Patent GB-1077411-A (GB)
Title: Relay apparatus
Inventor: HAYTHORNTHWAITE FRANK
IPC: H01H51/08
Filed: 1964-08-12
Abstract: 1,077,411. Coin box substations. H.M. POSTMASTER GENERAL. Aug. 12, 1965 [Aug. 12, 1964; Nov. 27, 1964], Nos. 32883/64 and 48390/64. Heading H4K. [Also in Divisions G4 and H2] Two ratchet relays of known construction are separately operable to drive in the same sense respective rotary members 22, 22A mounted on a common spindle 23 and one of the members carries a movable contact 36 which is actuated into engagement with different ones of at least two contact members 35, 46 at selected relative angular positions of the rotary members 22, 22A. The rotary members have ratchet-wheels 13, 13A respectively and sets of cams 17, 27 and 17A, 27A respectively. Member 22 carries a contact unit 28 comprising a movable blade 36 secured to a conductive collector disc 32 and a co-operating contact 35 secured to a second collector disc 31 (Fig. 3, not shown) which is insulated from the first collector disc. Member 22A carries a contact 46 secured to a collector disc 41 and a face cam 44 co-operating with a cam follower 38 of the blade 36. Brushes are provided for each collector disc. The device is designed for use in metering telephone calls from a prepayment coin operated call-box. On inserting coins in the box rotary member 22 is stepped round a number of steps according to the coinage inserted. On the first step, contacts 35, 36, which are normally held closed by the engagement of a projection 44 of the face cam with the cam follower 38, are opened. The rate of stepping of member 22A is determined during the setting up of the call and this member is stepped round in the same sense as member 22 until contacts 35, 36 are once more closed. This closure warns the caller audibly that the coinage is used up and further coins may be inserted to step member 22 on again. A recess 45 (Fig. 3, not shown) in the face cam ensures that member 22 cannot be stepped on so far as to give a false indication of coinage inserted. As soon as the member 22 has been stepped round so that the cam follower lies in the recess contacts 36, 46 are closed, thereby operating a slot-locking mechanism of the coin box and preventing the insertion of further coinage. On termination of the call the two rotary members are stepped to the " home " position over a homing circuit (Fig. 7, not shown). Each relay has an identical homing mechanism. In the home position a recess in cam 17 (17A) allows contacts operated thereby to open, but in all other positions they are closed. When the call is finished the armature of the relay is released closing interrupter contacts which are connected in series with the cam contacts, the relay coil and a battery. The relay is thus energized, steps member 22 (22A) one step and opens its interrupter contacts to de-energize the coil. The member 22 (22A) is thus stepped round until the recess in cam 17 (17A) again allows its contacts to open and finally breaks the energizing circuit of the relay. In an alternative arrangement (Fig. 8-11, not shown), one rotary member 22 carries all the contacts and the other 22A only the face cam. In another arrangement (Figs. 12-15, not shown), a further contact is provided in the cam track and co-operates with the movable contact blade over part of the angular displacement.