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--- Manual program SCOP ver.2010.3.4 2010-10-28 --- 1

SCOP

Hand book

Scania Optimizing Program

Copyright (c) Scania CV AB, Sweden, 2009

All rights reserved.

2010-10-28 Version 2010.3.4-----------------------------------------------------------------------


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ContentsThe SCOP-program:...................................................................................................................... 3

Hardware and software requirements........................................................................................... 4Installation....................................................................................................................................4Start of program ........................................................................................................................... 4General ......................................................................................................................................... 4

Configuration screen...................................................................................................................... 5Configuration environment ........................................................................................................... 6

Default values.................................................................................................................................. 7Print settings ...................................................................................................................................7Type of Vehicle ...............................................................................................................................8Main screen ..................................................................................................................................... 9Select Transport task ................................................................................................................... 10Topography...................................................................................................................................10Road surface ................................................................................................................................. 11Stop frequency .............................................................................................................................. 12

Fluid traffic ................................................................................................................................ 12Light traffic ................................................................................................................................ 12Residential traffic....................................................................................................................... 12Dense traffic...............................................................................................................................12

Stop-and-go................................................................................................................................ 12Powertrain screen......................................................................................................................... 13

Engine ........................................................................................................................................ 14Gearbox...................................................................................................................................... 15Wheels........................................................................................................................................17

Air drag .........................................................................................................................................18Result view .................................................................................................................................... 19Special functions screen ............................................................................................................... 21

Hill and acceleration test............................................................................................................ 22ADR test..................................................................................................................................... 23

Diagrams:...................................................................................................................................... 23

Power Diagram .......................................................................................................................... 24Gear shift Diagram..................................................................................................................... 24Brake diagram............................................................................................................................ 25Acceleration test diagram........................................................................................................... 26

Considerations and definitions.................................................................................................... 27Factors that influence service life................................................................................................ 32Market conditions ........................................................................................................................ 34Troubleshooting and feedback .................................................................................................... 36


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The SCOP-program:

SCOP is a utility program that will help you specify the powertrainof a truck or bus to perform a given transport task satisfactorily.The program can be used to: Arrive at a suitable combination of engine, gearbox and rear

axle ratio on the basis of a transport task defined by the user. Get an indication of the lower limit for an acceptable choice

of engine, gearbox and axle gear thus avoiding errors in thespecification of the powertrain of a truck or a bus.

Quickly calculate various performance parameters that are of

interest when comparing powertrain solutions. Indicate whether a given powertrain combination fails to satisfy

one or more of the transport task demands specified. Indicate whether a unit is unacceptably loaded in a given

transport task.The SCOP program can also be used to obtain answers to morespecific questions and for training purposes to demonstrate howdifferent parameters interact and influence the performance of avehicle from different angles.

It is very important to see the program as a calculation tool andas an aid that will supplement your knowledge and experience.


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Hardware and software requirements

To run the SCOP-program you will need:SoftwareScop is a .net 2.0 framework application and has the same requirements as the framework. (Fordetail information see Microsoft home page)

PrinterThe program will work on a wide range of printers.Since the SCOP -program is a Windows application the support of different printers depends onhow well different printers are supported by Windows.

Installation

Program SCOP can be downloaded from the SCOP homepage on SAIL (Scania AccessInformation Line). In the SCOP homepage you will find download and installation instructions.After installation the SCOP-program can be customised to your local needs.

Default values and settings can be selected from within the program and saved.

Start of program

To start the program just double-click the SCOP icon on the desktop or in the Start Menu.By adding a command to the filename some special functionality can be obtained.Examples of different commands:

c:\scopwin\sample.sco read saved calculation sample.sco from c:\scopwin\

c:\scopwin\specfile.ini read specification file from Cast/Cesow/ForceDifferent commands can be combined and separated with a space or a /. example:c:\scopwin\scop.exe p:\mypath\scop\/p:\scopcalc\sometruck.scoThis commandline runs SCOP located in c:\scopwin\ with my personal settings from p:\mypath\scop\

and reads my saved calculation file sometruck.sco from p:\scopcalc\

General

All performance calculations are performed on the lower tolerance limit of the engine power(3% below nominal) to avoid mistakes and misjudgements.

