AU2009213089B2 - A Coupling - Google Patents

Abstract

Abstract In the coupling (1) manual clockwise rotation of the handle (4) causes a pin (9) to move downwardly in the arcuate slot (13) in the latch (7). The outer surface of the slot (13) acts as a camming surface against the pin (9) in the course of this rotation. The camming action of the pin (9) and the outer surface of the slot (13) results in rotation of the latch (7) about the shaft (12) so that the latch (7) moves away from the tow ball (32). o

Description

Title A coupling Field of the invention 5 The present invention relates to couplings between vehicles, and is particularly applicable to a trailer coupling. Background of the invention Many coupling devices have been developed for providing a connection between 10 a towing vehicle and a trailer. Typically a tow bar is mounted to the chassis of the towing vehicle and carries a pin or ball. A draw bar is mounted to the towed vehicle and carries a receptacle which is essentially complementary in shape to the pin or ball on the tow bar. The coupling between the two vehicles, among other things: 15 transmits motive force from the towing vehicle to the towed vehicle; and allows relative movement of those vehicles about both a vertical axis and a horizontal axis passing through the coupling. It is desirable that such couplings devices be easily operable to couple the 20 vehicles together, be reliable in use, and be easily operable to decouple the vehicles. Summary of the invention The present invention accordingly provides a coupling for readily detachable 25 attachment to a towing pin such as is carried by a towing vehicle or the like, the coupling comprising: a head comprising a portion that is substantially complementary to the towing pin; a latch comprising a portion that is substantially complementary to the 30 towing pin, in which the head and the latch are adapted for receipt of the towing pin between the portion of the head that is substantially complimentary to the towing pin and the portion of the latch that is substantially complimentary to the towing pin; a hinge to allow relative rotational movement between the head and the {D1632813:I } - 1 latch about a hinge axis; and means for causing the relative rotational movement between the head and the latch comprising: a camming slot formed in the latch and comprising at least one 5 camming surface; and a cam pin moveable against the at least one camming surface to move the latch relative to the head. It is preferred that the camming slot comprises two camming surfaces, such that: movement of the cam pin in one direction in the camming slot causes 10 action of the cam pin against a first camming surface to move the head relatively towards the latch; and movement of the cam pin in another direction in the camming slot causes action of the cam pin against another camming surface to move the head relatively away from the latch. 15 It is preferred that: the head further comprises at least one recess; and when the head is in its furthest position relatively towards the latch, the cam pin is captured in the at least one recess. 20 It is preferred that: the portion of the head that is substantially complementary to the towing pin comprises a concave surface that conforms to the surface of portion of a sphere; and 25 the portion of the latch that is substantially complementary to the towing pin comprises a concave surface that conforms to the surface of portion of a sphere. It is preferred that: 30 the head further comprises at least two hinge legs; the latch has at least one hinge aperture through it; and the coupling further comprises a hinge shaft, and in which the hinge to allow relative rotational movement between the head and the latch about a hinge axis comprises the at least two hinge legs, the at least {D]632813:1} -2one hinge aperture and the hinge shaft. It is preferred that the camming slot is substantially arcuate. 5 It is preferred that one end of the camming slot is closer to the portion of the head that is substantially complementary to the towing pin than is the other end of the camming slot. It is preferred that the coupling further comprises a handle and in which movement 10 of the handle actuates the means for causing the relative rotational movement between the head and the latch. It is preferred that the handle carries the cam pin. 15 It is preferred that the handle is mounted for rotational movement relative to the head. It is preferred that the rotational movement of the handle relative to the head moves the cam pin in the camming slot. 20 It is preferred that the coupling further comprises means to selectively prevent rotational movement of the handle relative to the head. It is preferred that the means to selectively prevent rotational movement of the 25 handle relative to the head comprises: a protrusion from the head; and a trigger which carries a protrusion. It is preferred that the coupling further comprises means which biases the trigger 30 into a position in which the protrusion from the head engages with the protrusion from the trigger. It is preferred that the means which biases the trigger into a position in which the protrusion from the head engages the protrusion from the trigger comprises a {D1632813:1} - 3 helical spring. It is preferred that the coupling further comprises means to bias the head and the latch to move about the hinge axis in the direction relatively towards each other. 