Bendi came up with the principle articulated design in about 1982. Their first truck was an electric RWD and it was this principle that was first patented. Articulate trucks are the reverse of conventional machine with regards to the stability triangle. They get their stability from having more weight at the rear of the truck per say than an equivalent capacity counterbalance. The net effect of this is that most of the weight remains at the back even when loaded so RWD is the most effective solution for traction/braking. Aisle-Master built their first gas machines as front wheel drive to avoid patent issues but the its traction was compromised so a later collaboration with Bendi allowed Aisle-Master to use Bendi's 4WD patent and built trucks with four separate drive motors. After a split between Bendi and Aisle-Master in 2004, Aisle Master had to either revert to the twin front wheel drive or come up with another solution and they chose a three motor option to avoid the patent issues, missing out one of the rear drives.