If you want explanation about something on the screen just point at it with the mousepointerand hold still and a tip box will appear


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Configuration screen

1. Main configuration view2. Environment configuration view3. Configuration of default values4. Set language used in Scop

5. Enter password for more functionality6. Checked if configuration should not be showed when start-up7. Close configuration8. Configuration for printout and resultwindow

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Configuration environment

1. Sets the ambient temperature. Check all the zones that the transportmission runs through. Influence engine power, fuel consumption andrecommendations.

2. There are four categories of fuel. Different engines use different fueland in this group box you can set the properties of the four fuel types.

3. A number of standard fuels with default properties.4. Sets the fuel density at 15C. Influence engine power and fuel

consumption.5. Set the volumetric energy density. Influence fuel consumption6. Sets the amount of sulphur in the fuel. Influence recommendations

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Default values

1. Select vehicle type to change specification.2. Select a special vehicle or write a name to store a new specification.3. Delete the selected special vehicle (see field 2).4. Save a current specification to selected vehicle.5. Field to edit specification.

Print settings

1. Check the boxes for values that you want to show in result window and

printouts2. Load a default setting

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Type of Vehicle

Type of vehicle are the view were you select which configuration you start yourcalculation. To edit specification see default values above.


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Main screen

1. Select a new specification to start from2. Specify transport task3. Select power train

4. Specify front area and air drag coefficient5. Show selected power train6. Show environment settings7. Show basic performance for selected specification8. Exit SCOP9. Show special function e.g. static forces and ADR-calculation.10. Show selected transport task11. Calculate result for the selected specification12. Open file menu. Here you can open/save vehicle, enter config settings,and exit the program13. Open help menu. Here you can get information about the program, access

E-learning course, open the manual and access the SCOP homepage14. Show parameters that arent simulated

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Select Transport task

1. Select on which route calculation shall be based (For detail informationsee below).

2. Select direction for road simulation (e.g. from Norrkping to Linkpingor from Linkping to Norrkping)

3. Select road surface (For detail information see below).4. Select stop frequency (For detail information see below)5. Set cruising speed6. Set GTW (gross train weight)7. Set drive axle weight8. Set continues working PTO e.g. fridge units9. General information for the route.10. Sets number of stops. (Same as 4 but with higher resolution)11. Set road surface (Same as 3)12. Exit form and discard changes13. Exit form and save changes14. Set offset cruising speed. I.e. if your cruising speed is set to 89km/h

and your offset speed is set to 5km/h then the vehicle is allowed to

travel in 89+5 = 94 km/h downhill. This allows the vehicle to takeadvantage of the inclination, getting a higher velocity at no fuel cost.15. Enter the total expected lifetime mileage here and SCOP will do

calculations of the lifetime fuel consumption etc.

Topography

1. Flat roadOn the Flat road over 80% of the road has less than 2% gradient.

Gradients seldom over 3%.

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2. Hilly roadOn the Hilly road 60% - 80% of the road has less than 2% gradient.Gradients seldom over 8%.

3. Very Hilly roadOn the Very Hilly road less than 60% of the road has less than 2% gradient. Gradients often over8%.

Road surface

A road surface type is defined by a name, rolling resistance values and friction coefficient.There are 5 predefined road surface types to select between. Type number 6 gives a possibility to

create your own temporary special road surface.4 of the road surfaces are represented by symbols to select by clicking:

1. Very hard roadway1.st class dry asphalt or concrete road with a low rolling resistance.

2. Very hard roadway (wet)1.st class wet asphalt or concrete road with a low rolling resistance

3. Hard roadway2.nd class asphalt road or 1.st class gravel road.A road with a slightly higher rolling resistance due to an uneven road surface.

4. Soft roadway2.nd class gravel road.A road with an increased rolling resistance due to a soft and uneven surface.

5. Off roadVery bad road surface. High rolling resistance due to an uneven and soft surface.Could be a construction site or mining operation.


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Stop frequency

Stop frequency together with cruising speed forms the speed profile. Number ofstops and major speed reduction has large influence for powertrain wear and fuelconsumption.

Fluid traffic

Main roads and highways with very few stops and local speed restrictions.0-20 stops (or major speed reductions) per 100 km.

Light traffic

Secondary roads with some stops and local speed restrictions depending on sharpbends, traffic or other obstructions.

