| 摘要 |
A fluid transmission circuit in which three or more pumps, adapted to be driven in unison by a prime mover operating at constant power output, draw fluid from a reservoir and deliver it to a reversible fluid motor via a control valve incorporating forward, neutral and reverse positions, the motor being driven, when the circuit is in use, against a fluctuating resistive force. The fluid outputs of two or more of said pumps are controlled by the output of a diverting valve whose input is connected by a separate pressure-sensing line to the fluid flow through the motor and which is initially biassed into a position in which each of said fluid outputs from said pumps is delivered to the motor. The arrangement is such that, as the demands on the motor increase and the pressure of fluid passing through the motor rises through a succession of predetermined levels, the pressure-sensing line will sense the rises in pressure and, at each successive pressure level, will cause the diverting valve automatically to divert the fluid outputs of successive ones of said pumps back to the reservoir without passing through the motor, the pump outputs being automatically switched into the motor supply line again, one after the other and in the reverse order from that in which they were switched out, by the diverting valve as the demand on the motor subsequently falls. |
