GB1600846A - Coupling member - Google Patents

Description

PATENT SPECIFICATION

( 11) ( 21) Application No 20746/80 ( 22) Filed 27 April 1978 ( 19) ( 62) Divided out of No 1600845 ( 31) Convention Application No 7704893 ( 32) Filed 4 May 1977 in ( 33) Netherlands (NL) ( 44) Complete Specification published 21 Oct 1981 ( 51) INT CL 3 AO 1 B 61/02 F 16 D 9/00 ( 52) Index at acceptance Al P 5 9 F 2 X 2 ( 54) A COUPLING MEMBER ( 71) We, C VAN DER LELY N V a Dutch Limited Liability Company, of 10, Weverskade, Maasland, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the

following statement:-

This invention relates to a coupling member.

According to the present invention there is provided a coupling member for transferring load between two spaced locations, the coupling member comprising first and second coupling portions which are rigidly interconnected in normal operation by a shear pin, the two portions being relatively displaceable after fracture of the shear pin due to overload of the coupling member, the shear pin being advanceable to re-establish the interconnection between the portions after each of a plurality of successive overloads.

For a better understanding of the present invention and to show how it must be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a side elevation of part of a tractor having a three-point lifting device which support an implement; Figure 2 is a side elevation of a coupling member of the three-point lifting device; Figure 3 is a sectional view taken along the lines III-III of Figure 2; and Figure 4 is a sectional view taken along the lines IV-IV of Figure 2.

Figure 1 shows the rear part of a tractor I which is provided with a three-point lifting device 2 The lifting device 2 comprises two adjacent lower lifting arms 3, which can be turned together with respect to the tractor frame in a manner not shown by the hydraulic system of the tractor The lifting device 2 also comprises a coupling member in the form of a top rod 59, which is mounted pivotably at the front, with respect to the intended direction of operative travel of the tractor 1, indicated by an arrow A, about a horizontal pivotal shaft 5 fastened to the tractor frame and extending transversely of 50 the direction A The top rod 59, like each of the two lower lifting arms, is provided at the rear with a coupling point for connection to an agricultural implement to secure the implement to the tractor 1 In the embodi 55 ment shown in Figure 1, the lifting device 2 has attached to it a harrow 6 having a plurality of soil working members in the form of rotors 7 which are provided with tines and are driven by means of an auxiliary 60 shaft 9, which is connected with the power take-off shaft 8 of the tractor The harrow 6 is provided with a trestle 10, which has the shape of an inverted V or U, as viewed in the direction A, the top rod 59 being connected 65 near the top of the trestle 10 and the lower lifting arms 3 being connected at the two lower ends.

The top rod 59 is shown in greater detail in Figures 2 to 4 The top rod 59 comprises a 70 spigot 60 connected with an eyelet 15 and having at its end away from the eyelet 15 a screwthread for receiving a nut 61 The centreline 60 A of the spigot 60 coincides with the centreline of the spigot 62 located some 75 distance from the spigot 60 and also having a screw-thread Disposed coaxially with the spigots 60 and 62 is an adjusting mechanism comprising a hollow shaft 63, having an internal screwthread co-operating with the 80 external screwthreads on the two spigots 60 and 62 By turning the hollow shaft 63, the adjacent free ends of the spigots 60 and 62 can be moved towards and away from each other and can be fixed in position by the nut 85 61 Thus the length of the top rod 59 is variable The spigot 62 is rigidly secured by its end away from the spigot 60 to a carrier 64 which part of a shear-pin coupling 65 The carrier 64 (see Figure 4) has a substantially 90 1600846 1,600,846 U-shaped structure with two limbs which have a cylindrical bore with a centreline 66.