Residential traffic

Mainly urban areas with moderate traffic. 50-150 stops (or major speed reductions)per 100 km.

Dense traffic

Mainly city centres with dense traffic, also corresponds to local distribution orconstruction site operation. 150-250 stops (or major speed reductions) per 100 km.

Stop-and-go

Stop-and-go operation mainly in city centres with dense traffic, local distribution orconstruction site operation. More than 250 stops (or major speed reductions) per

100 km.


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Powertrain screen

Engine: Detailed information and selections regarding the engine.Gearbox: Detailed information and selection regarding the gearboxRear axle: Detailed information and selections regarding rear axle

Wheels: Extended information regarding the wheelsAxel gear ratio: Sets the axle gear ratio for the selected axle gear.Exhaust brake: Define if exhaust brake shall be usedAcceleration control: Sets if acceleration control is selectedPower gearing: Set if power gearing or economic gearing shall be used

Opticruise: Set if Opticruise or manual/automatic shall be usedSpeed range: Defines the lowest and highest speed possible without using theclutch or exceeding engine rev for max power output. Note: Maximum speed canbe lower then the upper limit of speed range if there is not enough power to reachmaximum power output.


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Engine

1. Engine type2. Engine emission level3. Engine maximum power4. Engine torque graph where recommended engine revs. are shown as

green area.5. Maximum engine torque6. Select if exhaust brake shall be used

7. Show primary engines8. Show secondary engines9. Show old engines

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Gearbox

1. Gearbox name2. Graph that shows if the gearbox is strong enough for the selected task.

The blue circle shows current transport were GTW is the vertical axleand load factor on the horizontal axle and if circle is in the green area

the gearbox is strong enough.3. Show primary gearboxes4. Show secondary gearboxes5. Show old gearboxes6. Shows ratio for each gear in the gearbox

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Wheels

1. Tyre dimension2. Dynamic rolling radius3. Maximum load for this tyre single mounted / double mounted4. Number of wheels in the vehicle combination affects acceleration time and

fuel consumption. Number wheels includes all wheels in the combination a(e.g. a twin mounted axle has four wheels).

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Air drag

1. Find an appropriate vehicle type in the diagram. Point, and a proposal of Air drag coefficient is

shown. Click, and the value is transferred to the air drag coefficient edit field (5).2. Edit field for overall width (m).

3. Edit field for overall height (m)4. Edit field for the air drag value. The value in this field is the value that will be used in the

calculations.5. Edit field for frontal area (m). The value in this field is the value that will be used in the

calculations.6. Click to go back to the Main screen and discard any changes made.7. Click to go back to the Main screen and keep any changes made.

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Result view

1. Specification for simulation2. Max performance result.3. Performance at selected cruising speed4. Fuel consumption result

5. Results of vehicle lifetime calculations6. Click to show diagram7. Delete the calculation8. Column for first calculation

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9. Column for second calculation10. Left and right click to simulate up and down shift.11. Areas with red background indicate reason for warning.12. Click to show warnings regarding that calculation.13. Click to show recommendations regarding that calculation.14. Click to printout current specifications.15. Close result windows


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Special functions screen

In special function screen it is possible to see static forces for down and uphill

driving. There are also possible to see result from ADR-type IIA calculations.

1 Definition of gradient, road speed, selected gear and engine rev.2 Forces and power with full engine power

Transferable force is the force that is possible to transfer to the ground due to drive axleload and friction between tyres and ground.Traction force is the engine power recalculated to the contact area between tyres androad surface.Available force is the force that can be transferred from the wheels to the ground.Force in reserve value means that the vehicle is able to climb the specified gradient in theselected gear at the defined speed.

3 Forces and power when braking.Exhaust brake and Retarder are the brake forces from these equipments recalculated tothe contact area between tyres and ground.Powertrain losses is the internal losses of the gearbox and rear axleBrake force in reserve value tells if the vhicle have enough brake power to keep aconstant velocity without using the wheel brakes.

4 SettingsSets the parameters for the calculations

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Hill and acceleration test

1. Acceleration testShows recommended gear to perform acceleration test and the calculated time foraccelerate from start engine speed to final engine speed.

2. Performance testSets parameters for the acceleration and hill test.

3. Hill testShows engine speed and vehicle speed for possible gears at steady-state in an uphill withthe slope stated in the Gradient field.

