Rotary hydraulic machines

Claim 1

A rotary hydraulic machine comprising a casing, a pintle within the casing, a rotor mounted on the pintle, first and second axially spaced rows of radial bores in the rotor, a plurality of pistons slidable in the radial bores constituting a motor and a pump respectively, a pair of cam rings surrounding the rotor within the casing and disposed eccentrically of the rotor, said rings having inside surfaces engaged by the pistons in the respective rows and the arrangement being such that, in use, the pistons in the first row constituting the motor have a larger displacement per revolution of the rotor than The pistons in the second row constituting the pump, two pairs of opposed ports in the pintle, the bores in the respective row successively communicating, in use, with the ports of a respective pair, an inlet for the machine communicating with one of the ports of a first pair thereof which communicates with the bores of said first row, a first outlet for the machine communicating with one of the ports of a second pair thereof which communicates with the bores of said second row, a passage connecting the other port of each pair, a spring loaded relief valve for said passage communicating on its downstream side with the casing interior and a second outlet communicating with the casing interior and through which is discharged, in use, fluid which is not discharged through the first outlet via the pistons in the second row.