Classification of Steam Engines According to Parts

A steam engine is an external combustion heat engine which makes use of the thermal energy that exists in steam, converting it to Mechanical Energy.

1. According to the number of working strokes:

(a) Single acting steam engine, and 

(b) Double acting steam engine.

When steam is admitted on one side of the position, and one working stork is produced during each revolution of the crankshaft, it is said to be “a single acting steam engine”. But when the steam is admitted, in turn, on both sides of the piston and two working strokes are produced during each revolution of the crankshaft, it is said to be “a double acting steam engine”. A double acting steam engine produces double the power than that produced by a acting steam engine.

2. According to the position of the cylinder:

(a) Horizontal steam engine, and 

(b) vertical steam engine.

When the axis of the cylinder is horizontal, it is said to be a “horizontal steam engine”. But when axis of the cylinder is vertical, it is called”vertical steam engine. A vertical steam engine requires less floor area than the horizontal steam engine.

3. According to the speed of the crankshafts:

(a) Slow speed steam engine

 (b) Medium speed steam engine, and 

(c) High speed steam engine.

When the speed of the crankshafts is less than 100 revolutions per minute(r.p.m.), It is called “a slow speed steam engine”. When the speed of the crankshafts is b/w 100 r.p.m. and 250 r.p.m., it is called “a medium speed steam engine”. When the speed of the crankshafts is above 250 r.p.m., it is known as “a high speed steam engine”.

4. According to the type of exhaust:

(a) Condensing steam engine, and 

(b) Non-condensing steam engine.

When steam after doing work in the cylinder passes into a condenses the steam into water at a pressure less than the atmospheric pressure, it is said to be “a condensing steam engine”. But when the steam after doing work in the cylinder is exhausted into atmosphere, it is said to be “a non condensing steam engine”. The steam pressure in the cylinder is, therefore, not allowed to fall below the atmospheric pressure.

5. According to the expansion of the steam in the engine cylinder:

(a) Simple steam engine, and 

(b) Compound steam engine.

When expansion the steam is carried out in a single cylinder and then exhausted into the atmosphere or condenser, it is said to be “a single steam engine”. But when the expansion of the steam is completed in two or more cylinders, the engine is called “a compound steam engine”. The compound steam engines are generally condensing engines. But some of them may be non-condensing as well.

6. According the method of governing employed:

(a) Throttling steam engine, and 

(b) Automatic cut off steam engine.

When the engine speed is controlled by means of a throttle valve in the steam pipe, which regulates the pressure of steam to the engine, it is called “a throttling steam engine”. But when the speed is controlled by controlling the steam pressure with an automatic cut-off governor, it is called an “automatic cut-off steam engine”.