4. CalculatePerform new calculated based on data submitted in the performance test box.

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ADR test

1. Test constantsCR1 is a rolling coefficient.CR2 is a rolling coefficientCd is the air drag coefficient

2. Test descriptionPush the buttons to see the test description

3. Result of calculationsGear chosen for optimal brake capacity (without harming the engine)

Diagrams:Click the type of diagram you want to see on the screen.

Power diagram. Engine power and engine torque vs. engine speed.

Gear shift diagram. Engine speed vs. road speed on different gears.

Brake diagram. Downhill gradient vs. road speed on different gears when braking withoutusing the wheel brakes.

Acceleration test diagram. Acceleration time vs. road speed when accelerating on a flatsurface.

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Power Diagram

1. Engine torque diagram. Torque on the vertical axle and engine revs on thehorizontal axle.

2. Engine type.3. Engine power diagram. Power in horse power on the vertical axle and

engine revs on the horizontal axle.4. Print diagram (A print out window will appear).5. Close diagram

Gear shift Diagram

The shift diagram shows the engine speeds as a function of vehicle speed for thedifferent gears.

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1. Engine type2. Engine revs scale.3. Gearbox type4. Axle gear and axle gear ratio5. Tyre dimension6. Name on gear7. Not recommended engine revs (red field).

8. Recommended engine revs (yellow/green field) for vehicles with tough drivingconditions.

9. Recommended engine revs (green field). This gives both good fuel economyand good driveability.

10. Recommended engine revs (light green field). This gives the best fueleconomy but Opticruise and easy driving conditions are required.

11. Click button to print (will open the printer setup screen).12. Click button to get back to Main screen.13. Road speed scale.

Brake diagram

1. Engine name2. Gearbox3. Down hill gradient scale.4. Axle gear and axle gear ratio5. Tyre dimension6. GTW (Gross train weight)7. Drive axle weight8. Brake curves for the different gears without using wheel brakes.9. Click button to print diagram (will open the printer setup screen).

10.Close diagram.11.Road speed scale.

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Acceleration test diagram

1. Engine name2. Gearbox name3. Acceleration time scale.4. Axle gear and Axle gear ratio5. Wheel dimension6. GTW (Gross train weight)7. Drive axle weight

8. Acceleration curve9. Click to print out diagram.10. Click to get back to Main screen11. Vehicle speed scale

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Considerations and definitions

Many different factors must be considered when choosing a powertrain (engine,gearbox, axle gear and axle gear ratio). Some of these factors are covered by theSCOP -program, but users of the program must be able to assess a number ofequally important factors themselves.

The program takes these factors into account: Gradeability and startability in lowest gear.

Drive axle weight required to be able to climb a given gradient without wheelslip.

A suitable engine speed at cruising speed,

Driveability in top gear at cruising speed on a specified type of road.

Permitted loading for gearboxes, axle gears, axles and clutches.The program takes these factors into account to a limited extent:

The scope of the transport task

Service life Driver attitude

Market conditionsIn view of this, the users judgement must play an important part in thechoicesmade.Mixed driving conditions

Vehicles are often used for several different types of duty, and the transport taskmay be made up of many different types of driving conditions. A transport task

may consist of different types of driving on roads with different surfaces,topographies and at different cruising speeds. Often the train weight changesthroughout the run. In such cases it may be tricky to decide what drivingconditions to specify the vehicle for.As a general rule, vehicles should be specified for the driving conditions thatapply to the major portion of the driving, but it is important to check that othertypes of driving not will raise problems. Sometimes this will mean departing fromthe optimum solution found and instead looking for a compromise to cover allthe actual driving conditions.

If two different driving conditions exist in equal proportions, the vehicle should bespecified for the case with the higher fuel consumption, since this is where mostcan be gained by an optimisation.This means, for example, that:

If a vehicle is driven laden in one direction and unladen in the other, it must beoptimised for the laden case.

If a vehicle is driven on a gravel road for half the run and on asphalt for the

other half (at the same speed), it should be optimised for the gravel road.

If the cruising speed on half the run is 70 km/h and on the other half 90 km/h,the vehicle should be optimised for 90 km/h.


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However, a rear axle ratio that allows the vehicle to be driven at 70 km/h intop gear should be chosen if possible.

