longwall mining




Cutting Machines - Shearer Cutting Drums and ancillaries



Cutting Machines - Shearer Cutting Drums and ancillaries

Shearer Shearer drums are not continuous cylinders but have a small diameter central section with scrolls or vanes from there to the full diameter, the picks being attached to the outer edges of the scroll. The pick lacing is set to optimize cutting for the seam being worked, while the vanes are used to move the coal efficiently from the cutting area onto the AFC. Inefficient loading will lead to a lot of the power applied to the drums being wasted in churning and crushing coal already cut in the drum area. The pick design is also important to maximize efficiency in cutting and avoid wasting power in this process.

Another device used to improve coal loading is a "cowl". This is a curved steel plate mounted on supporting arms so that it sits behind a cutting drum to prevent coal passing from the back of the drum into the area where the web has been cut, the coal being forced to move sideways towards the AFC instead. The cowl is fitted with a motor and drive pinion so that the cowl can be rotated from one side of the drum to the other when the cutting direction is reversed.

Some shearer drums now have a hollow shaft venturi ventilation system design to ventilate the area on the face side of the drum while cutting, thereby preventing a possible ignition of gas given off in the cutting process.

High pressure water is directed through the drums to the picks for dust suppression and pick cooling purposes, including water which has been used for cooling the shearer motors. Additional sprays are also fitted on the shearer for dust control, often acting as curtain sprays to keep dust on the face side of the shearer away from personnel rather than actually trying to settle the dust.