598 HYDRAULICS AND ITS APPLICATIONS 



into a gun-metal frame C. This valve is kept up to its seat by means of 

 the cylindrical indiarubber spring D, the compression of which may be 

 adjusted by means of the bolt E, while leather sealing rings are also 

 provided to ensure its efficient action. 



The inner end of the working cylinder carries a gun-metal guide 

 ring F, in which works the annular suction valve G. This valve is con- 

 structed with a wooden face let into a channel section annular brass ring, 

 and its range of opening is limited by the rubber ring H, let into the 

 guide ring F. 



The ram R passes through the suction valve, and at its inner end 

 carries a buffer stop S, which mechanically closes the suction valve at the 

 end of the outer or suction stroke. Shock at impact is minimised by the 

 provision of cylindrical rubber springs at J and K. A series of removable 

 brass liners L between the ram and the buffer permit of the latter being 

 adjusted so as to take up any wear in the buffer itself or in the suction 

 valve. 



The delivery valve is thus automatically regulated, while the suction 

 valve is mechanically operated only so far as affects its closing at the end 

 of the suction stroke, this valve being both opened and closed on the out- 

 stroke of the ram. On the in-stroke, water is delivered against the 

 resistance of the delivery valve into the annular chamber M, from which 

 it flows away through the pipe N into an air vessel and away to the 

 discharge. The chamber M is fitted with a starting valve at 0, 2 inches 

 in diameter, so that in starting the pump the pressure may be relieved 

 and the pump started light. The small spindle valve P allows of water 

 passing from the chamber M into the working barrel, so that if for 

 cause sufficient water cannot enter through the suction valves, more wat 

 may be allowed to enter through the valve P, so as to enable the pump 

 to run without shock. 



A small compound air pump, having a high pressure plunger 1 j inchc 

 diameter by 1*8 inches stroke and a low-pressure plunger 3 inchc 

 diameter by 2'7 inches stroke is provided, and is worked directly froi 

 the crank shaft of the main pump, exhausting air from the suction 

 vessel and discharging it into the delivery air vessel. 



Should the air supply in the suction air vessel be insufficient, more 

 be admitted through a small valve ; while should the air pump deliver 

 great a supply, the surplus air can be let out of the delivery air vessel. 

 Tests carried out on such a pump as described, 1 showed a combine 



1 By Mr. John Morris. See a paper on the " Un watering of the Achddu Colliery." Trar 

 Tnst. of Mining Engineers, Vol. 30, part 2, p. 131. 



