| 摘要 |
A leveling system for supporting a drill assembly includes at least one hydraulic actuator and a manifold coupled to the actuator. The hydraulic actuator supports the cab relative to a support surface, and includes a first end coupled to the cab and a second end that is extendable away from the first end. The manifold is coupled to the actuator and includes a directional flow control valve, a regenerative flow valve, and at least one counterbalance valve for controlling the extension of the actuator. The counterbalance valve is in direct fluid communication with the actuator.
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