I started my apprenticeship in 1967 one of my first jobs was to help clean and prepare a platypus tractor for reuse. It had been parked outside for many years and was to be used to pull lengths of steel pipe into place during a pipe-laying contract. We were told these tractors were often used for moving aircraft on poor ground. If I remember correctly the tractor had 4 gear sticks, due to the number of gear ratios available. When in low ratio at mid range RPM the tractor would barely move, while in high ratio it would throw muck up in the air off the tracks. It left South Wales for the Midlands and never returned.