Anyone know how it worked ? What's a "6 stroke" when it's at home?
Talking of at home, is anyone hereabouts looking after one ? There's
supposed to be one in Bath, ex- Brum Museum of Transport, but no-one
seems to know where it has got to. Best lead I've had is that a local
engine collector is looking after it.
J W French on the subject:
"The Griffin System: In engines of this cycle there are two explosions
every three strokes, but since the Griffin engine is double-acting,
one impulse is given to the piston every revolution and a half.
The successive stages are:
(1) Aspiration of the gas and air mixture.
(2) Compression.
(3) Ignition, expansion, driving stroke.
(4) Exhaust of the burnt gases.
(5) Admission of air blast to complete the expulsion of the burnt gases.
(6) Exhaust.
Admission and ignition are controlled by a slide valve, and the speed
is regulated within small limits by means of a governor, which acts on
the gas admission valve placed on the top of the cylinder. As the speed
varies the governor suitably advances a triangular wedge, which holds
the valve open for a longer or shorter period. Two valves worked by two
cams at periods of 1-1/2 revolution serve alternatively for the exhaust
from the two sides of the piston.
From official tests of a 12 h.p. engine, the consumption is stated to be
about 28 cu. ft. of gas per horse-power hour, and for regularity of
working the engine was placed in the first class. Considering the six-
-stage system of working, this result is worthy of notice."
Lyle Cummins:
".......Samuel Griffin's reasonably successful double-acting engine made
at Kilmarnock, Scotland, by Dick, Kerr and Co. By having a combustion
chamber on each end of the piston a power impulse was delivered every
one and a half revolutions. The "Griffin" was sometimes referred to as
a "three-cycle" engine. An opposed, single-acting piston version was
also brought out by Dick, Kerr. It had separate cylinders like the Beck,
each making one power stroke out of the six. This engine was thought of
highly enough to be included in the Society of Arts trials with the
Atkinson and Crossley engines. Its performance in gas consumption came
out slightly below the other two."
Tom
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