Construction equipment wear and damage

Bearing/Bushing fits on rotating construction equipment get worn and damaged when bushings/bearings fail.

Multiple clients requested us to find a method and material to repair a Pivot Shaft after the OEM indicated it was not feasible. In working with several customers, we developed an inspection and repair program based on returning the Pivot Shafts back to original dimensions.

The situation

Bearing/Bushing fits on rotating construction equipment get worn and damaged when bushings/bearings fail. Large dozers move significant amounts of earth, and to do so they have rotating components that experience high wear and load during service. In many units, there is a shaft that runs through the frame called a Pivot Shaft. The 6 bushing fits can get damaged and the OEM recommends undercutting and using undersized bushings. This increases inventory for end users and the risk that during service, the Pivot Shaft may have been modified and the service technician does not have the right size of bushings.

The task at hand

Multiple clients requested us to find a method and material to repair a Pivot Shaft after the OEM indicated it was not feasible. In working with several customers, we developed an inspection and repair program based on returning the Pivot Shafts back to original dimensions. We developed a laser process and new material with high hardness/toughness to provide improved performance vs. the parent material.

The action plan

We recommended a new laser technology. This technology would not introduce traditional ‘welding heat affected zones’ and therefore the Pivot Shafts would not break during use.

We developed a new SS alloy that has a Rc 55 – 60 hardness and excellent wear resistance.

For the bushing fits, we finished them to original equipment manufacturers dimensions and tolerances. Requested that customer(s) installed and inspected hourly services and we were involved in the inspections. We applied the new material to several sizes and models of Pivot Shafts.

The results

Over a 2 – 3 year period, we have found that the bushing fits were not wearing down during use. The bushings were wearing down normally. The bushing fit dimensions/tolerances were the same upon service as they were after repair. There was no change!

The cost to apply this new technology and material was 40 – 70% of the cost of new fits. Our customers are anticipating they will get 10 years of service life now compared to the 2 to 4 years on a new shaft. Our new technologies resulted in very large cost savings and maintenance cost savings. Depending on the customer and the number of hours of use, this cost savings could be seen over 1 to 5 years.