Waddle fan

They were noteworthy for their extremely large size and distinguished by an integral shroud for the fan, which makes it possible to mount them in the open air.

As high speed fans driven by electric motors became more common, Waddle failed to make this transition.

A typical installation comprised a pit head building, usually built of stone at this period, with a fan engine house alongside it.

[5] Although small fans of this form are common today, Waddle were the only company to make them of this size, or for mine ventilation.

As the fan impeller formed its own shroud, it required little additional installation and so was relatively easy to retro-fit to an existing pithead.

An 1896 fan at Chanters Colliery, Tyldesley, Lancashire, was of the same overall dimensions and speed, but moved 150,000 cu ft / minute.

These ran at higher speeds and so the large diameter fan was unsuitable, as its high linear air velocity at the rim led to turbulence and mechanical vibration.

[8][9] This was an unusual example of a double-sided Waddle fan, built to provide a higher draft pressure difference.