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Classification of Compound Steam Engine

Compound Steam Engine:


The Compound Steam Engines are invented in 1781, this type of technique was first employed on a Cornish beam engine in 1804. After these in 1850, compound engines were first introduced into Lancashire textile mills.


The compound steam engines may be classified a/c to the arrangement of cranks, and the angles b/w them. Two-cylinder compound engines are generally classified as :
1. Tandem type compound engines, 
2. Woolf type compound engines, and 
3. Receiver type compound engines.


1.TANDEM COMPOUND STEAM ENGINE:


The “tandem type compound engines”, in which the two cylinders (H.P. and L.P.) have common piston rod working on the same crank. These cylinders may be observed as having crank at zero degree to each other.The crucial factor is that they are parallel and driven from the same crank pin, so that they operate in phase. And the turning moment in this type of engine is not uniform due to common crank and piston rod where all the torque acts at the same time. So,this is the main disadvantage of such type of engines and it requires a large flywheel.









2.WOOLFE TYPE COMPOUND STEAM ENGINE:


Arthur Woolf was a Cornish engineer who invented something like a compound engine. He was born 1766 and died 1837. The engine combined expansion, compound and the Cornish principle in one engine.


The “Woolfe type compound engines”, in which the two cylinders (H.P. and L.P.) have different piston rods attached to the crank of the cylinder are at an angle of 180° to each other. These cranks are cast in the same crank shaft.The cylinders are arranged in a side by side manner, and exhaust steam from H.P cylinder passes directly into the L.P cylinder, the expansion is, therefore, continuous during the stroke.




3.RECEIVER TYPE COMPOUND STEAM ENGINE:


In “receiver type compound engines”, the two cylinders (H.P. and L.P.) have different piston rods attached to two different cranks set of 90° to each other . These cranks are cast in the same crank shaft.


A chamber, known as Receiver is used to collect steam from high pressure cylinder while low pressure cylinder draws steam from receiver for further expansion.It can also be run at reduced loads, with one cylinder in operation.




Note : The Woolfe type and receiver type compound engines are cross compound engines. In cross compounding, the cylinders are arranged side by side and each cylinder has separate piston, connecting rod and crank.


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