Patent ID: 7090200
Filing Date: 2006-08-15
Classification: B66D

Abstract:
1. A hoist comprising: a base; a motor; a gear reduction connected at an output of said motor; a drive shaft connected at an output of said gear reduction; a drive gear mounted on said drive shaft; an armature subassembly comprising a left armature and a right armature supported on said drive shaft with a left armature bearing and a right armature bearing; a spool shaft connecting said left armature and said right armature; one or more compression springs connected to said base and supporting said spool shaft with a supporting force; a spool gear which meshes with said drive gear and spins freely on said spool shaft; a spool fixed concentrically to said spool gear; a position transducer arranged to measure the deflection of said compression springs; a payload cable helically wound and terminated on said spool; a payload attached at the end of said payload cable; and a controller; wherein the compression springs compress in relation to the force on the payload; wherein the armature subassembly rotates around the drive shaft in relation to the force on the payload; wherein the hoist can provide a float mode in which the load feels substantially weightless to an operator physically lifting the load; and the controller provides a control signal to the motor in relation to the deflection of the compression springs as measured by the position transducer and a desired deflection.