US3500297A

US3500297A - Electrical contact member

Info

Publication number: US3500297A
Application number: US685424A
Authority: US
Inventors: Fernand Georges Bac
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-11-29
Filing date: 1967-11-24
Publication date: 1970-03-10
Anticipated expiration: 1987-03-10
Also published as: DE1615823B2; DE1615823C3; GB1180954A; DE1615823A1

Description

Marsh 10, 1970 F. a. BAC 3,500,297

ELECTRICAL CONTACT MEMBER Filed Nov. 24, 1967 5 Sheets-Sheet 1 I00 I; II

I NVE N TOR FERNA ND cams mo gill-M W/ ATTOR Y9 March 10, 1970 Filed Nov. 24, 1967 F. G. BAC

ELECTRICAL CONTACT MEMBER 5. Sheets-Sheet 2 10:; 1 is 112 T 121 121 m I I m 105 105 III 12 713 INVENTOR FERNAND OE ORGES BAC BY MW /WATT0RN EY$ March 10, 1970 Filed Nov. 24, 1967 FIG. 77

F. G. BAC

ELECTRICAL CONTACT MEMBER 5 Sheets-Sheet 5 INVENTOR FERNAND 050m BAC ATTORNEYS March 10, 1970 F. G. BAC

ELECTRICAL cormcw MEMBER 5 Sheets-Sheet 4 Filed Nov. 24, 3.967

F/GM

INVENTOR March 10, 1970 F. G. BAC

ELECTRICAL CONTACT MEMBER 5 Sheets-Sheet 5 Filed Nov. 24, 1967 FIG. 15

INVENTOR FERNAND GEORGEZfli AC BY M /MTTORNEYS United States Patent US. Cl. 339-217 14 Claims ABSTRACT OF THE DISCLOSURE In an electric connector having removable and lockable contact members slidably mounted in bores provided in an insulating block, the locking of each contact member is obtained by means of a radially contractile locking ring which engages a shoulder of said contact member when forced axially in a tapered section of the corresponding bore in said insulating block, said forcing being obtained by means of a second insulating block having an extension adapted to enter said tapered section, means being provided to press said second insulating block against said first block, thereby compressing said locking ring within said tapered section.

This invention relates to electric connector elements having removable and lockable contact members.

It is known that the electric connectors used in the electricity, electronic, or other industries for making a detachable connection between two conductors, or more frequently between two series or bundles of conductors belonging respectively to one or more circuits, comprise essentially one or more contact pins or other male members for engagement with one or more sockets or other female contact members, the contact pins and sockets respectively being connected to the end of a conductor, usually by soldering or by crimping. These contact mem bers are mounted in blocks of insulating material, in which they are secured by various means, one block generally carrying the male and the other the female members.

Until relatively recently, the contact members were formed in one with their supporting insulating block during manufacture of the connector element, the conductors being subsequently connected to their contact members when in position in their insulating block. The operation of connecting up the conductors is not without difliculty, particularly in the case of connectors of relatively small dimensions or those comprising a large number of conductors.

In order to facilitate these wiring operations, contact members have now for some time been connected to the conductors before being mounted in the insulating block. Such means include the use of a spring clip forming part either of the contact member or of the insulating block, interlocking of the parts being etfected by engaging the clip in a groove or behind a projection provided in or on the member or block. This arrangement has the disadvantage that it requires special equipment both for the introduction of the contact members into the insulating blocks and for their extraction from the latter, and it sets up stresses which are detrimental to the safety of the insulating blocks, which may become damaged after successive operations.

Notwithstanding it is necessary repeatedly to be able to insert and extract the contact members, particularly to correct errors that occur during assembly or in order to modify the distribution of the connectors; moreover specifications laid down by consumer industries require the ability to withstand a minimum of ten successive such stripping operations without damage to the parts concerned.

