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  NTEA ã 37400 Hills Tech DriveFarmington Hills, MI 48331-34141-800-441-NTEA ã (248) 489-7090 ã FAX  (248) 489-8590info@ntea.com ã www.ntea.com Calculates weight distribution on each axle, weight distribution on individual wheels, percentage of equip-ment and payload on the front and rear axles, percentageof vehicle curb weight on the front and rear axles andcenters-of-gravity (horizontal, lateral and vertical). WT&CG Spreadsheet Manual For Excel Weight &Center-Of-Gravity Calculations  WT&CG Spreadsheet Manual For Lotus 123 Weight & Center-Of-Gravity CalculationsIf you have problems using this Spreadsheet, call the NTEA at 1-800-441-NTEA. WEIGHT & CENTER-OF-GRAVITYSPREADSHEET (EXCEL) The Weight & Center-of-Gravity Spreadsheet  (saved onthe disk as WTCG) can be used to calculate the weightand center-of-gravity, the axle loadings, the individualwheel loadings, the percentage of equipment andpayload on each axle and the percentage of total vehicleweight on each axle for any combination of chassis andcomponents. The horizontal and vertical centers-of-gravity are used for a variety of compliance and weightdistribution calculations. Finding the individual wheelloadings and some compliance calculations will requirethe lateral center-of-gravity as measured from thecenterline of the truck to the side.Any one of the parameters can be calculated. Forexample, the center-of-gravity of the componentswithout the chassis can be calculated by not entering avalue for the front and rear weights of the chassis.Similarly, the horizontal center-of-gravity can be calcu-lated by entering horizontal center-of-gravity data foreach component.By including the front and rear axle treads, theindividual wheel loadings are calculated. This feature isvery helpful when making an “off-center” installationsuch as a digger derrick. When the axle tread dimen-sions are not included, the spreadsheet will calculate thetotal axle loading.Copies of WTCG are available in the followingformats with the listed file names and file extensions.Before using WTCG, insert the sample data in Figure 4into a test copy to insure that your results agree with theexample. If other formats are needed, this spreadsheet issupplied in printed form with all formulas listed: LOTUS 1-2-3 Release 1A...............................WTCG.WKSLOTUS 1-2-3 Release 2...................................WTCG.WKIMICROSOFT EXCEL..................................... WTCG.XLS First, make a copy of WTCG under another name fordata entry. WTCG should remain as the master without being used to make calculations. As an example, WTCGcould be saved in a customer’s name to perform thecalculation.Before data is entered, some of the cells will containthe message “ERR” or “0.00.” That indicates that the cellis a formula that depends on data from other cells thathave not been entered. As the information is entered intothe other cells, numbers will appear in these cells.On the copy, enter the date in cell E2 by writing overthe 7/16/89 date with a label. The “edit” function can be used to enter the vehicle description in cell A5 afterthe word “VEHICLE.”Print cells A2 through 53. Intermediate calculationsare performed in columns G through H. They arenecessary for the calculation process but do notcontain output information.Data for each parameter must be consistent in thechoice of a reference point. Horizontal center-of-gravity location can be measured from any point aslong as all horizontal measurements are taken fromthat point. Usually, the horizontal center-of gravitymeasurements are referenced from the center of thefront axle. Toward the rear is positive and toward thefront is negative. Similarly, the vertical center-of-gravityis usually referenced to the top of the frame rail at the back of the cab or to the ground. Lateral center-of-gravity location is measured from the centerline of thevehicle toward the right (curb) side and is positive. VEHICLE DATA Section Enter the WHEELBASE in cell B7 and the CAB-TO-AXLE in cell B8. The TREAD dimensions are enteredin cells E8 and E9 if the individual wheel loadings aredesired for those trucks with off-center loading. If theTREADs are not entered, the total axle-loadings will becalculated, not the individual wheels. The axle TREADdimension is the distance between the centers of thetire to the ground contact-points for the tires on anaxle. For