Patent GB-1177379-A (GB)
Title: Improvements in and relating to Electric Probes or Testing Devices
Inventor: FUTTER HANS WERNER
IPC: G01R1/067
Filed: 1967-11-23
Abstract: 1,177,379. Hand contact devices. FUTTERS (LONDON) Ltd. 22 Nov., 1968 [23 Nov., 1967], No. 53413/67. Heading H2E. An electric circuit testing device comprises a tubular insulating casing 1 within which is slidably mounted a wire or rod 5, one end of the wire or rod extending out of one end of the casing and being bent over to form a hook 6 with an upturned tip 7, this hooked part of the wire resting on a suitably shaped extension 2 of the casing, so that in operation, a circuit wire to be tested is gripped between said hooked wire and said extension. In one embodiment (Fig. 1) the portion 6 of a wire 5 rests in a groove 8 in an L-shaped extension 2 of the casing 1, the other end of the wire being secured to a cylindrical block 9 which is slidably mounted in a cup-shaped base 3. A helical spring 10 surrounds the wire, inside the casing, acting to keep the hooked end 6 firmly in the groove 8. In operation the block 9 is pushed into the base 3, so causing the hook 6 to lift off the casing and enabling a wire under test to be trapped between the wire and the extension 2. When the block 9 is released, the spring ensures good electrical contact. The circuit is completed by a further wire (not shown) to a test instrument, the wire being inserted in bores (shown dotted) in the block, and held, for example, by a grub screw (not shown). In a second embodiment (Figs. 4, 5, 6, not shown) the wire 5 is attached to a block (12) housed in a part-spherical cap (14) bored to fit slidably over the casing 1. The wire 5 is inclined at an angle to the casing axis and the inner aperture comprises an upper rectangular slot (11) and a lower cylindrical bore (13) where the spring 10 is housed. A wire or pin-type connector may fit in a transverse bore (16) in the base, and the device is operated by sliding the cap (14) relative to the casing 1, which causes the hook to lift off the extension. A third embodiment (Fig. 7, not shown) is similar, but has a flanged cylinder (18) slidably mounted in a cup-shaped base, as in the first embodiment. In fourth and fifth embodiments (Figs. 22, 23, not shown) a cylindrical casing is formed of a rear part (24) and a front part (25) held together by a spring-lip releasable spigot coupling (26). The wire 5 is held in a block (28) to which is attached an external slide button (32) through a slot (29) in the casing. In a sixth embodiment (Figs; 24, 25, not shown) a sheath (33) open at one end fits slidably over a block (34), there also being a slide button (32) as in the preceding embodiment. Above the spring (31) may be located a metal or plastics washer to provide a bearing surface for the spring. Alternatively the diameter of the top turns of the spring may be increased. In all embodiments, the casings and other non-conductive parts may be made from a plastics material by injection moulding. Several differently-shaped extensions, and several slidable caps for use with said second embodiment are disclosed (Figs. 8-17, not shown), and the rod or wire 5 may be of several alternative cross-sections (Fig. 21, not shown). Instead of the wire 10 being attached to a plastics block, a flat metal plate may be used (Figs. 19, 20, not shown). The undersurface of the hooked -tip 6 of the wire may be grooved or serrated.