GB2129628A - Terminal block - Google Patents

Abstract

A terminal block for connecting exchange side telephone cables to drop wires, and comprises an insulating body 11 and a plurality of spaced pairs of one-piece terminals 20 which include bifurcated solderless first connection points 21 to receive the drop wires and upstanding earth connection points 27 as well as downwardly extending second bifurcated solderless connectors 24 which receive the exchange side cable wires. Three pin lightning protectors are inserted to engage with third connection points 26 on the terminals and with an earthing connection point 30. <IMAGE>

Description

SPECIFICATION Terminal block The present invention relates to terminal blocks. Terminal blocks are used in a vast number of environments and one particular important environment is in telephony. It is quite common for the so-called exchange side cable, which has a large number of wire pairs, to lead to a telegraph pole and a terminal block connector is provided from which the individual drop wires go to the various subscribers. It is a requirement that not only should such a terminal block give a good electrical contact and insulation from the environment but that provision should also be made for preventing problems should lightning strike the telegraph poie. It is quite common, in fact, for the terminal block to be connected to a separate assembly including a large number of separate lightning protectors.

These are usually in the form of a small body having three plug terminals, the centre terminal being connected to earth and the outer terminals being connected to the two drop wires conductors of a pair, the lightning protector including carbon electrodes which are spaced a very small distance from an earthed electrode so that when lightning strikes, the lightning voltage is effectively shorted to earth without causing any current to flow down the drop wire.

The conventional assembly involving the terminal blocks are cumbersome and difficult to connect up in a simple manner so that they are consequently rather expensive both to manufacture and to install.

It is now proposed, according to the present invention, to provide a terminal block comprising an insulating body and a plurality of spaced pairs of one-piece metal terminals, each metal terminal including first, second and third connection points, the first connection point being positioned to connect and retain the conductors of a first wire pair, the second connection point being positioned to connect and retain the conductors of a second wire pair and a third connection point being positioned adjacent one another and adjacent an earthing connection point, whereby a lightning protector may be connected to both of the third connection points and to the earthing connection point.

It has been found that by providing the one-piece terminal with first, second and third connection points, a very simplified structure can be achieved in which there is no need to have the conventional fine wires which pass from the normal terminal block to a separate unit including the lightning protectors.

Advantageously, the first and second connection points are located on opposite faces of the insulating body and the first and third connection points are located on the same face of the insulating body. By having the first and third connection points so located, the connection of the lightning protector can be facilitated.

Preferably the first and second terminal points are in the form of bifurcated solderless connections which simplifies very considerably the introduction of the wires of a pair into them, since the wires do not have to be bared, but simply pushed into the solderless connectors. This act can be greatly facilitated if the body has pivotally mounted elements thereon, each having at least one passage for a wire, each element having a hole therein extending transverse to the passage or passages, a captive bolt passing through the hole and being engageable with the female thread, for example, a nut, mounted on the body, whereby when said bolt is screwed into the female thread, the elements pivot in a direction such that the wires are urged into the first bifurcated solderless connectors, so that the conductors therein make electrical contact with the connectors, and when the bolts are unscrewed the pivotal elements pivot back to disengage the wires from the connectors.

It is because the bolt is captive in the pivotally mounted elements that this disconnection of the wires from the solderless connector can be greatly facilitated. Relatively thick wires can be introduced into the solderless connectors because of the high degree of force which can be imparted easily by the screw action of the bolt and associated nut.

The actual construction of the pivotal element may be such as to include a block of insulating material having extending from one side edge at least one hinge lug which is pivotally connected with the body, either by being inserted in a recess therein, or by a conventional hinge pin and a t least one recess formed on the undersurface of the block position to receive the two bifurcated solderless connectors of a pair, and at least one annular ramp forming the side of the recess or recesses nearer the centre of pivoting of the block and having its centre of curvature approximately at the centre of pivoting, so that the ramp or ramps move closely adjacent the bifurcated solderless connector during pivoting movement of the element and whereby the connector is not distorted and the wire is held closely adjacent thereto during insertion.

The earthing connection point may be mounted in an insulating housing which can be inserted in the insulating body to cover the two third connection points of a pair, the insulating housing having on its surface, overlying the third connection points, apertures through which the plug terminals of the associated lightning protectors may pass, to make electrical connections with the two third terminal points and the earth connection point. The provision of this removable insulating housing can greatly facilitate the manufacture of the terminal block according to the invention Advantageously, the hinge covers are mounted on the insulating housing, to be movable from an open position in which the lightning protectors can be removed or inserted, and a closed position in which the lightning protector is sealed from the environment.A simple method of manufacture is for the hinged covers to be hinged by a solid plastic hinge which not only is inexpensive to manufacture, but also provides a very satisfactory sealing.

According to a further aspect of the present invention there is provided a terminal block comprising an insulating body, at least one bifurcated solderless connector mounted on said body, a pivotally mounted element carried by said body, said element having at least one passage therein for a wire, the element having a hole therein extending transverse to the passage or passages, a captive bolt passing through the hole and being engageable with the female thread mounted on the body, whereby when said bolt is screwed into the female thread, the elements pivot in a direction such that wires are urged into the bifurcated solderless connector so that the conductor therein may make electrical contact with the connector, and when the bolt is unscrewed, the pivotal element pivots back to disengage the wire from the connector.

