Fan drives

Claim 1

A cooling fan assembly including a rotary input drive member located at one axial end of the assembly and formed with means for attachment to a drive shaft, a viscous fluid clutch comprising two rotary elements, namely a rotary casing supported by a bearing from said input drive member and carrying a plurality of fAn blades, and an internal rotary element secured to said input drive member and spaced by a small fixed clearance from the walls of said casing, wall means defining a reservoir within said casing and communicating with said clearance, means for circulating a viscous fluid between said clearance and said reservoir including a fluid scoop carried by one of the rotary elements of said fluid clutch, said scoop being movable axially to control the rate of said circulating fluid flow, adjustment means within said casing and operatively connected to said scoop for varying the rate of said circulating fluid flow and thereby the quantity of fluid within said clearance and the torsional drive through said clutch to said fan blades, a fluid operated ram located at the end of said assembly remote from said rotary input drive member, the two operative parts of said ram being connected respectively through bearings with said adjustment means and said casing, an actuating member mounted within said casing and connected to said adjustment means and to said scoop and to an operative part of said ram, a remotely positioned nonrotating thermal sensing valve element, and a non-rotating fluid connection between said thermal sensing valve element and said ram, said fluid connection being located externally of said casing.