shape to which the negative shape of the hook-in groove 14 is adapted.

Figure 4 shows particularly clearly how small the underengagement is of the relevant hooked web 13 during projection into the hook-in groove 14 which corresponds equally to the depth of engagement of the stud projection 6 under the undercut section 10 of the pocket 9. Figure 4 shows the length of this underengagement by "T" which lies in a practical design in the range of a few millimetres..

It is crucial that only a slight displacement of the yokes 1 relative to each other against the fitting direction in the order of a few millimetres, e.g. 4 mm, is sufficient is in order to be able then to draw apart the halves of the chain lock across the dividing plane. Moreover the studded centre webs 12 help to transfer the forces acting in the main load direction on to the chain lock whereby at the same time the active length of the studs 5 in this main load direction and likewise the thickness of the wall lying in this load direction behind the locator pocket can be reduced.

P2425.P3 22 June 1999

Claims (6)

Claims

1. A chain lock for high-tensile steel chains, comprising two identical yokes which can be fitted together in a longitudinal direction and which are rotationally symmetric relative to each other, and each has, to match with the associated chain links, -a longitudinal arm with two curved ends, a stud arranged at one yoke end and having a coupling side with a projection pointing. outwards in the longitudinal direction, a coupling side at the other yoke end matching the coupling side of the stud and having a locator socket with an undercut section corresponding to the stud projection, wherein the one yoke end forms with the inside back of the stud an inner yoke curve which is biased by an inserted chain link in the event of tensile load, and wherein an inwardly projecting centre web is formed on the longitudinal arm the centre web having a hooked region at the end of the arm with the hook portion projecting in the fitting direction, and beneath the hook portion has a groove corresponding to the hook portion and adapted to receive the hook portion of a mating yoke.

2. A chain lock as claimed in Claim 1, wherein the centre web has a width across the longitudinal direction corresponding to the thickness of the long arm.

3. A chain lock as claimed in Claim 2, wherein the hook portion and the groove extend over the entire width of the centre web.

4. A chain lock as claimed in any preceding claim, wherein the dimension of the hook portion in the fitting direction is equal to that of the stud projection.

P2425.P3 22 June 1999

5. A chain lock as claimed in any preceding claim, wherein the hook portion as well as the groove and the stud projection as well as the locator pocket taper in cross-section in the fitting direction.

6. A chain lock substantially as herein described with reference to the accompanying drawings.

P2425.P3 22 June 1999