GB1270058A - Improvements in or relating to rail grinders - Google Patents

Abstract

1,270,058. Grinding rails in situ. FRANK SPENO RAILROAD BALLAST CLEANING CO. Inc. 23 July, 1970 [30 July, 1969], No. 35692/70. Heading B3D. A rail grinder comprises a vehicle V guided for movement along a rail R, a grinding head G having a drive motor 22 and grinding wheel 26, fluid pressure means 28 for supporting a portion only of the weight of the head, the balance of the weight constituting the operating pressure of the wheel against the rail, the fluid pressure means having an expansible chamber, the volume of which varies with variations in the operating level of the head, and a pressure control unit 56 communicating with the chamber for automatically varying the pressure of fluid in the chamber as the head deviates from a predetermined operating level. The grinding head is carried by a cradle 20 supported for angular adjustment on trunnions 18 carried by slides 14 adjustable on cross-beams 12 of the vehicle. Rods 30 of fixed pistons are secured to the cradle, the pistons being disposed in the cylinders 27 of the fluid pressure means. The chambers of the cylinders are joined by a pipe 42 to the control unit 56 and an isolating valve 78 connected to a tank 46 containing a reservoir of liquid 46 pressurized by a cushion of gas or air 48 by a regulator 52 and source 54. The control unit contains two differential pistons 62, 64 at their lower ends connected by a passage 74, 76 to the pipe 42 and at their upper ends by a passage 70, 72 to the regulator. Piston 62 has its larger end uppermost and normally engages an abutment shoulder 66 and piston 64 has its larger end lowermost and normally engages an abutment shoulder 68. In operation, valve 78 is opened and the regulator adjusted so that the pressure in the cylinders 27 supports a predetermined portion of the weight of the grinding head so that the wheel 26 engages the rail at a predetermined pressure. The valve 78 is then closed. If, on movement of the vehicle, the grinding wheel passes a depressed portion of the rail, the lowering of the head displaces liquid from the cylinders 27 and causes movement of the differential piston 62; although the pressure above piston 62 remains constant, the increased pressure below the piston acts in the cylinders 27 to reduce the grinding pressure. If, however, the grinding wheel passes over a raised portion of the rail increasing the volume in the cylinders will draw liquid from below the piston 64 which will move downwardly because of the lower pressure and such lower pressure allows more of the weight of the head to act to increase the grinding pressure.