GB2164403A

GB2164403A - A pipe coupling

Info

Publication number: GB2164403A
Application number: GB08522313A
Authority: GB
Inventors: Alan Belk
Original assignee: Bridon PLC
Current assignee: Bridon PLC
Priority date: 1984-09-10
Filing date: 1985-09-09
Publication date: 1986-03-19
Also published as: GB8422808D0; GB2164404B; GB2164403B; GB8522313D0; GB8522314D0; GB2164404A

Abstract

A pipe coupling (1) comprising a flange sealing face (3), at least one movably mounted clamping hook (8) having a flange-engaging head (13) and a cam follower (11), a turnable cam ring (5) having cam means (6) engageable with the cam follower(s) (11) and guide means (14, 15) for controlling the movement of the or each clamping hook (8) on turning of the cam ring (5). In particular the or each clamping hook (8) is guided so as to have components of both axial and transverse movement on rotation of the cam ring (5) between first and second positions. <IMAGE>

Description

SPECIFICATION A pipe coupling This invention relates to a pipe coupling and in particular to a pipe coupling of the kind comprising an axis, an apertured flange sealing face extending transversely of the axis, at least one movably mounted clamping hook having a flange engaging head for pressing a flange in leak-tight engagement with the flange sealing face and a cam ring turnable to cause movement of said clamping hooks. Hereinafter such a pipe coupling will be referred to as "a pipe coupling of the kind referred to".

In a pipe coupling of the kind referred to it is essential for the or each flange engaging head to have at least a component of movement in the axial direction to enable clamping pressure to be applied to a flange positioned against the flange sealing face to provide the leak-tight engagement. In addition it is also essential for the, or at least one of the, flange engaging heads to have at least a component of movement in a direction transverse to the axial direction to enable a flange to be positioned adjacent, or removed from a position adjacent, the flange sealing face.

In GB-A-2098295 there is disclosed a pipe coupling of the kind referred to in which the cam ring is turnable solely to move a number of clamping hooks, and thus the flange engaging heads, in the axial direction. At least one of the clamping hooks is mounted for manual pivotal movement to enable radial movement of its flange engaging head.

In GB-A-2098296 there is disclosed a pipe coupling of the kind referred to in which the cam ring has two cam means. Turning of the cam ring causes the first cam means to act through linkage means to pivot a number of clamping hooks and the second cam means to cause axial movement of the clamping hooks.

In EP-A-0092327 there is disclosed a pipe coupling of the kind referred to in which the cam ring is also provided with cam means in which a number of clamping hooks are mounted solely for pivotal movement. The cam means directly engage the clamping hooks to pivot the latter in first or second directions depending on the direction of turning of the cam ring.

The present invention seeks to provide an alternative pipe coupling of the kind referred to.

According to one aspect of the present invention there is provided a pipe coupling having an axis, an apertured, flange sealing face extending transversely of said axis, at least one movably mounted clamping hook having a flange engaging head for pressing a flange member in leak-tight engagement with the flange sealing face and a cam follower means, a cam ring mounted for turning movement of less than 3600 between first and second positions and provided with cam means directly engageable with the or each of said cam follower means for moving the or each of the latter from an axially outer position to an axially inner position on turning of the cam ring in a first direction from said first position to said second position, the or each of the cam follower means being moved from its said axially inner position to its said axially outer position on turning of the cam ring in a second direction opposite to said first direction from said second position to said first position, and guide means for controlling the movements of said at least one clamping hook during movement of the or each cam follower means between its axially inner and outer positions so that, on movement of the cam ring between its second position and an intermediate position, located between said first and second positions, the or each clamping hook and the or each flange engaging head are moved at least with a component of axial movement and so that, on movement of the cam ring between said first position and said intermediate position, the or at least one of the flange engaging heads is caused to move with at least a component of transverse motion so it is spaced radially further from said axis when the cam ring is in said first position than when the cam ring is in said intermediate position.

Preferably the turning angle of the cam ring when turned from its said first position to its said second poisition or from its said second position to its said first position is less than 360"in, where n is the number of clamping hooks, so that if three clamping hooks are provided, the turning angle will be no greater than 1200, e.g. from 300 to 1200.

