To provide a wheel motor device capable of preventing the difference of an oil pressure from occurring between a pair of first and second operation oil lines when a vehicle is forcedly tracted and reducing power loss at forced traction of the vehicle as much as possible.
On a casing provided with a first kidney port opened to a motor slide contact surface slide-contacted with a hydraulic motor body, a second kidney port opened to the motor slide contact surface at an opposite side to the first kidney port while clamping a motor shaft, a first operation oil passage fluid-connected to the first kidney port and a second operation oil passage fluid-connected to the second kidney port, a by-pass oil passage for communicating the first and second operation oil passage and a by-pass valve selectively communicating or shutting off the by-pass oil passage and operable at an outside are further provided.
SASAHARA KENGO
Minoru Ohnaka
Nobuo Ouchi
Satoshi Takada