Coupling ring assembly

Abstract

The following specification discloses a coupling assembly for electrical connector apparatus in which a threaded coupling ring rotatably mounted on one shell is threaded onto a second shell to couple the shells for electrically engaging the contacts carried by the shells. Axially extending teeth formed on a ratchet washer keyed to the ring for rotation therewith engage between axially extended teeth formed on a conventional retaining flange of the one shell and a conventional spring wave washer biases the ratchet washer against the flange under increasing pressure in response to the threading. Each tooth on the flange has a cam face formed at a small angle to the radial plane of the flange for engagement with a similar cam face on each tooth on the ratchet washer in response to the threading rotation of the ring to cam the ratchet washer from the flange against the spring bias so that resistance to threading rotation is minimized. A stop face having a large angle to the respective radial planes of the washer and flange is also formed on each tooth and the stop faces engage for providing a large resistance to rotation of the coupling ring in the unthreading or loosening direction to prevent inadvertent loosening, but do permit rotation in the loosening direction, if disassembly is desired.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to electrical connector coupling assemblies and more particularly to an improved economical coupling assembly for use in providing threaded engagement between electrical connector shells.

2. Summary of the Prior Art

Electrical connector apparatus usually includes a plug shell carrying a plurality of contacts each engageable with a respective contact of a plurality of contacts carried by a receptacle shell. A coupling ring rotatably mounted on one shell may be arranged for threaded engagement with the other shell to move the shells axially of each other and ensure electrical engagement between the respective contacts.

A flange on the one shell has a front radial face abutting an internal shoulder of the coupling ring and a rear radial face on the flange engages a wave washer captured between the flange and a retaining ring secured to the rear end of the coupling ring. The rings are thus capable of limited axial movement relative the one shell against the bias of the wave washer to permit the coupling ring to be threaded on the other shell. The biasing force of the spring wave washer acting in an axial direction provides a force for holding the threads engaged; however, this force is of substantially the same magnitude as the force required to thread the coupling ring on the other shell. Occasionally vibrational or other forces, having a magnitude corresponding to the force holding the threads engaged, are applied to the shells and therefore loosen the coupling ring from the other shell.

Arrangements for resisting loosening or unthreading forces between connector shells have incorporated axially extending smoothly curved contoured teeth fixed on a coupling ring and engaging similarly contoured fixed teeth on one connector shell with the ring and its teeth biased toward the mating shell. As the teeth move past each other in response to rotation of the ring, both the coupling ring and the mating shell must reciprocate axially to permit the rotation and therefore considerable force is required. In addition, the smooth contour provides no greater resistance to rotation of the ring in the loosening direction than for tightening. Alternatively teeth having faces which are perpendicular to each direction of rotation have been employed, but these must be disengaged to permit threading, and after the threading operation is completed, the perpendicular faces on the teeth are re-engaged to prevent loosening. Disassembly is permitted on retraction or disengagement of the engaged perpendicular faces of the teeth from one another against a spring bias. As may be visualized, this arrangement, while it holds the members against loosening and also permits disassembly, is relatively expensive, cumbersome and difficult to operate, since the teeth must be held disengaged while the ring is either tightened or loosened. Other arrangements may incorporate spring detents. Such detents can deform to move past a set of teeth in response to the threading rotation, but disassembly cannot be provided without auxiliary means for disengaging the detents from the teeth. In addition, springs used in electrical connector coupling assemblies require considerable wall thickness and sturdy construction in order to provide the desired spring force and therefore cannot be easily fabricated to provide reliable and durable operation or enable facile disengagement in the event disassembly is desired.

SUMMARY OF THE INVENTION

The present invention avoids the above problems through the simple provision of a ratchet washer keyed to the coupling ring and interposed between the conventional wave washer and the flange on one connector shell. The ratcher washer has axially extending ratchet teeth for nesting engagement between axially extending pawl teeth on the one shell flange with each tooth having a leading or cam face formed at a small angle to a radial plane for enabling facile threading of the coupling ring against the force of the wave washer and a stop face formed at a steep or large angle to the radial plane for strongly resisting rotation in the opposite or unthreading direction. Reference to the radial plane refers, of course, to a plane transverse to the axis of the particular part such as the flange, washer, ring or shell.