In order that the invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a top plan view of one embodiment of terminal block according to the present invention; Figure 2 is an underneath plan view of the terminal block of Fig. 1; Figure 3 is a perspective view of one of the one-piece metal terminals, to an enlarged scale; Figures 4 and 5 are perspective views of the pivotally mounted elements of the terminal block of Figs. 1 and 2; and Figure 6 is a perspective view of one of the insulating housings of the terminal block of Fig. 1.

Referring first to Figs. 1 and 2, the terminal block indicated by the reference numeral 10 comprises an insulating body 11 formed of plastics material and includes a support base (not shown) locatable below the lower surface illustrated in Fig. 2 and a slidable cover (not shown) which covers completely over the whole assembly to protect it from the weather. The base will be secured, for example, to a telegraph pole.

On the upper surface 1 2 of the body 11 there is provided an upstanding wall 1 3 on each side, this wall being provided with castellations forming a large number of indentations 14, 1 5 for the passage of two wires of a wire pair of a drop wire. The various drop wires which have their wire pairs passing through the indentations 14, 1 5 enter the housing through openings 1 6. The wires then extend along beside the castellations 1 3 and are then bent inwardly to the respective terminal areas of which there are in fact ten, only three of which are shown in full in Fig. 1, the other seven being indicated by phantom lines indicating their centre.Thus, ten drop wires can enter on each side so that the terminal block is capable of connecting an exchange side cable to twenty drop wires. Each connection zone 1 7 has associated therewith a pair of through openings 1 8 of rectangular crosssection which can be seen in Fig. 2. Each of these openings is designed to take a downwardly extending leg 1 9 of a one-piece metal terminal 20 illustrated in Fig. 3. This metal terminal 20 includes three connection points.

These are a first connection point 21 in the form of an upwardly facing bifurcated solderless connection having a central slot 22, this being mounted at the end of an arm 23 which is cranked as compared with the leg 1 9. A second bilfurcated solderless joint 24 having a slot 25 is mounted at the lower end of the leg 1 9 while the third connection point 26 is in the form of a bifurcated element having a central opening 27 and formed on an arm 28.

The first and third terminal points 21 and 26 extend upwardly above the upper surface of the connecting zone 1 7 whilst the second connecting point 24 extends down through the opening 1 8 and below the lower surface.

As can be seen from Fig. 1, each connection zone 1 7 has a pair of one-piece metal terminals 20 disposed in mirror image relationship so that the third terminals 26 are close to one another and also arranged on either side and adjacent to an earthing terminal 30.

The earthing terminal 30 is formed on an insulating housing 31 which is shared between two terminal zones 1 7 which are arranged side-by-side as seen in Fig. 1.This insulating housing 31 (Fig. 6) includes a base 32 which is insertable in an appropriately shaped opening in the body 11 and is provided with a flange 33 to prevent it being pushed completely through. The base 32 has formed therein six apertures (not shown) extending through the upper surface 34 of the base. These apertures are arranged in two sets of three to take the three terminal prongs of two lightning protectors 35 only one of which can be seen in Fig. 6. The two outer terminal prongs engage the two bifurcated connectors 26 while the inner terminal prong engages the earthing connection 30 for each protector.

The protectors are, in use, enclosed by a cover 36 which is hinged by a solid plastic hinge 37 to the base 32. In order to remove or insert a lightning protector, the cover 36 can be hinged back as shown on the left in Fig. 6, but in use, it is moved to the closed position in which it is held by a projection 38 engaging under a detent 39 formed in the flange 33.

Figs. 4 and 5 illustrate a pivotally mounted element 40 which is used to insert the wires into the connectors 21. Each element 40 includes a main block 41 and two laterally extending hinge lugs 42. These hinge lugs are engageable in deperessions formed in the lower part of the castellated wall 1 3 so that the blocks 41 can pivot.

As can be seen in Fig. 5, recsses 43 extend upwardly into the lower surface of the body 41 and one side of them forms a continuation of a pair of arcuately curved ramps 44 which have their centre of curvature at the centre of pivoting of the blocks 41 when they are installed. The recesses 4 are shaped to accommodate the connectors 21 of a pair of connectors.

Extending laterally through the block 41 are a pair of passages 45 which go from the side of the block having the lugs 42 as far as the recesses 43.

The upper surfaces of the blocks 41 are counter-sunk at 46 and are provided with a hole 47 which extends downwardly, that is perpendicular to the passages 45. A bolt 48, (Fig. 1) passes downwardly through the hole 47 and is retained in place, so that it is captive in the block 41, by a circlip (not shown).

Referring now to Fig. 2, it can be seen that on the undersurface the body 11 is provided with nuts 49 into which the bolts 48 can be screwed. As the bolts 48 are tightened up, the blocks 41 are caused to pivot downwardly and because the bolts are captive, when the bolts are unscrewed, the blocks will pivot upwardly.

