| 摘要 |
<p>A power takeoff clutch (22) is engaged (and a brake (24) disengaged) by application of hydraulic pressure via a modulating valve (34) which is shifted to the right by a control lever (16). The lever moves a plunger (29) to the right and this acts on the valve piston (32) initially through a compression spring (30) and then rigidly through a rod (92). A groove (54) connects the source (52) to a conduit (62) connected to the clutch (22). In order to vent the line (62) to a sump (122) and prevent a too sudden engagement of the clutch when the lever (16) is operated rapidly, the conduit (62) is connected by a further conduit (112) to one end of a further valve (96) and to a larger second end via a flow restrictor (118). Sudden pressure rises shift the valve to the left and uncover a recess (120) venting the line (112) to the sump. As pressures equalise through the resistor (118) the differential areas of the ends of this valve ensure movement back to cover the recess (120).</p> |
