Engineering Reference
Miniature & Instrument Ball Bearings
Torque
Starting torque is the minimum force required to initiate the rotation of a bearing from a standstill; running torque is what's needed to maintain rotation. These forces significantly affect the performance of highly sensitive precision components such as gyro gimbals, low power consumption motors, and precision positioning devices. In such applications, design engineers need to evaluate the total system for torque input versus torque reflected by the various driven components. In many cases, we can modify bearing design and manufacture to reduce torque. The table below provides the maximum starting torque for select part numbers. Consult the factory if the bearing you are evaluating is not listed here.
Maximum Starting Torque
NHBB Basic Size | Test Load (Thrust) Grams | Maximum Starting Torque mg/mm | ||
---|---|---|---|---|
Radial Play | ||||
Tight Fit .0001" –.0003" | Normal Fit .0002" –.0005" | Loose Fit .0005" –.0008" | ||
SSRI-2 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-2 1/2 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-3 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-4 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-5 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-418 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-518 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-618 | 75 | 2,000 | 1,600 | 1,500 |
SSR-2 | 400 | 5,000 | 4,500 | 4,200 |
SSR-2A | 400 | 5,000 | 4,500 | 4,200 |
SSRI-5532 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-5632 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-6632 | 75 | 2,000 | 1,600 | 1,500 |
SSR-3 | 400 | 6,500 | 5,500 | 5,000 |
SSRI-614 | 75 | 1,800 | 1,500 | 1,400 |
SSRI-814 | 400 | 6,000 | 5,200 | 4,800 |
SSR-4 | 400 | 7,000 | 6,500 | 5,500 |
SSRI-1214 | 400 | 8,000 | 7,000 | 6,500 |
SSRI-1438 | 400 | 11,000 | 9,500 | 9,000 |