Conveniently the guide means comprises, for the or each clamping hook, at least one cam surface and, slidable relatively thereto, and in engagement therewith, at least one cam follower. Typically the or each cam follower is fixed relative to the flange sealing face and the or each cam surface is formed in or on a respective clamping hook. Suitably the or each cam follower comprises a pin, roller, slider or other means.

Suitably the cam surface is in the form of a cam slot. In this case the or each cam slot may comprise a first portion along which its associated cam follower is relatively moved during movement of the cam ring between its second and intermediate positions in order to provide the clamping hook(s) and the flange engaging head(s) with the axial, or component of axial, movement. In order to provide the or the said at least one flange engaging head with said component of transverse motion, the or at least one of the cam slots may comprise a second portion which opens into its associated first slot portion so that the first and second slot portions form a continuous slot. Conveniently the or each second cam slot portion is at least substantially straight and makes an angle with its associated first cam slot portion which is also at least substantially straight.However, it is not essential to provide the or each cam slot with a second cam slot portion. Alternatively the component of transverse motion may be provided by arranging for the cam follower to reach a closed end of the at least one first cam slot portion when the cam ring is positioned in its intermediate position, turning of the cam ring from said intermediate position towards said first position causing the, or said at least one, clamping hook to pivot about its associated cam follower so that the, or the at least one, flange engaging head is pivoted outwards away from the said axis of the pipe coupling.

Instead of the cam surfaces comprising cam slots, each clamping hook may have profiled, external surfaces serving as the said cam surfaces contacting associated cam followers.

Conveniently each of the said at least one clamping hooks comprises a main body portion to which the associated cam follower means is pivotally connected. In this case the or each pivoted cam follower and the associated cam means may be slidably keyed together. For example one of the keyed together parts (e.g. the cam means) may comprise a cam slot, e.g. of T-shaped cross-section, and the other of the keyed together parts (e.g. the cam follower means) may comprise an interengaged part, e.g. of T-shaped cross-section, captively slidably received in the cam slot. Alternatively, each cam follower means may be resiliently urged against its associated cam means so as to make substantially planar face-to-face contact therewith.For example the cam ring may include separate cam means for each clamping hook, each cam means having an axial through slot, extending substantially in a helical direction of the cam means through an angle typically less than 1200, e.g.

from 300 to 1100. The or each cam follower means has a bolt connected thereto which passes through a respective one of the slots of the cam means. Helical springs, coaxially arranged around the bolts, ensure that the pivoted cam follower means are resiliently urged against their respective cam means.

The cam follower means of the or each clamping hook may be rigid with the remainder of the clamping hook. For example the cam follower means may be of bifurcated form, the cam means associated with each clamping hook extending circumferentially between the bifurcated parts of the cam follower means.

Suitably the cam means on the cam ring engageable with the or each cam follower means has a varying cam angle which is shallower over the hook clamping range in which axial movement of the hook takes place than over the range where the hook is moved transversely outwards. Independent locking means may be provided for locking the cam ring in its second position.However, such locking means are normally only required if the cam angle of the cam means in the clamping range exceeds 70 Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of one embodiment of a pipe coupling according to one aspect of the invention, Figures 2 and 3 are schematic side views of a clamping hook of the pipe coupling shown in Figure 1 with its cam follower means positioned, respectively, in an axially outer position and an axially inner position, Figures 4 and 5 are schematic side views of a clamping hook of another embodiment of a pipe coupling according to one aspect of the invention, the clamping hook being shown, respectively, in an axially outer position and an axially inner position, and Figures 6 and 7 are schematic side views of a clamping hook of a further embodiment of a pipe coupling according to one aspect of the invention, the clamping hook being shown, respectively, in an axially outer position and an axially inner position, Figure 1 shows one embodiment of a pipe coupling, according to one aspect of the invention, generally designated by the reference numeral 1. The pipe coupling 1 has an end flange 2 defining an apertured flange sealing face 3 extending transversely, e.g. perpendicular, to the longitudinal axis 4 of the pipe coupling.

A cam ring 5 is mounted on the pipe coupling 1 for turning movement about the axis 4. The cam ring 5 has three substantially helically disposed, spaced apart cams 6 which each extend through an angle preferably not exceeding 1200 (so as not to overlap each other) and each of which is provided with an axial through slot 7 which extends in the helical direction for a major part of the helical extent of the cam 6.

