On power units with the motor beneath the tank, which type of pump coupling may be used?

In power units where the motor is positioned beneath the tank, a belt-driven pump coupling is often used. This type of coupling provides flexibility in alignment between the motor and the pump, which is particularly valuable in systems where there may be slight variations in alignment due to thermal expansion or wear over time.

Belt drives also allow for a certain degree of shock absorption, which helps to protect the motor and the pump from potential damage due to sudden changes in load or mechanical stress. This makes belt-driven couplings suitable for applications in elevator power units, where reliability and maintenance considerations are crucial.

Additionally, the belt-driven setup allows for easier adjustments and replacements, as well as the option to alter the speed and torque characteristics by changing the belt’s configuration, which can be important in tailoring the elevator system performance to specific requirements.

In contrast, while gear-driven and pneumatic coupled systems have their applications, they may not offer the same level of variability and ease of maintenance in this specific configuration, and magnetic drive couplings are typically used in applications demanding a hermetic seal and not as commonly in standard elevator power units.