Radial load is a force pushing or pulling the side of the output shaft. It is shown in the diagram (at right) as Fr. Exceeding the allowable radial load for a motor or gearmotor will cause premature wear of output shaft bearings and gearing and could cause the shaft to break. Fr may be the result of a weight on the shaft, belt tension or torque transmitted through a belt, chain, gear, or certain flexible couplings. Our catalog shows the permissible radial load for each motor and gearmotor. In calculating these values, the following assumptions were made: The radial load is in the worst case direction, i.e. pushing or pulling the shaft sideways. The motor or gearmotor is delivering rated torque. The radial load was applied at distance "d" from the hub or mounting surface. Higher radial loads may be applied closer in on the shaft. Lower radial loads are permitted further out on the shaft. Flexible couplings are often used to avoid radial load. Most flexible couplings are designed so that they do not transmit radial load, however this should be verified by the coupling manufacturer.