A hub clutch device for connecting and disconnecting an axle and a wheel in a part time four-wheel drive vehicle is disclosed closed. The hub clutch device is provided with an outer race secured to a vehicle body, an inner race having a flange portion secured to the wheel and a hub portion provided with a gear portion at a peripheral inner portion, defining a fluid passage with the axle, and a roller member positioned between the outer race and the inner race. A movable wall is positioned inside of the hub portion. The movable wall defines a sealed chamber with the hub portion and is movable in an axial direction of the axle. The sealed chamber communicates with the fluid passage. A sliding gear always engages the gear portion of the hub portion and is axially movable according to the motion of the movable wall to engage a gear part of the axle to connect the axle with the wheel in a rotational direction. An air pump is provided for producing pressure to move the movable wall in an axial direction by transmitting the pressure through the fluid passage and the sealed chamber.
