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Assembly of slewing rings

We thank you for having chosen a La Leonessa slewing ring, we are sure that you will be fully satisfied with this product if it is installed according to the indications in this manual.
This installation and maintenance manual for slewing rings was created to offer our clients, old and new, a tool that will allow them to obtain the best working conditions and durability of the product.
We invite you to communicate the information contained in this installation and maintenance manual to the end users.

Transportation, packaging and preparation

The La Leonessa slewing ring must be transported and moved in a horizontal position, avoiding knocks and damage, above all in a radial direction. As it is a machine component, the bearing of any size must be handled with care. The slewing ring is packed on euro pallets, with straps, and protected by an anti-corrosion oil film. This protection allows for good maintenance of the surfaces for about 6 months, but only if the slewing ring is stored in a warehouse in cool and dry conditions. When unpacking the slewing ring, take care not to ruin the seals. To degrease the ring use a solvent, taking care not to taint the seals or allow the solvent to enter the raceway. We advise you not to use solvents that contain chlorides as they may damage the surfaces.

Identification of the slewing ring

Every La Leonessa slewing ring is identified by a stamp near the ball/roller loading plug. The stamp specifies:

  • The type of bearing
  • The year and month of manufacture
  • The progressive serial number

Example: CB-I-1345-99061654

CB = Slewing ring
I = internal gears
1345 = external diameter in mm
99 = year of manufacture
6 = month of manufacture
1654 = internal progressive number

We advise you always to write the serial number in the machine or system logbook, as this may be useful for the traceability of the product, considering that once mounted identification is not always possible, due to the paint or carters that cover the product.

Connecting structure

The quality and the suitability of the connecting structure are significant factors for the good functioning and the durability of the slewing ring.

The connecting structures must guarantee:

  • Sufficient rigidity to deflection
  • Sufficient rigidity to torsion
  • Compatibility with fixing bolts

Distorted structures such as that shown here are not permitted.
The supporting surfaces must be machined, with the maximum out-of-flatness errors, including slope, shown in the table below.

Out-of-flatness errors

Ball/roller pitch circle diameter in mm
4-point-contact ball bearings
8-point-contact ball bearings
Crossed roller bearings
Up to 1000
0.15
0.20
0.15
Up to 1500
0.20
0.25
0.20
Up to 2000
0.25
0.30
0.25

Positioning of the slewing ring

To allow for the correct positioning of the product and to permit excellent functioning and durability, some symbols that can be found on the La Leonessa slewing ring must be taken into consideration:

  • Hardness gap of hardening treatment: On the gear ring it is shown by a letter "T" printed on the surface. On the ungeared ring it can be found near the ball/roller loading plug. During assembly ensure that the hardness gaps of hardening treatment are placed in areas that are not subject to maximum loads.
  • Eccentricity of the gears: This is shown by three teeth that are painted light blue, and during assembly it is necessary to ensure that in correspondence to these the backlash between the edges of the teeth of the wheel and those of the pinion is at least 0.05 mm for the gear module.
  • Lubricators: La Leonessa slewing rings are provided with an adequate number of holes for lubrication.
    These holes must be positioned where they are easily accessible.

Fixing of bolts

Before starting connection between the La Leonessa slewing ring and the supporting structure, you must ensure that the fixing bolts correspond to the type required (8.8-10.9-12.9).

The bolts must be lightly oiled (µ=0,14)

Tempered flat washers may be used, above all for bearings in standardized steel, while it is strictly forbidden to use any type of elastic washer; otherwise every guarantee will be cancelled.

Assemble all the bolts on the first ring and fasten them loosely.

Proceed to tightening as indicated in the illustration

Tightening torques

The tightening of the bolts must be carried out using dynamometric wrenches or with hydraulic systems. The following table shows the tightening torques for bolts of quality class 8.8 and 10.9.



Level of resistance according to DIN/ISO 898
8.8
10.9

Limit tensile strength R02 in N/mm˛

640 for <M16
660 for >M16
940

 
Tensioning force N
Assembly and tightening torque Nm
Tensioning force N
Assembly and tightening torque Nm
M12
38500
78
56000
117
M14
53000
126
77000
184
M16
72000
193
106000
279
M18
91000
270
129000
387
M20
117000
387
166000
558
M22
146000
522
208000
747
M24
168000
666
239000
954
M27
221000
990
315000
1395
M30
270000
1350
385000
1890

Pinion installation

Gear/pinion assembly is carried out by placing the three red-painted teeth of the wheel, which represent the maximum eccentricity, into line with the pinion. The backlash between the edges of the wheel teeth and those of the pinion must be set, ensuring that it is at least:

gd = 0,05*module

The same procedure must always be carried out whenever more than one pinion is used. During installation a vertical alignment check between the teeth of the gear and the pinion must be carried out. It is good practise to record this information in the machine/system logbook. At the end of installation, before lubrication, it is advisable to allow the system to rotate for a few revs, to ensure that coupling is correct.

Lubrication

Before starting up the system the gears need to be lubricated; the lubricant must completely cover the sides of the teeth. The La Leonessa slewing ring is supplied with the raceways already lubricated, therefore the lubrication of these is necessary after the first 100 working hours (see paragraph on Maintenance). The standard grease used corresponds to ISO L-X-BCHB-2 and DIN 51825 KP2K-20 classifications.
The lubricants shown in the table are suitable for use at temperatures between -20°C and + 120°C . For use at lower temperatures, special grease must be used. The following shows some typical values of greases used in raceway systems.

Greases
Raceway systems
Gears
AGIP
GRMU EP2
SEAGUS 60
BR
LS-EP2
Energol WRL
ESSO
Becom EP2
Surret fluid NX
SHELL
Calithia EP2
Malleus Fluid C
MOBIL
Mobilux EP2
Mobiltac 81

Consistency NLGI = 2;
Dripping point ASTM °C = 185;
Worked penetration dmm = 280;
Viscosity of base oil at 40°C mm^2/s = 160

Assessment of machine backlash

After mounting the bearing, assessment must be made of the backlash of the machine. The value recorded will be used as a reference for the measurements that will be carried out during operation, which represent the state of wear of the bearing. The measurement must be taken between the upper structure and the lower structure, as near as possible to the bearing raceway, in order to reduce the influence of elastic distortion of the connecting structure.

Operational procedure

  • Use a 0.01 precision comparator, position it as shown in the illustration and reset it .
  • Allow the machine to reach maximum load conditions.
  • Record the variations of the instrument.
  • Carry out the test from various angle positions.

The maximum value recorded represents the initial backlash of the machine.


 
 
 
LA LEONESSA S.p.A. a socio unico
VL. Santa Maria, 90 - 25013 Carpenedolo Brescia - Tel. +39 0309965435 - Fax. +39 0309965629
P.IVA 02199340981 - Email