US Patent 11181194 Fluid pressure drive device

A fluid pressure drive device includes a flushing circuit configured to discharge a working fluid from one of the pair of main passages to a tank. The flushing circuit has a low pressure selection valve provided between the pair of main passages and configured to be switched by a pressure difference between the pair of main passages, the low pressure selection valve being configured to select the main passage on the low pressure side; and a flushing passage configured to lead the working fluid passing through the low pressure selection valve to the tank. The flushing passage has a first orifice and a bent portion formed on the downstream side of the first orifice.