| 摘要 |
<p>A variable displacement pump has a swashplate controlled by a pair of pistons. A shuttle valve communicates the highest pressure pump workport to an operator-controlled displacement control valve. A pressure-responsive override valve is connected in series between the displacement control valve and the pistons. When an override pressure is achieved, the override valve blocks communication of the control valve with the pair of pistons and communicates the pump workports directly to the pistons for rapid destroking. A neutral bypass valve is formed out of a sleeve of the displacement control valve to bypass control pressure to sump when the displacement control valve is in neutral. A pressure-reducing valve limits the pressure acting on the stroke control valve to limit response rates and reduce erosion. The override valve includes orifices which, in intermediate positions, provide flow rate control of the fluid flow to the swashplate control pistons.</p> |
