Abstract: A system for measuring the accuracy of a machines and mechanisms having a driving member and a driven member is disclosed. The absolute position of the driving member is determined using a first absolute encoder operatively engaged to the driving member. The actual absolute position of the driven member is also determined using a second absolute encoder operatively engaged to the driven member. The theoretical absolute position of the driven member is then calculated based upon the absolute position of the driving member. The actual absolute position of the driven member is compared to the theoretical absolute position of the driven member, preferably by subtraction, to determine the accuracy of the machines and mechanisms. Optical absolute encoders may be used and the process may be performed using a microprocessor which may utilize a ratio function to calculate the theoretical absolute position of the driven member based upon the absolute position of a driving member.

Abstract: A two-tank working gas supply and pump-down system is coupled to a hot gas engine, such as a Stirling engine. The system has a power control valve for admitting the working gas to the engine when increased power is needed, and for releasing the working gas from the engine when engine power is to be decreased. A compressor pumps the working gas that is released from the engine. Two storage vessels or tanks are provided, one for storing the working gas at a modest pressure (i.e., half maximum pressure), and another for storing the working gas at a higher pressure (i.e., about full engine pressure). Solenoid valves are associated with the gas line to each of the storage vessels, and are selectively actuated to couple the vessels one at a time to the compressor during pumpdown to fill the high-pressure vessel with working gas at high pressure and then to fill the low-pressure vessel with the gas at low pressure.