In hydraulic machines of the disc valve type, oil is communicated between inlet/outlet and the gear set through a valve element. This valve element adds an internal resistance against fluid flow, and thus an internal pressure drop.
It is therefore a principal object of this invention to provide a hydraulic motor with disc valve commutating slots complimentary in shape to port plate ports so as to reduce the magnitude of this pressure drop.
A further object of this invention is to provide a hydraulic machine of the disc valve type, where the geometry of the commutating part of the disc valve, in opening and in closing moment, fits with the geometry of the ports of the port plate.
These and other objects will be apparent to those skilled in the art.
A hydraulic motor of the disc valve type has a disc valve with a plurality of commutation slots that can sequentially register with ports in a port plate as the disc valve is rotated with respect to the port plate. The commutation slots have a geometrical configuration that is complimentary in shape to a portion of the geometric configuration of the ports in the port plate to reduce the resistance to fluid flow through the ports and the slots when the complimentary shapes move into or from superimposed registering positions at opening and closing moments of the ports.