Patent ID: 6886226

Claim:
A hand-held riveting tool driven by a battery-powered electric motor, comprising a hydraulically-actuated riveting head, and a hydraulic pump driven by the electric motor, whereby when the motor is operated it drives the hydraulic pump to actuate the riveting head, the tool including a tool-actuating device such as a trigger, and also including a reservoir for hydraulic fluid, the hydraulic supply line from the pump to the riveting head being connected to the reservoir by a reservoir inlet valve which is normally open to allow hydraulic fluid to flow from the supply line into the reservoir, in which operation of the tool-actuating device firstly closes the reservoir inlet valve, and then switches on the electric motor to operate the pump; and in which the reservoir inlet valve when closed by operation of the tool-actuating device as aforesaid also acts as a pressure-relief valve to relieve over-pressure of hydraulic fluid; and in which the reservoir inlet valve is urged closed by a first spring with a fist predetermined force and is urged open by a second spring with a second predetermined force, operation of the tool-actuating device removing the action of the second predetermined force, whereby the valve is thereafter held closed by the first predetermined force regardless of sustained operation of the tool-actuating device, thereby to provide a predetermined pressure at which the valve acts as a pressure relief valve as aforesaid.