Real-Life Math
You're responsible for maintaining a fleet of bulldozers,
backhoes and heavy-duty trucks for an excavation and construction firm. As
usual, you begin your day by running through a safety checklist for each piece
of equipment.
Most check out. But there's one truck -- an 18-wheel
dump trailer -- that has you concerned. The air pressure in the brakes isn't
building up properly, which could pose a safety problem. The truck has a gross
vehicle weight (how much the truck weighs with a maximum load) of 60,000 pounds.
You
have the truck backed into the garage and go to work. The air pressure pump
needs to be replaced. That's easy. You just have to figure out the piston
size that will provide the right amount of air pressure.
On the shelf
of your garage are 4 sizes of compressors: 9.5 inches, 14 inches, 18 inches
and 19.5 inches. You consult the manual for the truck and find the following
formulas apply:
Size of Air Compressor Piston = total air pressure
in pounds x 0.6
Air Pressure = 1/2 pound of pressure per thousand
pounds of gross vehicle weight (GVW)
So, which compressor will
you install -- 9.5 inches, 14 inches, 18 inches or 19.5 inches?