Pneumatically controlled hydromechanical railway car stabilizing apparatus

A control system for a stabilising apparatus for a rail vehicle body which is provided with jacks for controlling the tilt of the body with respect to a bogey, comprising the combination of an angular accelerometer which is responsive to the angular velocity of the body about the longitudinal axis thereof and which comprises a balanced mass, a lateral accelerometer, first and second hydromechanical servo-mechanisms having input members driven by said angular and lateral accelerometers respectively and output members, a control valve for selectively applying a fluid pressure to said tilting jacks, means coupling the output members of said servomechanisms to a movable part of said control valve and arranged so that, in use, lateral acceleration sensed by the lateral accelerometer causes the movable part of the control valve to be moved in one direction to cause angular movement to be applied to the body by the tilting jacks, such angular movement being sensed by the angular accelerometer to cause movement of the movable part of the control valve in the opposite direction, said servo-mechanism comprising a second pilot valve operable by said lateral accelerometer to provide further servo control signals, and a second actuator responsive to said further servo control signals to move the output member of said second servo-mechanism, said first pilot valve also being responsive to movement of said second servo-mechanism output member to vary said control signals so as to oppose the latter movement.