The cylindrical bore receives a sleeve 67 which is rigidly secured by bolts 67 A to the carrier 64 The sleeve 67 is surrounded between the limbs of the carrier 64 by a cylindrical sleeve 68, the centreline of which coincides with the centreline 66 The innersurface of the sleeve 68 engages the outer surface of the sleeve 67 and the sleeve 68 is retained axially between the limbs of the carrier 64 The sleeve 68 is rigidly secured on the side away from the region where the spigot 62 is fastened to a tube 69 of which the centreline 70 intersects, in normal operation, the centreline 62 at an acute angle of about 3 to 10 , preferably about 6 ' The end of the tube 69 remote from the sleeve 68 is connected by a socket 71 with an eyelet 17.

As shown in the elevational view of Figure 2, the top side of the tube 69 has, near the socket 71, a support member 72 having a cavity 73 which receives the end part of a holder 74 The holder 74 is, in this embodiment, cylindrical and extends parallel to the centreline 70 to near the sleeve 68 The end part of the holder 74 located in the cavity 73 is closed by a plug 75 One end of a compression spring 76 located in the holder 74 abuts the plug 75 The end of the compression spring 76 away from the plug 75 exerts pressure on a pressure pin 77, which engages an elongate shear pin 78 The shear pin 78 extends from the pressure pin 77 in the holder 74 towards the sleeve 68 The shear pin 78 preferably has equispaced grooves 79 defining shear pin portions 80 In order to support the shear pin 78 the sleeve 68 has an annular cutting plate 81 of hardened steel, which closely surrounds the shear pin 78.

One shear pin portion 80 of the shear pin 78 is located, in normal operation, in an opening 82 in the sleeve 67 In order to withstand cutting forces, the sleeve 67 is, in this embodiment, made from hardened metal, but the opening 82 may, as an alternative, be provided in a cutting plate comprising an insert in the sleeve 67 The shear pin portion is located with some clearance in the opening 82 The sleeve 68 has, on the side connected to the tube 69, an abutment member 83 having a substantially U-shaped form, as shown in the sectional view of Figure 4, and being shaped around the carrier 64 and the adjacent wall of the sleeve 67 so that one limb 84 projects into the interior of the sleeve 67, this limb 84 extending parallel to the centreline 66 The end of the limb 84 is positioned so that, in the normal operational position of Figure 4, the free end of the limb 84 limits the movement of the pin 78 towards the spigot 62.

The top rod 59 shown in the Figures operates as follows.

From the position of the top rod 59 shown in Figure 2, in which the centrelines of the spigot 62 and the tube 69 intersect at a small angle, an overload due to excessive operational force exerted on the implement 7 can cause the implement to exert such a force on 70 the lifting device 2 in the direction towards the eyelet 15 that the shear-pin coupling 65 breaks to interrupt the rigid connection between the spigot 62 and the tube 69 When the overload limit value determined by the 75 choice of the shear pin 78 is reached, the shear-pin portion 80 located in the opening 82 will break off from the rest of the shear pin at the groove 79 Immediately after this fracture the two members of the shear-pin 80 coupling, comprising the sleeve 68 as a first coupling portion and the sleeve 67 as a second coupling portion, will turn relative to one another about the centreline 66, this turn being caused by the force exerted by the 85 implement pushing the eyelet 17 towards the eyelet 15 This turn causes the pivotal axis 66 to move in the direction of the arrow B in Figure 2 During this movement the end portion of the limb 84 uncovers the opening 90 82 so that the opening 82 is fully open towards the space in the sleeve 67, and the broken off portion of the shear pin 80 can drop out As the eyelets 15 and 17 move nearer to one another, the implement with 95 the rotors 7 rises to eliminate the overload situation The new end portion of the shear pin 78, urged by the compression spring 76 against the sleeve 67, can snap into the opening 82 only when the top rod 59 re 100 assumes the position shown in Figure 2 To do this, the tractor driver raises the implement by means of the lifting device 2 so that a force in the direction opposite the force which caused the overload is exerted on the 105 top rod 59, and the shear pin coupling then performs a movement in the direction opposite the arrow B When the shear pin is opposite the opening 82, it snaps into the opening, the movement being limited by the 110 free end of the limb 84, which again covers the opening 82 in the direction towards the pivotal axis 66 in this position of the two coupling portions 67 and 68 In this position of the top rod, in which the shear pin 115 occupies a new connecting position, the top rod is again capable of supporting the implement 6 Owing to its length the shear pin 78 can overcome an overload situation a great many times, the shear pin being each 120 time moved into a new connecting position after overload In order to regulate the position of the attached implement with respect to the tractor, the top rod can be lengthened or shortened by adjusting the 125 spigots 60 and 62 by turning the hollow shaft 63 When the shear pin 78 is fully consumed, the holder 74 can be readily taken out of the cavity 73, which constitutes a quick-action joint, after which a new shaer pin can be 130 1,600,846 inserted in to the holder.