Three clamping hooks 8 are arranged around the pipe coupling 1 the clamping hooks 8 being mounted on brackets 9 fixed at equally spaced positions around the end flange 2. Each clamping hook 8 comprises a main body portion 10 and a cam follower means 11 pivotally connected thereto by means of a pivot pin 12. Each main body portion 10 has a flange engaging head 13 and a cam slot 14 in which is received a fixed pin 15 carried by the bracket 9. The cam slot 14 consists of a substantially straight first slot portion 14a which extends generally in the lengthwise direction of the main body portion 10 and a substantially straight second slot portion 14b arranged at an angle to the first slot portion 14a.

Each pivoted cam follower means has a bolt 16 fixed thereto which passes in a generally axial direction through the slot 7 formed in its associated helical cam 6. As can be seen more clearly in Figures 2 and 3, the slot 7 in each cam 6 is of stepped form, a part 7a of the slot 7 which opens into the surface of the cam 6 facing towards the end flange 2 having a greater radial width than a part 7b of the slot which opens into a camming surface 17 which makes substantially face-to-face contact with a confronting surface of its associated cam follower means. The follower means 11 are resiliently urged against the camming surfaces 17 by helical compression springs 18 which coaxially surround the bolts 16 and are seated within the parts 7b of the slots 7.

Nuts 19 are provided on the ends of the bolts 16 to retain the helical compression springs 18 on the shanks of the bolts 16 and to enable adjustment of the resilient force provided by the springs 18 for resiliently urging the-cam follower means 11 against the camming surfaces 17.

In use, the pipe coupling 1 is fixed, e.g.

welded, at 20 to one end of a pipe (not shown) and is employed to clamp a flange 21 of a pipe 22 (shown in chain lines in Figures 1 to 3) in a leak-tight manner to the apertured flange sealing face 3. Clamping and release of the flange 21 is achieved by turning the cam ring 5 through approximately 120 between first and second angular positions. Although not shown, the cam ring 5 may be manually turned (e.g. in a manner similar to that described with reference to GB-A-2098295) or turned with the aid of power means (e.g. as described with reference to GB-A-2098296).

In particular, Figure 1 shows the cam ring 5 in its second angular position with each pivoted cam follower means 11 in an axially inner position in face-to-face engagement with an end region of its associated camming surface 17. The cams 6 ensure that the flange engaging heads 13 of the clamping hooks 8 apply substantially axial clamping pressure on the rear annular face of the flange 21 to press the flange 21 into leak-tight engagement with the flange sealing face 3. On turning of the cam ring 5 in a counter-clockwise direction (as viewed when facing the flange sealing face 3-i.e. from the left-hand side of Figure 1), the bolts 16 move relatively along their respective slots 7.In view of the substantially helical arrangement of the cams 6 and because the bolts 16 and helical compression springs 18 hold the cam follower means 11 in contact with the camming surfaces 17, the means 11 are moved in a substantially axial direction, as the cam ring 5 is turned, until the cam ring 5 reaches its first angular position (e.g. a limit position) in which each cam follower means 11 is in an axially outer position (see Figure 2) in face-toface engagement with an opposite end region of its associated camming surface 17.

During axial movement of each cam follower means 11 from its axially inner position to its axially outer position, occasioned by turning of the cam ring 5 from its second angular position to its first angular position, the clamping hooks 8 are moved relative to their mounting brackets 9 in axial planes. The actual.movement of each clamping hook 8 is controlled by relative travel of each pin 15 along its associated cam slot 14. In particular, during turning of the cam ring 5 from its second angular position to an intermediate angular position between the first and second angular positions, each pin 15 travels along its associated first slot portion 14a so that the clamping hooks 8 and their flange engaging heads 13 move in substantially axial directions.At the intermediate angular position of the cam ring 5, each pin 15 is located at the angle between the first and second slot portions 14a and 14b, respectively. As the cam ring 5 is turned from its intermediate position into its first position, each pin 15 enters the second slot portion 14b of its associated cam slot 14. As the pins 15 move relatively along the second slot portions 14b, the main body portion 10 of each clamping hook 8 pivots outwardly (i.e. in a clockwise direction as viewed in Figure 1) about the pivot pin 12 so that the flange engaging heads 13 are moved radially and axially outwardly.This radial outward movement of the flange engaging heads 13 enables the flange 21 of the pipe 22 to be decoupled and removed from the pipe coupling 1 (or, alternatively, for a pipe flange 21 to be positioned adjacent the flange sealing face 3 ready to be coupled to the pipe coupling 1) when the cam follower means 11 are in their axially outer positions.

