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Calculate moments and loads acting on the slewing bearing:

The slewing bearing is subjected to surprisingly strong forces, and I highly recommend that these forces are examined prior to construction, or purchase. This tool will help you determine these forces, and are based on an excellent brochure from SKF, which can and should be downloaded by clicking here. (12MB, pdf.)

The tool has been modified to accept small, metric units which is more suitable to model building, while the brochure uses the more correct kN etc.


Although the different data are illustrated on an excavator, they are in the same places on a crane.


Source: SKF

User inputs (Input maximum values!):   ( Decimal point = komma )
Fr
External radial load applied to the bearing, eg work / wind force kg
G1
Weight fraction 1, eg the counterweight kg
G2
Weight fraction 2, eg the weight of the cabin kg
G3
Weight fraction 3, eg the weight of the boom kg
Hr
Distance from the bearing centre point to the line of action of the radial force Fr m
L
Distance from the centre of rotation to the centre of the lifting load m
L1
Distance from the centre of rotation to the centre of gravity of the weight fraction G1 m
L2
Distance from the centre of rotation to the centre of gravity of the weight fraction G2 m
L3
Distance from the centre of rotation to the centre of gravity of the weight fraction G3 m
Qa
Lifting load kg
   

Calculations (Minimum requirements):


Source: SKF

Result: Formula: Result: Unit:
Mt Mt = Qa * L + Fr * Hr + G3 * L3 - G1 * L1 - G2 * L2
0,0
kg*m
Fr  
0
kg
Fa Fa = Qa + G1 + G2 + G3
0,0
kg

This does not include a safety margin, which should be set to no less than 1,5 times the result. (For cranes)
More about this can be found in the pdf mentioned at the top.

This service is free of charge. I cannot be held responsible in any way. Use at your own risk.

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