With a very loud rumbling and rolling noise this Cat 247B rolled into the workshop.
The hour meter has been replaced once before , giving this machine a total of 1551 hours
After washing the machine down and careful inspection we found two major problems.
1) Cracked main drive beam
Notice where the crack is along the main drive beam.
Just in front of the track drive motor's main support.
Nathan removes the water tight bearing cover to inspect the front idler wheel bearing.
Closer examination reveals that the bearing cover was not so water tight after all.
In fact the bearing has collapsed completely.
It looks as if the water proof cap has been leaking for some time.
So many of the idler wheels have much to much play, so the owner gives us the go-head to remove both track drive beams and their idler wheels.
Nathan inspects the seized suspension arms , something that most probably contributed to the cracking of the drive beam. With seized bushes the poor beam had no movement when loaded up and so bent like a bow.
Next thing the weakest point fatigued and then cracked through.
It was a fair challenge to remove the track drive beam from these seized control arm shafts.
2) The second problem.
Many of the idler wheels were seized or very sloppy on there shafts.
Contamination was the cause, through the bearing cap and also the seal on the inside of the wheel.
Dirt captured between the wheel and the thrust washer had ground the seal away. This allowed sand to enter the bearings and destroy the wheel and bearings.
All the damaged beyond repair idler wheels.
Once the inner shoulder is worn away by the thrust washer, the seal cannot be retained in it's housing.
This calls for a new idler wheel assembly, nice one Cat.
After grooving and welding up the crack with low hydrogen rods , a flat bar was bent to fit the drive beam.
This was welded into place and then the beam was heated to release the welding stresses in it.
The long and tedious job begins, fitting all the idles wheels and bearings to the drive beams.
Genuine Caterpillar packaged parts were used and are the beast way to go.
Notice the seal held in place by the circlip.
Many of the idler wheels had to be replaced because the lip for the circlip to locate in had worn away.
Two drive beams completely assembled and ready to be fitted to the Cat 247B.
Notice the suspension control arm shafts have been greased up with red grease and now will move freely in the drive beam bushes.
An ingenious upgrade was devised to facilitate the greasing of the inner bushes.
Track drive motors fitted, tracks replaced and tensioned, and away we go!
Big job, big rewards.