With the described teeth on the washer and flange, no special retraction effort is required and rotation of the coupling ring to couple the mating shells rotates the washer therewith. The leading or cam faces of the teeth simply cam the wave washer against its bias to enable the teeth to move past each other with only a small force in addition to the normal threading force. The simple rotation of the coupling ring automatically disengages the teeth to permit the ratchet washer to rotate with the ring. As the coupling ring tightens, the force required to thread the same increases, and as the operator hears or feels the clicks of the teeth as they move past each other, he knows when the teeth on the ratchet washer are in nesting engagement between the teeth on the flange.

Thereafter the stop faces on the teeth are engaged against each other to prevent reverse rotation or unloosening of the coupling ring. The force required to move the ring and washer in the reverse direction is considerably greater than that required to thread the ring on the mating shell as the stop faces of the teeth are then engaged, and these faces are at a large angle to the radial planes of the flange and washer. This prevents the coupling ring from inadvertently becoming loose under vibrational or other ambient forces since rotation in the unthreading or loosening direction requires considerably greater force than the threading force. On the other hand, unthreading or loosening rotation of the coupling ring is possible, since the stop faces are not perpendicular to the radial plane. Therefore with a somewhat larger torque or force than is applied for threading rotation, the stop faces on the teeth will also compress the wave washer to enable the teeth to move past each other and permit unthreading of the coupling ring in the event disassembly of the connector apparatus is desired.

It is therefore a primary object of the present invention to provide an improved and economical electrical connector coupling assembly.

Other objects and features of the present invention will become apparent on examination of the following specification and claims together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating an electrical connector coupling assembly utilizing the principles of the present invention;

FIG. 2 is an isometric view illustrating a portion of the ratchet washer and coupling ring; and

FIG. 3 is an end view illustrating the pawl flange with a related portion of the shell and ring in section.

In FIG. 1, a coupling assembly 10 is shown for securing one electrical connector shell 12 to a second electrical connector shell 14.

The shells 12 and 14 are generally cylindrical and only a relevant portion of the front end 16 of a conventional plug shell 12 being shown for telescoping engagement within the front end 18 of receptacle shell 14. The front end 16 of shell 12 has one or more radially outwardly extending keys such as 20 for engagement in respective keyways 22 located in the internal surface at the front end 18 of shell 14. The keys and keyways serve to properly align the shells ensuring correct engagement between socket contacts, one of which is indicated by broken lines 24 in shell 12 and pin contacts, one of which is indicated by broken lines 26 in shell 14. The contacts 24 and 26 are secured in conventional dielectric inserts (not shown) in turn secured in the respective shells in accordance with accepted and conventional practice.

The coupling assembly 10 includes a coupling ring 28 having threads 29 formed on the internal surface thereof adjacent the front end of the ring for engagement with threads 30 on the external surface of the front end 18 of shell 14 to axially move the shells toward each other and provide secure electrical engagement between the contacts. An enlarged bore 31 formed in the ring 28 receives a radially outwardly extending flange 32 formed on shell 12 intermediate opposite axial ends of shell 12 with the bore having a shoulder 34 for engaging the front radial face of flange 32. The flange 32 and shoulder 34 limit movement of the ring 28 relative shell 12 in one or a rearward direction. The bore 31 also receives a ratchet washer 36 having integrally formed axially extending ratchet teeth 38 on the front radial face thereof for engagement with axially extending pawl teeth 40 integrally formed on the rear radial face of flange 32.

A spring wave washer 42 having a nominal wall thickness between 0.1 inch and 0.125 inch, depending on the connector shell size, is located in bore 31 to engage the rear radial face of washer 36 and the washers 36 and 40 are held in bore 31 by a retaining ring 44. Retaining ring 44 is secured in the rear end of ring 28 by a series of closed annular teeth on the external surface thereof which are force fit past similarly sized and shaped teeth on the internal surface of the rear end of bore 31 to interlock the teeth and secure the rings and washers on the shell 12.

Axially extending slots or recesses 46 are formed in the enlarged diameter surface of rear bore 31 of ring 32 for receiving teeth or keys 48 extending radially outwardly from the periphery of ratchet washer 38 and integrally formed thereon. The plurality of keys and keyways aid in maintaining the angle of the ratchet washer relative the axis of the ring and distribute the load transferred between the ring and washer. The ratchet washer 36 will therefore rotate with the ring 28 and is biased axially of shell 12 by the wave washer 42 against the flange 32 with the wave washer 42 resisting full compression with a force between 60 and 80 pounds, for example, dependent on the connector type or size. The ring 28 and washer 36 are thus rotatably mounted or carried by the shell 12 with both capable of limited axial movement of the shell and the washer capable of limited axial movement relative the ring.

