초록 ▼

Backhoe swing apparatus including a backhoe swing bracket for supporting a backhoe for side-to-side swinging movement. A pair of hydraulic actuators are connected with the swing bracket for actuating the swing bracket in opposite directions. The hydraulic actuators are of the piston and cylinder typ

Backhoe swing apparatus including a backhoe swing bracket for supporting a backhoe for side-to-side swinging movement. A pair of hydraulic actuators are connected with the swing bracket for actuating the swing bracket in opposite directions. The hydraulic actuators are of the piston and cylinder type, and are controlled by a hydraulic system including a pair of hydraulic lines for conducting hydraulic fluid to and from each of the hydraulic actuators. A normally open pressure reducing valve in one of the hydraulic lines is operable to control pressure to one of the actuators to actuate the swing bracket in one direction and to thereby limit the pressure of fluid flowing to the actuator. Simultaneously, flow from the other actuator through the other hydraulic line is controlled by a first normally closed metering valve, which opens a permit such flow only when a predetermined minimum pressure exists in the other hydraulic line. A second normally closed metering valve controls flow of hydraulic fluid from the first hydraulic actuator when the swing bracket swings in the opposite direction, and permits such flow only when a predetermined minimum pressure exists in the other line.

대표청구항 ▼

A hydraulic system for operating backhoe swing apparatus and the like comprising: a pair of hydraulic lines; a normally open pressure reducing valve controlling one of said hydraulic lines and operable to limit pressure in said one hydraulic line to a predetermined maximum pressure, a first normally

A hydraulic system for operating backhoe swing apparatus and the like comprising: a pair of hydraulic lines; a normally open pressure reducing valve controlling one of said hydraulic lines and operable to limit pressure in said one hydraulic line to a predetermined maximum pressure, a first normally closed, metering valve controlling said other hydraulic line and operable to permit flow of hydraulic fluid through said other hydraulic line only when a predetermined minimum pressure exists in said one hydraulic line in response to said flow in said one direction through said one hydraulic line, a second normally closed, metering valve operable to control flow of hydraulic fluid in the opposite direction through said one hydraulic line only when a predetermined minimum pressure exists in said other hydraulic line; and check valve means for preventing flow through said pressure reducing valve in said opposite direction.