Patent ID: 6264009
Filing Date: 2001-07-24
Classification: F16D

Abstract:
A multi-stage wet disc brake assembly comprising:a fixed housing having a cylinder portion;a rotatable member rotatable about an axis of rotation relative to said housing;a first and second set of friction discs adjacent one another in an alternating relationship and having a running clearance therebetween, said first set of friction discs in interlocking and sliding relation with said housing, said second set of friction discs in interlocking and sliding relation with said rotatable member;a first actuator including an annular first hydraulic piston supported within said cylinder portion, said first hydraulic piston having a face with a portion tapering to an inner perimeter proximate to and being moveable toward one of said friction discs, said first hydraulic piston having bores spaced radially about said first hydraulic piston; anda second actuator including second hydraulic pistons disposed in said bores with said second hydraulic pistons interposed between said first hydraulic piston and said one of said friction discs, and a pad adjacent said tapered portion and attached to each of said second hydraulic pistons by an arm, said pads sliding along said tapered portion when said second hydraulic pistons are actuated thereby moving said pads toward said one of said friction discs along said axis of rotation to reduce said running clearance, wherein said second hydraulic pistons move prior to said first hydraulic piston and then said first hydraulic piston forces said friction discs together for slowing rotation of said rotatable member relative to said housing.