| 摘要 |
The invention contemplates improved hydraulic-pressure control apparatus which will proportionally reflect input-signal changes governing a wide range of output pressures. Use of a separate preamplifier stage, between a signal-pressure stage and a power stage, enables the signal pressure to remain essentially unaffected by load reaction or other transients at the power stage. In the forms described, an input electrical signal determines a step-function program of signal-pressure levels, and the power stage includes a relief valve which so diverts system-line flow to a sump as to assure quick and accurate response of system-line pressure to the instantaneous input electrical-signal level, all without system-pressure overshoot.
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