| 摘要 |
An hydraulic system for actuating a swing-post mounted backhoe boom (19) comprises two double-acting hydraulic cylinders (17, 18) operated by a control valve (35). As the backhoe boom (19) swings into a swing stop, hydraulic fluid is trapped in the head end (28) of the swing side cylinder. This trapped fluid is discharged through a cylinder relief valve (47), thus absorbing the boom kinetic energy and providing a smooth deceleration of the boom. Fluid discharged from the relief valve (47) is routed to the rod end of the swing cylinder and the head end of the opposite cylinder. Because of the swing linkage geometry, the cylinder rod (30) of the other cylinder had passed over the pivot axis (16) about which the backhoe boom (19) was swinging and thus the piston (29) of the other cylinder was caused to move in the same direction as the swing side piston (29). The movement of this piston can be utilized to provide additional deceleration torque as long as no voiding is permitted to occur in the head end of this other cylinder. Voiding only occurs when the backhoe swing control lever (38) is released prior to the backhoe boom reaching the swing stop. Voiding does not occur when the control lever (38) is maintained in a full power-on or is stroked in the power-on mode until the swing stop is contacted. Fluid from the swing side cylinder relief valve is routed to provide the necessary fluid to prevent such voiding. The routing of the fluid from the swing cylinder to the other cylinder assures that the boom deceleration is independent of whether the control lever is stroked or released. |
