testing and evaluation of agricultural machinery and equipment pot

Thic means that it ust be compatible with he farming system andthe needs ofthe farm fay taking technical, socal and economic factors int account ‘Wilt recognising this comple of factors,

Testing and evaluation

of agricultural

Principles and practices

MEASURING PULL AND CALCULATION OF DRAFT

Testing and evaluation AGRICULTURAL

Principles and practices

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FOREWORD Formal testing of agricutual machinery was instigated during the industrial revolution atthe turn of the century, but it was only with the wide adoption of engine powered equipment that testing began to make &

‘Serious and valuable contribution to manuficturers and users of agricultural machinery Testing, im which the ‘ogincring parameters of a machine ae determined, as, without doubt, received the greatest stenton, The

‘valuation of machines, in whch heir characteristics of handling and performance, their economic impact, 8 well a ther enginering paameter, are determined, came a a auc ltr stage in development, despite thề tater potential benefits provided to the user and manufacturer by these activites, There is no universal terminology which can beusd to distinguish the sctvities of súng and evaluation

Because of misconceptions associated wih testing and evaluation of agricultural machinery, FAO devied that its Panel of Experts on Agricultural Engineering should discuss the topic at its Eleventh Session in October 1992, One ofthe Panel recommendations was the preparation of two AGS Bulletins: one directed towards

‘esting and evaluation stations, universes and students im developing counties, and one directed towards

‘government, policy makers, entrepreneurs former of th tuo and managers of testing and evaluation centres This Blltin thề

“This Bulletin has ben produced by the Overseas Divison of he Sse Rescrch Instat, ULK working under

ACKNOWLEDGEMENTS,

“This Manual isthe fait of an enterprise that was initiatd in 1950 withthe prpartion and delivery of « practical course on farm machinery evaluation for scientists of the Mexican National Forestry and Agricul Research Insitute (INIFAP) Since 1990 the material has been developed further during similar practical workshops in Cuba, Honduras and Chile Financial help from the UK Government's Overseas Development

‘Adminisirtion and the British Council enabled these workshops to take place and is gratefully acknowledged

{A penultimate version ofthe Test Procedures presented inthe second pat ofthe Manual was prepared forthe Eleventh FAO Panel of Experts on Agricultural Eagineeing vhịch met in Rome in October 1992 At chat smocing it was recommended that the Procedures be edited und supplemented and that practical guidelines should

be included, This commendation was adopted by FAO and resulted inthe preseat document

Many collegues hive reviewed drafts and have made valuable comments which have enhanced our Understanding of the project Among these we would like to single out for special hanks

Frank Inns; Ulrich Vihigs Derek Suton; Jim Elit-Jones; Steve Twomlow:; Graeme Rained: Adianus Rik: Terry Lester

We owe «special debt to Sue Robinson who bated with manuscripts and typed many drafts of the fn text

We also recognise the cheerful and consrictve efforts of Rosemary Bras; Maria Koaggs; Bob Wardell and Roger Cover of Slsoe Research Institute Graphics Deparineat who produced the illustrations

Despite the contributions fom al thse sho have collaborated the views contained inthe Manval ae those of the authors: likewise we are responsible forall omissions und ecrors

November 1993

(Overseas Division Silsoe Research Institute

CONTENTS

2's Temgerture 3

Feel Consumption 23 Rate of appisation 3

43 Measurement of power 0 43.1 Rotary power „ 35:1 Engine m

4# — Aimalpedonmanee “

£6 Machine performance 4 446.1 Cultivators (vimary and secondary) a S611 General a 4612- DatmaamaMBBE ‘4621.3 Machine capacity and Gal efficieny a rm Sod Sal venion GUS Sushae evennass

4.62 Seeder and planters ‘0

$620 Gena 4622 Laboratory tne a 50 feo Bellas 9

463 Butlise diab

‘46:4 Knapeack Sprayers 54 463— Field Sprgers s

KA En n

‘53.2 Dynamic workload 1

(62 — Partial Budgets mm

61 — Nu Beehi ValnsaniTuie ii BaaeS 64 Variability isk and sensitivity analysis =8 a7

S_——Eauiibrium point partial budget sĩ

ANNEX | INSTRUMENTATION AND EQUIPMENT: 269,

SEX 2 CONVERSION FACTORS TO SI UNITS "

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SECTION A: PRINCIPLES AND PRACTICES

