| 摘要 |
A hydraulically powered treelength log sawing apparatus has a log support lined with teeth opposing the outwardly-directed sawing force generated by its driveshaft-pivoted chainsaw. The chainsaw is driven by a hydraulic motor whose fluid exhaust flows through a conduit to an adjustable restriction which creates a backpressure in the fluid in the conduit. The magnitude of the backpressure is directly related to the speed of the motor and the saw, and the backpressure is directed to a hydraulic cylinder which forces the chainsaw into sawing engagement with logs on the support, thereby prevent stalling of the saw and in general causing the saw speed and engagement force respectively to be self-compensating and requiring no attention from the operator during sawing. An arrangement of automatic valves and bypass conduits removes the power from the motor and reverses the hydraulic cylinder to disengage the saw from the logs upon simple reversal of the inlet and outlet or exhaust connections between the motor and cylinder and the hydraulic power supply, as by shifting a four-way valve which passes the pressurized and exhaust fluid flows to the apparatus.
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