Historical information
This model was found in the collection of Bay Steamers Maritime Museum. It is not knowt who created it but it is supposed that it was constructed to educate the many masters of the Wattle in the operation of a steam engine - a not so common mode of power these days.
A Bay Steamers Maritime Museum examined the model in March 2012 and discovered that is was in poor repair. Using his existing knowledge, and with reference to some historic texts, he made some repairs and returned the model to working order.
Here is his anaylsis of the situation as an excerpt from the Bay Steamers Maritime Museum newsletter Steamlines May 2012
"I was confronted with a model of a steam
engine used years ago as a training aid for hopeful steam engineers. Already having a knowledge of steam operations, I considered a museum write-up for that model a ‘piece of cake’. However, on turning the model’s crankshaft, the valve timing seemed ‘out of kilter’ with the movement of the piston. Problem was that the two eccentrics on the crankshaft were not properly secured to it. Eventually I fastened the two eccentrics to the crankshaft where I felt that they should be and then
realized that one of them had a chain-driven valve-timing device attached. This would be adjusted while an engine was running to achieve best performance and fuel economy whilst in operation by accurately controlling the period of time during which steam under pressure from the boiler would be admitted to the cylinder and give greater time for the steam to expand in the cylinder, move the piston and turn the crankshaft and thus, drive the attached apparatus.
When the valves were correctly set up it was then possible to get the model to function properly.
Physical description
The model comprises a green section, which is the actual the model mounted on a brown painted board. There are two parts of the model, painted white representing the steam passages, and black representing the cast- iron portions of the cylinder-block casting, and of the main valve sliding between the cylinder a second sliding valve. Of the black portions, one slides back and forth being connected to a rod which is connected to an eccentric clamped to the crankshaft and is the nearer to the flywheel of two eccentrics. This eccentric is attached to the crankshaft at an angle of 90 degrees to the crank-pin attached to the flywheel.
To operate the model simply turn the flywheel by means of the handle attached to its crank-pin.
A second eccentric is also attached to the crankshaft, further away from the first eccentric, and it is adjusted to operate 90 degrees from the first eccentric (that is, 180 degrees from the crank-pin)
A piston (painted silver) is located in a plastic cylinder and has a piston rod which passes through one end of the cylinder, (in actual practice a steam-proof gland seals the cylinder against loss of steam) terminating in a cross-head slide between four rails guiding it. From this cross-head, a connecting rod joins the piston-rod to the flywheel via the crank-pin attached to the flywheel which is part of the crankshaft. (In actual practice, a flywheel may not be used, particularly in a multi-cylinder engine.)
The white portions of the model painted nearest to the cylinder represent the two steam ports cast into the main cylinder block, whilst one section painted in between those two represents the exhaust outlet (which may be connected to a condenser to conserve water, or to the open air).
The main slide valve has three white-painted portions painted thereon. It has two white-painted marks representing the steam passages to the steam ports into the cylinder, and a third section in between the other two, being that part of the valve through which exhaust steam passes in line with the ports in the cylinder block.
By rotating the flywheel, the operations of an engine will be observed as steam is admitted to the main valve via the gap between the two jaws of two moveable portions of a second sliding valve which is operated by the second eccentric attached to the crank-shaft. This eccentric is used to finely tune the valve timing of this model to obtain best running results of an engine.
There are various methods used for reversing a steam engine.
