Abstract: A hydraulic intensifier having a hydraulic motor driven from a low pressure source and operable to drive a low pressure pump for sucking oil from a reservoir and for delivering the oil as charge oil to a high pressure pump. The latter also is driven by the hydraulic motor and pressurizes the charge oil so as to deliver oil at high pressure to a hydraulic actuator. The intensifier is of a self-contained and modular construction and includes a case which defines the oil reservoir and which is closed by detachable end caps permitting the motor and the low pressure pump to be pulled out of one end of the case and permitting the high pressure pump to be pulled out of the other end of the case.