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Model Engineering Glossary: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Steam Engine Design

I′m often asked where a plan for one of my engines can be purchased and have to reply that I do not have plans, at most I have a few scribbled notes and some rough dimensions. It takes me some time to get a starting point and this can arrive in a number of different ways: a part eg a nice flywheel casting, an idea to mix materials eg wood and metal beam engine, an engine that I find desirable eg the 5 cylinder rotary.

So lets start with something simple, a single acting beam engine.

Let′s throw in some rough dimensions:

  • cylinder bore = 1/2"
  • stroke = 1"
  • flywheel diameter = 3"

Already you can see this is going to be quite compact.

As you can see in this simple sketch I have made the distance between beam pivot and crank bearing 2" and the same distance from the beam pivot to the conrod big end bearing.

A stroke of 1" means the crank needs to be designed with a distance of 1/2" between centres of the main crank and the centre of the big-end. This also means the beam will move 1/2" up and 1/2" down, this will then allow the clearance of the conrod and cylinder wall to be checked.

The dimensions and angles look quite reasonable. For the valve I do like a simple piston valve. As stated earlier this is for a simple single acting single cylinder engine.

With the piston valve in this position the cylinder is connected to the steam in port.

At this position the cylinder is closed to both steam and exhaust.

The cylinder is connected to the exhaust port.

Beam Engine - Wood and Metal - a beam engine built from metal and wood, the idea being to build an elegant pretty engine - well hopefully - this may be very hopeful as I'm starting the wrong way round...

See also: Engines, Model Engineering Gallery, Steam Engine Kits.

Model Engineering Glossary: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z