On turning of the cam ring 5 back from its first angular position to its second angular position, the surfaces 17 urge the cam follower means 11 to move from their axially outer positions to their axially inner positions. During turning of the cam ring 5 from its first position to its intermediate position, the flange engaging heads 13 are moved radially and axially inwards as the pins 15 travel relatively along the socond slot portion 14b of the cam slots 14. During turning of the cam ring 5 from its intermediate position towards its second position, the pins 15 travel relatively along the first slot portions 14a so that the main body portions 10 and the flange engaging heads 13 move substantially axially to enable clamping pressure to be applied to the rear annular face of the flange 20 so that the latter is pressed into leak-tight engagement with the flange sealing face 3.

Each cam 6 has a varying cam angle, the surface 17 of each cam which engages the cam follower means 11 being steeper when the cam ring 5 is turned between its first and intermediate positions than when the cam ring is turned between its second and intermediate positions (i.e. over a "hook clamping range").

Releasable locking means (not shown) may be provided for locking the cam ring in its second position (and, if required, in its first position). However, such locking means are usually not required if the cam angle of each cam 6, over the hook clamping range, is less than 70 Although all three clamping hooks 8 have been described as incorporating second slot portions 14b for providing radial outward movement of all three flange engaging heads 13 as the cam ring 5 is turned from its intermediate angular position to its first angular position, it will be appreciated that this is not essential. Indeed a pipe flange 21 can be removed from, or inserted into, a pipe clamping position adjacent the flange sealing face 3 if only one or two of the flange engaging heads 13 are positioned in a radially outer position when the cam ring 5 is in its first position.

Furthermore it is not essential for the first and second cam slot portions 14a and 14b to be straight.

Indeed the or each cam slot 14 could be curved, e.g.

arcuate, with one end of the slot (i.e. the first slot portion) providing substantially, although not solely, axial movement and the other end of the slot (i.e.

the second slot portion) providing a component of transverse or radial motion.

It will also be appreciated that although the coupling 1 has three clamping hooks 8, any convenient number of clamping hooks may be provided.

Figures 4 to 7 show other embodiments of pipe couplings according to the invention and, where possible, the same reference numerals have been used to identify similar parts in the various pipe couplings.

In Figures 4 and 5 there is shown a pipe coupling generally designated by the reference numeral 30. Each clamping hook 8 of the pipe coupling 30 is provided with a fixed cam follower in the form of a pair of bifurcated projections 31 and 32 defining a slot 33. The cam ring 5 is formed with three spaced apart, substantially helically arranged or axially expanding cams 6, each cam 6 passing through a respective slot 33 defined between the bifurcated projections 31 and 32. The cam slot 14 formed in each clamping hook 8 is substantially straight along its entire length between its closed opposite ends 34 and 35.

In use of the pipe coupling 30, turning of the cam ring 5 between its first angular position (shown in Figure 4) and its second angular position (shown in Figure 5) causes the bifurcated projections 31 and 32 to be moved between an axially outer position (shown in Figure 4) and an axially inner position (shown in Figure 5). When the cam ring 5 is in its first angular position, the pin 15 associated with each clamping hook is positioned adjacent the closed end 34 of the cam slot 14.

As the cam ring 5 is turned in the counterclockwise direction (as viewed when facing towards the flange sealing face 3) into its intermediate position, each pin 15 moves relatively along its associated cam slot 14 until it reaches the slot end 35 guiding the clamping hook 8 in a substantially axial direction. As the cam ring 5 is turned further from its intermediate position towards its first position, axial movement of each clamping hook 8 is prevented by the abutment of each pin 15 against its associated slot end 35. Instead of moving axially, each clamping hook is caused to pivot about is associated pin 15 causing the flange engaging heads 13 to pivot outwardly.

Although not shown, the cam ring 5 could, of course, be provided with a radially expanding cam surface additionally or alternatively to control the outward pivotal movement of the flange engaging heads 13. On return movement of the cam ring 5 from its first position, through its intermediate position to its second position, the flange engaging heads 13 asre firstly pivoted inwards before being moved axially inwards. It will be appreciated that the cam follower, comprising the bifurcated projections 31 and 32, moves with components of both axial and radial movement when the projections 31 and 32 move between the axially outer position and the intermediate position.

