What are
the formulas For Earth Moving?
Whenever their is a
movement, friction comes into action. The same is the case with earth
moving equipments. We term this as rolling
resistance and this has to be overcomed by
vehicle engine so that it can move on that surface. This is the formula to
calculate rolling resistance
R=RfW + RpPW
where
R = rolling resistance, lb (N)
p = tire penetration, in (mm)
Rf =
rolling-resistance factor, lb/ton (N/tonne)
W = weight on wheels, ton (tonne)
Rp = tire-penetration
factor, lb/ton in (N/tonne mm) penetration
Rf usually is taken as
40 lb/ton (or 2 percent lb/lb) (173 N/t) and Rp as
30 lb/ton in (1.5% lb/lb in) (3288 N/t mm).
So the above equation becomes
R=(2%+1.5 % p) W’=R’W’
where
W’ = weight on wheels, lb(N)
R’ = 2% + 1.5%p.
Case – When we have a slope
G = RgsW
where
G = grade resistance, lb(N)
Rg = grade-resistance
factor = 20 lb/ton (86.3 N/t) = 1%
s = percent grade which is positive for uphill motion and
negative for downhill motion.
The total road resistance is calculated by adding the rolling
and grade resistances and is given by:
T = (R’+Rg s )W’ =(2%b + 1.5%p + 1%s)W’
Loss due to Altitude
Generally we take 3 percent pull loss for each 1000 ft (305 m) above 2500 ft (762
m).
Measurement Units
Measurement units and standards are different in different
countries but to maintain a standard, SI units are mostly used when dealing
with projects involving different countries or even different states. Small
projects can be done with the locally used unit system but when the project is
big, one standard unit system is to be used.
Two most common system used in the United States are
United States Customary System (USCS)
System International (SI)
But the SI unit system is more widely used all over the world.
Following is the table which shows how you can convert USCS measurements in SI
measurements. ( Just multiply the USCS
amount with the corresponding figure given in table below
Convert USCS into SI Units
|
USCS unit X Factor = SI unit |
SI symbol |
|
Square foot X 0.0929 = Square meter |
M2 |
|
Cubic foot X 0.2831 = Cubic meter |
M3 |
|
Pound per square inch X 6.894 = Kilopascal |
KPa |
|
Pound force X 4.448 = Newton |
Nu |
|
Foot pound torque X 1.356 = Newton meter |
N-m |
|
Kip foot X 1.355 = Kilonewton meter |
LN-m |
|
Gallon per minute X 0.06309 = Liter per second |
L/s |
|
Kip per square inch X 6.89 = Megapascal |
MPa |