Wall Telephone Hooks

Kellogg. A typical form of hook switch, as employed in the ordinary wall telephone sets, is shown in Fig. 83, this being the standard hook of the Kellogg Switchboard and Supply Company. In this the lever 1 is pivoted at the point 3 in a bracket 5 that forms the base of all the working parts and the means of securing the entire hook switch to the box or framework of the telephone. This switch lever is normally pre ed upward by a spring 2 , mounted on the bracket 5 , and engaging the under side of the hook lever at the point 4 . Attached to the lever arm 1 is an insulated pin 6 . The contact springs by which the various electrical circuits are made and broken are shown at 7 , 8 , 9 , 10 , and 11 , these being mounted in one group with insulated bushings between them; the entire group is secured by machine screws to a lug projecting horizontally from the bracket 5 . The center spring 9 is provided with a forked extension which embraces the pin 6 on the hook lever. It is obvious that an up-and-down motion of the hook lever will move the long spring 9 in such manner as to cause electrical contact either between it and the two upper springs 7 and 8 , or between it and the two lower springs 10 and 11 . The hook is shown in its raised position, which is the position required for talking. When lowered the two springs 7 and 8 are disengaged from the long spring 9 and from each other, and the three springs 9 , 10 , and 11 are brought into electrical engagement, thus establishing the nece ary signaling conditions. IMG:384091999325875926_fig083_t.gif.png:Illustration_ Fig. 83. Long Lever Hook Switch Fig. 83. Long Lever Hook Switch View full size illustration. The right-hand ends of the contact springs are shown projecting beyond the insulating supports. This is for the purpose of facilitating making electrical joints between these springs and the various wires which lead from them. These projecting ends are commonly referred to as ears, and are usually provided with holes or notches into which the connecting wire is fastened by soldering. Western Electric. Fig. 84 shows the type of hook switch quite extensively employed by the Western Electric Company in wall telephone sets where the space is somewhat limited and a compact arrangement is desired. It will readily be seen that the principle on which this hook switch operates is similar to that employed in Fig. 83, although the mechanical arrangement of the parts differs radically. The hook lever 1 is pivoted at 3 on a bracket 2 , which serves to support all the other parts of the switch. The contact springs are shown at 4 , 5 , and 6 , and this latter spring 6 is so designed as to make it serve as an actuating spring for the hook. This is accomplished by having the curved end of this spring pre against the lug 7 of the hook and thus tend to raise the hook when it is relieved of the weight of the receiver. The two shorter springs 8 and 9 have no electrical function but merely serve as supports against which the springs 4 and 5 may rest, when the receiver is on the hook, these springs 4 and 5 being given a light normal tension toward the stop springs 8 and 9 . It is obvious that in the particular arrangement of the springs in this switch no contacts are closed when the receiver is on the hook. IMG:384091999325875926_fig084_t.gif.png:Illustration_ Fig. 84. Short Lever Hook Switch Fig. 84. Short Lever Hook Switch View full size illustration. Concerning this latter feature, it will be noted that the particular form of Kellogg hook switch, shown in Fig. 83, makes two contacts and breaks two when it is raised. Similarly the Western Electric Company's makes two contacts but does not break any when raised. From such considerations it is customary to speak of a hook such as that shown in Fig. 83 as having two make and two break contacts, and such a hook as that shown in Fig. 84 as having two make contacts. It will be seen from either of these switches that the modification of the spring arrangement, so as to make them include a varying number of make-and-break contacts, is a simple matter, and switches of almost any type are readily modified in this respect. IMG:384091999325875926_fig085_t.gif.png:Illustration_ Fig. 85. Removable Lever Hook Switch Fig. 85. Removable Lever Hook Switch View full size illustration. Dean . In Fig. 85 is shown a decidedly unique hook switch for wall telephone sets which forms the standard equipment of the Dean Electric Company. The hook lever 1 is pivoted at 2 , an auxiliary lever 3 also being pivoted at the same point. The auxiliary lever 3 carries at its rear end a slotted lug 4 , which engages the long contact spring 5 , and serves to move it up and down so as to engage and disengage the spring 6 , these two springs being mounted on a base lug extending from the base plate 7 , upon which the entire hook-switch mechanism is mounted. The curved spring 8 , also mounted on this same base, engages the auxiliary lever 3 at the point 9 and normally serves to pre this up so as to maintain the contact springs 5 in engagement with contact spring 6 . The switch springs are moved entirely by the auxiliary lever 3 , but in order that this lever 3 may be moved as required by the hook lever 1 , this lever is provided with a notched lug 10 on its lower side, which notch is engaged by a forwardly projecting lug 11 that is integral with the auxiliary lever 3 . The switch lever may be bodily removed from the remaining parts of the hook switch by depre ing the lug 11 with the finger, so that it disengages the notch in lug 10 , and then drawing the hook lever out of engagement with the pivot stud 2 , as shown in the lower portion of the figure. It will be noted that the pivotal end of the hook lever is made with a slot instead of a hole as is the customary practice. The advantage of being able to remove the hook switch bodily from the other portions arises mainly in connection with the shipment or transportation of instruments. The projecting hooks cause the instruments to take up more room and thus make larger packing boxes nece ary than would otherwise be used. Moreover, in handling the telephones in store houses or transporting them to the places where they are to be used, the projecting hook switch is particularly liable to become damaged. It is for convenience under such conditions that the Dean hook switch is made so that the switch lever may be removed bodily and placed, for instance, inside the telephone box for transportation.