A hydraulic device

Hydraulic device such as a motor or a pump comprising a first set of parts (1C) including a housing part and a second set of parts (1D) attached to said first assembly. Said sets each have a first and a second contact face (1C ', 1D') which are biased towards one another and arranged in mutual contact by means (15) exerting an axial stress. At least one of first and second contact faces has a rough friction surface. With this, a high torque can be transmitted between the two sets.