The object of the present invention is to provide a form of connector element which will enable these conditions to be complied with and even exceeded, will permit of contact members to be readily removed and replaced in their insulating block, and which does not require special tooling and with little risk of damage to the co-operating parts.

An electric connector element having removable, lockable contact members according to the invention comprises one or more male or female contact members slidably mounted in a bore or bores provided for that purpose in an insulating block characterised in that each bore provided in the block comprises, behind that portion in which the end of the contact member incorporates a male pin or female socket is secured, a tapered portion followed by a rear cylindrical portion, providing an annular space around the body of the contact member: that a second insulating block, at the rear of the first block and axially displaceable in relation to the latter, comprises on the one hand, for the passage of each contact member, a bore coaxial with the bore in the first block, and on the other hand a spigotted end or skirt designed to enter said annular space and engage an annular locking member capable provided therein so that on engagement therewith it will cause the locking member to contract when it will engage in an annular groove provided in the contact member when said compressible member is driven by said projection into said flared portion; and the actuating means is provided to move the second block into and out of an operative position in the first block in which the locking member locks onto the contact member.

Preferably the annular locking member consists of a split ring formed of contractile metal.

With the arrangement of this invention when the two insulating blocks are apart from one another and the compressible annular locking member is situated in the widest portion of the bore of the first block, all that is necessary is to push each contact member, previously connected to the corresponding conductor, through the bores provided in the two insulating blocks, until the grooves in the respective contact members lie adjacent the bottom of the flared portion of the bore in the first block, after which the blocks are brought into engagement.

Each of the s-pigotted ends or skirt on the second block will then enter the annular space provided in the first block around the corresponding contact member and thereby force the compressible locking ring or other member into the flared portion towards its narrow end with the result that the locking ring is compressed and on entering the groove in the contact member will secure the latter against any longitudinal displacement in relation to the insulating blocks.

In order to extract a contact member, the two blocks are moved apart and the contact member which is to be extracted is pulled out. The locking ring is then free to expand with the rise along the walls of the flared portion in which it was previously confined and thus to escape from the groove in the contact member, thereby unlocking the latter and enabling it to be freely extracted from the blocks.

Each contact member preferably has a surface forming a stop and co-operating with a shoulder provided in the portion of the bore receiving the end of said member, which is in the form of a pin or socket, in order to limit the penetration of the contact member to a position in which the front wall of the annular groove provided in it coincides substantially with the junction plane of the flared portion of the bore and of the narrowest portion of the latter. This stop surface may be constituted by the front face of a collar provided on the contact member, when the latter is in the form of a pin,

or by the end face of said member when the latter is a socket.

The compressible locking member may be formed of an elastic metal toric or cylindrical ring, which is split in order to permit of contraction when compressed so that it will readily enter the annular space provided between the wall of the widest portion of the bore in the first insulating block and the contact member when in position in the latter. To provide the tapered constricted portion to receive the metal locking ring a metal annulus may be inserted in the bore in the insulating block accommodating the male or female portion of each contact member, said annulus having an internal bevel or bevels along which the compressible ring or rings is or are slidable in order to be brought into its locking position.

The two insulating blocks may have plane mutual junction faces and the insulation distances between the contingous contact members may be extended by means of tubular sleeves of insulating material of relatively small thickness surrounding the contact means at the junction plane of the two blocks and of the compressible locking members.

The means for bringing the insulating blocks into operative engagement with one another are advantageously designed so that they will likewise separate the two blocks by contraint. For this purpose there may be provided a flanged actuating ring having inverse internal and external screw threads co-operating with corresponding threads provided respectively on and in the blocks or parts connected to the latter, or in one or more threaded rods solid with one of the blocks and co-operating in each case with a nut mounted rotatably but axially secured in the other block.

In certain cases it has been apparent that the guiding of the pins of a contractor member in the corresponding sockets of the other contact member was difiicult to effect and that in addition the compressible member tended to be displaced in the bore in the element containing it, thus making connections less easy.