Figures 6 and 7 show another pipe coupling generally designated by the reference numeral 40. As with the pipe coupling 1, the pipe coupling 40 has three clamping hooks 8 each comprising a main body portion 10 and a pivoted cam follower means 11. However, each main body portion 10 of the pipe coupling 40 is not provided with a cam slot, but instead has profiled external cam surfaces 41a and 41b for engaging, respectively, a cam follower roller 47, rotatable about a fixed axis, and part of the flange 2. In particular each cam surface 41a has a first portion 42 and a second portion 43 meeting the first portion 42 at an angle at point 44. The cam ring 5 of the pipe coupling 40 has three spaced apart helical or axially expanding cams 6 each having a helically extending slot 45 opening into its circumferential surface. The slots 45 have a generally T-shaped crosssection and have slidingly keyed therein correspondingly shaped portions 46 of the respective cam follower means 11 of the clamping hooks 8.

In use of the pipe coupling 40, turning of the cam ring 5 causes the cam follower means to be moved between an axially inner position (shown in Figure 7) when the cam ring 5 is in its second position and an axially outer position (shown in Figure 6) when the cam ring 5 is in its first position. The movement of each clamping hook 8 is controlled, as the cam ring 5 is turned, by engagement of the cam surface 41a or 41b, respectively, with the roller 47 or flange 2. During movement of the cam follower means between the axially inner position and the intermediate position, the first portion 42 engaging roller 47 controls the generally axial movement of the clamping hook 8.Movement of the cam follower means between the intermediate position and the axially outer position is controlled either by the cam surface 41b engaging flange 2 in the case where gravity causes a hook 8 to fall onto flange 2 or by the second portion 43 engaging roller 47 in the case where gravity causes hook 8 to fall onto the roller 47. In either case the flange engaging heads 13 move with a component of radial or transverse motion as the cam ring 5 is turned between its first and intermediate positions.

When the cam ring 5 is in its intermediate position each roller 47 is positioned adjacent point 44 on each cam surface 41a.

In each embodiment of pipe coupling described hereinbefore with reference to Figures 1 to 7, the clamping hooks 8 have all been movably mounted to enable the flange engaging heads 13 to move substantially entirely in the axial direction during movement into and out of flange clamping positions. At least one of the flange engaging heads of each pipe coupling is also movable with a component of transverse or radial motion when spaced from its flange clamping position. It is of course possible to incorporate features of one embodiment of pipe coupling into another embodiment of pipe coupling. For example any of the methods described for imparting axial movement to the cam follower means 11 may be combined in a pipe coupling according to the invention with any of the methods described for controlling or guiding the motions of the clamping hooks and their flange engaging heads.

With a pipe coupling according to the invention it is necessary to provide at least two clamping means for clamping the flange 21 to the apertured flange sealing face. Preferably each clamping means comprises a movably mounted clamping hook. However, it would be possible, at least in theory, to design a pipe coupling according to the invention having only one movably mounted clamping hook and at least one fixed clamping means. In this case the or each fixed clamping means may comprise, for example, a clamp part fixed relative to the apertured flange sealing face and provided with a wedging surface. The or each wedging surface would act on the flange 21, to urge the latter towards the apertured flange sealing face, when the flange 21 was urged against the wedging surface(s).

