Slam Valve Motor, supplying efficient steam engines for homeowners and professional solar installers
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Slam valve motor info

The slam valve motor is a revolutionary design of steam engine. The slam valve assembly requires no connections to the crankshaft, it simply bolts on top of the cylinder. All plumbing and mechanical connections in or out are contained within the head. Slam valve heads can be made to be compatible with the pistons and cylinders from almost any compressor or engine. If a piston has a head that can be unbolted, a slam valve head can be made to bolt on in its place.

The valves are timed to produce an expansion cycle within the cylinder. This improves energy efficiency over non expansion motors like the James Watt steam engine. For example, from saturated 405 degree F steam to 160 degree F radiator, the slam valve produces 2.5 times the work from the same volume of steam as an idealized non expansion motor. This gives the example slam valve motor a thermal efficiency over 20%.

The slam valve motor has a torque control, which works like the throttle on a gasoline engine but it is not a throttle and gives constant efficiency. The slam valve head is designed for a long lifespan. Based on long lifespan compressor technology, it contains no rotating or linear bearings and requires no lubrication itself. After thousands of hours of operation, when the piston and cylinder assembly is worn out, moving the slam valve head to a new identical piston and cylinder assembly is an easy process often not even requiring re-plumbing. Solar power generators that run every day may require this kind of service every five to ten years depending on operating RPM. See the spreadsheet tool for estimated piston lifespan for any application.

Ported slam valve motors also feature a non expansion mode, which allows higher power density. Over twice the torque of a gasoline motor of the same displacement is possible. This allows high power low RPM operation which leads to longer service life.

early slam valve head
On this early motor design, torque is controlled by screws on top.
later motor
In this later motor design, the flap hinge on top controls torque.