Technical specification of slewing bearing


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Calculation for type selection of slewing bearing
1 Static type selection   
Refer to the calculation of load Fa 1 and M 1.
(1)Single row four-point contact ball type
The type selection calculation of the single row four-point ball type slewing bearing is done according to the bearing angle 45  0  and 60  0  respectively.
1. a =450                                              2. a =600  
Fa 1 = (1.225*Fa+2.676*Fr) *fs       Fa 1 = (Fa+5.046 * Fr) * fs
M 1 =1.225 * M * fs                             M 1 = M * fs
Find the foresaid two points on the curve chart and one point is below the curve.
(2)Single -row crossed roller type
Fa 1 = (Fa+2.05 * Fr) * fs
M 1 =M * fs
(3)Double-row different diameter ball type
With regard to the type selection calculation of the double-row ball type slewing bearing, Fr may be omitted if the Fr≤ 10% Fa. If the Fr> 10% Fa, the change of pressure angle in the race must be considered; in this case, please contact us for the calculation.
Fa 1 =Fa*fs
M 1 =M*fs
(4)Three-row roller type
For the type selection calculation of the three-row roller type slewing rings, only calculate the axial race load and capsizing moment.
Fa 1 =Fa*fs
M 1 =M*fs
2 Dynamic type selections:
     For the application with continuous operation, high speed slewing and other specific requirement for the service life of slewing ring, please contact our Technical Department.
3 Checking calculation of bolt bearing capacity:
    1) Regard the max. Bearing load (not multiplied with the static safety factor fs) of the slewing bearing as the load for the bolt selection;
    2) Check whether the load falls bells below the curve of bolt limit load in the required class;
    3) If the bolt bearing capacity is not enough, you may change the slewing bearing or contact with our Technical Department.
 Table 1 
Applications
fs
fL
In principle, it is necessary to support the role of the maximum load value as a static calculations, the additional load must include loading and test load.
Was not included in the table of occasions, can refer to the table with the similar working conditions and application, select static safety factor fL.
*) Rotary tower crane
M = empty overturning the reverse torque
M = maximum rate of the overturning moment
**) The static safety factor of 1.45 fs admission applications, and due to higher average load heavy workload occasions, priority should be given choice of multi-Roller-slewing bearings.
Floating crane (Cargo Load)
Truck Crane (Cargo Load)
Marine deck crane (Grab)
Welding equipment
Table (continuous operation)
 
1.10
 
1.0
Tower Crane
Slewing*
Mf≤0.5M
 
 
1.25
1.0
0.5M≤Mf≥0.8M
1.15
Mf≥0.8M
1.25
Under Rotary
1.0
Rotary Crane (Cargo Load)
Shipyard Crane
Loading/unloader
 
1.15
Metallurgical Crane
1.45**
1.5
Truck Crane (Grab-or handling heavy workload)
Rotary Crane (grab or sucker)
Bridge Crane (grab or sucker)
Floating crane (grab or sucker)
 
1.7
Bucket wheel excavators
Stacker reclaimer
Cantilever conveyor
2.15
Offshore Crane
According to special standards
Railway Crane
Deck crane (Cargo Load)
1.00
 
In these applications, considerable changes in working conditions, for example, are not under the regular rotation of the use of slewing bearings, and we only require static checking. For continuous rotary intermittent and the use of the slewing bearings, it will be necessary for calculating dynamic life.
Reactor Feeder
Carriers
1.10
 
Rope excavator/Cable fight
1.25
 
Less than or equal to 1.5 m3 hydraulic excavators
1.45
 
More than 1.5 m3 hydraulic excavators
According to special standards
Ladle turret
1.75
 
Note: fl is the dynamic safety factor. It must be used under the combination with the dynamic bearing curve (It is not included in the sample). It originates from the experience and experiment, as a reference value based upon the max. working load. If the slewing ring has to be chosen according to the service life, please contact with our Technical Department.
 
