GB1305272A - - Google Patents

Abstract

1305272 Fluid-pressure servomotor systems M BEHR [trading as SUDDEUTSCHE KUHLERFABRIK JULIUS FR BEHR] 23 Feb 1970 [22 Feb 1969] 8486/70 Heading G3P The temperatures of a main coolant circuit 50 and a subsidiary coolant 49 in particular on a rail vehicle are regulated respectively by fan 5 and louvres 48 and fan 6 and louvres 47 which fans and louvres are controlled by a common hydraulic circuit having a pump 2 and a valve 8 regulating pressure supplied to fan motors 3, 4 and the piston-cylinders 12,13,10,11 for the louvres in accordance with the position of temperature responsive valves 43,52,53. The flow from port 33 of valve 8 determines the pressure differential across restriction 35 of spring-loaded valve member 37 and thus the position of the latter which controls the amount of flow from pressure line 15 back to reservoir 1 via line 21. Relief valve 36 loaded by spring 40 and the back pressure in line 21 controls the pressure at port 33 which may be adjusted by screwing crown 42 relative to the piston 39. Valve 43 is responsive to the coolant temperature of the subsidiary circuit and regulates the pressure fed to piston-cylinders 10, 11 and the flow back to the reservoir and also the flow to the fan motors. Even when the valve 43 is fully closed some flow takes place through restriction 51 and motors 3, 4 will only operate at 85% full speed. Valve 53 is responsive to the coolant temperature of the main circuit and in addition to controlling motors 3,4 and pistoncylinders 10,11 controls the pressure fed via line 28 to the piston-cylinders 12,13. Valve 52 is also responsive to the coolant temperature of the subsidiary circuit but will only close in response to a rise in temperature well above the normal operating range and caused by the heat exchange between an operated hydro-dynamic brake and the subsidiary circuit. Heat is dissipated sufficiently rapidly for excessive cooling of the main circuit not to take place.