BI-DIRECTIONAL BALLSCREW NO-BACK DEVICE

摘要

A bi-directional no-back device for a ballscrew rotatable in opposite directions has a ballscrew flange with radial surfaces at opposite sides thereof to receive and transfer a bi-directional axial and torque load from an external source. First and second thrust plates are moveable axially of the ballscrew in a housing to transfer compressive loads exerted on the ballscrew in one direction and tensile loads exerted on the ballscrew in the other direction. This maintains a first set of skewed roller brake rings in tight frictional engagement with the ballscrew flange, a first ratchet wheel and the first thrust plate assembly or a second set of skewed roller brake rings in tight frictional engagement with the ballscrew flange, a second ratchet wheel and the second thrust plate assembly, depending on the direction of the external force applied to the ballscrew. First and second pawl assemblies are mounted on the housing and cooperate with the first and second ratchet wheels to permit freewheeling of the first ratchet wheel in a first direction and freewheeling of the second ratchet wheel in the opposite direction, for controlling the effective brake torque applied by multi-stage brakes.