The ratchet teeth 38 and the detent or pawl teeth 40 may be formed accurately by investment casting, for example, and project axially in opposite directions from the respective front and rear radial faces of washer 36 and flange 32 for nesting engagement between each other to resist relative rotation in each direction. Teeth 40 are provided about the complete periphery of the respective radial face or plane of flange 32 perpendicular to the shell axis, but only four equi- angularly spaced teeth 38 are provided on the corresponding radial face or plane of washer 36. Each tooth 40 on flange 32 has a leading or pawl cam face 50 having a relatively small angle of substantially 30.degree. to the radial face or plane of the flange for engagement with a respective leading or ratchet cam face 52 of similar small angle to the front radial face or plane of washer 36 on each of the four teeth 38.

The faces 50 and 52 enable rotation of the ring 28 under relatively little additional force in one direction of rotation of the coupling ring 28 and washer 42 for threading ring 28 on shell 14, since the teeth faces 50 and 52 act as cams or as cam means and cam follower means to compress the spring wave washer 42 against its bias. The key means enables relative axial movement of the teeth for automatic disengagement against the bias of spring 42 so that the teeth may move past each other during rotation of ring 28 in the threading direction. Thus, the engaged teeth hold or resist rotation of the ring until a predetermined force or torque is applied to the coupling ring for threading it on the mating shell whereupon the cam faces automatically move the teeth independently of the shell and ring to disengage the ratchet teeth and washer from the pawl teeth and flange. This enables rotation of the ring without other than normal axial movement of the shells or ring and after the shells are coupled, the detent or stop means engage to prevent rotation in the loosening or opposite direction unless a substantially greater force is applied to loosen the rings than the force required to couple the rings.

The detent or pawl stop face 54 of each pawl tooth 40 is inclined at a relatively large or steep angle of substantially 60.degree. to the radial face of flange 32 for engagement with a detent or ratchet stop face 56 on each ratchet tooth 38 of washer 36 and arranged at a similar steep angle to the washer radial plane or face to resist rotation in the opposite direction between the flange and washer and thereby prevent loosening of the coupling assembly 10 from shell 14. With the described angles of the cam and stop faces, substantially twice the force is required to loosen the threads 29 and 30 as is required to thread the same, since the difference between the threading and unthreading forces is related to the difference between the angles of the cam and stop faces.

To assemble the coupling ring assembly on shell 12, the ring 28 receives the flange 32 in bore 31 in abutment with shoulder 34. Then the washer 36 is assembled in the bore 31 with key 48 located in the slot or keyway 46. The wave washer 42 is assembled in bore 31 followed by the assembly of retaining ring 44 so that the coupling assembly 10 is retained on shell 12 with the teeth 38 biased axially by the washer 42 for engagement between teeth 40.

Thereafter, to assemble shells 12 and 14 the front end 16 of shell 12 is telescoped in the front end 18 of shell 14 with the key 20 engaged in keyway 22 to angularly align the contacts 24 and 26. The thread 29 on coupling ring 28 is engaged with the thread 30 on shell 14 and the coupling ring 28 rotated in a threading or one direction in response to the application of a predetermined force to move the front ends of the shells toward each other as indicated by dashed lines 58 for coupling the shells. Rotation of the ring 28, of course, rotates the ratchet washer 36 since the washer 36 is keyed to ring 28 by the key means 46 and 48. The cam face 52 on each ratchet washer tooth 38 moves past respective cam faces 50 on the pawl teeth 40 against the bias of wave washer 42 by compressing the spring or wave washer enough to enable axial displacement corresponding to the height of the teeth. When sufficient tightening has occurred, usually as the leading edge of shell 14 engages the front radial face of flange 32, the reverse or stop faces 54 will act as pawls or detents in cooperation with stop faces 56 to prevent rotation in the opposite or unthreading direction despite the application of a second force substantially greater than the force required to thread the ring onto shell 14. The shells 12 and 14 are now held securely against vibration and other forces tending to loosen the coupling ring.

