Looking at an old HG OC3 edition of HPOCA mag, there is a section where an Oliver sales documents shows that the INDustrial version of OC3 had a 'rolled back' feature.
What does this mean? Someone mentioned to me that they thought it was something to do with placing more weight toward the back of the machine to counterbalance the addition of a front-end loader or heavy-duty backfill blade.
Thanks... (also posted on YT Oliver forum)
The HG was originally designed to pull with a drawbar. As loaders and blades became popular they put too much weight on the front of the tracks which damaged the front idler and roller. The factory moved the frame "back" relative to the undercarriage to move the weight to bear more evenly on the tracks. They did this by rotating the axle housings one stud on the transmission bringing the rear sprocket (and track frame) forward. It's easy to spot a "rollback" crawler. The rear sprocket is forward of the axle, the track support & spring attach to the frame below the starter instead of the bellhousing and the front of the tracks are forward of the grill. A different track support arm was used to accomodate a different bolt spacing on the frame.