Required braking torque depends on whether you need dynamic stopping, static holding, or both. For holding applications, start with the torque created by the load (including gravity effects in lifting) and apply an appropriate safety factor. For dynamic stopping, you also need to account for rotational inertia and the desired deceleration time. A simplified approach is: braking torque must overcome load torque plus the torque needed to decelerate inertia, while staying within allowable thermal limits.
Key inputs typically include: load weight, drum/disc radius, gear ratios, motor and gearbox efficiency, speed, total system inertia reflected to the brake shaft, and required stopping time or distance. For cranes and hoists, standards often require a minimum brake torque multiple of motor rated torque (and additional redundancy for critical lifts).
Because real systems include shock loads, wind loads, and friction variability, it’s best to validate calculations with application data: duty cycle, emergency stop scenarios, and worst-case environmental conditions.