Claims

I. A pipe coupling having an axis, an apertured, flange sealing face extending transversely of said axis, at least one movably mounted clamping hook having a flange engaging head for pressing a flange member in leak-tight engagement with the flange sealing face and a cam follower means, a cam ring mounted for turning movement of less than 3600 between first and second positions and provided with cam means directly engageable with the or each of said cam follower means for moving the or each of the latter from an axially outer position to an axially inner position on turning of the cam ring in a first direction from said first position to said second position, the or each of the cam follower means being moved from its said axially inner position to its said axially outer position on turning of the cam ring in a second direction opposite to said first direction from said second position to said first position, and guide means for controlling the movements of said at least one clamping hook during movement of the or each cam follower means between its axially inner and outer positions so that, on movement of the cam ring between its second position and an intermediate position, located between said first and second positions, the or each clamping hook and the or each flange engaging head are moved at least with a component of axial movement and so that, on movement of the cam ring between said first position and said intermediate position, the or at least one of the flange engaging heads is caused to move with at least a component of transverse motion so it is spaced radially further from said axis when the cam ring is in said first position than when the cam ring is in said intermediate position.
2. A pipe coupling according to claim 1, in which the turning angle of the cam ring, when turned from its said first position to its said second position or from its said second position to its said first position, is less than 360"in, where n is the number of clamping hooks.
3. A pipe coupling according to claim 2, in which three clamping hooks are provided, the turning angle of the cam ring being from 300 to 1200.
4. A pipe coupling according to any of the preceding claims, in which the guide means comprises, for the or each clamping hook, at least one cam surface and, slidable relatively thereto, and in engagement therewith, at least one cam follower.
5. A pipe coupling according to claim 4, in which the or each cam follower is fixed relative to the flange sealing face and the or each cam surface is formed in or on a respective clamping hook.
6. A pipe coupling according to claim 4 or 5, in which the or each cam follower comprises a pin, roller or slider.
7. A pipe coupling according to any of claims 4 to 6, in which the or each cam surface is in the form of a cam slot.
8. A pipe coupling according to claim 7, in which the or each cam slot comprises a first portion along which its associated cam follower is relatively moved during movement of the cam ring between its second and intermediate positions in order to provide the clamping hook(s) and the flange engaging head(s) with the axial, or component of axial, movement.
9. A pipe coupling according to claim 8, in which the or at least one of the cam slots comprises a second portion which opens into its associated first slot portion so that the first and second slot portions form a continuous slot in order to provide the or the said at least one flange engaging head with said component of transverse motion.
10. A pipe coupling according to claim 9, in which the or each second cam slot portion is at least substantially straight and makes an angle with its associated first cam slot portion which is also at least substantially straight.
11. A pipe coupling according to claim 8, in which the or each first cam slot portion has a closed end arranged so that the associated cam follower reaches the closed end when the cam ring is positioned in its intermediate position, turning of the cam ring from said intermediate position towards said first position causing the, or said at least one, clamping hook to pivot about its associated cam follower so that the, or the at least one, flange engaging head is pivoted outwards away from the said axis of the pipe coupling.
12. A pipe coupling according to claim 4 or 5, in which the or each clamping hook has profiled, external surface means serving as the said cam surface(s) and arranged to contact its associated cam follower.
13. A pipe coupling according to any of the preceding claims, in which the or each of the said at least one clamping hooks comprises a main body portion to which the associated cam follower means is pivotally connected.
14. A pipe coupling according to claim 13, in which the or each pivoted cam follower means and the associated cam means are slidably keyed together.
15. A pipe coupling according to claim 14, in which one of the keyed together parts comprises a cam slot and the other of the keyed together parts comprises an interengaged part captively slidably received in the cam slot.
16. A pipe coupling according to claim 14, in which the or each cam follower means is resiliently urged against its associated cam means so as to make substantially planar face-to-face contact therewith.
17. A pipe coupling according to claim 16, in which the cam ring includes separate cam means for the or each clamping hook, the or each cam means having an axial through slot, extending substantially in a helical direction of the cam means.
18. A pipe coupling according to claim 17, in which the or each cam follower means has a bolt connected thereto which passes through a respective one of the slots of the cam means.
19. A pipe coupling according to claim 18, comprising helical springs, coaxially arranged around the bolts, to ensure that the pivoted cam follower means are resiliently urged against their respective cam means.
20. A pipe coupling according to any of claims 1 to 12, in which the cam follower means of the or each clamping hook is rigid with the remainder of the clamping hook.
21. A pipe coupling according to claim 20, in which the cam follower means is of bifurcated form, the cam means associated with the or each clamping hook extending circumferentially between the bifurcated parts of the cam follower means.
22. A pipe coupling according to any of the preceding claims, in which the cam means engageable with the or each cam follower means has a varying cam angle, said cam angle being shallower over the hook clamping range in which axial movement of the hook occurs than over the range where the hook is moved transversely outwards.
23. A pipe coupling according to claim 22, in which the said cam angle is less than 70 over the hook clamping range.
24. A pipe coupling according to claim 22 including lock means for releasably locking the cam ring in its second position.
25. A pipe coupling according to claim 24, in which the said cam angle is greater than 70 over the hook clamping range.
26. A pipe coupling constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1 to 3, Figures 4 and 5 or Figures 6 and 7 of the accompanying drawings.