Slam Valve Motor, supplying
efficient steam engines for homeowners and professional solar installers
power economical, one watt at a time.
Gordon mode is the full expansion mode, available in
ported and unported slam valve motor types. Gordon mode is maximum
efficiency, but still features torque control if so equipped.
Ported motors (bearing the port shown in the illustration) also feature
higher power density Thomas and Henry modes. Some feature
the regenerative braking mode Percy as well.
The motor starts out with the piston just below top dead center,
pressure inside the cylinder at exhaust pressure, piston still going up
The piston going up cracks the intake valve open. Steam flows
across the piston head and out the exhaust valve (still open)
As the piston goes up, flow increases until it slams the exhaust valve
shut. The pressure rises rapidly to the intake pressure and
the intake valve, which now has no force on it, will spring up to
the control rod
The piston begins to descend, under full intake pressure. As
it descends, it accelerates (until it reaches 90 degrees from top dead
center which is maximum velocity). Once it reaches a critical
velocity set by the control rod (generally 30 to 45 degrees from top
dead center), the vacuum caused by the gas flow under the
intake valve causes it to slam shut. From this point on, the
gas will expand and cool as the piston descends.
Before the piston reaches bottom, the gas has expanded to the exhaust
pressure. At this point the exhaust valve will spring open
and remain open until the piston reaches top again. Because
the exhaust valve is opened before the piston uncovers the port, Gordon
mode will work whether or not the cylinder in question has a port
(ported vs unported motor). The other modes require the port
and therefore are only available for ported motors.
the exhaust valve stays open as the piston rises, this motor does not
re compress steam like the uniflow. Also the torque required to
start the motor is very low, just enough to overcome friction as the
piston goes up.
Gas expelled out the exhaust has had a full expansion cycle and is
therefore cooler. The energy removed by cooling the gas has been
transferred to the piston and crankshaft, giving a higher efficiency
than a motor that does not expand the gas.