axles with dual tires, the TREAD is thedistance between the midpoint of the dual tires on oneside to the midpoint of the dual tires on the other side.The WHEELBASE dimension must be entered tocalculate the axle weights. CAB-TO-AXLE is listed forreference and is not needed. CHASSIS COMPONENTS Section Enter the front weight and rear weight for the basechassis in cells B12 and C12.Descriptions of options are entered in cells A13through 16, with the corresponding front and rearweights in cells B13 through 16 and C13 through 16.The resulting front, rear and total weights are calcu-lated and shown in cells B17 through D17. The hori-zontal center-of-gravity for the chassis with options iscalculated and shown in cell C18, labeled HOR CG. 1   WT&CG Spreadsheet Manual For Excel Weight & Center-Of-Gravity Calculations  WT&CG Spreadsheet Manual For Lotus 123 Weight & Center-Of-Gravity CalculationsIf you have problems using this Spreadsheet, call the NTEA at 1-800-441-NTEA. ADDED COMPONENTS Section All horizontal center-of-gravity measurements must betaken from the same reference point; all vertical center-of-gravity measurements must be taken from the samereference point; all lateral center-of-gravity measure-ments must be taken from the same reference point.Horizontal center-of-gravity information is necessary tocalculate the weight distribution. Vertical and lateralcenter-of-gravity data is entered only if the resultantlateral or vertical center-of-gravity is needed. Neithervertical nor lateral C-G information affects the weightdistribution calculations.The data for the chassis center-of-gravity and theweight are automatically entered in cells B21 and E21from the calculations performed above in the spread-sheet. The front axle is used as the reference point for thecenter-of-gravity. The vertical and lateral centers-of-gravity data for the chassis is entered in cells C21 andD21 if the vertical and lateral centers-of-gravity calcula-tions are made. Rows 22 through 36 are for entering thedata for other components such as: body, bumper, framesections, hoists, lift gates, snowplows and winches.Horizontal centers-of-gravity, measured from thecenterline of the front axle, is entered in column B withpositive toward the rear and negative toward the front.For example, a front-mounted winch would have anegative center-of-gravity measurement. Vertical centers-of-gravity, measured from either the top of the frame railat the back of the cab or the ground, are entered incolumn C. Lateral centers-of-gravity are positive whenmeasured from the centerline of the vehicle toward theright (curb) side. These are entered incolumn D.Row 37 is labeled for PAYLOAD data. The payloadhorizontal center-of-gravity is entered in cell B37, thevertical and lateral C-Gs in cells C37 and D37 (if needed),and the weight in cell E37.If PAYLOAD data is entered, the weight of thePAYLOAD can be increased in steps to see whether thefront or the rear axles load to capacity first or the vehicleto GVWR. The PAYLOAD capacity of the vehicle isdetermined when one of the axles is loaded to capacityor the GVWR is reached. OUTPUT DATA Section TOTAL WEIGHT (cell E38)  is the sum of all of theentered weights for chassis, equipment and payload. HORIZONTAL CENTER-OF-GRAVITY (cell C40)  is thehorizontal center-of-gravity for all of the chassis, addedcomponents and payload listed in the input data sec-tions. VERTICAL CENTER-OF-GRAVITY (cell C41)  is thevertical center-of-gravity for all of the chassis, addedcomponents and payload items in the input data sec-tions. LATERAL CENTER-OF-GRAVITY (cell C42)  is thelateral center-of-gravity for all of the chassis, addedcomponents and payload items in the input data sec-tions. FRONT AXLE — LEFT, RIGHT and TOTAL (cells C45,D45 and E45): are the weights of the left and right wheelson the front axle, if the tread information was includedand the total weight on the front axle. REAR AXLE — LEFT, RIGHT and TOTAL (cells C46,D46 and E46): are the weights of the left and right wheelson the rear axle if the tread information was includedand the total weight on the rear axle. PERCENTAGE OF EQUIPMENT AND PAYLOADWEIGHT FRONT AND REAR AXLES (cells D49 andE49):  is the percentage of the equipment and payloadweight that are carried on the front and rear axles. If thechassis weights are entered, they are not included in thiscalculation. PERCENTAGE OF TOTAL VEHICLE WEIGHT—FRONT AND REAR AXLE (cells D50 and E50):  is thepercentage of the data items entered that is carried onthe front axle. Chassis weights are included in thiscalculation. EXAMPLES FIGURE 1 Shows the WTCG spreadsheet with no data. This is aprintout of the master. “0.00” indicates cells that aredependent on the data in other cells. “ERR” means errorand is the result of dividing by zero. As data is entered,the zeros and “ERR” output will be replaced withnumbers. 