Pitheadman was a common Scots description for the man charged with the unloading of cages (full tubs of mineral) and weighing of the mineral. Elsewhere in the UK this role was often known as the Banksman (a phrase still used in civil engineering for the guy responsible for directing loaded aggregate lorries and collecting delivery tcickets)
On the one hand this might be seen as a menial labour organising and shoving full tubs of coal, ironstone etc & empties about and keeping basic records ......... in reality it was one of the key rolls in most 19th century and early 20th century collieries where colliers were paid by 'piece work'
Banksman or Pitheadman featured often in disputes as they were employee of the colliery owner, hence the emergence of check-weighmen acting on the behalf of the colliers.
http://binged.it/15RtxOh and cross reference with www.old-maps.co.uk ]
In 1911 he could have been employed at any number of pits in the immediate area (perhaps Cairnhill Coal Co @ Rawyards, Drumshangie Coal Co. Ltd @ Drumshangie, Monkland Glen Coal Co. Ltd., Rochsoles Coal Co., Rochsoles, New Monkland, etc)
At 1915 living in Bargeddie I suspect the only collieries in the immediate area he might be employed would be the Kirkwood Collieries. This was a time when a series of contractions in the coal mining industry in North Lanarkshire resulted in many pits being abandoned simply because they couldn't cope with additional pumping duty required due to inter-connected workings.