Abstract: An assembly of plate members for forming a commutator valve for hydraulic devices of the expanding-contracting pocket type, such as hydraulic motors. The assembly includes a first end plate, a second end plate and a plurality of intermediate plates therebetween. The first end plate includes first and second arrays of fluid passageways for communicating with expanding and contracting fluid pockets, respectively, during operation of the motor. The intermediate plates may be assembled together in either a first or a second alignment depending upon the desired direction of rotation of the hydraulic motor. The intermediate plates are designed such that in the first alignment they direct high pressure fluid from a high pressure port to the first array of passageways and low pressure fluid from the second array of passageways to a low pressure port. The output shaft of the hydraulic motor thus rotates in one direction.