Profile: Solon Manufacturing Company offers engineered products for industry. We develop products such as solon relief valves with Solon Belleville Springs and Solon Industrial Controls. Solon Belleville Springs is a manufacturer of Belleville spring washers. Solon Industrial Controls Division manufactures a complete line of industrial pressure switches. This includes vacuum, differential, hydraulic, bellows actuated, diaphragm actuated, piston actuated, explosion proof, gauge indicating and temperature compensated pressure switches.