1 INTRODUCTION

Farm mechanisation i one component of agricultural enginering which canbe describe asthe application of

Al aspects of engineering technology to rural wd agricultural development In many industrialised countries the fruits of research in agricultural cence have made poasiblefor agricultural production to exceed nations food requirements, and complementary advances in agricultural engineering (especially farm mechannation) have helped to make the eppliation ofthese frat achaical reali

‘The situation in too many developing counts is quite he reverse Million of impoverished farmers labour near subsistence lve and do not have accest tothe technical improvements which would allow thm to Jimprove land and labour productivity and raise net farm incomes,

a the last few decades considerable effort has been expended by many research groups both national and intemtional on the design and development of “improved” equipment for small und medium sized farms Unfortunately farmer adoption, ad therefore the impct on standards of living, hasbeen well below the level, hoped for The numerous “improved” plougs; tol carr; equipment powered by pals, steam, biogas,

‘wind, solar energy or animal: driers sbllrs and trehers; pumps and mich more at wll a “Wactorstion” projects, either with conveationl actors or specially desigoed sll farm model, have failed in many cases

Im spite ofan impeccable programme oftechacal developmeat of the technology

‘A farm mochansation innovation wll nly be acept by farmers if it provides «solution thatthe farme i Actively soking, to» problem Kenly fl by the fare al Thic means that it ust be compatible with he farming system andthe needs ofthe farm fay taking technical, socal and economic factors int account

‘Wilt recognising this comple of factors, the sim ofthis manual sto focus on prosdres which have heen developed for testing and evaluating farm machinery, and on the criteria for testing small farmer onened technology

Improvement in the quality of equipment evaluation procedre in national or regional tating programmes will eof benefit to various groups These may include the following’

loại agricultural implement manufacturers

2 extensonist iru development projects decision makers in rural cet hanks tat extend credit linet to small sale producers

* programmers and decision makers inthe agricultural and industrial sector

dition the fundamental ingredient of discipline i scene evaluation develops an apitule for observation and precise measurement, important aspects i taining agricultural engineers

‘TESTING AND EVALUATION

‘The term “testing ie unsly used in connection with an analysis of the behaviour of x mache compared with well defined suadards under ideal and epeauble conditions Vohason, 1985)

In contrast “evalustion™ involves measiremet of machine performance under real farm conditions For

‘tarp: the behaviour of plough in soils ith diffrent textures and moisture contents and a range of vegetative covers (eg, weeds, stubble, gras)

‘Testing

‘Test procedures and standards for agricultural tractors have been established in several industrialised countries for many yeats, The evenval coincidence of North American (ASAE, 1980) and European (OECD, 1970) test procedures and the universal adoption ofthe International Standards Organisation code (GSO, 1983 wil mean inlermational standardisation and wil aoid the need to perform a tractor test n more

thân one country

(ficial tractor tests are designed to prose reliable and repeatable informatio, they donot include tests

‘under agricultural condition as these would be impossible to reproduce precisely In consequence the olf tess only cover measurement of parametcts which are not affected by ground conditions, for example

= complete tractor specifications

© engine power and fuel consumption

power and capacity of the hydraulic stem

turning area and turning cree

smoke emission centre of gravity

noe levels drawbar power

brake performance

resistance of protective structures (safety cabs),

In order to enable test results from differen tes sites tobe compared, drawbar power is measured on 4 special concrete track, The drawbar pulls achieved are, therefore, greatly in exces of those that eould be

‘apected under normal fed coodiiame

In addtion to tractor performance test procedures, several counties ave defined standards fora wide range

of technical aspects of specifeations (materials, dimensions and geometry) for actors and agricultural implements (e4, Society of Automotive Engincersin the USA and British Standards inthe UK) Adherence torthese standards (eg drawhar height and thee poat linkage geomet) allows compatibiliy of common parts and attachments Again the move is towards world wide homogencity with the publication of ISO

‘Sandards for tractor and may agricultural machinery component spesifiations (ISO, 1983)

‘Asa response, many developing countries and regions have developed thee own agricul machinery es codes Notable examples ate India, East Avia (Commonwealth Secretariat, I9BI & 1982) snd Ada (RNAM, 1983), which requite less sophisticated test equipmest

In practice all asessment procedures for agricultural equipment include asction done under controlled and repeatable conditions (less); and a section of Geld gvalustions For the remainder of this paper the term

