Hammer Blow - Principles

Principles

The aforementioned reciprocating balance on the wheels attempts to prevent the worst of the reciprocating forces at play on a locomotive, though as a compromise, this extra mass on the wheel causes it to be out of balance vertically, therefore creating hammer blow. Therefore, if reciprocating balancing is increased, it may appear that a locomotive is running smoothly, but at a high cost in hammer blow, especially at high speeds.

Locomotives are balanced to their individual cases, especially if several of the same design are constructed (a class). The normal operating speed is ascertained, resulting in each class member being balanced accordingly. Usually the reciprocating weight is balanced between 45 to 50% of total balance weight. High speed locomotives were the key recipients of such treatment due to the increased level of forces involved, and the exponential factor of stress on the track at these higher speeds.