It has been possible to obviate these disadvantages by forming, in connector elements comprising locking means in the form of a toric ring, a rounded support surface to receive the thrust or impact from the second insulating block on movement of the latter into locking position and acting on said ring.

The rounded support surface may be obtained by a moulding at the end of the extension of the second insulating block effecting the driving of the locking means into the flared portion of the contact member.

In another embodiment of the invention the rounded support surface is formed by a second ring, which may or may not be split and the inside diameter of which is substantially equal to the bore of the second block which permits the passage of and guides the contact member, the split, elastic locking toric ring having an inside diameter smaller than that of the cylindrical body of the contact member and being engaged in the groove in the latter after having permitted the passage of the cylindrical portion preceding said flared portion.

The rounded support surface may moreover be constituted by a second split or unsplit ring of cylindrical shape and having edges of semi-circular section.

When the locking member is constituted by a split, elastic cylindrical ring, the ring may be provided with a tongue extension, the terminal ending or tip of which is adapted to engage a shoulder formed in a groove in the bore in the block containing said ring, so as to fasten it to said block.

The invention is illustrated in the accompanying drawings, in which:

FIGURE 1. is an axial Section of an electrical connector 4 element having two contact members in accordance with one embodiment of the invention, the top portion of the figure showing the parts in their unlocked position and the bottom portion in the locked position.

FIGURE 2 is a perspective View on an enlarged scale of the compressible locking member shown in FIGURE 1.

FIGURES 3 and 4 are half-views in section, on an enlarged scale, corresponding to FIGURE 1, showing a connector element respectively in its unlocked and locked positions.

FIGURE 5 is a view partly in sectional of the two insulating blocks of a connector element according to another embodiment of the invention before introduction of a contact member.

FIGURE 6 is a sectional view corresponding to that of FIGURE 5 showing the contact member in course of introduction.

FIGURES 7 and 8 are corresponding views showing the locking action obtained respectively before and after the tightening of the two insulating blocks.

FIGURE 9 is a section of an alternative construction of locking device.

FIGURE 10 is a perspective view of an alternative construction for the compressible locking member.

FIGURES 11 and 12 are sectional views similar to those of FIGURES 3 and 4 but fitted with the locking device of FIGURE 10.

FIGURE 13 is a diametrical section of another embodiment of the invention showing four contact members with the two insulating blocks in the unlocked position.

FIGURE 14 is a section similar to that of FIGURE 13, but showing the two insulating blocks in the locked position and provided with a sealing device for the passage of the cables.

FIGURE 15 is a section of another form of construction of the connector element provided with a cylindrical locking member;

FIGURES 16 and 17E are respectively a perspective and plan view of the locking member;

FIGURE 18 is a section on the line IX--IX in FIG- URE 15.

Referring to FIGURE 1, the electric connector element of this invention comprises an outer cylinder or casing 1, provided with an inner shoulder 2, against which there is located a first block 3 of insulating material, which is held in position by a circlip or other means not shown. As described in more detail hereinafter, block 3 is provided with bores, each adapted to receive a contact member 5, each member 5 having an end 4 of reduced diameter in the form of a male pin for engagement in a socket forming part of the corresponding contact element of a second connector member. The main body of contact member 5 is formed with a counter bore 6 to receive the end of a conductor cable 7, which is secured in position by crimping or by soldering. Immediately behind the front end 5a of the body of contact member 5 is an annular groove 8.

Each of the above mentioned bores formed in block 3 for receiving a contact member comprises a front portion 9 followed by coaxial stepped portions 10, 12 of increasing diameters joined by a conical portion 11. It will be seen that the pin 4 of the contact member is frictionally engaged within front portion 9: that the front end 5a of the body 5 of the contact member bears against a shoulder 10a formed by portion 10 the diameter of which corresponds to the outside and that the cylindrical portion 12 has a diameter such that it provides an annular clearance around said body 5.