“est procedure” i taken lo ned both ypes of assessment

Categories of Tests

“The type of test procedure selected as appropriate wil be influenced by-

= the stage of development of the equipment to be tested

= the potemtial henefciaries of the test report

8) The Stage of Development

‘Whether the tess required atthe design, prototype development or manufacturing stage will affect the ype of procedure that should be applied

A the design stage, even before engineering drawings have been made, i is very important t justify the proposed inoration ‘The procedure involves the Mentifation and quanifeation of the aced forthe Innovation ia echnical, social and economic terms Any native effets (eg on the labour demand or the need for new inputs oF processes) must be inluded inthe anal

The stage of prototype development wil include practical tests of the prototypes and their componcats, smcchanisms nd processes, under laboratory and field coniions The iit Verily whether the prototype functions as expedted, effectively, ecosomicallyandsafes Almost always this process results ia modiiations which must, intra, be tested

Testing and evaluation atthe manufacturing stage are aimed at measuring the quality ofthe product its

<orahiity and elcincy They also permit comparsons between different models or makes of tke machine [AU this stage user experience surveys ca be insued which wll yield additional information ox reliability,

‘durability andthe epost common causes extension purposes of breakdown, This formation i generally very valuable or

Frequenlly in industrially developing counties, the quality of fabrication is ot always uniform between manufacturers, Series tet, in which several makes of « machine type are tested under similar conditions tenable the most appropriate machine to be selected from the alternatives available, Matthews (1%) Aeseribes the advantages of series test in India where they served asthe fist step in improving the "breed

‘ofa machine pe, Research areas were denied more easly and it was possible to draw othe attention ff manufacturers those snpocs of mediocre equipment which could be improved

»

‘An appropriate test procedure can only be selected ifthe ue ofthe information to be produced is well defined There i a range of possible

‘Test reports can help potential users of ä machine to compare the performance of alternatives and select the model most suited to their needs (Stevens, 182) Nevertheless, as Jason (1985) points out, in mest,

‘countries where this typeof information i asl it generates very litle intrest, The mos important Tuetr for potential atc the reputation of the manuladturer or đtibor

Information from tess canbe used to cones imports of tractors and implements with view to assuring gual ad service forthe ser, One of the frat examples was the Nebraska tractor tess (Barger sta, 1963) Since 1920 thas been state legal requirement To all tractors forsale in Nebraska to have been oficial tested and that replacement parts ae avaiable

‘The fundamental goal of OECD tests has ben to provide reliable information for governments and wsers in all the member countics to rodMe hamier to nternaiomal trade (Manby and Matthews, 1973) The Same authors mcaton a series of secondary sms and underline the importance of presenting th information inan ection om ene aes andiuclstownertnd the portance: ope in

of tractors and implements,

4 One of the motives frequently put forward by developing country goveraments to justly a ational testing programme isto protect the economy against a misuse of foreign exchange Its maintained that, by means

ff atest programme, only machinery approptate tothe country’s conditions is made avalable to farmers

‘This strategy has often proved to be inpratical as machinery manufacturers change specifications inthe normal course of product developmcot and sot may aot be possible to supply machinery tothe speciation

“as tested" Johnson, 1985) However, evaluation to asese 8 machine's suitability to local conditions is potentially beneficial both to the user and tothe national economy if modifications can be incorporated before widespread dissemination

Increasingly important are tests for safety and environmental impact Certain features of a machine which affect the user's comfort and health, or that may contribute to environmental degradation, ean be measured objectively (Matthews 197), Examples ar:- Poteetiveeab tests; operator vibration; nose; smoke and txie fumes (180, 1989 Confidential and impartial testing canbe of henefit to manufacturers for product development A test centre

‘may have the capital equipment and the expertise 1o carry out tests more cheaply than individual manufacturers

OPE OF THE MANUAL

‘The aim ofthis manuals to give a guide tothe sepecs of a machine's performance that ean be evaluated and the procedures given in Seton B give ths inforenation fora range of equipment

‘The am isnot to offer inflexible test procedures, quite the opposite Whilst the procedures include many ofthe characteristics which could be tested its comphassed thatthe user ofthe test information must only

‘cect for test those aspects of the procedure which are of particular fterest nd which wil ycld usable information,

In many situations, acces toa fll rage of testing facts isa varity and test personnel may no aways have the depth of experience required to interpret fly the procedures given Therefore the manual also ves guidelines (in Section A) on how to apply them in practice

