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# Road Rolling Resistance

IMPERIAL

The road rolling resistance is the force required to push a vehicle over the surface it is rolling over and may be expressed in several ways. One, in terms of pounds resistance per thousand pounds of gross weight. Other methods are derived from this basic expression. Following is a table of rolling resistance in pounds per thousand pounds of gross weight of various road surfaces.

Rolling resistance is the gross vehicle weight in lbs, times the rolling resistance of the surface divided by 1000.

Where:

RR = Road rolling resistance in pounds

GVW = Gross vehicle weight in pounds

R = Rolling resistance in pounds per thousand pounds vehicle weight

1000 = A constant to determine number of thousand pounds in vehicle

Example:

What is the rolling resistance of a vehicle have a gross weight of 10,000 pounds on poor asphalt

Many formulas are arranged to use the rolling resistance in the above table as a factor. To set the table data up in factor form divide the resistance in lbs by 1000.

Where:

Q = Rolling resistance factor per pound of gross vehicle weight

R = Rolling resistance in pounds per thousand vehicle weight.

Example:

What is the rolling resistance factor per pound of gross vehicle weight on poor concrete?

Another method of expressing road rolling resistance is percent of grade. To express rolling resistance in percent of grade multiply rolling resistance per thousand pounds vehicle by 100 and divide by
1000.

Where:

RR% Grade = Road rolling resistance in percent of grade

R = Rolling resistance pounds per thousand pounds vehicle weight

100 = A constant to express percent

Example:

What is the road rolling resistance expressed in percent of grade of a vehicle on poor concrete?

METRIC

The road rolling resistance is the force required to push a vehicle over the surface it is rolling over and may be expressed in several ways. One, in terms of newtons resistance per hundred kilograms of gross weight. Other methods are derived from this basic expression. Following is a table of rolling resistance in newtons per thousand kilograms of gross weight of various road surfaces.

Rolling resistance in newton per hundred kilograms is the gross vehicle weight in kg, times the rolling resistance of the surface divided by 100.

Where:

RR = Road rolling resistance in newtons

GVW = Gross vehicle weight in kilograms

R = Rolling resistance in newtons per hundred kilograms vehicle weight

100 = A constant to determine number of 100 kg in vehicle

Example:

What is the rolling resistance of a vehicle have a gross weight of 4,500 kg on poor asphalt

Many formulae are arranged to use the rolling resistance in the table below as a factor. To set the table data up in factor form divide the resistance in newtons by 100.

Where:

Q = Rolling resistance factor per kilogram of gross vehicle weight

R = Rolling resistance in newtons per hundred kilograms vehicle weight.

Example:

What is the rolling resistance factor per kilogram of gross vehicle weight on poor concrete?

Another method of expressing road rolling resistance is percent of grade. To express rolling resistance in percent of grade multiply rolling resistance per hundred kilograms vehicle by 100 and divide by 1000.

Where:

RR% Grade = Road rolling resistance in percent of grade

R = Rolling resistance newtons per hundred kilograms vehicle weight

100 = A constant to express percent

1000 = 10 * 100, where 10 is an approximation for acceleration due to gravity

Example:

What is the road rolling resistance expressed in percent of grade of a vehicle on poor concrete?