What driveability to demand?

Driveability in the SCOP program is the gradeability at cruising speed. This is ameasure of the amount of power reserve at cruising speed. A low driveabilitymeans that the vehicle will lose speed and the driver will have to change down

even for very slight gradients.Consequently, low driveability results in higher number of gear changes.A low driveability naturally also means that, at cruising speed, the engine will berunning closer to its maximum power, compared with a vehicle with a higherdriveability (better gradeability).A low gradeability figure will result in a lot of gearshifts when driving and a highfigure means comfortable driving without a lot of gear shifts.When specifying the powertrain of a vehicle the goal should be to get thegradeability good enough to climb most of the small gradients in top gear at

cruising speed.Gradeability recommendations at cruising speed:0.8% is the lower limit.Below this the vehicle will feel weak and underpowered. Its speed will drop evenfor slight gradients, and the driver will have to change down very often.1.5% This vehicle has a good driveability. The engine does not have to work sohard and will therefore last longer. A great portion of the transport can be carriedout in top gear without loosing speed and without need to change down to a lower

gear.2% Driveability in this case is so good that a choice of a less powerful enginemight be considered.The gradeability demand is normally lower on a flat road compared to a hillierroad, since the hills resulting in gear changes are less frequent.Rolling resistance

The rolling resistance depends on:

the nature of the road surface

the type of tires

the speed of the vehicle

the Gross train weight (GTW) of the vehicle

The rolling resistance is calculated on the basis of the rolling resistance coefficientwhich is in fact two coefficients:

Cr1 is a static coefficient and is expressed in N/tonne

Cr2 is a speed depending resistance part

Total rolling resistance coefficient:Cr = Cr1 + Cr2 * Vehicle speed (N/tonne)


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Friction coefficient.

The friction coefficient (Mu) is a measure of how much force can be transferredfrom tire to road without wheel slip.The friction coefficient depends among other things on:

the nature of the road surface

the type of tiresSome friction coefficient values used in SCOP:Road surface MuDry asphalt 0.8Wet asphalt 0.6Gravel road 0.4 0.6

Air resistance

The air resistance of a vehicle depends on:

Total frontal area of the vehicle, in other words how much air the vehicle mustforce aside as it drives forward.

Speed.

Density of the air, which depends on the temperature, among other things.

How the vehicle is designed in terms of air flow and the formation of possibleeddies. This is usually expressed as a figure known as the air resistancecoefficient (Cd) of the vehicle.

Fuel consumption

The program gives two different figures of fuel consumption for each transporttask parts.1. The first is a fuel consumption figure when driving on a completely flat

horizontal road at a constant speed equal to the cruising speed. This is amomentary fuel consumption that is lower than what can be expected in realdriving since there are no accelerations or speed changes and is on acompletely flat road.

2. The second fuel consumption figure is calculated for a road that is similar to

what you have specified. In this figure topography, average gradient (altitudedifference between start and end point) and speed variations (accelerationsand number of stops) are taken into account.

It is very important to remember that this second figure is based on a predefinedroad in the program and that the result can be different compared to the real liferesult. How big the difference is depends on how well the predefined road reflectsthe real road (topography and speed variations). Another factor that can make thereal fuel consumption differ quite a lot from the value given by the program is howthe driver is acting.

It is important to be very careful how to use the fuel consumption resultssince the values given by the program are valid only on the roads used inthe program.


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How good this reflects the reality depends on to what extent the used road issimilar to the real road (both topography and speed profile).The figures can be used for comparing different specifications on the sametransport task and as an indication of expected fuel consumption.Never use the fuel consumption figures as a promise or as guaranteed fuel

consumption.Speeds

The program is dealing with several different speed definitions:

Cruising speed is the speed you as a driver want to drive at on the major partof the transport task part. The cruising speed is together with the tyre size themost important factor when selecting rear axle ratio.

Maximum speed is the highest speed the vehicle can reach on a flat road

taking engine power and all resistances into account.

Total speed range is the range from the lowest driveable vehicle speed ( at1000 r/min) in lowest gear up to the vehicle speed at maximum power enginerev. when driving in top gear only taking ratios and tire size into account.Since neither the power of the engine nor the road or air resistances are takeninto account the maximum speed on a flat road can be higher or lower thanthe upper limit of the speed range depending on engine power andresistances.

