Technical Guides for Pins, Bushes & Wear Components

Measure pin diameter at an unworn section with a vernier caliper, then take overall length end to end including any head or flange.

Record the boss width of the bucket ear and the retention method — grease-fed head, keeper plate, snap ring or bolt-on collar. Those four values identify almost any pin.

A knocking sound when the bucket changes direction, visible side-to-side play at the joint and grease escaping immediately after charging all point to a finished bush.

Replace before the bore ovalises. Once the housing is out of round, the repair moves from a bush change to line boring and welding.

Mini excavators typically run 30–45 mm pins, 20-tonne class machines run 65–90 mm, and 45–50 tonne machines commonly exceed 110 mm.

Oversize pins exist to restore fit in a bore that has already worn, saving the cost of replacing the boom or bucket assembly.

Genuine parts guarantee fitment and are worth the premium on warranty machines and unusual geometry.

A premium aftermarket pin machined from correct grade steel and hardened to specification performs identically at a materially lower cost for out-of-warranty fleets.

Missed greasing intervals are the single largest cause. Dry joints run metal to metal and the surface breaks down quickly.

Contamination, mismatched hardness between pin and bush, and misalignment during fitting accelerate wear far beyond normal duty.

Induction hardening gives a hard case over a tough core — the default for most bucket and boom joints.

Through hardening suits smaller pins under uniform load, while case hardening (carburising) is preferred where impact loading is severe.

Sequence matters: assess bore wear, line bore or sleeve the housing, press new bushes, then fit correctly sized pins.

Rebuilding all joints in one shutdown restores geometry and avoids repeat downtime a few weeks later.