The various parts are briefly described below:
Frame: It is a heavy casting made of cast iron and supports cross-head guides and main bearing. It generally rests on the engine foundation.
Cylinder: It is also a casting to the frame in which the piston reciprocates.
Its both ends are closed and made steam tight. The stuffing box is fixed in one end through which piston rod reciprocates.
Steam chest: It is compartment in a steam engine through which steam is delivered from the boiler to a cylinder. It is connected to the cylinder through the valve passage known as ports. It contains the D-slide valve. The steam is supplied alternately to the cylinder through the ports and exhausted to the condenser. The same port serves as inlet port and exhaust port in double acting engines.
D-slide valve: It connects the cylinder to the steam chest and to the exhaust side through the ports at the correct crank positions. The valve is operated by an eccentric.
Piston: It is made of cast iron. The steam pressure exerts force on it on both sides to reciprocate the piston rod. Piston rings are provided on the piston for steam tightness.
Piston Rod: One end of piston rod is connected to the piston and the other end to the cross-head. It transmits the force from the piston to the cross-head.
Stuffing Box and Gland: It is placed at the point where the piston rod passes through the cylinder cover. It prevents the leakage of steam from the cylinder to atmosphere, at the same time allowing the piston rod to reciprocate freely.
Cross-Head: It connects the piston rod and connecting rod. It guides the piston rod along a straight line. The thrust on the cross-head is taken of by the cross-head guides.
Connecting Rod: One end of it is connected to the cross-head by a gudgeon pin and the other end is connected to the crank. It transmits force from the cross-head to the crank.It has oscillatory motion.
Crankshaft: The crank converts the reciprocating motion to rotary motion of the crankshaft.The crank shaft is supported on main bearings and carries the flywheel and eccentric
Eccentric: It converts rotary motion of crankshaft into reciprocating motion of D slide valve.
Valve rod and Eccentric rod: They connect the eccentric to D-slide valve.
Flywheel: It is connected to the crankshaft and helps to maintain a constant angular speed of the engine by storing excess energy during idle stroke of the device being operated.
Governor: It helps in maintaining uniform speed of the engine by regulating supply of stream to the cylinder.
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