Behind block 3 is arranged a second insulating block 13, having spigotted projections 14, 14' for sliding engagement in the sockets provided by portions 12 of the bores in the block 3. Through block 13 and its projections 14 are provided bores 15 coaxial with those in block 3 and having a diameter such that it permits the free passage of the body 5 of a contact member.

Block 13 is adapted for sliding movement in relation to block 3 it can be brought close to, and aligned axially in relation to the latter. For this purpose, said block 13 is provided with an external screw thread 16 with which co-operates an internally threaded and flanged ring 18 having an external thread 19 received in a thread 20 provided in the casing 1 of the connector element. The screw threads 16 and 17 on the one hand, and 18 and 19 on the other hand have inverse pitches, so that on rotation of the ring 18 in a direction, which drives it into casing 1, it effects displacement of block 13 towards block 3, and vice versa.

In the enlarged rear portion 12 of each of the bores 9 in block 3 is disposed, a radially compressible locking device formed of a toric ring 21 (FIG. 2) made of resilient metal, e.g. spring steel or beryllium bronze and provided with a slit 22, said ring 21 surrounding the corresponding contact member. The diameter of the split rings 21 which may consist of a piano wire, when expanded, is such that it can be freely accommodated in the annular space provided in the rear bore portion 12 of block 13, and that, when forced into the grooves 8 in each of the contact members 5 due to driving of the

projections

14, 14 of block 13 towards the flared portions 11 of said bores in block 3, which causes radial contraction of said rings by sliding thereof along said flared portions it will lock the contact members in position.

A seal 23, formed of a disc of deformable plastics material and in which are holes 24 corresponding to the bores provided in block 13, is located between the rear face of block 13 and a washer 27 having corresponding holes 28. Compression of sealing disc 23 is obtained by a ring 25, which is externally threaded for engagement in thread 17 of the flanged actuating ring 18.

The contact members are mounted in the device according to the invention in the following manner.

Having unscrewed the actuating ring 18 so as to withdraw block 13 from block 3 to the position-shown in the top part of FIGURE 1, ring 25 being likewise unscrewed so as to loosen the seal 23, also as shown in the same part of FIGURE 1, each of the contact members 4, 5, to which the corresponding cable 7 has pre viously been connected is introduced into the device, through the bore provided by the

successive bore apertures

28, 24, 15, 12, 11, and 9, until the front end 5a of the contact member 5 abuts against shoulder 10a of block 3. Ring 18 is now turned in the direction to drive it into casing 1 and bring the insulating

blocks

13 and 3 together.

The projection 14 on block 13 are then driven from the annular space within the rear portion 12 of bores 4 in block 3, with the result that each ring 21 is diametrically compressed by taper 11 causing it to engage in groove 8 of contact member 5 in the position shown in the bottom portion of FIG. 1 and in FIG. 4, thus effectively locking contact member 5 and preventing any longitudinal movement thereof in either direction.

Ring 25 is now screwed into the actuating ring 18 to compress seal 23, which expands into peripheral engagement with thread 17 of ring 18, the holes 24 therein being reduced in diameter to grip against cable 7, thus ensuring perfect tightness of the device in the rearward direction.

To extract a contact member, the operations are reversed, i.e. ring 25 is unscrewed to decompress seal 23, followed by ring 18 in order to positively move block 13 rearwardly away from block 3. Each locking ring 21 will now expand radially outwardly under its inherent elasticity following upon the withdrawal movement of projection 14 of block 13 until it resumes the position shownin the top portion of FIG. 1 and in FIG. 3.

FIGS. 5-8 each show a portion of a female connector element according to the invention, in different positions. Said figures show an insulating block 103 having a bore 112 to receive the contact member indicated at 105 and the locking means housed in bore 112, composed of a split toric ring 121.

