499 OF ENGINEERING FOBMULÆ.
Approximate Rules for the Proportions of
Stationary Condensing Engines. •
D = Diameter of cylinder in inches.
8 = Stroke of engine in inches.
S = from 2 D to 21 D.
Area of ports = area of cylinder X • 06.
Diameter of air-pump = D x 0’6.
Stroke of air-pump = f S.
Area of foot-valve = area of air-pump x ’25.
Area of delivery-valve = area of foot-valve.
Capacity of condenser = capacity of cylinder x *6.
Diameter of piston-rod = D X 0’1.
Diam. of air-pump rod — diam. of air-pump x 0’1.
Diameter of crank-piu = D x ' 14.
Length of crank-pin = D X ’21.
Diameter of crank-shaft journal = D X'3.
Length of crank-shaft journal = D x '44.
Length of connecting rod = 8x3.
Area of connecting rod at centre — area of cylin-
der x '056.
Area of connecting-rod straps = area of piston-rod.
Distance of key way from edge of butt = | diameter
of crank-pin.
Depth, of gib and cutter = diameter of crank-pin.
Depth of gib at centre = depth of cutter at centre.
Taper of key = ± inch per foot.
Length of key = breadth of butt and strap X 2.
Width of key = | the width of butt.
Depth of large eye of crank = diameter of shaft.
Thickness of metal round eye = | diam. of shaft.
Depth of small eye of crank = f diam. of shaft.
Diameter of motion-rods = D x ’ 04.
Swell of ditto = | inch per lineal foot.
Diameter of valve-spindle = piston-rod x 0'4.
Area of steam-pipe = area of steam-port x I'L
2 k 2