Final answer:
A thermatic viscous fan hub operates efficiently without slipping at a temperature of 155°F or 68°C. It is recommended to maintain the coolant temperature close to this rated temperature to achieve minimum slip drive as the temperature rises.
Step-by-step explanation:
A thermatic viscous fan hub is a device that controls the speed of a fan based on the temperature of the coolant in a car's radiator system. The temperature rating mentioned in the question refers to the maximum temperature at which the fan hub can operate efficiently without slipping. To achieve minimum slip drive as the temperature rises, the equivalent coolant temperature should be close to the rated temperature of 155°F or 68°C. However, the exact coolant temperature for minimum slip drive will depend on the specific design and characteristics of the fan hub. The temperature rating of a thermatic viscous fan hub is nominal at 155°F (68°C). At this temperature, the fan hub minimizes slip drive to maintain optimal cooling efficiency. As the coolant temperature rises, the viscous fan hub engages more, increasing the fan speed to enhance airflow for efficient engine cooling. The specific equivalent coolant temperature corresponding to minimum slip drive may vary depending on the design and calibration of the viscous fan hub. Regular monitoring of engine temperature and fan engagement is crucial to ensure effective cooling performance under various operating conditions, preventing overheating and maintaining engine efficiency.