Application Hollow pin (step pin) used in a high rise escalator.
Failure mode The pin pressure faces have suffered from severe galling where the surfaces have articulated and fused together.
Diagnosis The very high pressures experienced by these high rise escalators have led to squeeze-out and failure of the lubricant allowing the surfaces to touch and gall when the chain articulated.
Solution Use high quality, high pressure lubricants and ensure that the lubricant regime is such that the film of lubricant is constantly maintained between the surfaces.