In some eases (or example: engine speed and torque; sound pressure lewk implement drat forex) some instrumentation is necessary and in these cases the corret aplication of available equipment is deseibed together with sources to design adequate equipment with frequently salable resources without prejuicig the quality of the of supply In other cases where the priaciples are clearly understood it wil be possible information gathered Examples could he: "Patterators”for sprayer dtibuion assessment; engine fuel ‘consumplion messurcmen; stil properties assessment

“Two topes not dealt wit in detail in Section B ate eegonomic and economic evaluation of farm equipment

“The themes ate developed in Section A tothe extent that a general coverage of the principles involved is sven forthe respective appraisals twill be appreciated that each of the topics could merit a complete ‘manusl, the sim here isto emphasis the need for a complete appraisal of farm equipment from the tedhnieal, ergonomic and economic viewpoint and aot to foster the notion that a machine need only he technically efficent and effective to be asteptable to potential adopters

2 MEASUREMENTS

‘An essential part of any procedure for the mechanical evaluation of an itm of farm equipment isthe ‘measurement of parameters which will dctermine the performance characteristics Th lve of accuracy of the measurements wil depend on the panicular procedure used andthe sophistication ofthe measuring egwipmen sealuble, For example, it is generally trve that the smaller the measurement (0 be made, the treater accuracy required of the measuring equipment (eg the length of a sed compared with the length

‘of Geld po),

To compare results of tests on similar models and types of machine itis useful to ave the data presented

in consistent units The use of Sjtéme International (St) units has now been universally aecepted and has ben used throughout the test procedures in Section B, However, other unit are often used and where this the case, they have been incorporated into the te procedures Annex ites tales of conversion factors for Stuns,

petiods and canbe incoeporated ito other mulsfuntional measuring isruments,

For loger period of time such a when eaeyng out ld tests, durability rials and tials om farmers Fields, the times are measured in hours (h) If the tests are not under constant supervision, some wpe of hour recorder should be ured Electronic versions ate avalale for fing to power unite and tractors wally

*anajng (rom the hattry charging crits,

1 metre

Figure 25 Pace marker for measuring plot size Source: Crosley and Kilgour, 1981

214 Revolutions

The measurement of the numberof revolutions is simpy a counting procedure ‘The numberof revolutions

of land engaging wheels on tractors and machines on test rigs and inthe feld and pedals and handles of

‘machines such as small hreshers, grinders and water pumps, canbe counted by eye For shafts turning at higher speed, some form of counting apparatus is required Where the end ofthe shafts accesible, a rechanical electrical or electronie counter may be used driven directly from the end ofthe shalt, However, ifthe shaft is connected at each end, an electronic counter can be used which incorporates a ight emitter and a sensor working feom a reflective stip attached tothe rolling part Some shaft torgue measuring

‘devices have integral evolution counters to enable dteet power readings to be abtaned

245 Temperature

‘The measurement of temperatures may also require equipment to cover a wide range fom ambient at values

to those ofthe exhaust gasses from itera combustion engines The Sl unt of temperature is the Kelvin (K), degree Celsius (0) is also recognised for use in conjunction with the SI and has the sume datum and vale as the Kelvin Measuring equipment is usally graduated in degrees Celis

Mercuryinglans thermometers may be adequate for some ambient and fuel measurement, however, the

‘thermocouple typeof mearuring device hat a large temperature range and x commercially available and widely

‘wed The electrical device can be bul iat «hand-held unit (Fig 2.6) oF coupled to additional monstoiag recording equipment

Figure 2.6 Handheld electeicl thermometer

216 Bletrical

During tests of machines incorporating electrical equipment, it soften nscesty to measire the units eesti potential (vot), current (ampere) and esistance (ohm)

‘Standard commercial instruments are available with meters adequacy covering ranges and units suitable for iret current (DC) and alternating curent (AC) supplies Its recommended that measurements on electrical quipmeat should only he made hy experienced personnel

22 Derived Measurements

221 Are

“The square metre (m) isthe recommended unit of area and is usd for calculation of pot size, Measurement isby calibrated tapes or pace markers asin Section 2.1.3 Larger field areas are usualy quoted in hstaes (bt) qua to 10:0 suare metres Smuller multiples such asthe squresentinete (cm) are used for plot sampling seas sucha stra eoleton for combine tts or wed area for culation work, Sizes of small components

