These adjustable belt drive motor bases allow mounting position adjustments after the motor is secured to a base. Adjusting the motor's base ensures proper belt tensioning in a belt drive system, reducing stress on the motor, belt, and bearings. Linear bases and slide rails allow for back and forth adjustments. Angular pivot bases adjust the base up and down. Automatic bases adjust the belt tensioning while the motor is running. These adjustable mounting bases accept standard NEMA motor frame sizes and are used to power HVAC equipment such as air coolers, belt-drive fans, and roof ventilators.