If disassembly is desired, the stop faces 54 and 56 will also act as cam means and cam follower means and move past each other against the bias or pressure of the spring wave washer 42; however, the force required for this movement in the opposite or uncoupling direction is substantially greater than that required for rotation in the direction for coupling the shells or the second force resulting from ambient conditions.

It will be noted that the operator may hear or feel the teeth 38 as they move past the teeth 40 and thereby notes when they are in proper nesting engagement, while the bias of the spring 42 also tends to ensure that the crowns of the teeth disengage from each other for placing the teeth in nesting engagement and that since the washer 36 and flange 32 together with their teeth are of substantial cross section, deformation of the parts is avoided.

The foregoing constitutes a description of an improved coupling assembly for electrical connector apparatus incorporating the principles of the present invention; however, those principles are not limited to the described embodiment, but are believed set forth in the accompanying claims.

Claims

What is claimed is:

1. A coupling assembly for coupling one electrical connector shell with another shell having threads,

a coupling ring with threads rotatably carried on said one shell and rotatable in one direction for engaging the threads on said ring with the threads on the other shell to couple the shells,

first cam means rotatable with said coupling ring, second cam means on said one shell,

means engaging said first cam means with said second cam means,

means including the engaged cam means for automatically disengaging one of the cam means from the other of the cam means in response to the application of one predetermined force to said ring and cam means for rotating said ring in one direction to thereby engage the threads on said ring with the threads on the other shell to couple the shells,

and means on each cam means for automatically disengaging one of the cam means from the other of the cam means only in response to the application of another force greater than said one predetermined force to said ring and cam means for rotating said ring in a direction opposite said one direction to thereby uncouple said shells.

2. The coupling assembly claimed in claim 1, in which said means engaging said first cam means with said other cam means includes a spring, and said means for automatically disengaging the one cam means from the other cam means includes means keying the one cam means to said ring for movement axially of said ring against the bias of said spring.

3. In the coupling assembly claimed in claim 2, a retaining ring engaging said spring and having a plurality of closed annular teeth, and a plurality of closed annular teeth on said coupling ring having substantially the same diameter as the closed annular teeth on said retaining ring with the teeth on said retaining ring force fit past the teeth on said coupling ring to interlock said teeth for securing said retaining ring to said coupling ring.

4. The coupling assembly claimed in claim 2, in which said second cam means includes a flange fixed to said one shell, and a plurality of pawl teeth each having a cam face and located on said flange.

5. The coupling ring claimed in claim 4, in which said first cam means includes a ratchet washer, and a plurality of ratchet teeth each having a cam face and located on said ratchet washer.

6. The coupling assembly claimed in claim 5, in which all of said teeth project axially of said ring, and in which said means for automatically disengaging the engaged cam means includes a cam face on each ratchet tooth engaging with a cam face on a respective pawl tooth for moving said washer against the bias of said spring in response to the application of said one predetermined force to said ring in said one direction to disengage said ratchet teeth from said pawl teeth.

7. In the assembly claimed in claim 6, a stop face on each tooth with each stop face on each ratchet tooth engaged with a stop face on a respective pawl tooth for resisting rotation of said ring in a direction opposite said one direction.

8. A coupling assembly for coupling one electrical connector shell with another shell having threads,

a coupling ring with threads rotatably carried on said one shell and rotatable in one direction for engaging the threads on said ring with the threads on the other shell to couple the shells,

first cam means rotatable with said coupling ring,

second cam means on said one shell,

means for engaging said first cam means with said second cam means,

means including the engaged cam means for automatically disengaging one of the cam means independently of said ring and one shell from the other of the cam means without deformation of said cam means in response to the application of a predetermined force to said ring and cam means for rotating said ring in one direction to thereby engage the threads on said ring with the threads on the other shell to couple the shells,

said means for engaging said first cam means with said second cam means including a spring,

said means for automatically disengaging the one cam means from the other cam means including means keying the one cam means to said ring for movement axially of said ring against the bias of said spring,

one additional cam means rotatable with said ring,

and other additional cam means on said shell engaged with said one additional cam means by said spring for holding said ring against rotation in a direction opposite said one direction in response to the application in said opposite direction of a second force to said ring greater than said predetermined force.

9. In the coupling assembly claimed in claim 8, in which said keying means for automatically disengaging the one cam means from the other cam means also enables the disengagement of said one additional cam means from the other additional cam means independently of said ring against the bias of said spring in response to the application of a third force in said opposite direction to said ring greater than said second force in said opposite direction to rotate said ring in said opposite direction for uncoupling said shells.

