Holding brake for manipulator

Claim 1

A holding brake effective between a rotating part and a nonrotating part of a manipulator, said brake comprising: a substantially nondeformable brake disk secured to one of said parts, centered on an axis corresponding to the axis about which the rotating part turns relative to the nonrotating part, and having a pair of axially oppositely directed and annular brake-disk faces centered on the axis; a housing secured to the other of said parts, at least partially surrounding said brake disk, and having a pair of end walls having wall faces axially confronting the respective disk faces; respective brake elements limitedly axially displaceable independently of each other between said wall faces and the respective disk faces and having annular brake-element faces centered on the axis and flatly axially engageable with the respective disk faces; means including formations on said elements and housing for rotationally coupling said elements and said housing and preventing relative rotation between said elements and said housing; biasing means including respective similar pluralities of springs angularly equispaced about the axis and axially compressed between each of said brake elements and the respective wall face for normally urging said elements with a substantially constant force axially together into braking engagement with said disk and thereby normally locking the disk against rotation in the housing; seal means between said brake elements and between said brake elements and said housing for defining an annular pressurizable chamber between said brake elements centered on the axis radially offset from said disk and said disk faces, the axial width of said chamber being substantially less than the thickness of said disk between said disk faces; and means disposed along the periphery of said chamber and including at least two valves angularly equispaced about the axis for admitting a fluid under pressure radially at respective angularly equispaced locations into the chamber and thereby pressurizing said chamber and moving said elements axially apart and substantially instantaneously out of braking engagement with said disk.