Right,
Allegra 20220 set:
I am calling the car with driver figure the A car..
Motor-blocks at front of A car and rear (cab end) of the B power-car. There are skates on the motor-blocks, and 'brush' pickups on all axles on the A and B cars. The intermediate car does not have pickups on the bogies (at least, as far as I can see from a cursory inspection). I mounted the intermediate car with the pantograph closest to the A car.
A or B car alone, power to track, no response from the units.
A car plus intermediate car (NOTE: the jumper/interconnecting cables will only fit one way round!), power to track, unit will run in both directions, and lighting works.
This makes sense, as the power and track/catenary switches are in the centre car.
The pantographs appear to have a link into the body, but do not respond to direction-changes of the unit. - We are talking analogue here remember. I am not taking them apart, or fitting the Massoth decoder at this time.
The B power-car will not run on it's own. It will run with the intermediate car connected.
Just to be belligerent! I tried 180-ing the intermediate car.. The connectors at both ends of the car are handed the same way, so you can connect it either way round in your formation.
The combination of a power-car and intermediate car will run. The orientation of the intermediate car does not matter to the unit running.
The underside of the intermediate car has holes for a speaker (the power-cars do not) so it would appear you would be on your own if you missed to put a speaker in both power-cars.
(I will copy this into the 'review' thread as well).