Reseating / Isolating Bearing Bushes
Common Defects
Excessive movement of bush within housing caused by – electrolytic corrosion or impact wear.
Preparation
All work should be carried out in strict accordance with the relevant ThistleBond Technical Data Sheet. The product selection and application techniques should be based on the nature and severity of the damage and the application technique. For in situ repairs a work area must be created in order to protect the repair area from the weather conditions. It may also be necessary to control the temperature within the work area in order to reduce humidity and prevent condensation. Specific attention should be given to the method used to align and centralise the bearing bush within the damaged housing and consequently jacking bolts, shims, jig or mandrel must be prefabricated. The techniques described below can beused to rebuild, realign and electrically isolate types of bearing bush housing, including,
Rudder Bush Housing, Internal Stern Tube Bush Housings, A Frame Bracket, bush Housings, Stabilizer in Shaft Bearing Bush Housings, Oversized Cutlass Bearing Housings.
Surface Preparation
Wash down all components to be treated with UPS TAC 883 Universal Cleaner to remove all dirt, grease and other surface contamination. Coat the entire surface of a new bearing bush or cutlass bearing and all centralising and aligning equipment with a minimum of 2 coats of UPS TAC 872 Release Agent to prevent bonding.
Grit Blast the internal surfaces of the damaged Housing to give a surface finish of Swedish Std Sa2½ ensuring a profile of 75 microns minimum using angular abrasive. On completion of all preparation, rewash all blasted surfaces with UPS TAC 883 Universal Cleaner.
Application Technique
There are two techniques available for rebuilding Housings.
▪ Slip Method
▪.Injection Method
Mix the selected ThistleBond Product (please use appropriate product depending on enviroment) UPS 105 EG Metal Repair Paste (TR1025, UPS 115 XL Extended Life Metal Repair (TR115), UPS 200 EG Ceramic Repair Paste (TR200) or UPS 230 EG Urethane Ceramic Paste (TR230). Then using the flexible applicator provided apply a thin, even film to the prepared inside surface of the housing and also to the outside surface of the liner or bush. Ensure the product is pushed well into the prepared surface of the housing. Apply further material, in excess to the internal surface of the housing. The liner or bush must then be jacked into position in the housing and correctly aligned. Any excess product extruded during the assembly should be removed immediately.
The liner or bush should be aligned with the housing. Seal the annular space between the bush and the housing where required, to prevent loss of product during the injection process. This may be done by mechanical means or by the use of the UPS 19065 RG Rapid Grade Metal Repair (TR19065) a fast curing ThistleBond Product. Injections holes should be carefully positioned together with the vent holes to prevent formation of the air traps ideally, injection points should be spaced no more than 24” apart. The selected product should be loaded into disposable injection cartridges and injected using pneumatic equipment. The application should progress from the lowest injection point to the highest injection point. Material is injected until it is exuded from the next highest injection point. This process should be continued until the annular space between the bush and the housing has been completely filled with the product indicated by leakage of the product through small vent holed drilled at the highest point available.
