REPORT DOCUMENTATION PAGE C2A WETENG

1 SCvTYCLASSIFICA7,QJR Oe THIfS PAGE ("IW. D8,1 ~rldREPORT DOCUMENTATION PAGE BEOR C2A WETENG ORKREO& NUBE GVT ACCRVON #"D .RfCtPtErTS CATALOG NUMBER4 TOP 2-2-801 A102702 ( ) S. TYPE OF REPORT 6 PERIOD COVEREDUS ARMY TEST AND EVALUATION COMMIAND Finalla FST OPERATIONS PROCEDURE_____tN WEIGHT DISTRIBUTION AND GROUND PRESSURE (Wheeled 1. P 1 FRMII4G ORO. REPORT hNUMBER~ .anuqT~gked Veh icl es) 4 ATO GRANT NUMBER(*)9. PERFORING ORGANIZATION NAME AND ADDRESS 10. PHOGRAM ELEMENT. PROjECT, TASKAREA & WORK UNIT NUMBERSUS ARMY ABERDEEN PROVING GROUND (STEAP-MT-M) DPO- 1-ABERDEEN PROVINGGROUND,_MARYLAND__21005 _____II. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE7 Auqust 19131US ARMY TEST AND EVALUATION COMMAND (ORSTE-AD-M) 1.)

2 MU111CR OF PAGESABERDEEN PROVING GROUND, MARYLAND 21005 6-?14. MONITORING AGENCY NAME & AORES(If frumv Conltrolling Office) IS. SECURMITY CLASS. (of thi. repor)UnclassifiedIS. DECLASSI FICATION/DOWNGRADINGSCH1 EDULE16. DISTRIBUTION STATEMENT (of thise REPORT )Approved for public r-elease; distribution DiSTRIBUTION STATEMENT (of the, abstracd entered In Block 20, It different from REPORT )IP- SUPPLEMENTARY NOTES12. KEY WORDS (Continue on re~etse aide It necesay and by block numiber)Ground PressureWeight DistributionWheeled VehiclesTracked Vehicles20. A GNACT (Qm ,* so si if ane0iny OW identitr br block V1,00bw)Provides a method for accurately determining weight distribution and groundpressure of wheeled and tracked JAN7343 E~OIO6I~ UNCLASSIFIEDSECURITY CLASSIFICATION OF THIS PAGE (Whegn Delta Ent".)

3 US ARMY TEST AND EVALUATION COMMANDTEST OPERATIONS PROCEDUREDRSTE-RP-702-101*Tnt Operations Procedure TOP 2-2-801 7 August 1981AD No. A102702 WEIGHT DISTRIBUTION AND GROUND PRESSURE(Wheeled and Tracked Vehicles)Paragraph 1. SCOPE .. 12. FACILITIES AND INSTRUMENTATION .. 13. REQUIRED TEST CONDITIONS .. 24. TEST PROCEDURES .. 25. DATA PRESENTATION .. 4 Appendix A. REFERENCES .. A-11. SCOPE. This TOP describes procedures for accurately determining weight dis-tribution and ground pressure of wheeled and tracked vehicles. It does notprovide procedures for determining ground pressure distribution on surfaces suchas aircraft floors for tracked vehicles. For information on this subject, seeYPC REPORT No.

4 **2. FACILITIES AND REQUIREMENTB allast material to simulatevehicle loadMaterial for making inked imprintof contact PERMISSIBLEITEM ERROR OF MEASUREMENT**Platform scales or portable + or +1% readingwheel scalesPlanimeter + readingTape measure +3 mm*This TOP supersedes MTP 2-2-801, 22 May **Footnote numbers correspond to reference numbers in Appendix A.**Values may be assumed to represent + 2 standard deviations; thus, the statedtolerances should not be exceeded in more than I veasurement of for public release; distributioa August 1I81 TOP 2-2-8013. REQUIRED TEST Inspect the test vehicle as described in TOP 2-2-5052 to determine thecondition of the test vehicle and to ensure that vehicle configuration is asspecified in the test plan, including:(1) Equipment on the vehicle(2) Fuel quantityb.

