Warman Slurry Pump Bearing Inspection and Replacement
Slurry Pump Bearings, whether new or re-used after overhaul, should be correctly packed with grease when fitted to the Bearing Assembly. It is recommended that a systematic monitoring program be implemented to determine the following maintenance parameters:
• if grease addition is required between Bearing Assembly overhauls
• frequency of grease addition, if required
• quantity of grease addition, if required
Recommendations regarding amount and frequency of grease addition depend on slurry pump speed, and are indicated in the appropriate issue number of Part 3 of the Instruction Manual, corresponding to the particular type of Bearing Assembly fitted.
A typical monitoring program is briefly outlined below for a number of slurry pumps having identical Bearing Assemblies.
(i) Commence the program by monitoring two slurry pumps having bearings newly overhauled, and correctly packed with grease.
(ii) After a specified number of operating hours (depending on the slurry pump duty and environment), dismantle the Bearing Assembly of one slurry pump, and inspect the Bearing condition, and distribution of grease in the bearing cavity.
(iii) Determine if grease addition was required at the present inspection interval for the observed Bearing. If grease addition was not required, assess if the second Bearing can be safely run, without grease addition, for twice the operating time of the inspected Bearing.
(iv) Repeat this procedure on the remaining pairs of slurry pumps, in turn, until the maximum recommended time interval between grease addition is determined. Depending on the type of slurry pump duty, it may be possible to run slurry pumps for the life of wearing parts without re-greasing Bearings.
Adopting a monitoring program similar to that described above should enable Bearing contamination to be prevented, while minimising maintenance requirements.
It is recommended that a spare Bearing Assembly be carried in store for immediate replacement of each operating Bearing Assembly as overhaul falls due. The worn Bearing Assembly may then be reconditioned in the workshop, and returned to store ready for replacement of the next Bearing Assembly due for overhaul.
With appropriate maintenance procedures, deterioration of Bearings should be detected during routine maintenance overhauls before malfunction becomes evident in slurry pump operation.
If, during routine maintenance overhauls, any doubt exists as to the capacity of any Bearing to survive until the next overhaul, the Bearing should be replaced. Early replacement of a Bearing may prevent a failure which could otherwise directly result in costly damage to other slurry pump components.
(a) When to Replace Bearings
Bearings should be replaced if any of the following indications of wear are apparent:
• A shoulder is detectable at the edge of the rolling track.
• Excessive slackness, or burrs, are apparent on the cage.
• Roughness or pitting is observed on rollers or rolling track.
It is normal for the rolling track surface to be darker than the non-contacting surfaces of the Bearing races, and this appearance by itself does not indicate deterioration of the Bearing.
(b) Removal of Bearings
Bearing Assemblies should be carefully dismantled to avoid damage to slurry pump components. When driving Bearing cups from the housing bore by force applied from the Shaft and rollers, the Shaft should be held firmly in the direction of load to eliminate slackness, and minimise impact load between the rollers and Bearing cup surface.
As Bearing components are removed they should be identified with suitable tags, so that if re-used they may be replaced in their correct position.
If Bearings require replacement, they should be removed by a press or bearing puller applying load directly to the Bearings and Shaft end.
If part of a Bearing requires replacement, the complete Bearing must be replaced. It is not acceptable to mix new with worn components within a single Bearing unit. A new Bearing may be fitted together with a used Bearing at the other end of the Bearing Assembly. However it is normally considered better practice to renew both Bearings concurrently.