Engineering Reference
Precision Ball & Roller Bearings
(Medium to Large Diameter)
Seals and Shields
NHBB offers a variety of protective closures designed to retain lubricants and prevent contamination from reaching critical bearing surfaces. When specifying closures, you need to consider the bearing's width● along with the compatibility of the retainer and shield type to allow for appropriate clearance. Depending on the requirements of your application, it may be necessary to customize a closure by modifying the models listed here.
Seal Types
Seals are generally used in high contamination environments where a positive closure is required, but they can increase torque and heat generation, which may affect operating speed limits.
| D, D1 |
S, S1
Q
Q4
Shield Types
The shields shown below provide a barrier to gross contamination without unduly affecting speed and torque.
H
Z
Table of Seals and Shields
| Type | Description | Material | Max. Temp. | Speed Limit (dN♦) | Comments |
|---|---|---|---|---|---|
| D | Seal — removable | Nitrile rubber bonded to steel insert | 250° F | 180,000 | Positive contact, high torque, most effective in excluding contamination |
| D1 | Seal — removable | Fluorocarbon rubber bonded to steel insert | 400° F | 180,000 | Positive contact, high torque, most effective in excluding contamination |
| Q | Seal with snap wire — removable | Glass reinforced PTFE* | 600° F | 200,000 | Positive contact, lower torque than D or D1, very effective in excluding contamination |
| Q4 | Seal with outboard shield and snap wire — removable | Glass reinforced PTFE*, 300 series stainless steel | 600° F | 200,000 | Positive contact, high torque, most effective in excluding contamination |
| S | Seal — removable, noncontact | Nitrile rubber bonded to steel insert | 250° F | No influence on speed | Noncontact, no effect on bearing torque, less protection than D or Q |
| S1 | Seal — removable, noncontact | Fluorocarbon rubber bonded to steel insert | 400° F | No influence on speed | Noncontact, no effect on bearing torque, less protection than D or Q |
| Z | Shield — removable, noncontact | 300 series stainless steel | 600° F | No influence on speed | No effect on bearing torque, less protection than seal |
| H | Seal — nonremovable | 300 series stainless steel | 600° F | No influence on speed | No effect on bearing torque, less protection than seal |
♦dN = bore (in millimeters) x rpm.
*Polytetrafluoroethylene is a high-melt-temperature thermoplastic.
● Width dimensions noted in the product tables of this Design Guide are for open bearings. Please consult the factory to identify widths for bearings with closures. In NHBB’s part numbering system, RW refers to radial bearings with cartridge widths.
