Patent GB-401812-A (GB)
Title: Improvements in or relating to electric projector lamps for railway signalling or similar purposes
IPC: B61L5/18
Filed: 1932-07-14
Abstract: 401,812. Signal &c. lamps. BRITISH POWER RAILWAY SIGNAL CO., Ltd., Windsor Works, Slough, RAILWAY SUPPLIES CO., Ltd., River Plate House, Finsbury Circus, London, GLENN, S. L., and PIERCE, E. E., Windsor Works, Slough. July 14, 1932, No. 19980. [Classes 75 (ii) and 75 (iv).] In an electric railway signalling or like lamp the casing 2 is fitted at the front end with a plain or deflecting cover glass 51 and at the rear end with a combined unit which includes a fixed reflector 1 and an end cover 10 to protect the reflector and to form a closure for the casing, and captive clamping means are provided for securing the combined unit to the casing whereby it may be removed without detaching its clamping means or disturbing any part of the mounting and adjusting means of an electric lamp bulb 29 which is adjustably mounted in the casing independently of the unit. The reflector 1 may have the central portion of its silvering removed to co-operate with a back-light 27 and it is non-rotatably mounted in an annular member the flange 6 of which is secured by screws to a flange 21 on the end cover 10, the latter carrying leaf springs 11 with resilient packing 12 to engage the back of the reflector. Fig. 5 (not shown) illustrates alternative means for mounting a smaller reflector, the back light being replaced by a blanking plate. The flange 6 is provided with unequally spaced key-hole slots 22 to engage correspondingly placed studs 15, Fig. 7, on the rear face 5 of the casing 2, each stud carrying a helical spring 18 between a head 19 and a slidably mounted locking disc 16 with a coned face 17, and the cover 10 is formed with hollow bosses 26 to accommodate these studs and to form gripping bosses. A small portion of chain 28 prevents the complete removal of the unit. The bulb 29, which may comprise a spherical silvered or light-absorbing portion 59 or be fitted with a correspondingly shaped separate reflector or other phantom eliminating device, is carried by a thin vertical bar 30 which is pivoted at its lower end on a bracket 46 which is locked in position by a screw 49, packing plates 47 and an elongated slot 48 in the casing allowing for vertical and lateral adjustments respectively. A slot 35 at the upper end of the bar is engaged by a pin 36 carried by lugs on a bar 38 into which is screwed a rod 37 surrounded by a spring 39 and engaged by a nut 40 adapted to adjust the bulb to the focus of the reflector. To seal the bulb in position a split pin 43 passes through slots 41 in the nut 40 and one of a series of holes 42 in the rod 37, and a cap 44 is soldered to the nut. For focussing purposes a number of inwardly projecting tongues may be formed integrally with or secured to the front of the casing, or suitable markings may be painted on the cover glass 51. The latter may be formed to produce a close-up indication as by the means described in Specification 276,040, [Class 75 (ii), Lamp chimneys &c.], or by means of prisms 56, Fig. 12, separated by non-deflecting strips. The cover glass is held in position by an annular member 54. Fig. 4 (not shown) illustrates alternative means for mounting a smaller cover glass. The bar 30 may removably carry an emergency bulb 60 controlled through a relay mounted on a panel in a recess in one side of the lamp casing, this panel having a window for viewing the focussing tongues 50. The recess is covered by a door which may be locked in position with the reflector unit by means of a padlock engaging a hasp on one member and a staple on the other. The casing may also be fitted with side-lights and with a sighting tube b which may also serve as a carrying handle for the lamp.