The design of a novel axial air gap hoist motor

Traditional electric chain hoists comprise a separate motor and brake package. This is a new design incorporating an axial air gap motor with an integral brake. The motor has been designed to operate inside a 125 Kg chain hoist. The novel design feature of this axial air gap motor is that the force of attraction between the stator and rotor is used to overcome a spring loaded brake, therefore, as soon as the field collapses the brake is applied. In the design of hoist systems safety is paramount, this design has an inherent fail-safe feature in that the hoist is brought to a standstill immediately the motor is de-energised. In the event of loss of supply or a control system failure resulting in shut down, the brake would automatically be applied ensuring that the load and the surrounding environment are in no danger. The motor is designed to ensure that the force of attraction is sufficient to overcome the brake springs. The springs are designed to arrest the load in a smooth and controlled manner. This paper details the mechanical and electrical design of the motor characteristics, the software used and the overall motor performance.