STUDY OF TRUNNION CAPS

Sammanfattning: This thesis compiles information of a kind of bracket named “Trunnion cap” which is used at some of the loaders and trucks that are developed at Atlas Copco Rock Drills AB in Örebro, the information is needed to create a technical guideline for design of new trunnion caps. The thesis is limited to investigate trunnion caps that are used to attach steering cylinders on six different vehicles, MT436B, MT5020, MT6020, ST1030, ST14 and ST1520. It investigates what angles the force generated by the steering cylinders acts from, which varies from a range of 6 to 96 degrees depending on which vehicle and frame it is. The forces generated by the steering cylinder have also been calculated regarding the maximum pressure which is between 21,5 and 30 MPa for the different vehicles. Any kind of useful information from customers has also been searched partly by asking employees at Atlas Copco customer centres around the world if they are aware of any occasions were trunnion caps or bolts to trunnion caps have broke down. The results indicate that no problems exist today and that old problems had to do with lack of service. Even the internal databases for service reports have been searched for failures that regard parts to trunnion caps but no relevant information was found. The tolerances for the holes in the trunnion caps and to the pins that are assembled to the trunnion caps has also been identified with a result that vary, some assemblies have a tight fitting while others have a loose fitting. Finally has the availability of bolts with property class 8.8 and 10.9 been investigated where it has been noticed that the lead time for bolts with property class 8.8 more often is shorter than it is for bolts with property class 10.9.