GB613333A - Improvements in or relating to telegraph keys - Google Patents

Abstract

613,333. Tapping keys. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and WASSELL, H. J. H. June 20, 1946, No. 18626. [Class 38 (v)] In a telegraph key both the range of movement or " play " of the key and the force of the return spring are capable of adjustment, the settings being shown by indicators. A key bar 1 consisting of upper and lower L- shaped sections 1a, 1b, held together at the centre by the rivets 22 and pivoted at one end by the knife edges 2, carries the contacts 19, 24 mounted on the sections 1a, 1b respectively, co-operating with the fixed contacts 17, 23. The upward return force on the key, provided by a spring 3 of which the end 4 engages in a loop 5 mounted on the bar 1, is adjusted by the rotation of an indexed knob 6, thus causing the rotation of a collar 8 into which is secured the anchored end 7 of the spring 3. The collar 8 is held in position by a pin 9 engaging in a ring of holes in the side of the base 10 and before adjusting the spring, the knob 6 is pushed inwards to disengage the pin. An operating knob 16 and a collar 12, having the upstanding pins 13, screw on a stem 11, of which the square head 27 is situated between the members 1a, 1b. The distance rods 28, 29 are free to slide in diagonally placed holes in the member 1a and the head 27. A knurled skirt 15, loose on the stem 11 has a ring of holes 14 into which the pins 13 engage. The " play " of the key is adjusted by slacking off the knob 16 and then screwing down the skirt 15 and with it the collar 12, which forces the members 1a, 1b apart, via the rods 28, 29, a zero adjustment being made initially, index marks on the skirt indicate the setting. The key-arm 1 is preferably made of aluminium and has preferably a natural period of transverse vibrations above 4000 c.p.s.