GP300 Eccentric Bushing E28/E36 (MM0227358)

Metso GP300 Eccentric Bushing: MM0227358 Replacement

The Eccentric Bushing (Part No. MM0227358) is the critical sacrificial interface in the Metso GP300 cone crusher. It resides within the eccentric assembly and supports the radial load of the Main Shaft. Unlike steel components, this part is engineered to be softer than the shaft it protects. It acts as a fuse: in the event of overload or lubrication failure, the bushing sacrifices itself to prevent catastrophic damage to the expensive Main Shaft.

We manufacture this component using ASTM B505 C93700 High-Leaded Tin Bronze via a Centrifugal Casting process. This method ensures a dense, porosity-free grain structure, which is essential for withstanding the high hydraulic crushing pressures of the GP300 series. Standard sand-cast bronze often contains hidden voids that can lead to premature cracking under load.

Metallurgy: Why Bronze, Not Steel?

For the GP300 eccentric application, material properties are balanced between strength and lubricity:

• Anti-Seize Properties: The 10% Lead content in C93700 acts as a solid lubricant. If the oil film momentarily ruptures (e.g., during a power stop), the lead smears onto the shaft, preventing the bronze from welding to the steel.
• Embeddability: The moderate hardness (70-100 HBW) allows abrasive particles (like silica dust) to embed into the bronze matrix, preventing them from scoring the polished surface of the Main Shaft.

Field Diagnosis: When to Replace

Replacing the eccentric bushing is a strategic maintenance decision. Watch for these signs:

1. The “Burnished” Look
Inspect the inner bore during liner changes. A healthy bushing has a matte bronze finish. If you see mirror-like, highly polished patches (Burnishing), the bushing has overheated locally and lost its ability to hold an oil film. Replacement is imminent.

2. Counter-Rotation (Spin)
If the crusher head starts spinning rapidly in the opposite direction of the drive when empty (no load), it indicates that the bushing clearance has tightened due to thermal expansion or deformation. This “clamping” effect will overheat the oil rapidly.

3. Metal Flakes in Filter
Large, non-magnetic bronze flakes in the return oil filter are a clear sign of mechanical delamination. Stop the crusher immediately to save the shaft.

Installation Best Practices: Cryogenic Fit

Installing the MM0227358 requires precision to avoid distorting the bore:

1. Cryogenic Cooling: Do not press-fit this bushing at room temperature. Cool the bushing to -50°C using Dry Ice or Liquid Nitrogen. This shrinks the OD by approx. 0.08mm, allowing it to drop into the eccentric assembly freely.
2. Alignment: Ensure the oil feed holes align perfectly with the eccentric casting’s oil galleries. Misalignment here guarantees instant failure.
3. Stabilization: Allow the assembly to return to ambient temperature naturally before installing the Main Shaft.

Compatibility

This part is a direct dimensional replacement for:

• Metso Nordberg GP300 Cone Crusher
• Metso Nordberg GP300S Cone Crusher
• OEM Part Reference: MM0227358

Performance Upgrade

[Expert Warning] Never use steel or hardened alloy bushings in this position. While they are “stronger,” they lack the embeddability and anti-seize properties of leaded bronze. A steel bushing will destroy your Main Shaft within hours of operation. Stick to the OEM-specified C93700 Bronze.