Reciprocating Weight

Reciprocating weight is any weight which reciprocates, or moves back and forth repeatedly. Pistons and piston rods are examples of parts which are recipricating weight.

Although most cars have piston engines, which have reciprocating weight, it is an undesired waste of energy which reduces engine power and causes vibrations. Lightening these parts reduces reciprocating weight, which is beneficial for engine performance, as long as the part can withstand other forces applied to it.

The reason why reciprocating weight is a problem for power is that it takes energy to move it, then it has to be stopped and moved the other way. Making these components lighter means less energy is required for both actions, and that means more energy can be used to move the vehicle, or less energy has to be used to move the vehicle the same amount.