The engineering that allows articulated buses to bend

This explains how articulated buses - the familiar “bendy” coaches - were invented and how their joints and drivetrains let very long vehicles navigate city streets. It traces the idea from 1920s experiments (a Dutch Ford Model T with an accordion center), through oddball vertical-articulation examples like the 1937 Alfa Romeo and the Twin Coach in Baltimore, to postwar highway articulations and contemporary preserved examples at the Illinois Railway Museum. The piece notes simple alternatives that still exist, such as trailer buses in Cuba and Munich’s recent bus-trailer combinations, and it uses specific preserved and production models to show how designers solved capacity and routing problems without stacking passengers vertically.

The core technical discussion contrasts four practical approaches: pure trailers, towed trailer-buses, puller designs (front section powered, rear unpowered) and rear-engine “pusher” designs. Puller buses use a robust articulation assembly - front and rear subframes meeting on a bearing ring, a turntable, bellows to seal the joint and flexible cabling - and keep the driven axle ahead of the joint, which aids traction and simpler mechanics but often prevents a fully low floor. Rear-engine layouts move the power unit to the very back to maximize passenger space; that layout turns the front into a trailer and demands additional engineering to prevent jackknifing while still allowing tight turning and vertical compliance.