What is a slewing ring and what does it do?
The slewing ring, also called a slewing bearing or ball slewing ring, connects the upper carriage of the excavator to the undercarriage. It is a large rolling bearing with internal or external gearing that allows the upper carriage to rotate through 360 degrees. The swing drive engages this gearing with its pinion and generates the slewing motion.
The slewing ring and swing drive work together but are two separate components: the slewing ring carries and guides, the swing drive provides the force. If there is a fault, it is therefore worth diagnosing exactly which part is affected.
Faulty slewing ring? Typical signs of wear
A worn slewing ring usually gives early warning. Look out for these signs:
- jerky or uneven rotation of the upper carriage
- grinding, cracking or metallic noises when slewing
- noticeable play between the upper carriage and undercarriage
- swarf or metal particles in the grease on the slewing ring
- uneven resistance over one full rotation
The sooner you act, the less consequential damage there will be to the gearing and the swing drive. A damaged slewing ring can also destroy the pinion of the swing drive.
Replacing a slewing ring: how the job is done
The replacement belongs in experienced hands. Here is an overview of the procedure so you know what to expect:
- Preparation: support the machine securely, lock the upper carriage against rotation, depressurise the hydraulics.
- Separation: detach the upper carriage from the undercarriage. This involves removing lines, the rotary joint and bolted connections.
- Replacement: remove the old slewing ring, clean the mounting surfaces and check them for flatness, then bolt the new slewing ring in the correct sequence to the specified tightening torque.
- Greasing and testing: grease the bearing and gearing, carry out a test run, measure the play and record it as a baseline value.
An exact fit is essential: slewing rings differ by manufacturer and model in diameter, bolt pattern and gearing, often even within a single series. How to measure a slewing ring without a part number is explained on the Slewing rings page.
How much does a new slewing ring cost?
There is no flat answer. The price depends on the machine size, manufacturer and version: slewing rings for mini excavators cost considerably less than those for large crawler excavators. On top of this comes installation and, depending on condition, new bolts and grease.
We use the machine type and serial number to check which slewing ring fits and send you a quote with price and delivery time. You can find examples with all dimensions under Liebherr slewing rings.
Read more: Slewing rings
