Test the reducer

Temperature testing during the break-in period: The primary heat sources in a transmission are seal friction, bearing friction, and oil churning. Heat generated by oil churning is distributed throughout the transmission and dissipated through the housing. Seal and bearing friction, on the other hand, is localized; if excessive, it can lead to failure.

Check the temperature near the high-speed shaft bearings; measurements from the prototype gearbox indicate the highest temperatures in these areas. These regions are also located close to the seals. Although it is not possible to separate the heat generated by the bearings from that produced by the seals, the seals appear to be the primary source of heat.

Temperature was recorded over a two-hour period, with the enclosure operating at maximum speed. After a cooling interval, the test was repeated in the reverse direction. The temperature initially rose rapidly before declining. Although equilibrium was not reached, the enclosure does not run continuously for the full two hours during operation, and it only attains its maximum speed intermittently.

Gear train stiffness: Stiffness is defined as the ratio of the input shaft’s angular displacement to the applied torque when the output is locked, with units of [N·m/rad]. Torque is applied using a hydraulic actuator. The actuator features two opposing cylinders that drive two racks against a pinion. The racks are secured within the pinion via bushings, generating friction that opposes the direction of motion. Because this friction in the hydraulic actuator can lead to measurement inaccuracies, a DATAFLEX 42/1000 torque sensor is used to measure the torque between the actuator and the input shaft.

The sensor has a capacity of 1,000 Nm in either direction. Torque is determined by measuring the twist of the sensor shaft using rotary encoders in a differential circuit. An encoder rotor is mounted at each end of the shaft. Since the encoder read heads are mounted on the sensor’s stationary part, there are no slip rings. The sensor’s A‑quad‑B output is converted to a voltage by the encoder electronics box. The voltage output ranges from 0 V to 10 V, with a no‑load value of 5 V and a calibration constant of 0.200 N·m/mV.

Rotational motion is measured using a 2,000-line rotary encoder with a resolution of 0.018 degrees. Since the input shaft passes through the housing, the encoder is mounted on the opposite end of the shaft, facing the hydraulic actuator. When the housing is in operation, the brake is installed at this end of the shaft. The encoder’s A‑quad‑B output is converted into a voltage by a programmable encoder control unit. The range and volts per degree can be configured according to the desired measurement. The output range spans from 0–V to 10–V. For this test, the output was set to 8.100 degrees/V, with a no‑rotation voltage of 5 V.