Effect of Partial Balancing of Reciprocating Parts of Two Cylinder Locomotives

          We have discussed in the previous article that the reciprocating parts are only partially balanced. Due to this partial balancing of the reciprocating parts, there is an unbalanced primary force along the line of stroke and also an unbalanced primary force perpendicular to the line of stroke. 

          Locomotive engines operate at low speed and the ratio of length of connecting rod to radius of crank is generally large enough to neglect the effect of secondary force. 

The effect of an unbalanced primary force along the line of stroke is to produce:

1. Variation in tractive force along the line of stroke,  and 

2. Swaying couple

          The effect of an unbalanced primary force perpendicular to the line of stroke is to produce variation in pressure on the rails, which results in hammering action on the rails. The maximum magnitude of the unbalanced force along the perpendicular to the line of stroke is known as Hammer blow.