The entire railway is fitted with the rack rail.
On sidings and around the yard at Llanberis, the rack rail comprises a single rack bar,
but on the running line and through all the loops up the mountain,
two rack bars are used, mated side by side, and their teeth staggered by a ½ a pitch difference.
This is one of the major features of the Abt system,
and helps to reduce the shock of the pinions running along the rack.
It also ensures the pinion maintains continuous contact with the rack.
The joints between rack bars are also staggered and align with the sleepers[clarify]
each sleeper supports the rack rail as well as the running rails.

The locomotive pinions engage the rack and provide all the traction and braking effort
- the wheels are free to revolve on the drive axles,
to allow for the inevitable difference between the wheel radius
and the effective radius of the pinion.