Trailer Ring Technical
Installation & maintenance information for low precision trailer rings
Applications and use of ball turntable bearings
Ball turntable bearings are used in applications such as agricultural trailers, irrigation systems and airport luggage carriers. In applications on vehicles, ball turntable bearings transmit not only axial load, but also radial load and torque.
Turntable bearings in the U Series size L range are suitable for use on light vehicles with a speed of up to 25 Km/h . Turntable bearings in the U Series of the N,P and T ranges can be used on vehicles with a speed of up to 40 Km/h .
The catalogue includes the limit values of axial load capacity for a speed of 25 km/h . For applications with speeds above 25 km/h and up to 40 km/h , the load capacity decreases. For applications with speeds of less than 25 km/h , the load capacity may increase.
Turntable bearings are supplied with a protective coating of black rust-proofing paint, this is usually sufficient to adequately protect the product for life.
Turntable bearings are supplied undrilled. We regret that to supply bearings with customer specific hole patterns is possible only for volume orders.
Assembly of ball turntable bearings
Turntable bearings are supplied undrilled. Turntable bearings must be fixed to the structure by bolts, never by welding. Thrust plates can be welded to the structure to limit radial movement before the trailer ring is fitted.
For smooth operation, it is important that the supporting surfaces be as flat and rigid as possible. It should be ensured that the turntable bearing is supported by the connecting structure over at least 50% of its surface and that the supporting areas are distributed symmetrically in regard to the direction of movement.
Holes should not be drilled in line with the ball loading plug which may be recognised by the welding on the raceway of the external ring. The plug should be placed at an angle between 45° and 90° with regard to the direction of movement.
To fix the turntable bearing, use Grade 8.8 bolts. The size of the bolts and the recommended tightening torque values are indicated in the table.
|Series U||Min no of bolts||Bolt size|
|N Section <750mm||6||M14|
|N Section >800mm||6||M16|
|P Section||8||M14 - M16|
The use of suitable welded tags (at least 4 per side), attached to the supporting structure, allows discharge of any of the radial load that occurs due to acceleration and deceleration through the structure and limits bolt shear force.
Maintenance of ball turntable bearings
It is imperative that customers check that the turntables are adequately lubricated before entering service.
Turntable bearings leave the factory lightly greased and have grease nipples on the outside surfaces. It is good practice to carry out periodic lubrication of the bearing. The frequency of greasing must be adjusted according to working conditions, but on average once a month should be sufficient.
New grease should be pumped into the bearing until it extrudes or leaks out of the fissure between the two rings. During the greasing operation, allow the turntable bearing to rotate. As trailer rings are generally unsealed this will purge contaminants and emulsified grease from the bearing.
Any general purpose lithium or lithium-calcium EP2 grease can be used.
Bolt torques should be checked as part of a routine maintenance schedule, or at least once a month and depending on use.
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