Wagons loaded with coal for export were shunted onto 'loading' sidings which ran in a gradual slope down towards the coal hoist approach, allowing the coal tipper to bring a wagon forward under its own gravity and to control its travel by using a brake stick. A small hydraulic capstan was on hand to be employed if a coal wagon was 'reluctant' to move forward and, if required, a turntable enabled the wagon's end-door to be lined up ready to proceed onto the hoist platform. There were also two separate weighbridges - one to weigh full wagons in and another to weigh empty wagons out. The standard mineral wagons were 16 ton capacity but later 21 ton wagons were introduced.
The chute of the coal hoist would be adjusted to suit the height of the ship below, and its nose lowered into the ship's hold. The chute could be manoeuvred slightly to the left or right as required. The hoist platform and the coal wagon would then be raised level with the top of the chute and lifted at an angle so that, when the wagon's end-door pin was struck out, the coal was delivered onto the chute and into the hold of the vessel below. After the coal had been tipped, the hoist platform would be lowered and the empty wagon directed onto the 'empty' road, which ran off on a slight downwards slope into sidings away from the coal hoist.
Three of the Kings Dock coal hoists were fitted with a device called a 'Norfolk Spade', a hydraulically-operated digger which could be used to shift damp or frozen coal from a wagon when it would not tip out of its own accord. This was operated by two rotary three ram engines.
Also available for use on a number of hoists was an anti-breakage device known as a 'Hancock Escalator', a vertical assembly of an endless chain of trays suspended in front of the hoist's chute which allowed coal to descend under its own weight down into the ship's hold.
From notes provided by Viv Howells, Mechanical Engineering Supervisor, Swansea & Port Talbot Docks