5 It is preferred that the means to bias the head and the latch to move about the hinge axis in the direction relatively to wards each other comprises a helical spring. 10 Brief description of the drawings So that the present invention may be more readily understood, preferred embodiments of it are described in conjunction with the accompanying drawings in which: figure 1 is a perspective view of a coupling according to embodiments of 15 the present invention; figure 2 is a partially exploded perspective view of the embodiment of figure 1; figure 3 is a partially exploded perspective view of the embodiment of figure 1 from a different view-point; 20 figure 4 is an exploded perspective view of the embodiment of figure 1, figure 5 is a plan view of the embodiment of figure 1; figures 6 and 7 are further perspective views of the embodiment of figure 1; figures 8 is a perspective view of a component of the embodiment of figure 1; 25 figure 9 is a view, partly in section and partly in elevation, of components of the embodiment of figure 1; figure 10 is a perspective view of components of the embodiment of figure 1; figure 11 is a perspective view of the embodiment of figure 1; 30 figure 12 is a cross-sectional view of a portion of the embodiment of figure 1, showing hidden detail, of a portion of the embodiment of figure 1, illustrating how it operates; figures 13 and 14 are exploded perspective views of the embodiment of figure 1; {D1632813:1} -4figures 15, 16 and 17 are perspective views of details of the embodiment of figure 1; and figures 18 to 21 are cross-sectional view of a portion of the embodiment of figure 1, illustrating how it operates. 5 Description of preferred embodiments of the invention Components Figure 1 illustrates apparatus 1 which includes a coupling 10 according to embodiments of the present invention as mounted within a draw bar. The draw 10 bar 89 is illustrated in figure 14. The draw bar 89 includes a rearwardly-extending shaft 5 for mounting to a towed vehicle which is formed integrally with a bifurcated yoke 2 which has forwardly-extending arms 29 and 31. The coupling 10 includes a head 3, a handle 4, a trigger 6, a latch 7 and a handle 15 return spring 94. As is illustrated in figures 18to 21 and as is described in detail below, the coupling is adapted for readily-detachable mounting on a conventional tow ball 32. The tow ball 32 includes a mounting shaft 33 which passes through aperture 36 in a tow bar 34 for mounting on the tow bar in the conventional way. 20 As is illustrated in figures 4 and 12, the handle return spring 94 comprises right and left lower loops 103 and 104, right and left helical portions 106 and 107, right and left leg portions 108 and 109, and a bight 111. The right and left helical portions 106 and 107 locate over right and left bosses 26 and 27 respectively on the head 3. The right and left lower loops 103 and 104 respectively, engage with 25 oval bosses 122 and 123 of head 3. As is illustrated in figures 15 and 16, the bight 111 of the handle return spring 94 rests against the lower surface 151 of the handle 4. As is illustrated in figures 5 and 18 to 21, the head 3 has an inner concave surface 30 37 which is adapted to substantially complement a portion of a tow ball 32. As is illustrated in figure 4, the head 3 has mounting bosses 26 and 27 which are integrally formed in the outer surface of the head 3. The mounting bosses 26 and 27 define cylindrical, blind-ended depressions 26 and 27 which are coaxially aligned. {D1632813:i } -5- Opposite legs 18 and 19 extend rearwardly from the head 3, remote from the mounting bosses 26 and 37. Substantially cylindrical apertures 16 and 17 pass through the legs 18 and 19 respectively. The apertures 16 and 17 are 5 substantially coaxially aligned. As is shown in figures 4 and 13, each of legs 18 and 19 carry recesses 91. The recesses 91 are adjacent to and below the apertures 16 and 17, and run transversally across the direction of the head 3. A protrusion 38 extends from the outer surface of the head 3 and extends in a 10 fore-and-aft direction. As is illustrated in cross-section in figures 18 to 21, the protrusion 38 has surfaces 39 and 41 which define an acute angle between them. Adjacent the protrusion 38 is