The preceding analysis is primarily concerned with demonstrating the relationships among the various factors affecting the transfer of energy from the piston to the bolt. For the purpose of this demonstration it was assumed that the initial velocities and masses of the piston and bolt were known values. However, an actual design problem usually must be approachcd from a different point of view. Ordinarily the weight of the bolt will be known from a preliminary design layout, its initial velocity will be known from a motion study, and its velocity after impact will be selected on the basis of the rate of fire requirements. The problem is then to determine what piston weight and velocity are required to produce the desired final bolt velocity. These values can then be used to arrive at the design of the gas actuating mechanism. The procedure to be followed in this case is illustrated by the following example:
Let the following data be known:
Desired final bolt velocity, W- 60 (ft./sec.) Coefficient of restitution, e______0.55
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