See Our Calculator Hints For Help. Symbol Description Unit Vehicle Data En Nominal voltage volts Wt Weight lbs. Rr Rolling resistance no. Vmph Velocity mph Dt Drive tire diameter inches Symbol Description Unit Vehicle Data Gr Gear ratio no. Pg Percent grade % Cd Coefficient of drag no. Af Frontal area sq. ft. % gear efficiency used is : Calculator Hints: For motor evalutation, fill the appropriate vehicle data above then press "Evaluate Motor." A window will appear displaying the results of the evaluation. If an error message appears simply close the window and follow its instructions. For further explanation of the symbols used above click here or click on the appropriate symbol above. To return to the calculator from any description click on back to calculator. For typical material handling applications, traction motors are selected based on loaded level conditions. This is because very little time is spent on the grade. (For this situation enter 0 for the percent grade.) If substantial time will be spent on the grade or you want to evaluate the grade performance, enter the grade percentage. For on-road applications, the vehicle may spend a fair amount of time on the grade and this must be considered in motor selection. 3% is a typical on-road grade percentage. For Futher Assistance, Contact Us.   Symbol Descriptions Nominal Voltage (En):   The nominal voltage should be entered here.   back to calculator   Weight (Wt): Enter the loaded vehicle weight. If the vehicle is a dual motor type, enter half of the loaded vehicle weigh there. back to calculator Rolling Resistance (Rr): Enter the rolling resistance here. Example Value Solid Rubber tires on concrete 0.035 Polly tires on concrete 0.020 Pheneumatic tires on concrete 0.015 Steel tires on steel rails 0.010 back to calculator Velocity (Vmph): Enter vehicle's speed in mph here. Usually this will be the loaded level speed for material handling application motor selection. Typical material handling grade speeds are 1.0 to 1.5 mph. For on road vehicles, enter the desired speed on the grade. (Usually 3% is the maximum road grade.) back to calculator Drive Tire Diameter (Dt): The drive tire diameter should be entered in inches. back to calculator Gear Ratio (Gr): Enter the gear ratio here. Example: For a 12:1 ratio enter 12. If there is more than one gear reduction, multiply the two ratios together and enter the result. Example: For a 12:1 ratio and a 3:1 ratio enter 12 x 3 or 36. back to calculator Percent Grade (Pg): Percent grade is the rise of the grade divided by run of grade. If no grade enter 0. Example Value Trailor loading ramp 30% Sit down rider lift truck 15 % Walkie truck 5 % On road vehicle 3 % If you need help calculating the percent grade try our Grade Calculator . back to calculator Coefficient Of Drag (Cd): Coefficient of drag (If speed is 10 mph or less you may use 0 for drag.) Example Value Squared off car 1.00 Almost squared off car 0.80 A car of the 1970's 0.45 Average car of the 1990's 0.35 A streamlined car of the 1990's 0.29 back to calculator Frontal Area (Af): Frontal area of vehicle in square feet (If speed is 10 mph or less you may use 0 for frontal area.) Frontal area = 36 sq.ft. for a car of the 1970's'; 12 sq. ft. for a typical golf cart. back to calculator Gear Efficiency : Typical gear efficiency is 90 %. You may enter the actual number if known. back to calculator