an indentation 101 which is defined by the surface 41 and the surface 102. As is illustrated in figures 9 and 18, the angular surface 125 of the trigger 6 will collide with the surface 41 of the head 3 when the trigger 6 15 is moved clockwise together with handle 4 unless trigger 6 is moved out of the way into the position which is illustrated in figure 18. As is illustrated in figures 4, 8 and 18 to 21, the latch 7 has two integrally-formed lobes, being an upper lobe 42 and a lower lobe 43. The upper lobe 42 has: 20 two opposite planar surfaces, only one of which (44) is shown in the drawings; and a substantially arcuate, convex circumferential surface 46. A cylindrical aperture 14 extends through the upper lobe 42, between the opposite 25 planar surfaces. As is also illustrated in figures 4, 8 and 18 to 21, the lower lobe 43 has: two opposite planar surfaces, only one of which (48) is shown in the drawings; a substantially arcuate, convex circumferential surface 49; 30 a substantially planar transition surface 51; a concave outer end surface 52 which forms a depression in the lower lobe 43; and an arcuate slot 13 which: extends between the planar surface 48 and the opposite planar {D1632813:11 -6surface (which is not shown in the drawings); and is bowed away from the concave outer surface 52 of lower lobe 43. The configuration of the arcuate slot 13 has its lower edge radially closer to the concave outer surface 52 than is its upper edge. 5 As is illustrated in figures 1, 4, 5 and 4, the handle 6 has: an upper portion 53 comprising a bar 57; a middle portion comprising middle right and left side legs 62 and 61 respectively; and 10 a lower portion 56 comprising lower right and left side legs 63 and 64 respectively. The upper and lower portions 53 and 56 of the handle 4 extend substantially parallel to, and away from, each other and the middle portion (comprising right 15 and left side legs 62 and 61) extends between them. Right and left upper hubs 66 and 67 respectively are formed integrally in the region of the transition between upper portion 53 and middle portion (comprising side legs 61 and 62) of the handle 4. As is shown in figure 7, the left upper hub 20 67 of handle 4 has a bore 65 in it. That bore 65 is of relatively small diameter and extends parallel to the axis of the upper hub 67. Right and left middle hubs 68 and 69 respectively are formed integrally in the region of the transition between the middle portion (comprising side legs 61 and 25 62) and the lower portion 65 of the handle 4. Right and left lower hubs 71 and 72 respectively are formed integrally at the ends of the lower right and left side legs 71 and 72 respectively. 30 As is illustrated in figures 15, 16 and 17, the trigger 6 comprises a body 137 which has an operating button 138 at one end and a bore 134 through it at the opposite end. Between the operating 138 and the bore 134 there is an upstanding protrusion 133 from the upper side of the trigger 6. The bore 134 is adapted to receive the shaft 11. The body 137 of the trigger 6 defines a right planar surface (D1632813:1} -7- 129 and a left planar surface 130 adjacent the protrusion 133. There is a protrusion 125 which projects downwardly from the body 137 of the trigger 6 to receive the bight 154 of the trigger spring 21. 5 As is illustrated in figures 4 and 6, the coupling includes a handle return spring 94. As is illustrated in figure 4, the handle return spring 94 is a double torsion wire spring which comprises lower right and left loops 103 and 104, right and left helical spring portions 106 and 107, right and left leg 108 and 109, and a bight 10 111. As is particularly illustrated in figures 2, 3 and 13, the coupling 1 further includes a locking cap 113. The locking cap is has a an aperture 139 which is square in cross-section and which is adapted to receive the square-sectioned end 119 of 15 the right hand mounting pin 132. A locking gear 112 is non-rotationally fixed to the yoke 2 and has a profile which complements an inner toothed profile of the locking cap 113. The locking cap 113 is placed on the locking gear 112 when the trailer is to be coupled to the towing vehicle. When the locking cap 113 is located in place on the locking gear 112, it operates to immobilize the shaft 114, 20 preventing the rotation of the head 3 to allow the assembly to work. The locking cap 113 is retained on the locking gear 112 by friction, and is removed by the operator after the towing vehicle and trailer have been coupled together Assembly 25 As is illustrated in figures 18 to 21, the head 3 and the latch 7 are hinged together about shaft 12. The shaft 12 passes through each of: the aperture 16 through the right leg 18 of the head 3; the right helical end-portion 82 of the spring 8; the aperture 14 of the latch 7; 30 the left helical end-portion of the spring 8; and the