Load on Rotating Hydraulic Footstep Bearing
 

I studied Fluid Mechanics in a Civil Engineering course that I did some years ago. From my textbook, I have this question that I would like to work out, but I am not sure where to start with the calculations, and need a bit of help, just to keep me started.

Question

An hydraulic footsteps bearing on a 100 mm diameter shaft consists of a 500 mm diameter disc rotating in water in a pressure cylinder.

The lower face of the disc is plane and is supported by radial ribs on the base of the pressure cylinder, its upper face has radial ribs and the upper surface of the pressure cylinder is plane.

The two portions of the cylinder are in free communication with each other around the periphery of the disc.

Find the load which the bearing will support at 500 revolutions per minute without pressure between the disc and the fixed ribs ?

The first thing I would like to understand is, what are hydraulic footstep bearing and radial ribs ?

Then I need to workout out the procedure for the calculations.

Textbook Answer is given as 8400 Newtons

Any feedback will be much appreciated.