Project Description : Roller Rehab Bridge Bearing Service , 21th April, 2018.
Bearing rust removal, internal cleaning, painting, greasing and oiling. Mark bearings to gauge future movement and report on service and any defects identified.
Bearings are generally dry, rusted and covered in dirt and plant life.
A slide plate bearing at the start of the truss which has the lead based undercoat showing through. Slide bearings are very dry and required high pressure cleaning to clear out oiling and greasing points before being lubricated with a combination of penetrating oil and grease.
The bottom chords on both sides of the bridge are heavily rusted due to debris and pigeon faeces which accelerates the rusting process. These chords require urgent cleaning and application of an anti corrosion coating.
The bearings were pressure washed with water only (no abrasives). When set at the right pressure rust and top coat is removed leaving the lead undercoat.
The crack on pier 14 bearing bed plate can be monitored to see if it is operable. The most likely cause of this crack is lack of lubrication.
The bearing on pier 22 (left ) is inconsistent with the bearings on Piers 20, 21 and 23 (right) The slotted hole that allows longitudinal girder movement is not visible on the top image and visible on the other three. This may be due to bearing seizure or simply the positioning when the girder was set on the bearing. All bearings have been marked and will be monitored to see. ARTC staff have flagged the possibility it is seized. After cleaning heavy oiling and greasing we are confident it will be free.
Once pressure washed externally and internally, we oiled the bearings. Here the oil is pumped into the slotted hole and appears at the join of the bearing bed plate. This way we are satisfied the bearing has been cleaned sufficiently. The oil was left to penetrate for a day before painting and greasing commenced.
The bearings were painted and marked to gauge future movement.