The GEARLEC & TRACTELEC are generators towed by an agricultural tractor.
A gearbox compensates for the difference in speed between the tractor power take-off shaft and the alternator. The oil gearbox is coupled to the alternators.
Tractelec is towed to the tractor, which can move around, whereas Gearlec is intended to be fixed to the building, driven by the tractor's PTO.