Slewing Bearing Clearance Measurement
Slewing Bearing Clearance Measurement:
The clearance of the slewing ring bearing is the maximum amount of movement in which one ferrule is fixed and the other rim is radially or axially.
The maximum amount of motion in the radial direction is called the radial clearance, and the maximum amount of motion in the axial direction is called the axial clearance.
The larger the radial clearance, the larger the axial clearance.
The slewing ring bearing clearance can be divided into the following three types:
Original clearance
The slewing bearing clearance in the free state before the bearing is installed. The slewing bearing original clearance is determined by the processing and assembly of the manufacturer.
Installation clearance
Also called the fit clearance is the clearance when the bearing and the shaft and the bearing housing are installed and not working. The installation clearance is smaller than the original clearance due to the interference installation, or the increase of the inner ring, or the reduction of the outer ring, or both.
Work clearance
When the bearing is in working condition, the inner ring temperature rises the most, the thermal expansion is maximum, and the bearing clearance is reduced. At the same time, due to the load, the rolling element and the raceway are elastically deformed, which makes the bearing clearance increase. Big. Whether the bearing working clearance is larger or smaller than the installation clearance depends on the combined effect of these two factors.
Repeat the tilting clearance or axial reduction measurements under the same conditions at appropriate intervals, after first checking the bearing fastening bolts.
Double-row ball bearing slewing rings clearance:
| Track diameter | Ball diameter mm | ||||||||||
| up to mm | 18 20 22 25 30 35 40 45 50 60 70 | ||||||||||
| permissible increase in bearing clearance mm | |||||||||||
| 1000 | 1.8 | 1.8 | 1.9 | 1.9 | 2 | 2.1 | 2.5 | 2.8 | |||
| 1250 | 1.9 | 1.9 | 2 | 2 | 2.1 | 2.2 | 2.6 | 2.9 | 3.4 | 3.6 | |
| 1500 | 2 | 2.1 | 2.1 | 2.2 | 2.3 | 2.7 | 3 | 3.5 | 3.7 | ||
| 1750 | 2.2 | 2.2 | 2.3 | 2.4 | 2.8 | 3.1 | 3.6 | 3.8 | 4 | ||
| 2000 | 2.3 | 2.4 | 2.5 | 2.9 | 3.2 | 3.7 | 3.9 | 4.1 | |||
| 2250 | 2.5 | 2.6 | 3 | 3.3 | 3.8 | 4 | 4.2 | ||||
| 2500 | 2.7 | 3.1 | 3.4 | 3.9 | 4.1 | 4.3 | |||||
| 2750 | 2.8 | 3.2 | 3.5 | 4 | 4.2 | 4.4 | |||||
| 3000 | 3.3 | 3.6 | 4.1 | 4.3 | 4.5 | ||||||
| 3250 | 3.4 | 3.7 | 4.2 | 4.4 | 4.6 | ||||||
| 3500 | 3.5 | 3.8 | 4.3 | 4.5 | 4.7 | ||||||
| 3750 | 3.6 | 3.9 | 4.4 | 4.6 | 4.8 | ||||||
| 4000 | 4 | 4.5 | 4.7 | 5 | |||||||
| 4500 | 4.2 | 4.7 | 4.9 | 5.2 | |||||||
| 5000 | 4.9 | 5.1 | 5.4 | ||||||||
| 5500 | 5.1 | 5.3 | 5.5 | ||||||||
| 6000 | 5.3 | 5.5 | 5.7 | ||||||||
| 6500 | 5.7 | 5.9 | |||||||||
| 7000 | 5.9 | 6.1 | |||||||||
| 7500 | 6.3 | ||||||||||
| 8000 | 6.5 | ||||||||||
Single-row ball bearings (4-point bearings) double four-point contact bearings clearance:
| Track diameter | Ball diameter mm | ||||||||||
| up to mm | 20 22 25 30 35 40 45 50 60 70 | ||||||||||
| permissible increase in bearing clearance mm | |||||||||||
| 1000 | 1.4 | 1.4 | 1.4 | 1.5 | 1.7 | 2 | 2.1 | 2.5 | |||
| 1250 | 1.5 | 1.5 | 1.6 | 1.7 | 2 | 2.2 | 2.6 | 2.7 | |||
| 1500 | 1.6 | 1.7 | 1.7 | 2 | 2.3 | 2.6 | 2.8 | ||||
| 1750 | 1.7 | 1.8 | 2 | 2.3 | 2.7 | 2.9 | 3 | ||||
| 2000 | 1.8 | 1.9 | 2 | 2.4 | 2.8 | 2.9 | 3.1 | ||||
| 2250 | 2 | 2 | 2.5 | 2.9 | 3 | 3.2 | |||||
| 2500 | 2 | 2 | 2.6 | 2.9 | 3.1 | 3.2 | |||||
| 2750 | 2 | 2.6 | 3 | 3.2 | 3.3 | ||||||
