2. Engines Introduction
Introduction to Engine Design Basics:
The next section covers the most popular product in our catalogue, the “Integrated Steam
Plant” of which there is a large range - all made from MSM products. They are sized to
match boats from 800mm long to over 2300mm.
An early comment about the two engine designs is desirable at this stage:
Both MSM engine types are “double acting” in that power is generated by high pressure
steam being admitted by a valve system working on both sides of the piston so that while
one side of the piston is being driven by the steam the other side of the piston is exhausting
the spent steam from its previous power stroke. Thus there are two power inputs for each
turn of the crankshaft.
An “oscillating” engine valve system operates by the cylinder rocking sideways on a pivot to
expose one side of the piston in the cylinder to high pressure steam delivered from a port in
the engine trunk while the spent steam on the other side of the piston is exhausted through a
separate port in the trunk.
Again there are two power inputs for each turn of the crankshaft.
A “slide valve” engine has a valve system that operates in a sealed chamber supplied with
high pressure steam. The steam is admitted to the cylinder through a port into the cylinder
that, on a power input, is opened to the pressure by a “slide valve” The longitudinal movement
of the slide valve is controlled by eccentric cams fitted to the crankshaft of the engine,
connected to a “valve rod” that passes into the steam chamber through a sealed “gland”. The
slide valve has a recess cut into its side facing the cylinder so that while high pressure steam
is entering one side of the piston the slide valve covers a second port to exhaust spent steam
from the other side of the piston.
Twin cylinder engines are designed to be “self starting". This means that at any position of
the crankshaft steam is able to enter a cylinder and start the rotation. This is not necessarily
the case with single cylinder engines. If the engine comes to rest with the piston at the top or
bottom of its stroke it will require a “nudge” to the flywheel to position it where pressure on
the connecting rod is able to lever rotary action on the crankshaft and start it rotating. Once
started it will continue until the steam or gas runs out.
Thus Radio Control (RC) features are only available on twin cylinder engines.
The whole MSM engine range is suitable for static installations where the “nudge” is readily
available when needed.