Geo.
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« on: September 23, 2016, 03:26:51 PM » 

Hi All I was writing lesson plans and I lost the formula for calculating brake horsepower by hydraulic pressure This is what i have so far:
Definitions for Work and Power • Foot pound (ftlb) = 1lb of force exerted over a distance of 1ft in any direction • Power – foot pounds per minute • Horse power (hp) = 33,000 ftlb per minute
Calculations for Work and Power • Horsepower for steam engines o hp = (P x L x A x N) / 33,000 hp = Indicated horsepower P = effective pressure in inlb per sqin L = length of stroke in feet A = area of piston in sqin N = number of strokes per minute ( = 2 x rpm for double acting engines)
• Horsepower for gas engines (simplified) (SAE) o hp = (D2 x N) / 2.5 = 0.4 X D2 x N D = diameter of Cylinders in inches N = number of cylinders
• Brake Horsepower (bhp) o Determined by Pony brake (Old school: steel or leather belt carrying wooden blocks or shoes clamped around the flywheel with adjustment to vary friction on flywheel an lever arm is attached to the outside of band, the pull on lever by friction is measured by platform scale on which the lever rests)
Actual power available for use • bhp = (2 x 3.1416 x L x N x W) / 33,000 o L = length of lever o N = RPM o W = net force = scale reading – weight of lever
o Determined by Hydraulic pressure (Modern pony brake: engine runs a hydraulic pump, gage on output, valve on return line is slowly closed until engine loses rpm
Can anyone help out?
