Analysis of Drive Shaft Speed Variations in a Scotch Yoke Mechanism

Abstract

Two analyses are presented for determining the drive shaft speed variations in a scotch yoke mechanism. The first analysis determines the speed variations when the mechanism is rigidly connected to a motor having a quadratic speed versus torque characteristic. The second analysis determines the speed variations when the mechanism is connected to a constant speed source through a flexible coupling. Together these models represent the two most common drive configurations. The results are of practical importance since they can be used in the preliminary calculations necessary in either the design of a main drive or the diagnosis of a drive problem in an existing machine. The methods are also of theoretical importance since they may be extended to the analysis of mechanisms having a greater harmonic content than the simple scotch yoke mechanism.