|The Ingersol Rand 'ES'
class compressor. This was the model that replaced the earlier four head
system from 1880. On the nearside is the flywheel and the larger wheel
was the belt drive from the turbine. The 'plate' valves can be seen
around the compressor head with the free air unloader valves. These
valves were held open by compressed air to allow the air in the cylinder
to move freely until the machine reached running speed. The outlet is the open hole on
the top which delivered the air to the receiver just outside the