This is a view of the coupling between carriages. The pipe on the left hand carriage is the vacuum pipe and it should be connected by means of two hoses to the carriage on the right. Because there is no airtight pipe connection, the brakes on all the carriages will be on. Hence the need to move the brake shoes physically away from the wheels as in the previous photo. I might be wrong in that the vehicles are air-braked not vacuum-braked but the same rules apply. No connection - brakes on!
The net result of this is that the driver is relying on the locomotive brakes all of the time and in the event of a breakaway there would be nothing to stop the loose vehicles. What we noticed at the time was that our carriage bumped back and forth every time the train stopped!