Pull type installation tool

Abstract

An improved pneumatic-hydraulic actuated single action pull type installation tool for installing pull type fasteners is disclosed which includes a continuously pressurized fluid reservoir operative to maintain a minimum positive pressure on the hydraulic circuit during operation so as to protect the integrity of the hydraulic circuit during normal operating pressure fluctuations and to reduce the possibility of air being drawn into the hydraulic system during sudden pressure drops in the actuating pressure chamber which may occur at the time the pintail portion is separated from the fastener. Further, the reservoir provides a source of make up hydraulic fluid to replace any fluid which may be lost due to leakage. Suitable valves are provided to enable the reservoir to selectively communicate with both driving and return portions of the hydraulic circuit while still enabling selective pressurization thereof. Apparatus is also provided for enabling convenient and efficient refilling of the reservoir and to depressurize the reservoir such as for service. A high pressure relief valve is also provided in the circuit which is operative to vent the hydraulic system to atmosphere in the event of abnormal pressure build up.