Aircraft Wheel Bearings – Timken Taper Bearing 629 Inspection codes

Timken aerospace

For many years Timken Aerospace have provided the mass majority of the worlds aircraft wheel bearings and for good reason they retain their dominant position in this field. Identifying authentic aircraft wheel bearings (taper roller bearings) should be relatively easy because all approved Timken product undergoes a special level of inspection before it leaves the manufacturing plant. This is denoted by the 629 code which is appended to the bearing reference. Without this the bearing is not deemed flight approved and should not be used. Timken aircraft wheel bearings are also packaged in suitably robust and appropriately marked with anti forgery devices.

Timken aerospace

The specialised inspection process includes visual, X-ray crack detection and other methods which standard commercial taper bearings do not receive. When you consider the violent acceleration and heat generated when an stationary aircraft wheel touches the runway at 120 knots and then the immense amount of heat from this acceleration, spike loading plus the heat from the breaking system, you need to ensure the bearings you are fitting have undergone all the appropriate inspection requirements and are airworthy. The 629 code provides you this assurance.

The 629 code is often preceded with a “20? hence you may see 20629 after the cup (taper outer ring) or cone (inner ring, cage and rollers) reference. The “2? implies the precision level and the “0? is simply a spacer character.

The permutations of cups and cones which make up a taper bearing assembly are many but to ensure you have the correct combination you can view the Commercial Aviation Timken aircraft wheel bearings FAA PMA list here.

source: Timken Company