2   WT&CG Spreadsheet Manual For Excel Weight & Center-Of-Gravity Calculations  WT&CG Spreadsheet Manual For Lotus 123 Weight & Center-Of-Gravity CalculationsIf you have problems using this Spreadsheet, call the NTEA at 1-800-441-NTEA. FIGURE 2 Shows the analysis of the equipment that is added to thechassis with no data entered for the chassis except forthe wheelbase. When the wheelbase is entered, the frontand rear axle weights and the percentages of weights oneach axle are calculated. Without the wheelbase, thecenters-of-gravity will be calculated but the axle load-ings and percentages will not. This calculation showsthe effect of the added equipment on the front and rearaxle weights and the centers-of-gravity. In this example,the horizontal center-of-gravity reference point is thecenter of the front axle. The vertical center-of-gravity ismeasured from the ground. The lateral center-of-gravityis measured from the centerline of the chassis, with thecurbside being positive. Notice that all of the center-of-gravity measurements are positive.The results show the three centers-of-gravity (hori-zontal, lateral and vertical), the front and rear axleweights and the percentages of weight on the axles forthe body and hoist and related equipment. Because thechassis data was not entered, the percentage of EQUIP-MENT and PAYLOAD WEIGHTS and the percentageof the TOTAL VEHICLE WEIGHTS are the same. FIGURE 3 Shows the same truck as in Figure 2, except with dataentered for the front and rear chassis weights, the cab-to-axle and the payload. Maximum payload can bedetermined by increasing the payload weight untileither the front or rear axles reach their capacity, or thelegal load limit of 48,500 lbs. is reached. However, sincethe tread information is missing, the right and leftwheel weights were not calculated. In this example, thehorizontal center-of-gravity reference point is thecenter of the front axle. The vertical center-of-gravity ismeasured from the ground. The lateral center-of-gravity is measured from the centerline of the chassis,with the curbside being positive.The results show the three centers-of-gravity (hori-zontal, vertical and lateral) for the chassis and all of theequipment, the front and rear axle weights and thepercentages of weight on each axle with the truck fullyloaded. The PAYLOAD was adjusted to 26,872 lbs. toachieve a gross vehicle weight of 48,500 lbs., which isthe legal limit. FIGURE 4 Shows a different GMC Brigadier with a single rear axle, aservice body, high roof and a digger derrick. Because thedigger derrick is relatively heavy and mounted off-center,the lateral center-of-gravity and the individual wheelloadings become significant. With off-center loading, theaxle weights will not divide equally between the left andright wheels. The PAYLOAD was not included in thisexample. The horizontal center-of-gravity reference pointis the center of the front axle. The vertical center-of-gravityis measured from the ground. The lateral center-of-gravityis measured from the centerline of the chassis, with thecurbside being positive. The results show the threecenters-of-gravity (horizontal, vertical and lateral),individual wheel loadings, axle weights and the percent-age of weight on each axle for the chassis and equipment.Because the digger derrick is heavy and is mounted behind the rear axle, the front axle weight of 5,160 lbs.with all of the equipment mounted is less than the basechassis weight of 5,800 lbs. The percentage of EQUIP-MENT and PAY LOAD WEIGHTS show that the FRONTAXLE percentage is –7.62% and the REAR AXLE percent-age is 107.62%. 7.62% of the equipment weight is removedfrom the front axle and transferred to the rear axle. 3   WT&CG Spreadsheet Manual For Excel Weight & Center-Of-Gravity Calculations

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Jul 23, 2017

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Jul 23, 2017
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