Basically as described above, the units were meant to operate as a self contained unit, a generator vehicle [in Scotland it was a 12cyl Rolls Royce engine and it made a very nice noise at full throttle], the generator powered the emergency winder unit [winch].
All mines had to have a periodical emergency test, there was a dedicated position at the shaft side where the winder was anchored to the ground, the rope threaded over a pulley and a kibble lowered down the shaft.
The kibble was a bucket that held 4 men, and that was a bit of fun from the routine having a trip down the shaft in the kibble.
These units were immaculate and a credit to the maintainers, we only got to play with it during the test.