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 press 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 depressing 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 necessary 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.

Desk-Stand Hooks. The problem of hook-switch design for portable desk telephones, while presenting the same general characteristics, differs in the details of construction on account of the necessarily restricted space available for the switch contacts in the desk telephone.

Western Electric. In Fig. 86 is shown an excellent example of hook-switch design as applied to the requirements of the ordinary portable desk set. This figure is a cross-sectional view of the base and standard of a familiar type of desk telephone. The base itself is of stamped metal construction, as indicated, and the standard which supports the transmitter and the switch hook for the receiver is composed of a black enameled or nickel-plated brass tube 1, attached to the base by a screw-threaded joint, as shown. The switch lever 2 is pivoted at 3 in a brass plug 4, closing the upper end of the tube forming the standard. This brass plug supports also the transmitter, which is not shown in this figure. Attached to the plug 4 by the screw 5 is a heavy strip 6, which reaches down through the tube to the base plate of the standard and is held therein by a screw 7. The plug 4, carrying with it the switch-hook lever 2 and the brass strip 6, may be lifted bodily out of the standard 1 by taking out the screw 7 which holds the strip 6 in place, as is clearly indicated. On the strip 6 there is mounted the group of switch springs by which the circuit changes of the instrument are brought about when the hook is raised or lowered. The spring 8 is longer than the others, and projects upwardly far enough to engage the lug on the switch-hook lever 2. This spring, which is so bent as to close the contacts at the right when not prevented by the switch lever, also serves as an actuating spring to raise the lever 2 when the receiver is removed from it. This spring, when the receiver is removed from the hook, engages the two springs at the right, as shown, or when the receiver is placed on the hook, breaks contact with the two right-hand springs and makes contact respectively with the left-hand spring and also with the contact 9 which forms the transmitter terminal.

Fig. 86. Desk-Stand Hook Switch
[View full size illustration.]

It is seen from an inspection of this switch hook that it has two make and two break contacts. The various contact springs are connected with the several binding posts shown, these forming the connectors for the flexible cord conductors leading into the base and up through the standard of the desk stand. By means of the conductors in this cord the circuits are led to the other parts of the instrument, such as the induction coil, call bell, and generator, if there is one, which, in the case of the Western Electric Company's desk set, are all mounted separately from the portable desk stand proper.

This hook switch is accessible in an easy manner and yet not subject to the tampering of idle or mischievous persons. By taking out the screw 7 the entire hook switch may be lifted out of the tube forming the standard, the cords leading to the various binding posts being slid along through the tube. By this means the connections to the hook switch, as well as the contact of the switch itself, are readily inspected or repaired by those whose duty it is to perform such operations.

Kellogg. In Fig. 87 is shown a sectional view of the desk-stand hook switch of the Kellogg Switchboard and Supply Company. In this it will be seen that instead of placing the switch-hook springs within the standard or tube, as in the case of the Western Electric Company, they are mounted in the base where they are readily accessible by merely taking off the base plate from the bottom of the stand. The hook lever operates on the long spring of the group of switch springs by means of a toggle joint in an obvious manner. This switch spring itself serves by its own strength to raise the hook lever when released from the weight of the receiver.