‘sch as pump pistons are expres in Square ailimetres(r

222 Volume

ard ui of yume is he eaic mete (a) wih smaller mips ofebicceatimere (em!) and cubic millet (om?) However, the ize () with alu of 100 ex? bsg common ws or siedĐjng

the volume of gus and granular material eg hopper capac)

‘ylindrs of known volume required for th field sampling of sis ean be manufactured from steel tubes

of various sizes (Fig 27) When checking specifications, the volume of tanks and containers on machines such as sprayers, seeders and spreaders can be calculated from ternal dimensions or by filing with measured quanties During performance tess, dhe (tal output ofthe distribution of sprayer aozlee measured sing propictary made calibrated eyinders either sng) (Fig 28) or in a row asin the distribution measuring “Paternator” described ia Section 44 Larger volumes can be measured using previously calibrated buckets or tans,

Figure 27 Construction of stel einer for sil density determination

‘The measurement of fel eosumed by power units and tractors over peo of Field work ean be obtained byy measuring the volume of ful eequied to top up the tank alter each work period, The use of more sophisticated fuel measuring devices is discussed under Section 229 (Rate of ow),

Figure 2.8 Sprayer nozzle output measured with graduated cylinder

223 Fore

‘The newton (N) i the SI unit of force whichis defined atthe force Which, when applied l a ody of one

‘ilogram mas, gives tan acceleration of one metre per sevnd squared (kgm), The Kilogram force (kg) ithe force that when applied to body of mas of one kilogram give the standard acceleration đạc o gray (6.8067 ale) Therefore 1 kg = 9.8067 km? = 9.8067 NI can be seen, therefore, that tis possible

to calculate forces fom results obtained by using the same equipment as that used for measuring mas (Section 312)

Spring type blancs may be used for measurement of force on hand ols ad ight implements drawn manually

‘ory annals However, under Fld conditions because of lack of damping, they may be dificult ead with secure,

Deaf forces of tractors and machines may be considerably greater an the capacity of these weighing units and Figure 2.9 shows an arrangement wing a system of levers which could he we

Hydraulic dynamometers using calibrated pressure gauge indicators (Fig 210 are avaiable to measure heey

‘rat Toads but these have generally hee superseded by electronic stain gaged teasion links (Fig 211) These

‘units, with thee indicators canbe purchased in various die to measure deft forces ofthe smallest manual Imachine to those af the ages tractor of fel machine The units are easily calibrated, portable and can be Iter powered for fel ut They can alo be connected to sable recording or analyzing equipment In

‘he cue of machines with ined dra poles sone rodietion may be necenary to sccm the menting device, Fig 212 gives tu examples,

2 ramon

Figure 29° Method for increasing the capacity of weighing unit, Taking moments about the pivot

Pra = Rxb P= Reb

Souree: Crosley and Kilgour, 1983,

Draw pole

Force transducer 4

Fred ring

Sliding ngs Irmplement it lever

Main tool easier eross member Dynamameter

‘swinging rks Figure 2.12 Two methods of draft measurement for implements with rigid draw pols (a) for an animal drawn wheeled tol carr (Source: Sims, 1987) (b) «universal stem,

224 Pressure

Pressure measurements are reuited tobe made in tests of power units, tractors, prayers and wat

‘These cover a wide range and can be positive or negative pumps

Lower levels such as depressions in engine inlet manifolds and in water pump sueton pipes can be measured

‘sing simple water or mercury fled manometers In this ease, the pressure in the stem is aleulated using the diference in height ofthe liquid column,

Pressore and vam gauges are manufactured in various ranges and grated and scaled in units such as bars, hlograms force per square centimetre (kgf/em?),Pascals (Pa) oF Newtons per square metee (N/a), this latter unit being preferred bythe SI Eledronic sjnems using pressure sensors may be obtained together wid thei asocated display and recording equipment

Figure 213 Range of mechanical and electronic revolution cousters The unit of near sped isthe metre per second (m/s) However, the unit normally used when presenting the travelling speed of tractors and machines is the Kilometre per hour (km/b) which is derived by calculation,

‘A method of measuring travel speed during fed was of machines sto setup marker poles aross the width ‘ofthe work at say 20m apart to form a restangle, Aa observer wil then be able to sight across the poles

fd measure the time taken forthe machine to travel the known distance (Fig 2.14),