aperture 17 through the left leg 19 of the head 3. The right and left straight outer legs 86 and 87 of the spring 8 rest against faces of the head 3 {D1632813:1} -8- As is illustrated in figures 1, 5 and 6, the head 3 and the handle 4 are hinged together and to the yoke 2. As is illustrated in figure 13, a mounting pin 114: passes through the mounting boss 27 of the right yoke-arm 2931; passes through the left middle hub 69 of the handle 4; and 5 is anchored in the mounting boss 26 in the head 3. Although it is not illustrated in the drawings, a corresponding mounting pin 116 performs the same function on the left hand side. The mounting pin 114 differs from the mounting pin 116 in that it features a square protrusion rather than a flanged end. 10 As is shown in figures 6 and 13, the right and left helical spring portions 106 and 107 of the handle return spring 94 locate over the external cylindrical surfaces of boss 26 and 27 respectively of head 3. As is illustrated in figures 4 and 12, the lower right and left loops 103 and 104 respectively, engage with oval bosses 122 15 and 123 of head 3. As is illustrated in figures 15 and 16, the bight 111 of the handle return spring 94, rests against the lower surface 151 of the handle 4. The action of the handle return spring 94 is to bias the handle in the anti-clockwise direction (relative to figure 1) to constantly push the handle towards the closed position. 20 As is shown in figures 18 to 21, the pin 9 is fixedly mounted in the right and left lower hubs 71 and 72 respectively of the handle 4 and passes through the arcuate slot 13 in the latch 7. 25 The coupling 1 can be manufactured from any suitable material. However it is preferred that the yoke 2, the head 3, the draw bar 5, the latch 7 are manufactured in cast steel or cast iron. It is preferred that the spring 8, the spring 21 and the handle return spring 94 are manufactured in spring steel. Steel is the preferred material for the pin 9, the shafts 11 and 12, and the circlip 24. 30 Plastic is the preferred material for the trigger 6. Operation Figures 18 to 21 illustrate operation of embodiments of the invention. {D1632813:1 } -9- Figure 18 illustrates the coupling 1 in locked position on a tow ball 32. In this position, the head 3 and latch 7 are biased towards each other about the shaft 12 by operation of the spring 8. The trigger 6 is biased in the anti-clockwise direction 5 about the shaft 11 by operation of the spring 21. In the position of the trigger 6 as shown in figure 9, the protrusion 125 from the trigger 6 is captured under the protrusion 38 from the head 3.. This capture of the protrusion 125 under the protrusion prevents movement of the handle 4 in the clockwise direction (of figures 18 to 21) about the mounting bosses 26 and 27. 10 As is shown in figure 19, the trigger 6 is manually rotated in the clockwise direction to initiate the removal of the coupling 1 from the tow ball 32. On such rotation of the trigger 6, the protrusion 128 is no longer captured under the protrusion 38 and the handle is free to rotate in the clockwise direction. 15 As is shown in figures 20 and 21, rotation of the handle 4 in the clockwise direction causes the pin 9 to move downwardly in the arcuate slot 13 in the latch 7. Because of the configuration of the arcuate slot 13, with its lower end being close to the spherical surface of the tow ball 32 than is its upper end, the outer 20 surface of the slot 13 acts as a camming surface against the pin 9 in the course of this rotation. The calming action of the pin 9 and the outer surface of the slot 13 results in rotation of the latch 7 about the shaft 12 so that the latch 7 moves away from the tow ball 32. 25 When the coupling 1 is in the closed position and is in use in towing, forces between the coupling 1 and the tow ball 32 tend to act in the vicinity of the region which is indicated by the reference number 88 in figure 18 These forces action in that region tend to impose an anti-clockwise turning moment on the latch 7. When this happens the inner camping surface of the arcuate slot 13 then tends to 30 force the shaft 9 into the two recesses 91 in the back of the head 3 as is shown in figures 4 and 13, preventing unlocking movement. While the present invention has been described with reference to a few specific embodiments, the description is illustrative of the invention and is not to be {D1632813:1} - 10 construed as limiting the invention. Various modifications may occur to those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims. 5 "Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. 10 In the claims, each dependent claim is to be read as being within the scope of its parent claim or claims, in the sense that a dependent claim is not to be interpreted as infringed unless each of its parent claims are also infringed. {D1632813:1} - it -

