PO Box 19, Coolspring, Pennsylvania 15730
We found a story in the Rough & Tumble Engineers’
newsletter about a very rare engine that had been on display there
last summer, courtesy of the Coolspring Power Museum. So, we wrote
to Preston Foster at the museum who was kind enough to reply with
the following explanation and photos.
The Harvard engine in the Coolspring Power Museum came from the
collection of the late Neils A. ‘Andy’ Kruse of Park Ridge,
Illinois. Andy died November 28, 1986. He had a very extensive
collection of engines numbering about 225.
Andy had been an early supporter of the Coolspring Power Museum,
and his wife Ruth and son Nelson thought it fitting that the engine
should go to CPM for permanent display. This engine came to CPM in
1987. Though the engine was restored and was in sound mechanical
condition, it never ran as designed.
Dr. John Wilcox, a director at CPM, has long had an interest in
seeing how the engine did govern. In 1995 the engine was hauled to
his home in Delaware, Ohio, and he did a very complete rebuild of
the engine. With some machining help from fellow director, Preston
Foster, John returned this engine to factory design running
specifications. This engine now runs as it did when it left the
factory and even possibly better.
Total credit for this very time consuming project goes to
John.
The following is a drawing that explains how the engine governs
and shows a section of its construction:
Stickney Junior 3 HP
Charles A. Stickney Company, St. Paul, Minnesota.
Design circa 1900. Sold by Sears, Roebuck as ‘Harvard’
19024903.
Stickney Vacuum Governing System: Under power,
governing valve is open. To initiate an idle cycle, governing valve
is pressed shut for a short time at beginning of intake stroke,
resulting in these events:
1) Intake Stroke. Main valve open.
Increasing vacuum bounded by governing valve and exhaust check.
Vacuum holds governing valve shut against its spring.
2) Compression Stroke. Main valve shut.
Decreasing vacuum in cylinder. Maximum vacuum is maintained between
main valve, governing valve, and exhaust check. This vacuum holds
governing valve shut.
3) Power Stroke. Main valve shut.
Increasing vacuum in cylinder.
4) Exhaust Stroke. Main valve open.
Decreasing vacuum everywhere. Governing valve pops open near end of
stroke, unless pressed shut to initiate another idle cycle.
The Stickney Junior is the only engine known to govern on this
principle.