\When drawbar tess and sip measurements are being made inthe fel he distance for atractor or machine

to trae! fora numberof whe! revolutions femeasuted If the travel ime is leo recorded, the travel speed say be caleulated (Fig 215),

“6 Selected org values may be appli tothe driveshaft by variation of he intra loading In mos propitary

‘machines the length of the arm i designed to give constants of whole numbers inthe power calculations

‘Transmission dynamometer: that canbe fied into an enginelmachine or tractor power take-offimachine rive line (Fig 2-16) ae available to cover large range of torque and speed requirements These units are portable sod comprise an intemal strain gauged shaft or tube with suitable monitoring and read-out equipment, they an

‘be mains or batery operated

Figure 2.16 Torgue meter fit into the driveline between an engine and water pump

2.2.7 Work and Power

“The ST dt of energy and work is the jole (1) whichis defined a the work done when a free of one newton ste through a distance of one mre i the direction ofthe force, Th joule () is equivalent to ane neon

‘etre (Nm) The unit of power i the wat (W) which is equal to one joule per Second (is) or one newton

‘mete per second (Nas) The uit mest commonly used isthe EW which sequal to one kilo newton mete per second (KN)

For measurement of linear power, fora actor drawhar test for example, the following equation i ws

Force (AN) x distance (a) Po) CÔ TH TRƯ., me (9)

= Fowe x velosity

„ For rotating mechanisms such as engines,

Power (W) = Torque (Nm) x Speed of rotation (rad/s)

If the speed of rotation is measured in revolutions per minute (R) and since there are 2x radians i one revolution then:

Ni x Speed of rotation 2k

Power (kW) = Torque ¬ For measurement of power of tractor hyraulic stems, the fllowing formula is use

For this the relationship powcr (W) = vollge (V) x curren (A) i used However, is possible to obtain

‘rious iypes of wat meters which when connected betwen the supply ad the motor wil give dret power dings (Figs 2.17 and 2.18) The diagram gives connections for ects upto approximately 5A, higher power rang re required, transformer is needed inthe current measuring crcit and should be wired

fe accordance withthe meter manufactures instructions

1 should be understood that measuring the power inthe drive fine will give the exact requirement of the

‘machine The watt meter measures the electrical power input tothe motor ad the efiency ofthe motoe

to transit that power tthe machine shouldbe taken ito secount, The motor efcioncy valves wll pend fon the level of loading and will range from approximately 70% to 90%

228 Rate of Work

This measurement is concerned wih the output of machines i Field evaluations, Rate of work is defined

as atca worked in square metres (?) for Unit of ime, say on hor (b), ivng the equation:

sea (a

Rate of Work = time (8) For field work, the number of square metres may be very lage so the hectare (ha) equal to 10 000m? is uscd, giving the expression hectare per hour (hah), The total work ime used for this calculation includes time taken for turing atthe headlands, rests and any breakdowns or adjusments

339 Rate of Flow

Volume of flow is measured 10 establish he fuel consumption of peeol and desl engiaes, and the output

of sprayers and pumps ‘The basic funtion for fow rat, volume per unit of time is used in each ease Fuel consumption of engines is measured in miles or lites per second (nis o/s) For stationary engines a simple apparatus ean he constructed (Fig 219) The vertical lar tube forming the fuel column should have a capacity of approximately 0 | andthe scale ealirated After filling the column fom the Separate supply the tap is closed and operation ofthe three-way valve will ert the supply to the engine from the main tank tothe column After measuring time fora given volume, the sequence i reversed, refling the column (Fig 2.20),

n Propriotary meters ising direct read-out of lw rat are wed forests on hydraulic systems, Fig 2.23 shows how meters fied into the Naw line ofa eator hydraulic sytem In ease of tractors wth “sedi systems, the meter must be of pe to withstand the pressure of the boost pump supply ino which the

‘eturn ow is connected, Before iting est equipment to ths type of tritorBydraule cut, information fon testing methods shouldbe Sought from the Wactor manufacture

Rate of fw, Q = kx /3gx —— xÊS whore Q = rate of flow (o/s) f= aeccleration dục to ghi (28067 m/s)

HL = height of liquid lve en) = plate coufcent

For each notch, the coefficient k must be determined by experiment toys the cortex eatonship between rate of flow and uid beight Ths information may be supplied by s plate manufacturer

‘This ical example shows bow measurement of specific fuel consumption can be used to highlight areas ot higher fel efficiency in terms of power and speed It shows, generally, tat for tractor operation, iis

