Patent GB-492402-A (GB)
Abstract: 492,402. Signal lamps. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. May 4, 1937, No. 12755. Convention date, July 9, 1936. [Classes 75 (ii) and 75 (iv)] In a signal lamp of the searchlight type in which a light unit comprises a source of light and a reflector for bringing the rays to a focus, the light unit being adjustably mounted in a casing carrying a lens unit so as to enable the light focus to be brought into coincidence with the focus of the lens unit, the means for securing the light unit in position are independent of the adjusting means so that the light unit can be removed and fixed again without impairing the adjustment. In the form shown, the light unit A comprises an electric light bulb 82 with its filament at the proximate focus of an ellipsoidal reflector 30, and the lens unit L comprises a doublet of two spaced plano-convex lenses 9, 10 mounted in a lens barrel 11 secured to the front of the lamp casing 1. The light unit A is mounted on a triangular supporting bracket 45 which is adjustably secured by three adjustable fastening devices 46 to three lugs 49 projecting inwardly from the top and sides of the casing 1. Each fastening device comprises a threaded sleeve 46a screwed into a tapped hole 52 in the bracket 45, and a fillister head screw 46b which extends with clearance through the sleeve 46a and screws into a tapped hole 54 in the lug 49. The rear surfaces of the lugs 49 are machined flat and all lie in a common vertical plane bearing a fixed relationship to the lens unit L. The engaging ends of the sleeves 46a are also machined flat, and they are brought into engagement with the lugs by means of a wrench grip 46c, the sleeve being locked by means of a lock nut 46d. The reflector 30 is mounted in a two-part casing 31a, 31b made of a phenol condensation product, and is held therein by a forward annular flange 34 on the part 31b and by a rear ring member 35 abutting against a shoulder 36 on the part 31a, a felt band 35a being interposed between the ring member and the reflector. A socket 41 for the bulb 82 extends with clearance through a hole 42 in the rear wall of part 31a and is carried by a plate 40 mounted on studs 37 projecting from said rear wall, the bulb being adjusted by means of nuts 39 and coil springs 38. The part 31a is moulded with two semicircular projections 55, 56 having forward surfaces 55a, 56a adapted to engage an accurately machined vertically disposed surface 45c on a boss 45b on the bracket 45 around the hole 45a which receives the casing 31a, 31b with a sliding fit. The projections 55, 56 are formed with integral latches such as 556 to co-operate with latch springs 57, 58 on the bracket 45 so that the light unit is returned to its correct position. The colour screen 64 operates between colourless glasses 62, 63 carried by an auxiliary casing 61, the screen 64 being mounted on an arm 60 which projects upwardly through a slot in the top plate 59 of a mechanism casing 5. The latter is held in position by means of a supporting pin 65 and by two screws which project through upwardly extending lugs formed on a strap on the top plate 59 and screw into tapped holes in lugs directly below the screws which hold the light unit in position on the two lower lugs 49. The pin 65 projects into a socket 66 and is held in position by the lens barrel 11. The mechanism casing 5 may therefore be removed independently of the light unit. Between the lenses 9, 10 two clips 20 carry a prismatic screen 19 provided with horizontal prisms 19a to spread the light upwardly so as to produce an auxiliary indication close to a dwarf signal. Access to the lens barrel is given by means of a hand hole 21 closed by a removable cover 22. Sighting means is provided by means of a bracket 76 with vertical arms 76a, 76b with aligned holes 76c, 76d. The hole 76c is covered by an adjustable washer with a peep hole 78, and the hole 76d with a tube 79 with cross-hairs.