Installation bolt pair   
    1. The bolt dimension of the slewing bearing should conform to GB/T5782-2000 and GB/T5783-2000. The strength grade should be no lower than 8.8 in GB/T3098.1-2000, chosen according to the force the bearing bears.
    2. The nut dimension should conform to GB/T6170-2000 and GB/T6175-2000 and its mechanical performance should conform to GB3098.2-2000.     
    3. The washer dimension should conform to GB/T97.1-1985 and GB/T97.2-1985 and it needs the quenching and tempering treatment. The spring washer should not be used.  
    4. The bolt tightening way should follow the design of the principle machine. Certain pre-tightening force should be ensured. Unless otherwise specified, the pre-tightening force usually should be 0.7 times as much as the bolt yield limit. During the tighteing , little oil may be spread at the thread . For the pre-tightening torque or pre-tightening force, see Table 4.
    5. The bolt clamping length LK >5d (d-bolt diameter).
TABLE 2 Pre-tightening Torque or Pre-tightening Moment:
 
Bolt Specification   (GB/T5782-2000 GB/T5783-2000
The size of mounting hole (mm)
The bolt strength and grade(GB/T3098.1-2000)
8.8
10.9
Limit of yielding σ min   ( N / mm 2 )
640
900
Pre-tightening torque Ma (Nm)
M10
11
44
62
M12
13.5
77.5
110
M14
15.5
120
170
M16
18
190
265
M18
20
260
365
M20
22
370
520
M22
24
500
700
M24
26
640
900
M27
30
950
1350
M30
33
1300
1800
 
 
Pre-tightening force Fa (1000N)
M33
36
293
412
M36
39
344
484
M39
42
414
581
M42
45
473
665
M45
48
553
777
M48
52
623
876
M52
56
749
1054
M56
62
863
1214
M60
66
1008
1418
 
Note: (1) when the bolt dimension does not conform to GB/T5782-2000 or GB/T5783-2000, the values in the table needs the re-calculation.
     (2)The total frictional coefficient between the bolt head and the clamped surface, μ=0.14. Spread little oil on the thread.
Clearance of turntable bearing
      The bearing clearance of slewing bearing is mainly used to compensate the parts of slewing bearing and the disassembly position of the principle machine against the manufacture error and installation error, so as to ensure the normal use of bearing .The clearance values or interferences are listed from Table 3 to Table 6 according to the slewing bearing structure type, tolerance grade and the pitch diameter of rolling element group.
Table 3 Axial Clearance of Four-point Contact Ball Slewing Ring Bearing μ m
Dpw      mm
Tolerance grade
G
E
D
Axial clearance
over
upto
Min
Max
Min
Max
Min
Max
280
450
70
170
50
130
30
90
450
710
100
220
70
170
40
120
710
1120
120
280
100
220
50
150
1120
1800
150
350
100
260
60
180
1800
2800
200
440
150
350
80
240
3800
4500
260
540
200
440
100
300
 
Table4 Axial Clearance of Double-row Angular Contact Thrust Ball Slewing Bearing μ m 
Dpw    mm
Tolerance grade
G
E
D
Axial clearance
over
upto
Min
Max
Min
Max
Min
Max
280
450
50
130
30
90
25
70
450
710
70
170
40
120
30
90
710
1120
100
220
50
150
40
120
1120
1800
100
260
60
180
40
140
1800
2800
150
350
80
240
60
180
3800
4500
200
440
100
300
80
240
 
Table5 Axial Clearance of Cylindrical Roller  Slewing Bearing μ m
 
Dpw    mm
Tolerance grade
G
E
D
Axial clearance
over
upto
Min
Max
Min
Max
Min
Max
280
450
50
130
30
90
25
70
450
710
70
170
40
120
30
90
710
1120
100
220
50
150
40
120
1120
1800
100
260
60
180
40
140
1800
2800
150
350
80
240
60
180
3800
4500
200
440
100
300
80
240
 
Table 6 Clearance of Three-row Cylindrical Roller Combined Slewing Bearing μm
 

Dpw mm
Toleance grade 
G
E
D
Axial
Radial
Axial
Radial
Axial
Radial
over
upto
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
280
450
30
90
50
130
25
70
30
90
10
50
25
70
450
710
40
120
70
170
30
90
40
120
15
65
30
90
710
1120
50
150
100
220
40
120
50
150
20
80
40
120
1120
1800
60
180
100
260
40
140
60
180
20
100
40
140
1800
2800
80
240
150
350
60
180
80
240
30
130
60
180
3800
4500
100
300
200
440
80
240
100
300
40
160
80
240