Low-Profile 4R & 4B BLOCK-HEAD®

Low-Profile 4R & 4B air bearings are used in applications where overall height is limited. The smaller thrust plates also have a lower moment of inertia, allowing more rapid accelerations and shorter settling time in servo applications.

Specifications (at 150 psi)

Load Capacity Ultimate Working
Radial 440 N 220 N
Axial 1780 N 890 N
Tilt 45 N-m 23 N-m
Stiffness Radial 120 N/micrometer
Axial 350 N/micrometer
Tilt 0.45 N-m/ microradian
Error Motion Radial < 25 nanometers
Axial < 25 nanometers
Tilt < 0.1 microradian
Total Weight 71 N
Rotor Weight 22 N
Rotor Inertia 0.0028 kg-m2
Maximum Speed 10,000 rpm
Air Consumption < 55 L/min
English 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.