10. A coupling assembly for coupling one electrical connector shell with another shell having threads,

a coupling ring with threads rotatably carried on said one shell and rotatable in one direction for engaging the threads on said ring with the threads on the other shell to couple the shells,

first cam means rotatable with said coupling ring,

second cam means on said one shell,

means for engaging said first cam means with said second cam means,

and means including the engaged cam means for automatically disengaging one of the cam means independently of said ring and one shell from the other of the cam means without deformation of said cam means in response to the application of a predetermined force to said ring and cam means for rotating said ring in one direction to thereby engage the threads on said ring with the threads on the other shell to couple the shells, said second cam means including a flange fixed to said one shell, and a plurality of pawl teeth each having a cam face and located on said flange,

said first cam means including a ratchet washer, and a plurality of ratchet teeth each having a cam face and located on said ratchet washer,

said means for engaging the cam means comprising a spring on said one shell for biasing said washer including the cam faces on the ratchet teeth into engagement with the cam faces on the pawl teeth,

said ratchet teeth and pawl teeth each projecting axially of said ring, and said means for automatically disengaging the engaged cam faces including means keying said ratchet washer to said ring for movement axially of said ring whereby a cam face on each ratchet tooth engaging with each cam face on a respective pawl tooth moves said washer against the bias of said spring in response to the application of said predetermined force to said ring in said one direction to disengage said ratchet teeth from said pawl teeth, and

a stop face on each tooth with each stop face on each ratchet tooth engaged with a stop face on a respective pawl tooth for resisting rotation of said ring in a direction opposite said one direction,

each cam face having one angle to a radial plane and each stop face having a greater angle to said radial plane whereby a substantially greater force is required to rotate said ring in said opposite direction than the force required for rotating said ring in said one direction.

11. In the assembly claimed in claim 10, in which each stop face has an angle to said radial plane of less than 90.degree..

12. A coupling assembly for use with electrical connector apparatus including a first shell carrying a threaded rotatable coupling ring and a plurality of electrical contacts each adapted to engage a respective electrical contact of a second plurality of contacts carried by a second shell having threads for engagement with said threaded coupling ring to couple the shells to each other in response to the rotation of said coupling ring in one direction, the improvement comprising:

a first pawl cam face and a first pawl stop face carried on said first shell;

a first ratchet cam face and a first ratchet stop face rotatable with said coupling ring with said ratchet cam face located for engaging with the pawl cam face in response to rotation of said ring and ratchet cam face in one direction and the ratchet stop face located for engaging with the pawl stop face in response to rotation of said ring and ratchet stop face in the opposite direction;

and means for biasing and moving each ratchet face relative to each pawl face independently of said ring whereby the engagement of the ratchet cam face with the pawl cam face in response to the application of one force to said ring for rotating said ring and the ratchet cam face in said one direction enables one of said cam faces to move against the bias of said means for disengaging the cam faces to enable the threading of said coupling ring on said second shell and the engagement of said contacts whereafter the engagement of the ratchet stop face with the pawl stop face prevents rotation of the ratchet faces and coupling ring in response to the application in the opposite direction of a force greater than said one force.

13. In the assembly claimed in claim 12 a ratchet washer with a plurality of ratchet teeth on said ratchet washer, one tooth having said first ratchet cam face and said first ratchet stop face and each other tooth having a ratchet cam face and a ratchet stop face corresponding to the first ratchet cam face and first ratchet stop face respectively.

14. The assembly claimed in claim 13 in which said means for biasing and moving includes a wave washer engaged between said ratchet washer and said coupling ring, and means keying said ratchet washer for rotation with said coupling ring and for movement of said washer axially relative said ring.

15. In the assembly claimed in claim 14 a flange extending radially outwardly of said first shell and secured to said first shell with a plurality of pawl teeth on said flange, one pawl tooth having said first pawl cam face and said first pawl stop face and each other pawl tooth having a pawl cam face and a pawl stop face corresponding to the first pawl cam face and first pawl stop face respectively.

16. The assembly claimed in claim 15 in which each ratchet tooth is formed on the front radial face of said washer and each pawl tooth is formed on the rear radial face of said flange and the cam faces extend axially at an angle of substantially 30.degree. to the respective radial face of said washer and flange, and said stop faces extend axially at an angle of substantially 60.degree. to the respective radial face of said washer and flange whereby rotation of said washer and ring in said opposite direction is provided in response to the application of a force to said ring in said opposite direction of substantially twice said one force.