The lower surface of the body 11 is provided with a conducting strip 50 which is connected to each of the earthing connection points 30.

When the terminal block is used for connecting an exchange side cable to the drop wires at a telegraph pole, the exchange side cable is introduced through an opening 52 in the underside and the cable is clamped in a conventional way by a clamp 53 (Fig. 1). The various wire pairs are introduced into the appropriate ones of the second terminal bifurcated solderless connectors 24 which extend through the slots 18.

The drop wires are introduced at 1 6 and the wire pairs are fed into the appropriate ones of the passages 45 in the blocks 41.

The bolts 48 are then screwed down so that the wires, which had not been bared, are pushed forcibly down through the slots 22 in the first bifurcated solderless connectors 21.

The drop wires are generally fairly heavy duty and the screw action of the bolt provides adequate force to push the insulators into these slots. It may, occasionally, be necessary to disconnect a drop wire and this is achieved by unscrewing the bolts 48, and since these are captive, the blocks themselves pivot up thus drawing the wire out of the slots 22.

The lightning connectors 35 are introduced in the manner described above and the covers 36 closed down. Then an overall cover (not shown) is slid over the base 11 to isolate the interior from the environment. It will be appreciated that the wiring of this terminal block is particularly simple and yet is very effective.

An alternative arrangement of the pivotal block 41 would be to have the hinge lugs disposed so that they are at the centre of the body 11 rather than near the edge. The advantage of this would be that it would ease the insertion of the drop wire pairs into the passages 45 which, in this construction, would be on the opposite side of the block from the hinge lugs so that they are again at the outer side of the block. The insertion of the wire would then be slightly downward rather than upward.

Claims (11)

1. A terminal block comprising an insulating body and a plurality of spaced pairs of one-piece metal terminals, each metal terminal including first, second and third connection points, the first connection points being positioned to connect and retain the conductors of a first wire pair, the second connection points being positioned to connect and retain the conductors of a second wire pair and the third connection points being positioned adjacent one another and adjacent an earthing connection point, whereby a lightning protector may be connected to both of the third connection points and to the earthing connection point.

2. A terminal block according to claim 1, wherein the first and second connection points are located on opposite faces of the insulating body.

3. A terminal block according to claim 1 or 2, wherein the first and third connection points are located in the same face of the insulating body.

4. A terminal block according to any preceding claim, wherein the first and second terminal points are in the form of bifurcated solderless connections.

5. A terminal block according to claim 4, wherein the body has pivotally mounted elements thereon, each having at least one passage for a wire, the element having a hole therein extending transverse to the passage or passages, a captive bolt passing through the hole and being engageable with a female thread mounted on the body, whereby when said bolt is screwed into the female thread, the elements pivot in a direction such that the wires are urged into the first bifurcated solder less connectors, so that the conductors therein make electrical contact with the connectors, and when the bolts are unscrewed, the pivotal elements pivot back to disengage the wires from the connectors.

6. A terminal block according to claim 5, wherein each pivotal element includes a block of insulating material having extending from one side edge at least one hinge lug pivotally connectable with the body, at least one recess on its undersurface positioned to receive the two bifurcated solderless connectors of a pair, at least one annular ramp forming the side of the recess or recesses nearer the centre of pivoting of the block and having its centre of curvature approximately at the centre of pivoting, so that the ramp or ramps move closely adjacent the bifurcated solderless connector during pivoting movement of the element.

7. A terminal block according to any preceding claim, wherein the earthing connection point is mounted in an insulating housing which can be inserted in the insulating body to cover the two third connection points of a pair, the insulating housing having on its surface, overlying the third connection points, apertures through which the plug terminals of the associated lightning protector may pass, to make electrical connections with the two third terminal points and the earth connection point.

8. A terminal block according to claim 7, wherein hinged covers are mounted on the insulating housings to be movable from an open position in which the lightning protectors can be removed or inserted and a closed position in which the lightning protector is sealed from the environment.

9. A terminal block comprising an insulating body, at least one bifurcated solderless connector mounted on said body, a pivotally mounted element carried by said body, said element having at least one passage therein for a wire, the element having a hole therein extending transverse to the passage or passages, a captive bolt passing through the hole and being engageable with the female thread mounted on the body, whereby when said bolt is screwed into the female thread, the elements pivot in a direction such that wires are urged into the bifurcated solderless connector so that the conductor therein may make electrical contact with the connector, and when the bolt is unscrewed, the pivotal element pivots back to disengage the wire from the connector.

10. A terminal block according to claim 9, wherein the pivotal element includes a block of insulating material having extending from one side edge at least one hinge lug pivotally connectable to the body, a recess on its under-surface to receive the bifurcated solderless connector and an arcuate ramp forming the side of the recess nearer the centre of pivoting of the block and having its centre of gravity approximately at the centre of pivoting, so that the ramp moves closely adjacent the bifurcated solderless connector during pivoting movement of the element.

11. A terminal block substantially as here it before described with reference to and as illustrated in the accompanying drawings.