‘more economical to work nthe highest gear ratio posible, adjusting the tote to maintain the required load and forward speed,

2211 Rate of application

‘The volume or weigh (mass) of insecticide, fertile oe seed applied related to erop oF Fel areas the most ‘useful expression of rate of application I is measured in lites per hectare (I/ha) ot Kilogram per hectare (kg/ha) IC these tems are mulled by the rate af workin hectares per hour (h/t), the appliation eats per hour can he achieved,

se in Kiograme por hectare (ke/k),

%

3 CALIBRATION OF TEST EQUIPMENT

‘The reliability of data fom measurements made during tests and evaluations wil depend on the accuracy ofthe instruments used This supposes thatthe use of such equipment is understood by testing personnel and operated correctly with accurate data recording ‘The level of accuracy wil depend on the purpose of| the text greater accuracy i generally required for smaller quantities (og engine fuel consumption oF Aimensions of small components) Such accuracy i not required for larger quaniis, og Geld ize Tnsruments with high levels of acaracy wil generally be more expensive,

‘The range ofthe measuring equipment used shouldbe consistent with the range expected during the test (a expected drat ores of up t0'5 KN should be measured witha tense nk of § BN rated Toad), All proprietary measuring equipment wil be produced and supplied calibrated to known standaeds and Fits

‘of accuracy oer suitable meastring ranges, Instrument accuracy wil depend on such actors a: hysteresis ron-lincariy, repeatability, creep and temperature, Simple measuring devices such as rules apes, and fraduated eslndces and thermometers will not requice regular ealibation as changes dv to damage and

‘rear wil be obvious andthe units are relatively inexpensive to replace,

Much of the mechanically based test equipment has now been superseded by electric and electronic measuring devices which can be mains or battery operated and are suitable for laboratory or field ws Testing engineers without stable knowledge to wndertand al the basic processes of the new systems wl reed to have total reliance on the continued accuracy ofthe equipment, Because of this reliance on accuracy, all test measuring equipment should have periodic calibration checks especial if there are any

‘doubts about the results of measurements, Manufacturers may include standards fo cllration within the

‘ipment sch asa standard noise source fr sound level meters and means for measuring frequency of light for revolution counters

Many checks can be made within the testing organisation using “standard” equipment for comparison, uated einders maybe ued to check the volume oF ouput of fuel measuring devices andthe capacity

‘of various containers, pressure gauges, balances and timers ean be checked agaist further units ofthe same type However, these should only he used for spot” cheeks and instruments should be returned tothe

‘manufacturer of to suitably equipped standard test laboratory

Fig 3.1 shows a laboratory set-up for testing a pressure gauge where the pressure in the system is provided

by known standard weights acting on avery accurately machined piston and elinder The reservoir and

‘mp ae ited to ensure thatthe stem i AI an thatthe piston is supported by the Higuid column when measurements are made

Strain gauge devies used on engines, teactoes and machines inthe Fld are particulary vulcrabe to damage

‘and adverse conditions and will require more frequent checks A well equipped laboratory may have a Specially designed machine for calbating compression of tension links However, standard weights of Sulcient quantity may be used as shown in Fig 32 for calbating a teason link used for drat free

‘A set-up for applying loads when clbrating sft attached tothe test stand anda torque am is atached to the other A weight tray and weights are a torque meters shown ia Fig 33 One end of the meter drive ded to the arm ata suitable distance which is accurately measured and defined For accuracy, the torque Sem shouldbe a light as posible and balanced hefore weighs are added

Alltest equipment and instrumentation should be stored ina cean environment and records kept of periods

‘tase requeney of calibation and any bvealdovns or tcp,

ance warp m

Wight ray 0%) Torque = y+ Wa)

Figure 33 Mechanical arrangement for torque meter calibration

»

4 [APPLICATION OF MEASUREMENT TECHNIQUES TO TESTING PROCEDURES

an Selection of material fr tests

During evaluations, machines are asessed on their ability o meet certain design criteria Fediler lstribotors, seeders, planter, tresbers and harvesters are specially designed to proces particular types

‘of bulk material The material selected or the tests should e in accordance withthe design eter ofthe ‘machine and should be adequately checked and specified inthe test report This is particularly important

‘where varios tyes of machines are being compared for performance

to assese machine performance, the germination rate ofthe original sample wil ced to be established

‘Threshers and shellers ae asessed on their ability to separate grains from straw or cobs without damage

