Water lifting pump
Bucket pump installed at York Building's water works
The York Building waterworks were equipped with two pumps — one suction pump and one forcing pump — that were installed close to one another and being connected to the same beam of a steam engine. The suction pump was depicted around 1775, but it may have been built as early as 1736. It had exactly the same components as a typical mining pump comprising a bucket O, a working barrel MM mounted on its windbore and a clack-piece N with a clack n fitted into it. This type of pump, known as a jack-head pump, raised the water during the engine's working stroke.
The rod steered the piston downward during the steam engine's downstroke. The piston's upper surface was equipped with valve flaps, which were pushed upward by the pressure of the water below the piston. This allowed the piston to descend with little resistance. The valves closed once they reached the bottom of the stroke as a result of their own weight. The water above the piston's pressure kept the valves closed as the upward stroke began. Because it was unable to escape, the water above the piston was forced upward.
In order to be tightly fitted through a collar of leathers at Q in the cover that closed the top of the pump, a pump-rod or bucket-shank was made cylindrically. A jackhead piece R S was attached to the top of the working barrel M with a flange and screw bolts. A pipe S extended horizontally from it to convey the water away. This pipe S was connected to another pipe T, which turned upwards and served as the foundation for a perpendicular column of pipes V that rose all the way to the cistern at the top of the tower.
A flat cover or circular lid was screwed onto the top flange of the jackhead piece R S at Q. The polished pump-rod p passed through a small tube in the center of this structure. The upper portion of the tube was made larger to accommodate leather rings that were placed around the rod and embraced it so tightly as to prevent any water from escaping by the rod. A hard wood plug with holes that was precisely sized to fit into the enlarged part of the tube held the leathers in place. The plug was screwed down by three or four screw-bolts that passed through a small flange protruding at the top of the nozzle, Q. The wooden plug was pressed firmly against the leather by a flat circular plate that was also perforated in the center to admit the rod through it.
Calculating the required power of a steam engine
It was assumed that the greatest possible velocity during a stroke occurred when the resistance of the water in the pumps was equal to the counterweight of the steam engine. Taking into account further considerations such as that the arms of the beam be of equal length, the ascending and descending strokes should be made at equal times, the motion commences with an excess of power, which diminishes with the increase of resistance, considerations become uniform, the areas of the passages of the valves are only half the area of the pump, and the mass of matter moved is twice the excess of moving force, the maximum stroke length per minute should not exceed 98 times the square root of the length of the stroke. On the other hand, a pump's stroke should not be longer than eight feet; otherwise, the bucket or piston will leak too much water. Given the length L of the stroke in feet and the diameter D of the pump in inches the quantity of water a pump in the best order delivers at one stroke is 0.00518 L⋅A2 cubic feet per stroke. [Tredgod, page 274]