Patent Page: Make-and-Break, Take 2

Learn about the Tremper’s igniter scheme’s move away from a spring-loaded rod in the piston to a more stationary sparking strip.

| December/January 2020

Tremper’s second igniter patent, granted just four months after his first, dispensed with the spring-loaded contact in the piston crown and instead incorporated a “flexible sparking strip,” which could be designed any number of ways, giving far more flexibility to design.

Last issue, we looked at San Francisco, California, engine pioneer Frank E. Tremper’s 1893 patent for a “make-and-break” ignition system. A key feature of Tremper’s patent no. 495,281 was a spring-loaded contact set into the crown of the piston.

Patent no. 503,016, granted just four months later on Aug. 8, 1893, was a further development of Tremper’s igniter scheme, but it dispensed with the spring-loaded rod in the piston. Instead, a bolt was firmly set protruding from the crown of the piston, and a “flexible sparking strip” was attached to the bolt. The strip, which could be configured in any number of ways, made contact with fixed electrodes protruding into the combustion chamber at whatever position in the cylinder deemed desirable.

This design appears inherently simpler than Tremper’s first patent, and is similar to other early piston-tripped igniter designs. It’s not clear which design was actually more effective, but the existence of the later design suggests there may have been problems with Tremper’s original scheme.

Rotary Valve

Incorporated in Tremper’s original patent and not discussed last issue was Tremper’s design for a rotary valve, the most visually intriguing feature of the early Safety Vapor engines.

Tremper’s design for a rotary valve was integrated into his original patent. “Fig. 3” shows the ports in the cylinder, with “P” and “P4” representing the disc valve and valve port, respectively. “Fig. 4” shows the ports in the valve body. The valve could also be head-mounted, chain driven through bevel gears, as shown in “Fig. 5.”


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