Slewing bearing also called swing bearing, turntable bearing, is a medium or large scale bearing which can bear axle load, radial load and composite load. It mainly applied in excavator, crane, metallurgy machinery, excavation machinery or other large scale engineering machinery.
Slewing bearing can be assembly to contact ball type slewing bearings, double-row ball type slewing bearings, crossed roller slewing bearings, different types of slewing bearings have different functions. These types of slewing bearings have large bearing capacity, stand all kinds of bearings loading force.
Slewing bearing Materials of the rolling rings usually use 50Mn or 42CrMo. The raceway has been treated by quenching to guarantee the hardness of HRC55-62, while the teeth surface hardness is at HRC55±5 to guarantee enough depth.
Our slewing bearings work conditions normally at the temperature -30℃ to +70℃, if it works in extremely-terrible conditions such as marine climate, dust or abrasive particles(dust, cement, coal powder, etc.), please special indicate that, our technicians will develop specially for you.
The working life of a slewing bearing depends on its working conditions, load, rotation speed, lubricating, precision of the seat base and the maintenance. In normal conditions, the working life is 6000-10000 hours.
It is normal when replacing the new slewing bearing there is abnormal sound, it mainly due to the lack of the lubricant, please wipe lubricant to solve the problem. But if the slewing bearing used for a long time and there is abnormal sound during the working process, that is not the lack of lubricant, it probably because of the damage of the parts in the slewing bearing, stop running the slewing bearing and check it carefully.
Many customers feedback to us the slewing bearing will rust after a period of time of storage and the slewing bearing is not that flexible as before. That is because of the wrong way to storage.
So how to store the slewing bearing:
Slewing bearing surface must be wiped with anti-rust oil. Single packed or the whole turn packed. During storage, it should be wiped with anti-rust oil on the surface every six months to prevent from rusting. In wet area, this process should be every three months. After maintenance, restore to original state and packed with thin film. The idle slewing bearing should be stored in non-corrosive media, dry and flat indoors, don’t steep or rain. The idle slewing bearing should be placed stable, vertical and incline are not allowed. When placing the slewing bearing, you must set 3 to 5 pieces of cushion block between them.
Another suggestion is don’t put the slewing bearing under the wet circumstance, it will shorten your products’ service life.
The correct installation steps of slewing bearings are as follows:
First. Unpack the wooden case, remove the plastic bag, and check the certificate and label
1. Check the installation platform
The installation platform should be flat and the surface should be smooth. The error of the flatness of the installation surface should be detected with the axial error and radial error.
In order to avoid the uneven installation platform or deformation of the installation base resulting in local overload of the slewing bearings, the axial flatness error can only have one wave fluctuation in any 180 degree range, and the change is gentle.
2. The hardness of the base
Note that standard slewing bearings and none-interval slewing bearings have different requirements on the hardness of the mounting base.
3. Positioning of slewing bearing
Put the soft belt “S” mark in the non-bearing area, and check the fitting of the slewing bearing and the mounting surface.
Second. Ensure that the slewing bearing is installed without load
The installation bolt contains three staggered firmness steps, the first step is 30%, the second step is 80%, and the third step is 100% firmness.
1. Adjust the tooth side interval of the slewing bearings
When installing a slewing bearing with teeth, it is important to adjust the side interval correctly.We can measure and adjust the gear at the highest point of radial runout with a feeler, or by pressing wire or other methods.Check the side intervals again after the slewing bearing is finally fixed.
2. Raceway lubrication
Few grease is added to the slewing bearing before leaving the factory. In order to ensure sufficient lubrication, the grease specified in the manual should be added before the first use.Be noted that all the nozzles should be filled with grease, it is best to rotate the slewing bearings when filling oil, until you see the grease extrusion from the sealing ring.
3.Gear lubrication
When the gear is lubricated, the tooth surface should be cleaned and dirt and burr removed.Use a clean brush to brush the grease over the gears and apply evenly.
4. Check and maintain regularly
Check the working condition regularly, install bolt firmness, fill oil regularly, and further shorten the time interval for filling lubricating grease in the case of bad working condition.
1.The reason of the slewing bearing tooth damage: the gear tooth material forging and casting quality problems (the sand hole or space or other defects weaken the gear tooth bending resistance effect), there are some stone or metal entered the gear tooth during use, which makes the gear tooth local bending to cause fracture
2.Repairing methods: local welding and inlaying:
1.Welding: at first, rubdown the remained crack of the damage area by hand grinding wheel, clean it with the gasoline or engine oil, heated the area by the welding torch, until to the certain temperature, weld the rudiment with the carbon steel welding rod at the damage area and the rudiment should be 1-2 millimeter higher than the common gear tooth. Send the experienced mechanical bench worker to test the gear tooth sample until meet the demands.
2. Inlaying method: when the slewing bearing the whole gear tooth got destroyed, cut off the tooth at the tooth root, then filing the tooth root to a certain shape, then choose another normal tooth ,machining it to the same shape of the slewing bearing tooth, put it inside the groove, fix and locate with the gear shape model to guarantee the consistency of the tooth distance, welding with the low carbon steel around the tooth. At last, repair the weld seam by the file, and make sure that the gear combination normally.
KEN slewing bearings warranty period is ONE YEAR after delivery.
Slewing bearing common faults mainly contains slewing bearing interval oversize, slewing bearing system move slowly or immobility. System pressure disorder, leakage or the slewing shut off valve doesn’t lock
1.slewing bearing interval oversize
When this situation occurred, we can use the dial indicator to check the interval. If too large, overhaul the slewing bearing, replace related parts to solve this problem.
2.unable to slewing
Hydraulic motor roller plug or bearing got serious damage, the gear reducer or the worm gear damaged, overhaul them. The hydraulic motor output shaft also should be checked to see whether break off, and replace it timely.
3.slewing hydraulic system low pressure
This situation cannot be checked when empty or light load,the sound and the speed all normal. But it will appearance when heavy load, slewing hard or immobility situation will appearance.
4.Slewing hard or unable to slewing.
Hydraulic motor got trouble, the motivate cant output normally, maintain or replace it.
Reducer got trouble, overfill valve、hand control valve got trouble, examination and adjustment.
If overload, recheck the weight and avoid overloading.
5.Leakage
If the hydraulic parts combination surface leakage, it should be removed and cleaned. Using the oil stone or sandpaper to grind the combination surface and using the grinder to process if having suitable condition. If the pipeline screw thread loose, tight it. Replace the seals if damage, if the hydraulic parts body leakage, replace the body or parts.
the first method to solve the trouble is adjustment, which contains two methods: if in the load situation, adjustment should be taken after slewing stopped, until the slewing normal in the heavy load situation. Second is using the pressure indicator, readjust the overfill pressure according to the reference, then overhaul the hydraulic motor and control rod, replace the damaged parts.
Normally the slewing bearings are packed by 3 layers to protect: waterproof film, crash-proof cotton and woven bag.
During transportation, reinforced wooden box and wooden pallet are for optional.
KEN slewing bearings can work 8-10 years in normal conditions, the common Warranty is ONE YEAR after delivery. Each slewing bearing has its steel seal on its body, we will track each process with this series number and find the best solution for customers.
1. KEN special for almost all excavator models slewing bearings, we are more professional.
2. KEN factory directly sales which provide the most competitive prices in the markets, we save each penny for you.
3. KEN offer the shortest delivery time, in stock or 15 days delivery time.
4. KEN provide 7*24 services all year round, Our after-sale service timely and responsibly.