5 Add ballast to simulate crew, passengers, cargo, or aumunition Data Required. Measure and record the following:a. Net and gross weights of vehicleb. Weight and location (distribution) of ballastc. Prescribed tire pressures (wheeled vehicles)d. Data as obtained in ahove4. TEST Weight Distribution Test. Weight distribution is a term used to describethe division of vehicle weight aong suspension members that transmit the weightto the ground. Weight distribution influences the life of all suspension partsand, to a great extent, temperature buildup in rubber components. It also af-fects mobility, riding quality, steering, and braking. Weight distribution isdetermined with and without payload weights, each wheel (single or dual) beingmeasured statically.

6 For tracked vehicles, weight reactions are obtained underthe track beneath each road distribution of tracked and wheeled vehicles is determined with platformscales or highway wheel Wheeled Method. Perform the following with full payload and then with no load:(I) Position wheeled vehicle with each wheel on a separate : Dual wheels are considered one wheel for test purposes.(2) Record scale value for each wheel Data Required. Record the following for each wheel:(1) Location of wheel(2) Scale readings of each wheel in Tracked Method. Perform the following with full payload and then with no load(if required):27 August 1981 TOP 2-2-801(l) Position tracked vehicle so that it can be driven one track at atime over the scales.

7 (2) Drive the tracked vehicle slowly forward onto the scale. Stop thevehicle as each road wheel is sequentially positioned on the scale : Use of vehicle brakes should be minimal for accurate scale readings. Thewheel loads resulting from a towed vehicle without tracks will be different.(3) Observe and record the scale reading.(4) Observe and record total weight of the vehicle on the track whenall road wheels are on the scale.(5) Drive the tracked vehicle slowly off the scales. Stop the vehicleas each road wheel is removed from the platform.(6) Observe and record the scale Data Required. Record the following:(1) Scale readings for each track as each road wheel is positioned onthe scale, driving onto and off the scale platform(2) Total weight of vehicle on track being tested with all road wheelson the scale (in kilograms) Ground Pressure Test.

8 Ground pressure is the unit loading produced byvehicle suspension components in contact with the ground, &nd is based on totalvehicle weight divided by the track or tire contact area. The contact area isthat part of a suspension system that is in direct contact with the ground andhas a function in supporting the vehicle or nominal ground pressure is the gross weight of the vehicle divided by thearea in contact with soft ground. For tracked vehicles, this assumes a depth ofpenetration of track blocks to a level permitting the entire projected area ofthe track to impose a load on the ground. Specific ground pressure is the grossvehicle weight divided by the actual contact area at zero penetration.

9 The ac-tual ground pressure produced by suspension components on a local area of groundis usually nonuniformly distributed beneath the ground-contacting part and can bedetermined only from complex calculations that take into consideration any un-equal wheel loading and the flexibility, form, and dimensions of the ground-contacting pressure affects mobility and rate of wear tI tires and tracks. Groundpressure is particularly used to check the design objective or specification. Itgives some indication of mobility under soft-surface conditions requiring flota-tion (mud or snow), although other factors su'h as track dimensions may influercethe pressures are normally determined with the vehicle carrying the specifiedload (payload or on-vehicle equiprent).

10 Nominal ground pressure is obtained forgeneral comparison of vehicles; specific ground pressure is more applicable tounit loading on wheeled vehicle tires and is indicdtive of wear rate and tempera-ture buildup that can be Wheeled Vehicles. Perform the following with the vehicle carrying fullpayload, unless otherwise specified:37 August 1981 iuk 2-2-801a. Method.(1) Determine the load at each wheel (in kilogram) using procedures asdescribed in paragraph (2) Measure contact area of each tire (in square centimeters) usingplanimeter and inked imprint of the tire at standard inflation Data Required. Record the following:(1) Location of wheel(2) Data as obtained in step a Tracked Vehicles.