Ring 121, which is formed of a piano or other elastic wire, has an internal diameter smaller than the outside diameter of the cylindrical body of the contact memher.

In this embodiment the ring 121 co-operates with a support surface of semi-circular section, which may be obtained by a suitable moulding on the forward edge of the projection 114 of the second insulating block.

Preferably however said rounded surface is provided by means of a second toric ring 122, which may or may not be split and the inside diameter of which is very slightly larger than the outside diameter of the cylindrical body 105. Said ring 121 rests on the projection 114 of the second insulating block (not shown).

This arrangement makes it possible to obtain a better guiding action for the contact member 105 (FIG. 6) when it is introduced into block 103. When said contact member is so introduced, ring 121 undergoes circumferential expansion while permitting the passage of member 105, and bearing against the flared portion 111 of bore 112.

When groove 108 of contact member 105 comes opposite ring 121, the latter is again tightened and forced into the groove.

When the second block is moved towards block 103 for the purpose of locking the contact member 105, ring 122 is pushed by projection 114 (FIG. 8) and forces ring 121 to slide along the flared portion 111 of block 103 and to be completely inserted into the groove 108 in said member 105.

In the course of this operation, only the circular lines formed by the tangent points of contact of

rings

121 and 122 are in contact, thus reducing friction and the risk of jamming between the parts.

In the modification relating to a male contact element shown in FIG. 9, which is turned with respect to FIGS. 5-8, the support surface is obtained by using a ring 123 which has a cylindrical shape and the edges of which have a semi-circular section.

This ring may be of insulating material or of metal, the surface of which has been made insulating in order to avoid current leakages. The operation is identical with that of the preceding embodiment.

In the embodiment of FIGS. 10, 11 and 12 the lock ing ring 21 of FIGS. l-4 is replaced by a collar 29 having a slit 30. The device operates in the same manner as previously described, the references in FIGS. 11 and 12 designating the same parts as in FIGS. 14.

In the unlocked position (FIG. 11), the collar or tubular ring 29 is in its expanded condition in the annular space 12 surrounding the body 5 of the contact member. When ring 18 (FIG. 1) is screwed into casing 1, projection 14 pushes back tubular ring 21 so that its front edge 29a engages the convergent wall portion 11 of bore in block 3. As the ring 29 is gradually closed it assumes a truncated conical shape, until its front edge 29:: bears against the front wall of groove 8 in the contact member, thus locking the latter. Slackening of ring 18 will withdraw block 13, thus allowing ring 29 to resume its original position.

In the modification shown in FIGS. 13 and 14 the connector member comprises a casing made of two blocks 53-63 each of insulating material.

The first block 53 in which there are provided bores 65 four of which are shown and, each receiving a contact member having a cylindrical bodies 55 which is extended by another cylindrical portion 55a designed to constitute either a male or female contact organ connector. In the example shown, the contact members are female members and each extension 55a has a bore 54 adapted to receive the pin of a cooperating corresponding male member of the connector element, the insulating block 53 having holes 65a for passage of the pins of said corresponding members.

Between the body 55 and the extension 55a of each of the contact members is an annular groove 58.

In each of the bores 65 is a counter bore 65b of larger diameter forming a shoulder 65c. Housed within counter bore 65b is a metal ring 61 one end of which bears against shoulder 65c and the upper end of which has a chamber or conical portion 61a for constricting movement of a locking ring 29 which is tubular and made of resilient metal, being slit longitudinally. Said ring 29 operates as the compressible locking member of this invention.

The second insulating block 63 has bores 75 of the sam diameter as and in alignment with the bores 65 in block 53.

Counter bores 75a and 75b at each end of each bore 75 form

annular shoulders

75c and 75d in said bore 75, which serve respectively to locate ring 29 and a collar 551; formed on the body 55 of the contact member, collar 55 being freely slidable in an enlarged portion 752 of the bore 75.

