The devices are fitted with adjustable bolt patterns suitable for different-sized motors that allow necessary position modifications to the motor. Most bases fit NEMA motor sizes. The base regulates the pressure in a belt-driven system.
This is critical for avoiding belt slippage and excessive strain that lead to higher maintenance costs and additional downtime. Optimal belt tension helps lengthen the service lifetime of components, such as belts and motor bearings.
Fixed-position adjustable bases: These adjust via manual alteration of the center distance that separates a driver and driven pulleys. They allow pushing or pulling a motor into place to install or adjust the belt. Once the belt is pulled over the pulley, single or multiple screws force the motor away from the driven pulley until the desired tension level is attained. The mounting bolts are then tightened to complete the process.
Base design ranges from simple, one-piece, formed plates to more complex models featuring Z-bars with continuous welding to improve strength. Select versions correspond to NEMA mounting dimensions. Fixed-position bases are preferred due to low initial costs. The equipment is further broken down into the following classifications: Single-screw adjustable base possesses a central screw for tension positioning.
Dual-screw positioning base has two adjustable screws placed beneath the motor feet. Pivot bases rely on a motor's weight along with its direction of rotation for applying and controlling tension. The motor is mounted on pivoting arms and is held in place with bolt holes and slots configured to fit the frame.
Spring-loading bases employ built-in springs to control belt strain. This unit features a motor positioned on cross members connected to tubes. The formed carriage shifts towards or away from a driven member in response to fluctuating load. The motor is bolted to the free-moving carriage. When the adjustment screw is turned clockwise, the follower nut, spring, and carriage move in the direction opposite to the driven pulley. Conversion motor bases match newer, smaller motors after they have undergone rerating to accommodate older mounts.