Patent GB-843815-A (GB)
Title: A method of, and apparatus for, locating hot axle bearings in railway vehicles
IPC: B61K9/06
Filed: 1956-12-10
Abstract: 843,815. Detecting hot axle bearings of railway vehicles. HEIMANN, W. [trading as PHYSIKALISCH-TECHNISCHE WERKSTATTEN PROF. Dr-ING W. HEIMANN]. Dec. 10, 1956 [Dec. 9, 1955; June 13, 1956; Sept. 5, 1956], No. 37724/56. Class 40(3). [Also in Groups XXIX and XXX]  In infra-red radiation detection apparatus for locating hot axle bearings in railway vehicles, the radiation from the bearings impinging on the radiation sensitive element is compared with infrared radiation from a comparison radiator, a mechanism for identifying a hot bearing is operated when the radiation from the bearing reaches a predetermined proportion of the infrared radiation from the comparison radiator, and means are provided for preventing operation of the identifying mechanism by any source (e.g. a brake shoe) other than an axle bearing. In Fig. 1, radiation from an axle bearing of a wheel 10 is reflected by mirrors 1, 2, modulator disc 3 and mirror 5 on to a bolometer 4, and radiation from a comparison radiator 7 is directed through perforations in the modulator disc 3 and is reflected by the mirror 5 on to the bolometer 4. The bolometer is connected to a phase sensitive circuit which, when the bearing temperature is higher than the temperature of the comparison radiator, operates a relay of an identifying mechanism which releases a colour spray to mark the hot bearing. The means for preventing operation of the identifying mechanism by any source other than a hot axle bearing comprises a light source 12, Fig. 3, from which a ray is directed across and close to the rail, on to a photo-cell 13, the identifying mechanism being operable only when the light ray is obscured by the wheel. In another embodiment, Fig. 4, a differential bolometer 16 is used, one element of the bolometer being arranged to receive radiation from the axle bearings 10, and the other bolometer element being arranged to receive infra-red radiation from a comparison radiator 19, the elements of the bolometer being connected in two limbs of a Wheatstone bridge circuit so that the passing of a hot bearing causes a reversal of current in the bridge of the circuit to operate a thermionic amplifier coupled to the operating relay of a colour spraying mechanism. In a modified control circuit, Fig. 13 (not shown), including a Wheatstone bridge coupled to a differential bolometer, the approach of a train towards the infra-red detector is detected by a photo-cell, which causes the ray from the comparison radiator to be allowed to momentarily fall equally upon both elements of the differential bolometer, the circuit being so arranged that any unbalance of the Wheatstone bridge when the bolometer elements are equally excited, is compensated by means of a motor driven potentiometer in the limbs of the bridge, the bridge thereby being brought into a correctly balanced condition before the axle bearings are passing the bolometer. The radiation of the comparison radiator may be automatically adjusted to compensate for changes in temperature of the axle bearings due to the prevailing air temperature, wind velocity and solar radiation. In Fig. 9 the comparison radiator 27 and heating device 23 are connected by a rod 26 and are mounted in a heat insulating casing 28, and an external cooling vane 29 is connected by a rod 30 to the radiator 27. By suitable selection of the diameter of the rod 26 and the cooling effect of the vane 29 and rod 30, the effect of the external temperature on the axle bearings can be compensated for.. In a modification, Fig. 14 (not shown), the cooling vane is polished on the side parallel to and facing the railway track; the other side of the vane having a black coating to absorb solar radiation. The radiating element 27 may alternatively be cooled by a liquid coolant flowing through anexternal cooling coil 32, Fig. 11, and through a pipeline 31 in the element 27. In Fig. 11, the cooling coil 32 is mounted in a tube 34 parallel with the direction of travel of the train, and is associated with a conical baffle 35 so that following winds relative to the railway train will not blow through the tube 34 and head winds relative to the train will blow through the tube 34. In further modifications, Figs. 15 and 16 (not shown), a hollow body exposed to the sun and a hollow body in a shaded housing are filled with a thermal expansion liquid and are connected by capillaries with a pressure regulator which functions to adjust a valve in a liquid cooling circuit for the element 27 or to adjust a resistor in the electric heating circuit of the element 27. In another modification, the exposed and shaded hollow bodies 67, 68, Fig. 17, contain thermocouples 77, 78 connected to an instrument 79 which indicates their temperature difference by means of a pointer carrying a photo-cell 81. A pointer 80 controls the valve of a resistance 82 in the heating circuit of the heating device 23 and the output of the photocell is arranged to act on the pointer 80 causing it to follow up the pointer 81 until it covers the photo-cell which then receives no more light.