How deep, how long
In 1950s Britain a coal shaft went down at 30-60 metres a month, so a 600 m shaft meant ten to twenty months of continuous sinking — and then about a year of lining and equipping. Depths in the northern English coalfield ran from about 300 m to the 619 m of Kellingley No.1 in North Yorkshire, the deepest coal shaft in Britain. This page follows the whole job: the sinking sequence, the dimensions, the failures and the winding gear that turned a lined hole into a working mine.
| Measurement | Typical value | Where it applied |
|---|---|---|
| Shaft depth | 300-620 m | Northern coalfield shafts generally |
| Deepest shaft | 619 m (2,031 ft) | Kellingley No.1, North Yorkshire, 1958 |
| Sinking rate | 30-60 m per month | British collieries, 1950s |
| Main shaft clear diameter | 5.5-7.0 m | Winding shafts |
| Ventilation shaft diameter | 3.0-4.5 m | Ventilation and return shafts |
| Headgear height | 25-40 m | Above ground level |
| Cage load | 1.5-3.0 tonnes | Two or three tubs per lift |
| Water pumped | 500-2,000 gal/min (2,300-9,500 L/min) | Larger pits |
From the first head drift to a fully lined and equipped winding shaft, the job ran in a fixed order, and each stage had its own crew and its own clock.
Sinking was a continuous operation, not a series of campaigns: once the head drift was opened and the first drum cut, the crew stayed on the face until the shaft reached its level. At 30-60 m a month, the 1950s norm in Britain, a 300 m shaft was five to ten months of sinking and a 600 m shaft ten to twenty.
The lining chased the face down. Concrete rings were cast on the surface and lowered as the shaft advanced, roughly a metre of lining for every five to ten metres sunk; after 1950 concrete was steadily replacing the older timber and cast-iron segments in British collieries.
Water decided the pace more than any other factor. Larger pits pumped 500-2,000 imperial gallons a minute — 2,300-9,500 litres — first by steam and then by electric pumps, and a sinking that outran its pumps stopped until the water was mastered.
Divide the depth by the sinking rate — 30 to 60 metres a month in 1950s Britain — then add about a year for lining and equipping.
The arithmetic is simple: months of sinking equal the depth divided by the monthly rate. At the fast end, 60 m a month, a 300 m shaft took about five months; at the slow end, 30 m a month, the same shaft took ten.
Kellingley No.1 in North Yorkshire, about 619 m (2,031 ft) and the deepest coal shaft in Britain, sat at the top of the range: at 1950s rates that depth alone represented roughly ten to twenty months on the face before equipping began.
The sinking figure is never the whole job. Lining and equipping — hanging the guides, cabling, installing the cage — often took another year after the last metre was cut, so a deep shaft was a two-year undertaking from first sod to first coal.
A main winding shaft was 5.5-7.0 m across inside the lining; the ventilation shaft was smaller at 3.0-4.5 m.
Main winding shafts were generally 5.5-7.0 m in clear diameter — the measurement inside the lining — and the cage that rode the guides was about 1.8 m wide. The clear figure is what mattered: it fixed the size of the cage, the tubs and everything that ever went down the pit.
Ventilation shafts were smaller, commonly 3.0-4.5 m, because they moved air rather than coal and men. Even so, a working mine needed at least three shafts — one for the incoming cage, one for the outgoing and one for ventilation.
A two-shaft colliery was a deliberate rarity, not a norm. Ventilation needs scaled with the coal output, and a pit raising 1,000-2,000 tonnes a day could not push the required air through a single return.
Three dated points anchor the figures on this page: the 1950s rates, the 1958 depth record and the post-1950 lining change.
Period values for the northern English coalfield — depth, rate, diameter, load, water and tower.
The figures reflect commonly published values for British colliery practice of the 1950s and the recorded 1958 depth of Kellingley No.1 shaft.