17. In the assembly claimed in claim 12 a plurality of ratchet cam faces, a plurality of ratchet stop faces, a plurality of pawl cam faces and a plurality of pawl stop faces, said cam faces extending axially from a respective radial plane at a relatively small angle and said stop faces extending axially from the respective radial plane at a second angle greater than said small angle whereby rotation of said coupling ring in said opposite direction is enabled in response to the application of a force greater than said one force by an amount corresponding to the difference in said small angle and said second angle.

18. The assembly claimed in claim 17 in which said second angle is substantially twice as great as said relatively small angle.

19. The coupling assembly claimed in claim 17 in which said stop faces extend axially from a respective radial plane at an angle of less than 90.degree. to enable rotation of said coupling ring and ratchet teeth in said other direction.

20. A coupling assembly for use with electrical connector apparatus including a first shell carrying a plurality of electrical contacts each adapted to engage a respective electrical contact of a second plurality of contacts carried by a second shell having a threaded periphery, the improvement comprising:

a plurality of axially extending pawl teeth fixed to said first shell with each tooth having a cam face and a stop face;

a plurality of axially extending ratchet teeth movable axially relative said shell with each ratchet tooth having a cam face for engagement with a cam face of each pawl tooth and a stop face for engagement with a stop face on each pawl tooth;

a coupling ring rotatably carried on said first shell and having threads for engaging the threaded periphery of said second shell to secure said second shell to said first shell in response to the rotation of said coupling ring in one direction; and

means for keying said ratchet teeth to said ring for rotation with said ring and for axially biasing said ratchet teeth independently of said ring against said pawl teeth with a cam face on each ratchet tooth engaging a cam face on a respective pawl tooth for enabling said ratchet teeth to move axially against the bias of said means in response to the application of one force to said coupling ring for rotating said coupling ring and ratchet teeth in one direction to thread said coupling ring on said second shell to engage said contacts, whereafter the stop face on each ratchet tooth engaged with a stop face on a respective pawl tooth prevents rotation of said ratchet teeth and coupling ring in the opposite direction under a greater force than said one force.

21. A coupling assembly for use with electrical connector apparatus including a first shell carrying a plurality of electrical contacts each adapted to engage a respective electrical contact of a second plurality of contacts carried by a second shell having a threaded periphery, the improvement comprising:

a flange secured on said first shell and extending radially outwardly from said first shell;

a plurality of pawl teeth integrally formed on said flange and extending axially rearwardly of said first shell with each pawl tooth having a cam face extending at a relatively small angle from a radial plane of said flange and a stop face extending at a relatively large angle to said radial plane;

a ratchet washer having a plurality of axially extending ratchet teeth integrally formed on said washer for engagement between the pawl teeth with the ratchet teeth each having a cam face extending at said relatively small angle to a radial plane of said ratchet washer for engaging a cam face on a pawl tooth and a stop face on each ratchet tooth extending at said large angle to a radial plane of said ratchet washer for engaging a stop face of a pawl tooth;

a coupling ring rotatably carried on said first shell and having threads for engaging the threaded periphery of the second shell to secure said second shell to said first shell in response to rotation of said coupling ring in one direction with each contact carried by said first shell engaged with a respective contact carried by said second shell;

means on said ratchet washer and said coupling ring for rotating said ratchet washer in response to rotation of said coupling ring and for enabling said ratchet washer to move axially of said coupling ring;

and means for biasing said ratchet washer axially of said ring against said flange with said ratchet teeth engaged between the pawl teeth and the cam face on each ratchet tooth engaging a cam face on a respective pawl tooth for enabling said washer to move axially against the bias of said means in response to the application of one force to said ring for rotating said ring and ratchet washer in one direction and for threading said coupling ring on said second shell to engage said contacts and the stop face on each ratchet tooth engaged with a stop face on a respective one of the pawl teeth for preventing rotation of said washer and coupling ring in the opposite direction under a greater force than said one force.

22. The coupling assembly claimed in claim 21 in which the large angle at which said stop faces extend is substantially less than 90.degree. to enable rotation of said ratchet washer and coupling ring in said opposite direction in response to the application of another force greater than said one force.