- 24,344
- Midlantic Area
- GTP_Duke
I had the opportunity to watch one of those things in action in the early '70s. It was about the size of the Silver Spade there and it was located in the central Pennsylvania coal region. It was really amazing to watch. I saw it both digging and getting moved. This one didn't have crawler treads - it had sleds that lifted it up, then it would move itself to the other end of the sled.