For ascending and descending the mountain,
the carriage is not coupled to the locomotive, as gravity keeps the two in contact.
Not being coupled also prevents a carriage being dragged down the mountain
if a locomotive derailed, as happened in the opening day accident.
Couplings are used during shunting operations as the yard is on level ground.
An electric cable is run between the locomotive and the carriage,
which enables a buzzer to be used to signal between the driver and the guard.
The cable is designed to pull free if the locomotive and carriage separate.

It was originally intended that each steam locomotive push two carriages to the summit,
but this has not been normal practice since 1914.