The Rastrick Notebook

[Page 18] 5 Octr. 1829. Mr. Robt. Stephenson’s Rocket Black & Yellow. Boiler 3’.. 4” Dr. 6 feet long ¼ In thick full, Ends the Same. Fire Place 2 feet long 3 feet wide and 3 feet deep. 25 Copper Tubes run thro the Boiler each 3 In Dr. 6 ft long and 3/32 thick. Chimney 14 In dr. at top and 15 High from the Rails. 2 Cylinders each 8 Inches Dr. 16 ½ Stroke. 2 Engine Wheels 4’ .. 8 ½” Dr. 3 ¼” wide on Soal 7/8 thick ___ inside Tyre ½ thick. 2 Small Wheels 2’.. 8½” Dr. Cast Iron case hardened. Axis for Engine Wheels 3 ¼ Dr. – Axis for small wheels 3 In Dr. Forcing Pump 1 ½ Inch diamr. 16 ½ Stroke. Lock Up & Safety Valves each 2.55 Inches diamr. [Page 19] weight of Valve 1 1/8 lbs. Weight of Leaver 4 ½ lbs. The Weight of the Leaver will operate impress upon the Valve, according to the Ratio of the distance of the Fulcrum is to the full length. At the end of the Leaver it would require 2 ¼ lbs. to hold it up & consequently it pushes down with the force of 2 ¼ lbs. 22.5 x 2.25lbs./3 = 16.875 Pounds pressure which the Leaver produces upon the Valve. Area of Valve 2.55 Dr. - 5.1 Area 50 255 total pressure on Valve ibs Valve 1.125 Leaver 16.875 ----- 18 237 Pressure to be produced by Valve 237 x 3/32.5 = 21.5 Inches distance the Weight must be from the Fulcrum to produce a Pressure of 237 lbs. on the Valve. 10 Miles is 52.800 Feet – and 52,800/60 = 880 feet per minute equal to ten miles per hour. A Wheel 4 .. 8 ½ Dr. or 56.5 Inches diamr. is equal to 177.5 Inches Circumference equal to 14.8 feet Circumference. 880/14.8 – 50.459 say 59 ½ Strokes per Mt. will be ten Miles per Hour. “I believe 60 Strokes per Minute were need for 10 Miles per Hour. 16.5 Inch Stroke/12 = 1.375 foot Stroke = 2.75 double Stroke 2.75 x 59.5 = 163.625 full Velocity of Piston per Minute 8 In Dr. = 50.25 Area 25 lbs effective Pressure Load on Piston 1256.25 x 163.625 205,554 Pounds raised one foot high per Mt. equal to 205,554/33,000 = 6.225 Horse Power for one Cylinder 6.225 x 2 = 12.45 Horse Power at 10 Miles per Hour supposing the steam kept constantly up to 50 Pounds per square Inch on the safety Valve Or at 20 lbs effective pressure per Square Inch on the Piston it will be 10 Horse Power.