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PREVENTING CREEP IN SUBMERSIBLE PUMP BEARINGS

Submersible pumps are commonly used in various industries such as construction, mining, wastewater treatment, agriculture, and general manufacturing. Typically, these pumps consist of a vertical electric drive motor that is directly connected to the impeller, and they are designed to operate for long periods with minimal maintenance.

BEARING ARRANGEMENT

The bottom bearing, also known as the locating bearing, usually consists of a double-row angular contact ball bearing or a pair of angular contact bearings, which are responsible for supporting the axial and radial loads generated by the pumped fluid. Since the bearing is subjected to heavy loads, it is important to select the appropriate bearing to achieve the desired service life. On the other hand, the top free bearing is generally a deep groove ball bearing that takes a light radial load. Typically, C3 clearance is used to compensate for the reduction in clearance caused by the heat generated by the electric motor.

CREEP PHENOMENON IN TOP BEARINGS

The lightly loaded top bearing is expected to have a long service life. However, sometimes, its life is significantly reduced due to creep. The combination of a light radial load and a loose fit in the housing can result in relative slippage between the outer ring and the housing. Creep is a phenomenon where surfaces that fit together move relative to each other, resulting in a polished bearing ring surface, which may be accompanied by scoring or wear.

COUNTERMEASURE

One popular countermeasure used by pump manufacturers is to machine an annular groove in the housing bore and insert an O-ring to prevent creep between the bearing's outer diameter and the housing.

NSK SOLUTION

NSK offers Creep-Free bearings that provide better creep prevention with their integrated double O-rings. These bearings offer submersible pump manufacturers the following advantages:

  • Excellent creep prevention.
  • Easy assembly as the Creep-Free bearings can be fitted with a loose housing bore tolerance
  • Reusable housing as very little abrasion occurs on the housing bore.
  • Cost savings as pump manufacturers do not need to machine a groove in the housing bore and insert their own O-ring.
Download NSK Pump and compressor bearings Brochure:


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