Vehicles are equipped with proprietary couplings front and rear. The front coupling (called a PowerBar) retracts when not in use to conform with crash safety requirements. Soft longitudinal springs and dampers are used in the PowerBar to minimise jolting while coupling up, and to give a smooth ride in the train.
Once connected, the couplings are able to transmit multiplexed data as well as power down the length of the train. Any combination of vehicles is possible: a vehicle is classified as an engine when only the rear coupling is connected. (This provides a failsafe mode should a coupling fail in a train) The driver of an engine has control over all the following connected vehicles; their steering, accelerator and brakes are disabled after completing a systems check in a handshake routine while coupling up. An emergency brake activated by the parking brake may however be activated while in the train.
The intelligent coupling permits optimal operation of the train. Some benefits:
acceleration and braking are modulated to give a smooth ride The engine can transmit instructions to each vehicle according to its position in the train. This allows the most energy-efficient acceleration/braking/turning parameters to be used. tight turns are possible because vehicles follow each other's tracks (unlike a dumb towbar) The PowerBar geometry, combined with the control software, limits jack-knifing and provides good crash protection by controlling angular accelerations.
A small multifunction display in each vehicle shows train data such as:
The vehicle's position in the train Position on satnav map Trip origin/current destination Elapsed time/time to destination
Communication between any vehicle is possible by means of a dedicated interface. Commercial engines would also transmit relevant reports to each vehicle in a train.