The temperature and recirculation control lifetime test system on the HVAC unit uses three control heads. Two of them are used to control rotary temperature and exhaust regulators; the third head is designed to control the recirculation rod and generates a linear movement.

DC motors with planetary gearbox are used for control. The control torque is transmitted via a mechanical clutch with adjustable torque. The position is sensed by a multi-turn potentiometric angular position sensor.

This measuring system supports adjustment of the positions of the controls, which are then repeated in a large number of cycles. Definition of scenario how many times each movement should be repeated is possible, too. Program monitors the movement of the controls during the measurement, and if the control stops moving (usually because the control grids in and mechanical clutch starts slipping), it records the time the failure occurred (including other data, such as how many cycles the failure occurred) and the motor stops movement. At the end of the measurement, the system generates a report.

The LabJack module is used for measurement. The module is connected by USB bus to the measuring computer, which also provides program control of the system.

More information request here.