Claims (20)

1. A coupling adapted for readily detachable attachment to a towing pin such as is carried by a vehicle or the like, the coupling comprising: a head comprising a portion that is substantially complementary to 5 the towing pin; a latch comprising a portion that is substantially complementary to the towing pin, in which the head and the latch are adapted for receipt of the towing pin between the portion of the head that is substantially complementary to the towing pin and the portion of the 10 latch that is substantially complementary to the towing pin; a hinge to allow relative rotational movement between the head and the latch about a hinge axis; and means for causing the relative rotational movement between the head and the latch; comprising: 15 a camming slot formed in the latch and comprising at least one camming surface; and a cam pin moveable against the at least one camming surface to move the latch relative to the head. 20

2. A coupling as claimed in claim 1 in which the camming slot comprises two camming surfaces, such that: movement of the cam pin in one direction in the camming slot causes action of the cam pin against a first camming surface to move the head relatively towards the latch; and 25 movement of the cam pin in another direction in the camming slot causes action of the cam pin against another camming surface to move the head relatively away from the latch.

3. A coupling as claimed in claim 1 or claim 2, in which: 30 the head further comprises at least one recess; and when the head is in its furthest position relatively towards the latch, the cam pin is captured in the at least one recess.

4. A coupling as claimed in any one of the preceding claims, in which: (D1632813:1 - 12 - the portion of the head that is substantially complementary to the towing pin comprises a concave surface that conforms to the surface of portion of a sphere; and the portion of the latch that is substantially complementary to the 5 towing pin comprises a concave surface that conforms to the surface of portion of a sphere.

5. A coupling as claimed in any one of the preceding claims in which: the head further comprises at least two hinge legs; 10 the latch has at least one hinge aperture through it; and the coupling further comprises a hinge shaft, and in which the hinge to allow relative rotational movement between the head and the latch about a hinge axis comprises the at least two hinge legs, the at least one hinge aperture and the hinge shaft. 15

6. A coupling as claimed in any one of the preceding claims, in which the camming slot is substantially arcuate.

7. A coupling as claimed in claim 6, in which one end of the camming slot is 20 closer to the portion of the head that is substantially complementary to the towing pin than is the other end of the camming slot.

8. A coupling as claimed in any one of the preceding claims further comprising a handle and in which movement of the handle actuates the 25 means for causing the relative rotational movement between the head and the latch.

9. A coupling as claimed in claim 8 in which the handle carries the cam pin. 30

10. A coupling as claimed in claim 8 or claim 9, in which the handle is mounted for rotational movement relative to the head.

11. A coupling as claimed in claim 10 in which the rotational movement of the handle relative to the head moves the cam pin in the camming slot. {D1632813:1) - 13 -

12. A coupling as claimed in claim 10 or claim 11 further comprising means to selectively prevent rotational movement of the handle relative to the head. 5

13. A coupling as claimed in claim 13 in which the means to selectively prevent rotational movement of the handle relative to the head comprises: a protrusion from the head; and a trigger which carries a protrusion. 10

14. A coupling as claimed in claim 12, further comprising means which biases the trigger into a position in which the protrusion from the head engages with the protrusion from the trigger.

15. A coupling as claimed in claim 14, in which the means which biases the 15 trigger into a position in which the protrusion from the head engages the protrusion from the trigger comprises a helical spring.

16. A coupling as claimed in any one of the preceding claims, further comprising means to bias the head and the latch to move about the hinge 20 axis in the direction relatively towards each other.

17. A coupling as claimed in claim 16, in which means to bias the head and the latch to move about the hinge axis in the direction relatively towards each other comprises a helical spring. 25

18. A coupling as claimed in claim 8, or as claimed in any one of claims 8 to 17 as appended to claim 8, further comprising means to bias the handle to move in the direction which is opposite to the unlocking direction. 30

19. A coupling as claimed in any one of the preceding claims, substantially as described with reference to any one or more of the drawings.

20. A coupling substantially as described with reference to, and as illustrated in, the drawings. {D16328L3:1} - 14 -