The contact member has at its outer end a secon collar 550, to the upper face of which the end of a conductor cable or wire 67 (FIG. 14) can be soldered.

Enclosing rings 29 are relatively thin insulating sleeves 57, the purpose of which is to extend the available length of insulation between contiguous contact members 55, so that the thickness of the boundary or

partition walls

53a and 63a of the

respective blocks

53 and 63 can be reduced to a minimum.

It will be understood that the connector elements of FIGS. 13 and 14 are assembled in a manner similar to that previously described in relation to the embodiments of the previous figures.

From FIG. 13 which shows locking members in unlocked position, it will be seen that it is easy to remove the contact members 55 completely or partially from the bores in the insulating blocks, which are interconnected by one or more screws 59 passing through block 53 and screwing into a threaded bore 60 in block 63. A split elastic ring 62 engages a groove in screw 59 to prevent the latter from being pulled out and lost.

Locking studs or other interlocking means, not shown, may be provided to ensure that the bores in the two blocks coincide when said blocks are brought together.

The contact members may then be connected to the respective electric conductors 67, if previously removed. The screw or screws 59 are then tightened to bring the two

blocks

53 and 63 into close contact. When this is done, the locking rings 29 engage in the rings 61 and, as their ends slide along the tapers 61a on the latter, they assume the position shown in FIGURE 14 in which they lock all the contact members in the two

blocks

53 and 63.

The connector member thus constructed is advantageously completed by an end plate or cap 64 of elastic insulating material having holes 66 formed with an internal bead or beads 68 adapted to grip conductors 67. Plate 64, through which the electric conductors pass before connection to contact members 55, is slid along the conductors into engagement with the block 63 until the bottom head 68 presses against the collar 550 .of each of said contact members, close to the point at whichthe cables are soldered, thus ensuring a tight joint with said cables. Under the pressure of the cover of the protective casing (not shown) enclosing the insulating blocks equipped as just described, plate 64 prevents the withdrawal of the contact members.

The tubes 57 of thin insulating material may be rigid or flexible and e.g. are formed of plastic material, such as Teflon, thus providing good insulation between neighbouring contact members.

Ring 61, which has an inwardly bevelled edge, may be of stainless steel, of beryllium bronze, or other very hard material not liable to oxidation.

It should be noted that in FIGS. 13 and 14 the rigid insulating blocks have plane junction surfaces instead of interlocking as in the previously described embodiments, thus considerably simplifying their manufacture and adjustment.

FIGS. 15 to 18 illustrate another embodiment in which the locking ring consists of a tubular element 129 which is split at and is intended to cooperate with an extension 105a of the cylindrical body,105 of the corresponding contact member, an annular groove 108 separating the two

portions

105 and 105a of said contact member.

The tubular ring element 129 has a tongue 131 terminating in a tip 132 adapted to engage behind a shoulder 133 provided in a groove 134 (FIGS. 15-18) formed in a bore 135 in block 113. It is thus seen' that ring 129 is resiliently attached to said block.

The length of ring 129 is such that it can be engaged in bore 136 in block 103 after sliding over the tapering bore portion 111 in said block 103 when the two insulating blocks are-brought together as previously described, so as to ensure accurate centering on the contact member.

The slope of the tapering bore portionlll, that is to say the angle 0: (FIGS. 5 and 15), has a value between 40 and 50.

An insulating sheath 57 is preferably placed around ring 129 in order to avoid current leakage between contiguous contact members.

