Abstract: An automatic air valve assembly for alternately delivering pressurized air to one of a pair of control ports of a reciprocal power unit comprises a valve body having a bore, a plurality of inlet, cylinder, and exhaust ports, with the inlet port adapted for connection to a pressurized air supply, and a valve spool movable between a pair of control positions. A pair of pilot valves are mounted upon the ends of the valve body to move the spool between its control positions. Each pilot valve is connected to a cylinder port and has a normally closed air signal port connected to opposite ends of the valve body respectively whereby a build up of pressure at one cylinder port momentarily moves a spring biased spool in one pilot valve to open its signal port, the spool in the valve body continuously and automatically oscillating.

Abstract: In combination with a double-acting cylinder having pressure and exhaust ports, a cylinder control valve having a spool having a pair of control positions with pressure, cylinder and exhaust ports, and conduits between the valve cylinder ports and cylinder ports, and a source of compressed air connected to the valve pressure port, a safety control system which comprises a pilot-operated valve housing having a pressure port connected to the source of compressed air, a pilot port and a pair of cylinder ports connected to the cylinder conduits. A valve spool within said housing has first and second control positions with an operative device on the housing which normally biases the safety valve spool to a first control position pressurizing opposite ends of the cylinder and with the pilot port connected to the source of compressed air. A build up of pressure to the pilot port moves the safety valve spool to its second control position, blocking communication between the safety valve and the cylinder ports.