Mercedes Benz O405G/GN and other variants, including Citaro G
that is in production run now are rear 'section' powered, so these
are coined 'pusher type' bendy/articulated buses.
Volvo B10MA/B12MA are front section powered, by the middle axle,
so they have a true technical trailer (non-powered rear).
The 'pusher's' mechanism is with a rear section chassis, then
the 'turntable' which features a joint, a turntable for passengers
to stand/pass by on, and underneath to run cables and finally to
transmit the forces (thrust) to the front portion via the front
section chassis, to 'push' the front section and move the bus.
How the electronics work? Wires are run underneath the bus, and
through the joint area. Batteries and computer(s) are on the front
section. For the Mercedes 'pusher' type bendy, fuel tanks and lines
only restrict to the rear section. Air conditioner condenser/fans
are fitted on each section. The front of a O405G has a underfloor
storage area. Hence the vital components are spread out on the
bus.
Note the use of 'section' and 'trailer' are to avoid confusion.
A rear section powered vehicle would technically have no
'trailer'.