PARTIAL BALANCING OF LOCOMOTIVES:

Variation of Tractive force:

 The resultant unbalanced force due to the cylinders, along the line of stroke, is known as tractive force.

Swaying Couple:

 The couple has swaying effect about a vertical axis, and tends to sway the engine alternately in clock wise and anticlockwise directions. Hence the couple is known as swaying couple.

Hammer blow: 

The maximum magnitude of the unbalanced force along the perpendicular to the line of stroke is known as Hammer blow.

BALANCING OF INERTIAL FORCES IN THE MULTI-CYLINDER ENGINE:

 oIn multi-cylinder engines the mutual counteractions of the various components in the Crank shaft assembly are one of the essential factors determining the selection of the Crank shafts configuration and with it the design of the engine itself. The inertial forces are Balanced if the common centre of gravity for all moving crankshaft-assembly components lies at the crankshaft's midpoint, i.e. if the crankshaft is symmetrical (as viewed from the front). The crankshaft's symmetry level can be defined using geometrical representations of 1st - and 2nd-order forces (star diagrams). The 2nd order star diagram for the four-cylinder in-line engine is asymmetrical, meaning that this order is characterized by substantial free inertial Forces. These forces can be balanced using two countershafts rotating in opposite directions at double the rate of the crankshaft (Lanchester system).