Below is the OptiTruck Power and Gradeability Module Input and Calculation Screen.

OptiTruck’s power and gradeability module provides a means for estimating horsepower and torque requirements, given a wide variety of weight, driveline and truck configurations. OptiTruck uses standard J2188, updated by the Society of Automotive Engineers in 1996. OptiTruck takes the J2188 calculations to the next step by predicting the maximum possible top speed, given a specific truck and powertrain combination.

OptiTruck is arranged to provide the user with a finite number of choices using drop down boxes, making specification of tires, road conditions, driveline characteristics and the all of the other important variables intuitive and easy to identify.

OptiTruck uses the information you enter to solve a force-balance equation. On one side of the equation are all of the things that serve to slow the truck down – aerodynamic forces, rolling resistance from the tires, drivetrain inefficiency and the effort necessary to overcome an uphill grade. On the other side of the equation are the terms that describe the engine’s ability to produce tractive effort – e.g. the force required to move the truck – including the engine’s torque versus RPM curve, transmission ratios, axle ratios and tire size.

By setting the two sides of the equation equal and solving for the velocity terms that are contained within it, OptiTruck calculates the maximum speed that the setup you enter is capable of producing on level ground, then makes a second calculation to determine the maximum grade the truck will be capable of climbing at the desired speed you entered.