- Oscillating cylinder steam engine
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This article is about small oscillating steam engines. For marine oscillating engines, see Marine oscillating steam engine.
Also known as a "Wobbler" in USA and possibly other countries.
An oscillating cylinder steam engine is a simple arrangement which does not require valves to direct steam into and out of the cylinder. Instead of valves, the entire cylinder rocks, or oscillates, such that one or more holes in the cylinder line up with holes in a fixed port face or in the pivot mounting (trunnion).
Oscillating cylinder steam engines are mainly used in toys and models but have been used in full-size working engines, mainly on ships and small stationary engines. They have the advantage of simplicity and, therefore, low manufacturing costs. They also tend to be more compact than other types of cylinder of the same size, which makes them advantageous for use in ships. In full-size engines, the steam and exhaust ports are usually built into the pivot (trunnion) mounting.
Contents
Operation
The steam needs to be fed into the end of the cylinder at just the right time in the cycle to push the piston in the correct direction. In the other direction, the steam needs to be allowed to escape into the atmosphere. As the crankshaft rotates, the piston rod moves up and down (or side to side) as well as in and out. Because the piston rod is not flexible, this causes the cylinder to rock, or "oscillate" on its special mounting. In the design usually found in a toy or model engine, a hole in the side of the cylinder (one at each end for a double-acting cylinder) and a pair of holes in the mounting block are arranged so that this rocking motion lines up the holes at the correct times, allowing steam to enter the cylinder in one direction and to escape into the atmosphere or condenser in the other direction.[1].
Reversing
Reversing of the engine can be achieved by reversing the steam connections between inlet and exhaust or by shifting the pivot point so that the hole in the cylinder lines up with a different pair of holes in the port face.
Examples
Examples of oscillating cylinder steam engines A reversible oscillating cylinder on a toy steam engineA typical small stationary oscillating cylinder engineModel of a marine oscillating steam engine designed by Joseph Maudslay, clearly showing how the cylinders pivot on the trunnions, through which the steam is passed.See also
- Elbow engine
- Carpet railway – the 'Birmingham Dribbler' toy locomotives used this type of engine
References
- ^ Roly Williams (2003-2010) Live Steam Toys - A Users Guide, published by the author
Categories:- Steam engines
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