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You are here: Home » SUPPORT » Installation of Bearing

INSTALLATION OF SLEWING RING

Xuzhou WanDa Slewing Bearing Co.,Ltd

   1. Installation preparation

  1.1 Unpacking slewing rings  
Carefully unpack the slewing ring. Care must be taken not to cut and damage the integral seals.
 
  1.2 Slewing ring mounting structure requirement
The supporting surfaces must have a flat machined surface ( usually machine roughness 6.3 ) and be rigid enough to eliminate torsional buckling under load that would affect the smooth operation  of the slewing ring.
The thickness if the supporting plates should be no less than that indicated below-which is offered as a rough approximation only.
 
Raceway Dia(mm) 500 750 1000 1250 1500 2000 2500 3000
Min
Suport Thickness(mm)
25 30 35 40 50 60 70 80
 
The width of the supporting surface must be at least equal to the width of the ring it supports.
 
Permissible flatness deviation and deflections in supporting structure
In order for the bearing to slew smoothly, the mounting structure should be stress-relieved after welding procedure. The maximum permissible out-of-flatness, including slope and axial deflections is detailed in the respective tables.
The permissible deviations listed in Table 1 for the different design types are indicative values.
 
Regarding the slope of the machined surfaces, the figures shown in the table refer to a support width of 100mm. Another important factor is to ensure that the maximum value is reached only once per 180°sector.
To avoid larger deviations and occurrence of peaks in smaller sectors, any deviations in the range of 0°- 90°- 180°must only rise or fall gradually.
As in the case of out-of-flatness, any deflections in the supporting structure must not be allowed to lead to localized buckling which might cause tight spots in the raceways. This could easily lead to over-loads. For this reason, the same conditions as for the out-of flatness will apply.
For the maximum permissible deflections in Table 2, the permissible slope may be twice the value “P” in Table 1 (Reference width 100mm)
The maximum permissible axial deflections ”V” shown in Table 2 apply to all bearings types and are indicated as a function of the track diameter of the bearing.
 
Table 1
Permissible out-of-flatness including slope “P” of the machined support surface
 
Track Diameter Out of flatness including slope per support surface “P” in mm
DL(mm) Single-row ball   Four point contact ball bearings Double-row ball  Eight point contact ball bearings Roller bearing slewing rings
To 1000 0.15 0.20 0.10
To 1500 0.19 0.25 0.12
To 2000 0.22 0.30 0.15
To 2500 0.25 0.35 0.17
To 4000 0.30 0.40 0.20
4000~6000 0.40 0.50 0.30
>6000~8000 0.50 0.60 0.40
 
Table 2:
Maximum permissible axial deflections for contact surfaces at maximum operating load
 
  Track Diameter
  in mm DL
  To 1000   To 1500   To 2000   To 2500   To 3000   To 3500   To 4000   To 5000   To 5500   To 6000
  Max. axial
  deflections in
  mm V
  0.6   0.8   1.0   1.3   1.6   2.0   2.5   3.0   3.6   4.2
 
Besides, the inner and outer ring of a slewing ring must rest fully on the supporting structure surface. 
 
  1.3 Mounting elements selection:
Choose bolts of recommended grade, quality class 10.9(metric) or SAE Grade 8 bolts. Don’t use a fully threaded bolt.  Grade 12.9 bolts are used in very rare circumstances.
Only use treated hardened flat washers.
Use of elastic washers is absolutely prohibited. Do not reuse bolts, nuts and washers.
 
 
   2 Installation of slewing ring

  2.1 Hardness gap on slewing rings
The hardness gap occurs in the process of raceway inductive hardening and is located between the end and the beginning of the hardening. These areas must be placed in the area of least load: ideally at zero load when installing slewing ring.
The position of the hardness gap on each of the slewing ring can be told as follows:
 
Slewing ring Internal geared type External geared type Gearless type
Inner ring S marking Filler plug S marking or filler plug
Outer ring Filler plug S marking S marking or filler plug
 
  2.2 Fastening of slewing ring
Before fastening, use a feeler gauge to check whether the surface of the slewing ring is completely supported by the mounting structure. If this is not the case, the support surface of the mounting structure must be reworked.
Install all fasteners tighten lightly. Then tighten to specified value using a properly calibrated torque wrench; hydraulic devices are advisable. Follow the sequence pattern of the sketch below:
Before fastening, the mounting bolts should be coated slightly with oil. When tightening the whole bolt circle, ensure a uniform tightening torque.The recommend bolt tightening torque values are listed in the table below: 
 
Bolt Thread Size Bore dia(mm)
DIN/ISO 273
Tightening Torque at μ=0.14 Nm
 Bolt Class 8.8 Bolt Class 10.9
M12 14 79 117
M14 16 126 184
M16 17.5 193 279
M18 20 270 387
M20 22 387 558
M24 26 666 954
M27 30 990 1395
M30 33 1350 1890
UNC   Grade 5 Grade 8
UNC 5/8”-11 18 180 260
UNC 3/4”-10 21 320 460
UNC 7/8”-9 25 520 730
UNC 1”-8 27.5 770 1100
UNC 1 1/8”-7 32 970 1560
UNC 1 1/4”-7 35 1370 2190
UNF   Grade 5 Grade 8
UNF 5/8”-18 18 210 290
UNF 3/4”-16 21 360 510
UNF 7/8”-14 25 580 820
UNF 1”-12 27.5 860 1210
UNF 1 1/8”-12 32 1100 1760
UNF 1 1/4”-12 35 1520 2440
 
The slewing ring should be rotated during tightening process as this will indicate the development of any tight spots, the cause of which must be investigated.
The bolt torque should be checked before machine is finally operated to check for any loss of pre-load due to the structure settling.
 
  2.3 Pinion installation
The pinion should be located approximately at 90°of the major loading axis. Adjust the driving pinion to maximum eccentric point of the gear ring, usually with green or red paint coving 2 to 3 teeth. The backlash of the slewing ring gear and pinion must be within the limits of the calculated values or minimum at 0.05 x module. When several pinions are used, each one must be adjusted to the same conditions. During test, make sure good alignment of the pinion and of the slewing ring axes permits a satisfactory contact across all gear width. Before running, lubricate the slewing ring gear and pinion gear.
 
   2.4 Running test
After final tightening of all fasteners:
Rotate the ring for at least 3 turns. Recheck the backlash value on the gear mesh over one full revolution. Measure the total deflection under a known load. The checked point should be marked. It is advisable to register these values in a maintenance logbook specific to the machine. 
Deflection measurement under load mounted slewing ring
Operating process:
Place a measuring device between the two rings as closes as possible to the raceway on the main load axis: precision grade 0.1mm minimum. Calibrate to zero under a known load. Apply a measured load. Read the deflection value at the point considered. Repeat this measurement in the previously marked points. Take into account the deflection of the support structure and the fasteners elongation corresponding to the instrument position.
 
 
 
 
Xuzhou WanDa Slewing Bearing Co.,Ltd.
 No.15,Huaxia Road,the 3rd Industrial Park,Tongshan District, Xuzhou, Jiangsu,China.
  +86-516-83309366     +86-516-83303986
   info@slew-bearing.com
  +86-133-37939399   +86-180 2053 7858

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