The coupling member can be used not only as a top rod a described above, but also as other kinds of coupling rods establishing a connection between an agricultural implement and a tractor, for example, as the lower lifting arms 3 It can also be applied to machinery other than agricultural machinery.

Claims (19)

WHAT WE CLAIM IS:-

1 A coupling member for transferring load between two spaced locations, the coupling member comprising first and second coupling portions which are rigidly interconnected in normal operation by a shear pin, the two portions being relatively displaceable after fracture of the shear pin due to overload of the coupling member, the shear pin being advanceable to re-establish the interconnection between the portions after each of a plurality of successive overloads.

2 A coupling member as claimed in claim 1, in which the shear pin extends substantially parallel to the centreline of one of the portions.

3 A coupling member as claimed in claim 1 or 2, in which the two portions are relatively pivotable after fraction of the shear pin.

4 A coupling member as claimed in claim 3, which is disposed such that the pivotal axis between the first and second members moves upwardly after overload.

5 A coupling member as claimed in any one of the preceding claims, in which the shear pin is mounted in a holder on the first coupling portion.

6 A coupling member as claimed in claim 5, in which the holder is releasably connected to the first coupling portion by means of a quick-action connection.

7 A coupling member as claimed in any one of the preceding claims, in which, in normal operation, the shear pin is received in an opening in the second coupling portion and in which movement of the shear pin into the opening is limited, in normal operation, by an abutment member.

8 A coupling member as claimed in claim 7 in which the abutment member is mounted with respect to the second coupling portion so that, after fracture of the shear pin, relative displacement of the coupling portions exposes the opening to allow discharge of the broken off shear pin portion.

9 A coupling member as claimed in any one of the preceding claims, in which the second coupling portion comprises a forked carrier in which a sleeve is arranged, a cylindrical part of the first coupling portion being disposed around the sleeve between the limbs of the fork.

A coupling member as claimed in claim 9, when appendant to claim 6, in which part of the abutment member extends into the interior of the sleeve.

11 A coupling member as claimed in any one of the preceding claims, in which the centrelines of the two portions are inclined to 70 one another in normal operation.

12 A coupling member as claimed in claim 11, in which the angle of inclination is not less than 3 and not more than 100.

13 A coupling member as claimed in 75 claim 14, in which the angle of inclination is about 6 .

14 A coupling member as claimed in any one of the preceding claims in which the length of the member can be adjusted and 80 fixed by means of a setting mechanism.

A coupling member as claimed in any one of the preceding claims, in which, after overload, the ends of the member are at a smaller distance from one another than in 85 normal operation.

16 A coupling member as claimed in any one of the preceding claims, which is a top rod of a lifting device.

17 A coupling member as claimed in 90 claim 16, in which the member can be returned to the operational state by lifting the lifting device.

18 A coupling member substantially as described herein with reference to and as 95 illustrated in the accompanying drawings.

19 In combination, a tractor and an agricultural implement which are interconnected by a coupling including a coupling member as claimed in any one of the 100 preceding claims.

HASELTINE, LAKE & CO, Chartered Patent Agents, 28 Southampton Buildings, Chancery Lane, London WC 2 A IAT, and Temple Gate House, Temple Gate, Bristol B 51 6 PT, and 9 Park Square, Leeds LSI 2 LM.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd -1981 Published at The Patent Office, Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.