| 3000 | 3 | 2.7 | 3.1 | 3.2 | 3.4 | ||||||
| 3250 | 3 | 2.8 | 3.2 | 3.3 | 3.5 | ||||||
| 3500 | 2.9 | 3.2 | 3.4 | 3.5 | |||||||
| 3750 | 3 | 3.3 | 3.5 | 3.6 | |||||||
| 4000 | 3.3 | 3.6 | 3.7 | ||||||||
| 4500 | 3.5 | 3.8 | 3.9 | ||||||||
| 5000 | 3.7 | 4 | 4.1 | ||||||||
| 5500 | 3.9 | 4.2 | 4.3 | ||||||||
| 6000 | 4.1 | 4.5 | 4.6 | ||||||||
| 6500 | 4.6 | 4.7 | |||||||||
| 7000 | 4.8 | 4.9 | |||||||||
| 5.1 | |||||||||||
| 8000 | 5.3 |
The inspection method for the axial clearance of the slewing bearing crane is as follows:
1. Feeling method
Check the axial clearance of the rolling bearing with your fingers. This method is applied to the case where the shaft end is exposed. When the shaft end is closed or cannot be checked with a finger for other reasons, it can be checked whether the shaft is flexible or not.
2,slewing bearing clearance measurement method
(1) Check with a feeler gauge. The method of operation is the same as that for checking the radial clearance with a feeler gauge, but the axial clearance should be
c=λ/(2sinβ)
Where c – axial clearance, mm;
Λ——the thickness of the feeler gauge, mm;
Β——bearing cone angle, (°).
(2) Check with a dial gauge. When the shaft is tilted with the crowbar to make the shaft at two extreme positions, the difference between the dial gauge readings is the axial clearance of the bearing.
However, the force applied to the crowbar should not be too large, otherwise the shell will be elastically deformed, and even if the deformation is small, the accuracy of the measured axial play is affected.
| Certificate for Slewing Rings clearance | Application: | Location: | ||||||||
| RE drawing-no.: | RE-order-no.: | Year of manufacture: | ||||||||
| Date | ||||||||||
| Repeated measurements (every 12 months) | ||||||||||
| Measuring point | Basic measurement | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ||
| 1 | Boom | |||||||||
| 180offset | ||||||||||
| 2 | Boom | |||||||||
| 180offset | ||||||||||
| 3 | Boom | |||||||||
| 180offset | ||||||||||
| 4 | Boom | |||||||||
| 180offset | ||||||||||
| Grease-sample no Fe-magn. particle (%) | 1 | |||||||||
| 2 | ||||||||||
| 3 | ||||||||||
| 4 | ||||||||||
| 5 | ||||||||||
| 6 | ||||||||||
| Greasing system Quantity/interval | ||||||||||
| Remarks | ||||||||||
Given conclusive assessment of the crane slew ring ‘s condition, worn parts can be replaced in good time. In conjunction with optimum spare parts management, it is thus possible to avoid incidents of damage and lengthy downtimes.
- Measurement of axial clearance for slewing bearing
First, the connecting screw of double half rings in slewing bearing should be tightened uniformly, to ensure the uniform fitting. Then place a datum level of the slewing bearing on the large platform, Three adjustable bearings are equidistantplaced from the neutral position of the lower two steps. Three measuring frame are equidistant placed on the end face of the upper slewing ring, put the pointer on the end face of the other slewing ring. When measuring, first push the three pointer to zero, adjust the bearing, make the slewing bearing face away from the large platform, the average of three pointer is the axial clearance of the slewing bearing.
- Measurement of radial clearance for slewing bearing
Place the slewing bearing on the platform vertically, lift a slewing ring, Measure the clearance with the dead weight of the other slewing ring, Measure three point along the circumference of 120° and take the average .Other measurements are allowed.
