The programmed control variable loading unit was constructed. This unit consists of hydraulic power unit, optical reader by photo-transistor, amplifier and prony brake for loading.
The process of signal flow is as follows: The input signal is supplied by the punched tape and amplified. Then the relay acted and drives the directional valve. The change of the oil flow drives the hydraulic cylinder back and forth. The displacement of the hydraulic cylnder is related to the action of loading or unloading to the Prony brake.
This unit was used for the hundred hours engine test. The effects of the STP additives will be discussed in the following report. Through the development of this unit, the followings are summarized:
1. The programmed control variable loading unit worked satisfactorily as the loading unit for engine test.
2. The outputs such as torque of axle and the displacement of the hydraulic cylinder were predicted through the punched tape signal input. The graphical integration method and the cycle diagram were applied to predict the output signals and the predicted output signals were compared with the ones obtained from the experiments.
3. The maximum frequency response of this unit is due to the ones of the directional valve and the relay, therefore it should be less than two or theree hertz.
4. For the simulation of the variable loading with high frequency, the electrical clutching device will be more effective instead of the hydraulic prony brake.
5. Further inspection how the real load variation in the field operation should be transfered onto the punched tape should be done.
