A hydraulic pump/motor includes a rotational shaft rotatably attached inside a casing, a cylinder block configured to rotate together with the rotational shaft, a plurality of pistons, a swash plate, a valve plate, and a rotation detection mechanism. The rotation detection mechanism includes a detection target section having three or more recesses formed on an outer peripheral surface of the cylinder block in a unique arrangement pattern with different arc lengths between the three continuous recesses with respect to one rotational direction of the rotational shaft and being formed so as not to include the unique arrangement pattern with respect to the other rotational direction of the rotational shaft, each of the three or more recesses having a cross section having a same semicircular shape perpendicular to a direction of the rotational shaft; and a rotation sensor arranged in the casing in a state of facing the detection target section.

A hydraulic motor apparatus includes a motor housing engaged to an end cap having a first porting system and an adapter connected to an external surface of the end cap and having a second porting system. A filter may be attached to the adapter and connected to the second porting system and a pressure reducing valve in the adapter is connected to the second porting system. The assembly may also include a controller operatively connected to the pressure reducing valve and system sensors measuring parameters affected by the output of the hydraulic motor apparatus, whereby the pressure reducing valve is operatively controlled by the controller in response to input from the system sensors.

A hydraulic motor apparatus includes a motor housing engaged to an end cap having a first porting system and an adapter connected to an external surface of the end cap and having a second porting system. A filter may be attached to the adapter and connected to the second porting system and a pressure reducing valve in the adapter is connected to the second porting system. The assembly may also include a controller operatively connected to the pressure reducing valve and system sensors measuring parameters affected by the output of the hydraulic motor apparatus, whereby the pressure reducing valve is operatively controlled by the controller in response to input from the system sensors.