Bristol Hercules sleeve valve engine
Year:
Manufacturer:
Number Produced:
Specifications:
Description:
Additional information (and noted photos) kindly provided by John Skene
The Sleeve Valve ‘Hercules’ engine
These smooth-running engines were largely hand-built, which was incompatible with the needs of wartime production. At that time, the tolerances were simply not sufficiently accurate to ensure the mass production of reliable engines.
Mr Roy Fedden, the designer’ drove his teams mercilessly, at both Bristol and its suppliers and thousands of combinations of alloys and methods were tried before a process was discovered which used centrifugal casting to make the sleeves perfectly round.
This final success arrived just before the start of the Second World War. This engine went on to produce some 1300 reliable horsepower.