What is claimed is:

1. An electrical connector element comprising a first and a second insulating blocks each having reciprocal, substantially parallel facing and remote surfaces, means for urging said first and second blocks towards one another along an axis substantially perpendicular to said surfaces, at least one bore provided through said first block, substantially parallel with said axis, for slidingly receiving a removable, male or female, metal contact member, said contact member comprising coaxially a central body portion, a front terminal contact portion, a rear portion for connection with a connecting lead, and an annular groove in a front part of said body portion, said bore in said first block comprising, from the vicinity of said remote surface to said facing surface of said first block, a first narrow section admitting passage of said terminal contact portion of said contact member, a second section providing passage for the front end of said body portion of said contact member, a third tapered section flaring out from said second section, and joining therewith a fourth larger section having a transverse dimension adapted to receive a contractile, resilient annular locking member engageable around said body portion when said locking member is engaged on said body portion, abutting means for limiting the penetration of said contact member within said bore in said first block to a point where at least part of the annular groove in said body portion of said contact member faces said tapered section of said bore, a bore through said second insulating block, adapted to be placed coaxially with said bore in said first block to receive the rear part of said body portion of said contact member and actuating means on said second block for driving at least the front part of saidannular locking member against said tapered section of said bore in said first block, whereby said annular locking member is contracted in said annular groove in said contact member.

2. An electrical connector element as claimed in claim 1, in which said contractile, resilient annular locking member is a toric split ring.

3. An electrical connector element as claimed in claim 1, in which said contractile, resilient annular locking member is a split sleeve.

4. An electrical connector element as claimed in claim 3, in which each bore in said second insulating block has a front section adapted to receive said split sleeve when engaged on the body portion of said contact member, and said actuating means on said second block is a shoulder provided in said bore to press against the rear end of said sleeve.

5. An electrical connector element as claimed in claim 1, in which said actuating means on said second block for driving said annular locking member is a substantially cylindrical skirt-shaped extension provided on said facing of said second block substantially coaxially with the bore in said second block and adapted to penetrate said fourth larger section of said bore in said first block.

6. An electrical connector element as claimed in claim 5, in which said skirt-shaped extension is solid with said second block.

7. An electrical connector element as claimed in claim 5, in which said annular locking member is a toric split ring, and a further toric ring member having an outer diameter substantially equal to that of the fourth larger section of the bore in the first insulating block is inserted between said skirt-shaped extension and said split ring for making linear contact with said split ring.

8. An electrical connector element as claimed in claim 5, in which said annular locking member is a toric split ring, and said skirt-shaped extension has a rounded free end for making linear contact with said toric split ring.

9. An electrical connector element as claimed in claim 5, in which said skirt-shaped extension is formed of an independent annular member arranged within a recess provided substantially coaxially with said bore in said second block.

10. An electrical connector element as claimed in claim 9, in which said independent annular member ring has a rounded end for making linear contact with the toric split ring.

11. An electrical connector element as claimed in claim 1, in which said contact member is a male contact member wherein the front terminal contact portion is of smaller transverse dimension than said body portion thereof, whereby a shoulder part is provided at the junction of said front portion and said body portion, and said first and second sections of said bore in said first block have respective transverse dimensions corresponding to the transverse dimensions of said front and body portions of said contact member, respectively, a shoulder thus being provided between said two portions to cooperate with the shoulder part on said contact member for limiting the penetration thereof in said bore.

12. An electrical connector element as claimed in claim 1, in which said contact member is a female contact member wherein said front terminal contact portion of said contact is of substantially the same transverse dimension as said body portion thereof, and said first and second sections of said bore in said first block form to gether a common section of constant transverse dimension, said bore comprising a restricted section at said re mote surface of said first block, whereby a shoulder is formed within said bore for cooperation with said front terminal portion of said contact member to limit the penetration thereof in said bore.

13. An electrical connector element as claimed in claim 1, in which said contractile, resilient annular locking member is a split sleeve, and said sleeve is provided with a tongue for engagement with a shoulder in a groove pro vided in the bore in said second insulating 'block.

14. An electrical connector element as claimed in claim 1, in which the taper section of each bore in said first insulating block is provided by a metal ring in each bore, said metal ring having an internally beveled edge.

References Cited UNITED STATES PATENTS Kent 339270 X RICHARD E. MOORE, Primary Examiner US. Cl. X.R. 339-103