Fluid pressure released clutch for fans

Claim 1

A rotary fan hub assembly including a rotary input drive member at one axial eNd thereof and having means for securing said drive member to rotary drive means, a rotary output member supported by bearings on said input drive member for rotary and axial movement relative to said input drive member, said rotary output member having means for attachment of a plurality of fan blades, and said input drive member and said ouput member being rigidly connected respectively to clutch input and output members constituting a slipping clutch which is selectively engaged and disengaged by relative axial movement of said output member, a single-acting fluid-operated ram located at the other axial end of said assembly, remote from said input drive member, said ram including a non-rotating cylinder and non-rotating piston, two thrust bearings one connecting said cylinder to said input member and the other connecting said piston to said output member, a non-rotating fluid pressure conduit fixedly connected to said ram cylinder, whereby pressure fluid admitted to said ram cylinder causes relative axial movement between said cylinder and piston and consequent relative axial movement between said input and output members in a direction to disengage said clutch, and spring means connected between said ram cylinder and piston, said spring means acting through said one thrust bearing on said input member and through said other thrust bearing on said ouput member in an axial direction to engage said clutch.