Im addition to specifying the type and varity, moisture content, size and density ofthe original materi the average ratio of grain/straw and grain/eob should be established

The type and condition ofthe crop will considerably affect the performance of combine harvesters The rain output test should be made With cops in “average to good coniton which means thatthe majority

‘standing with a minimum amount of weeds and atthe desired moisture content, Where investigations ae

‘made under poor condition (id or weedy crops), these should be adequately specified,

Measurement of sil particle size distribution requires very accurate equipment and is normally undertaken ina suitably equipped sil laboratory The method i by sedimentation (Brsh Standard Institution, 1973) Figs shows percentages of clay (below 0.002 mm), sit (0.002 - 206 mm) and sand (0.06 - 2.0 mm) inthe Ina wil textural clases The subdivisions reflec he various combination of particles present

4211 Field Estimation

1 detis ofthe soil type are not salable using the particle size and distribution method, the type may be sstimated using the folowing sampling procedure and manual method (Fig 4.2)

usttsy gi ey arin d9 sity a5 orn sty om) (5Ÿ sy) 1o ory ay ami si on oy Giả

0 deal, samples for tillage studies should be taken at intervals of 0.1 m oF less, throughout the culation layer eg srface (140.05 m), 05.0.1 m, 0150.25 m and possibly to 0.10 m below the layer of intended depth of elation, The minimum sample size taken at each depth 200g and should be replicated al ae tree times throughout the fest area toe a representative estimate of sil txture forthe area

‘A ball of about 2.5m diameter is formed of fine soil Water i slowly dripped onto the soil unt it proaches the sticky point ithe point at which the silos starts to sick fo the hand The extent to which {he moist soil can be shaped by hind is indicative of is texture

a sat F11

¬ Iam, hgh hi can been in Ut oa, ih ring

‘When dry, loam or silt wil gve of fine powdery dus ifseratehed or Blown upon, but a clayey sil will not; alts exeemely powdery hecause of i very low clay content A loam when wet fel soapy and mote or Tess plastic, when rubbed etwecn the Finger wai dey t leaves dust om the skin ely docs ot

‘oot development, Less directly bulk density is also elated to si strength and permeability Soils witha high total pore space have alow bulk density and conversely low porosity leads to high bulk density Bulk densities in exces of 16 Mm can restrict root growth and result in very low levels of water movement

‘into and within the so Some typical values for diferent soil textures are given in Table 4.1

422.1 Field estimation of bulk density

‘ofthe sample would be to fill the voids with fine dry sand, and then empty out the sand and measuring its

‘lume, “An alerts, approach f time allows and water content snot bing determined, sto thoroughly

‘wet the sampling ste porto the taking of the sample

st

Figure 43 Sol core sampling for bulk density measurement Each sample shouldbe taken othe laboratory in a sealed container, After weighing the samples are oven Arid at 108°C for 8 hours and then cooled in a desiccator before te-weighing

M (Oven dred bulk density (Dy) Tel

Mi Mass ofthe dried sample

Re Radius (internal) of elinder

Length of elindrcal sample corrected for any less of sil a above

4222

Sampling strateyy for hulk density measurements

[Atleast four replicate determin increments from the soil surface t0 010m below the estimated depth of tillage work, Pos! <illge ions are normally made at each ste prior to any tillage work at 005 m

‘measurements require more precise determinations to characterise the degree of soi disturbance which will,

‘ary withthe implement sed For general clvation implements, such as plowghs and eliatos, i Fecommended that atleast tem replicate determinations he made pee ste at 008 m inrements from the oil, Surfaee to 0.10 determinations should he made at leat thee literal ponitions, 0, O10 and 0.20 m a right angles tothe m below the depth of tlle work Where tined implements are used for single passes pasta ofthe ine Figure tt shows how dy lke density vies with increasing distance from the passage

fa tne

100 pth sr

Hoos

300 Figure 44 Variation in dey bulk density with depth for thece positions (0 0.1 and 0.2 mộ at eight angles to the passage of eltivator tine

4223 Dey bulk density and porosity

The relationship between dry bulk density and porosity is

4281 Measurement method

‘Methods of determining sil water content ca be divided into tw groups, those occuring in the fc, and those thal necessitate the removal of sample for laboratory determination by oven drying The latter technique isthe one recommended her, 361 ithe ullimate reference agains which al eld techniques are calibrated,