On this tube is a spring valve which is opened by pressing a lever.
Generally steam from the boiler is admitted direct to the low-pressure cylinder through a reducing valve, and valves and devices are used to prevent the steam so admitted acting as a back pressure on the high-pressure cylinder.
The lower cut is of a skip for either ore or water; note valve in bottom.
Distribution of steam is effected by a slide valve, sometimes fitted with a balancing device, and sometimes formed into a piston valve.
The steam is passed through the valve and emerges at the pressure required generally from 3 lb upwards.