Assembly of ball turntable bearings
Turntable bearings must be fixed to the structure by using bolts. For correct fixing of the turntable bearing, it is important that the supporting surfaces be as flat and rigid as possible. It should be ensured that the turntable bearing rests on the connecting structure with at least 50% of its surface and that the supporting areas are distributed symmetrically in regard to the direction of movement. Holes in line with the ball loading plug are not permitted; this plug may be recognised by the welding on the raceway of the external ring. The plug should be placed between 45 degrees and 90 degrees with regard to the direction of movement. To fix the turntable bearing, at least 8.8 quality bolts must be used. The size of the bolts and the recommended tightening torque values are indicated in the table.
The addition of suitable steel locating blocks (at least 4 per side), welded to the supporting structure, allows the bolts to discharge the radial thrust that occurs due to acceleration and deceleration. The ball turntable bearing must not be fixed to the structure by welding. It is advisable to carry out a second greasing before assembly.
It is very important that at no time the small manufactures plate on the outer circumference of the turn table is damaged during the drilling of the fixing holes. When fitting the turn table position the manufactures plate so it faces the direction of travel.
| Bolts | ||||
| Type of turntable bearing | Minimum no. bolts | Type | Quality | Nut |
|
L-300-400-500-600 |
4 |
M12 |
8.8 min. |
Hexagonal or self-blocking |
|
N-600-650-700-750 |
6 |
M12-M14 |
||
|
N-800-850-900-950 |
6 |
M14-M16 |
||
|
P-900-1000-1100 |
8 |
|||
|
Level of resistance according to DIN/ISO 898 |
8.8 |
|
Limit tensile strength Rp in N/mm² |
640 |
|
DIN/ISO 13 Metric thread |
Resisting section |
Core section |
Tensioning force |
Assembly and tightening torque |
|
|
|
As |
A3 |
Fn |
Ms |
|
|
|
mm² |
mm² |
M |
Nm |
Kgm |
|
M12 |
84.3 |
76.2 |
38500 |
78 |
8 |
|
M14 |
115 |
105 |
53000 |
126 |
13 |
|
M16 |
157 |
144 |
72000 |
193 |
20 |
Maintenance of ball turntable bearings
It is good practise to carry out periodic lubrication of the turntable bearing.
The frequency of greasing must be programmed according to working conditions, on average once a month. The operation of pumping new grease should be carried out until the grease leaks out of the fissure between the two rings. During the greasing operation, allow the turntable bearing to rotate.
Lithium grease designated with the marking EP2 or 2 by the leading manufacturers, may be used. For bolts, we advise that you carry out inspections, once a month and depending on use, on the tightening force of the screws, according to the values indicated in the table.