23R BLOCK-HEAD®

Designed to support a liquid-mirror telescope lens, the model 23R is an example of the large-scale, special-purpose air bearing Professional Instruments Company builds to solve a customer’s particular problem. When ultra-high accuracy is paramount, regardless of load, our design services will offer you a solution.

Specifications (at 150 psi)

Load Capacity Ultimate Working
Radial 1,500 lb 750 lb
Axial 15,000 lb 7,500 lb
Tilt 50,000 lb-in 25,000 lb-in
Stiffness Radial 4 lb/microinch
Axial 40 lb/microinch
Tilt 1,500 lb-in/microradian
Error Motion Radial < 1 microinch
Axial < 1 microinch
Tilt < 0.1 microradian
Total Weight 2,200 lb
Rotor Weight 1,400 lb
Rotor Inertia 245 oz-in-sec2
Maximum Speed Application Dependent
Air Consumption < 10 scfm
Metric Specifications


Load capacity and stiffness are approximately linear with air pressure.

Ultimate load capacity is measured when metal-to-metal contact is made across the bearing surfaces. Working load capacity is half of the ultimate load capacity. Rotor weight must be included as part of total spindle load.

Axial and tilt loads are supported by the same bearing surfaces. Consequently, a load applied in one mode reduces the other mode proportionally.

High speed or high inertia applications require rotor containment. Maximum speed is dependent on application. Consult Professional Instruments for further information with regard to speed.