What are the maintenance tasks for the slewing drive?

The wear and tear of the gear teeth can cause rotation clearances in the worm screw. It is therefore necessary to check that rotation after 700 hours of operation or every 6 months, so as not to exceed approximately 20° of free rotation. 

In order to measure that rotational clearance, the motor must be disconnected and the screw turned manually, measuring the angle rotated by the screw with respect to a previously specified starting position. 

The previously specified inspection interval must be reduced to 200 hours of operation if the clearance reaches approximately a 15° rotation. Should the clearance continue to increase, the inspection should be reduced to 50-100 hours of operation, and in the event that it exceeds the maximum permissible value the system must be replaced.

Checking mounting bolts

To compensate for possible settling, it is necessary to retighten the bolts to the prescribed torque. This shall be done after no more than 100 hours of operation and without external load applied to the bolt connection.

The inspection shall be repeated after every 700 hours in operation or at least every 6 months. The inspection period shall be reduced under special operating conditions. In case of loose bolts, nuts and washers, replace all bolts, nuts and washers with new ones.

Checking the tilting clearance

Raceway wear leads to increased tilting clearance. It is therefore necessary to check the tilting clearance after 700 operating hours, or at the latest after 6 months.

• The value of measure points determined after installation of the slewing drive is considered as the basic value and is deducted from the measured value.

• The difference between the last value and the first value may not exceed 0.2 mm.

• Reduce the inspection intervals to 200 operating hours if the measured increase in tilting clearance amounts to approx. 75% of the maximum permissible increase in tilting clearance.

• Reduce the inspection intervals once again after further increase in tilting clearance (to 50 – 100 operating hours).

• Replace the slewing drive if the maximum permissible increase in tilting clearance is reached.

Relubrication of slewing drive

For the re-greasing of the worm screw, the grease is injected into all nozzles whilst the system rotates, ensuring that the old grease can flow freely from the unit. Grease recommended for the slewing drive unit by is Shell Gadus S5 T460.

Relubrication time schedule recommended by IRAUNDI in general:

• Worm bearings > 20 – 40 gr each 6 months or 300h operation.

• Worm area > 100 – 150 gr each 6 months or 300h operation.

• Slewing ring > 100 – 150 gr each 6 months or 300h operation.

Relubrication intervals:

• Relubrication intervals depend mainly on the prevailing operating and environmental conditions.

• Exact relubrication intervals can only be determined by tests under operating conditions.

• slewing drive shall generally be relubricated: after every cleaning, e.g. spraying off with water, washing system etc, before and after long inactive periods, e.g. for cranes and construction machines during 

winter months. 

• The most frequent cause of failure of slewing drive is insufficient lubrication.

• Operating temperature on slewing drive in the range from – 25ºC to 70ºC.

• Speed in the permissible ranges. Output speed <5 rpm .

• Low to medium loads.

Checking the seals

Within the course of maintenance work it is also essential to check the seals. Damaged seals must be replaced. To obtain replacement seals please contact to and have the complete drawing number ready. The replacement seals can be cut to the required length and installed with simple tools.

Dismantling the slewing drive unit

If it is found that the limits of tilting clearance have been exceeded during an inspection according to 2.2, the slewing drive must be exchanged. It is thereby necessary to proceed in the general sense in the reverse order to that for installation.

slewing drive shall be disposed of according to the materials of the individual components and are not taken back by the manufacturer. The corresponding environmental regulations shall be strictly observed during their disposal.

View more about slewing drive: https://en.u-transmission.com