TRIPLE VALVE SPRINGS A HISTORY

I first believed that TRIPLE valve springs were first used during the Second World War in aircraft engines. I was told that valve springs were not very reliable and failed from breakage. This caused a valve to fall into the cylinder of a radial aircraft engine thus causing total engine failure! Therefore 3 springs were used in case one of the 3 springs broke. The load of the other 2 springs had enough tension to keep the valve from falling in the cylinder and causing an engine failure.

I now know I was wrong as to the date first used by at least 21 years.

Copies of blueprints from Miller Engine & Foundry Works dated October 7, 1924 show OUTER-MIDDLE-INNER VALVE SPRINGS!

The prints mention the 122 CID engine. Interestingly only the VALVE
OPEN PRESSURE is mentioned. Total loads open were specified as 110
to 135 pounds of pressure.

The outer spring was made from .135" O.D. wire with 6 FULL coils and
1.078" I.D.

The MIDDLE spring was made from .105" O.D. wire with 6 FULL coils and .750" I.D.

The INNER spring was made from .072" O.D. wire with 7 FULL coils and .660" O.D.

All three springs were counter wound to each other. These sizes are
not an interference fit to each other.
 

My first use of TRIPLE VALVE SPRINGS was in 1974, as listed on page 51 of "The Winners Handbook", resulted in a Trademark being issued later. The new three piece valve spring designs were not patentable! A few years later most other cam manufacturers were offering 3 PIECE SPRINGS. Now everybody sells them.

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