Average speed is the average speed obtained on the predefined road thathas been selected in that transport task part when using the specified cruisingspeed.When calculating the average speed engine power and all resistances aretaken into account. If a number of stops or differences between start and endaltitudes have been entered this is also taken into account.Differences between the real road result and the value given by the programcan (and will) occur if the road used by the program differs from the real road(topography and/or speed profile).

Topography and Maximum gradientTopography and Maximum gradient must not be mixed up.Topography is a measure of the variations of altitudes existing on the transporttask part as a whole.Maximum gradient is dealing with the very steepest hill on the transport taskpart.This means that a road with a flat topography can have a very high gradient asmaximum gradient.

On the other hand it is not necessary that the maximum gradient of a hilly road isvery steep.


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If the topography of a road is flat in the first half and is very hilly in the second halfit can be defined as a hilly road as a total.However it might be more accurate to split the road into two parts and definethem as flat and very hilly respectively.This method makes it possible even to adjust other parameters for the differentparts separately (i.e. cruising speed, road surface etc.).

If a road starts on a low altitude and ends up in a high altitude it can still belong toany of the three different topography types.If the road has few altitude fluctuations when ascending it should be entered as aflat road with a difference between start and end altitude.If a road is defined as a flat road, a lower value of gradeability at cruising speedcan be accepted compared to if the road is hilly, because of the fewer number ofgradients occurring on the flat road.


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Factors that influence service life

The life of the various parts of a powertrain depends, among other things on:

How well the parts are suited for the transport task for which they are to beused.

What other powertrain components the parts are to operate in conjunctionwith.

Here are some comments on factors that affect the service life of differentcomponents.

EngineThe life of an engine depends among other things on power output and enginespeed.If an engine has to operate close to its maximum power for most of the time it isrunning, its life will be reduced.In other words, engine life can be increased by choosing an engine that gives a

higher hp/tonnes figure compared with that obtained if a 'minimum' engine ischosen.If the engine speed at cruising speed is high, the number of engine revolutionsper km will of course be higher than at a low engine speed. The wear of certainparts of the engine is a function of the number of engine revolutions. Engine lifewill be longer for lower cruising speed revolutions.Note: The engine revolutions at cruising speed should not be too low since thiscan cause some driveability problems as for example poor engine response when

driving uphill.

GearboxThe life of the gearbox depends on several factors:

Amount and duration of torque transferred.

Which gear that is used.

Temperature in the gearbox.These factors are in turn influenced by:

Gross train weight. If the train weight is high the torque will be higher thanwith a lower train weight. This is valid both for the mean torque and themaximum torque that can occur in certain extreme situations, for examplewhen starting on a steep slope.

Road topography. If driving involves roads with many long, steep hills, hightorques in certain gears will predominate, compared with driving on flatterroads. This may shorten the life of certain parts of the gearbox.

Road speed. Driving at high speeds will increase the torque passing throughthe gearbox because of increased rolling and air resistances.

Rear axle ratio. If the rear axle ratio is too low, the vehicle may seldom or

never be driven in top gear. This puts an abnormally high strain on the lower


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gears, and leads to higher temperatures in the gearbox, since efficiency is notas good in lower gears as in top gear.This will cause the fuel consumption increase as well.

Tyre size. Tyre size will affect in the same way as rear axle ratio (see above)since it is a part of the total ratio.

Engine size. A powerful engine provides a higher input torque on the gearbox

than a weaker engine on accelerating and when climbing hills.Clutch

The life of the clutch depends largely on how and how often it is used.The greatest strain on the clutch is when the vehicle is being started.The clutch has to be slipped while the vehicle is accelerated from stationary up tothe lowest driveable speed in starting gear. To preserve the clutch, this period ofslip should be kept as short as possible.

Of this reason it is important to ensure that the lowest driving speed in startinggear is not too high. This is particularly important when driving with high trainweights.The lowest driving speed in bottom gear depends on gearbox, axle ratio and tiresize.Rear axle and axle gear.As far as life is concerned, rear axle housing must be regarded as one part andaxle gear as another.

The life of the axle gear depends on the torque transmitted and the time forwhich the torque is applied. Factors that influence this include:

train weight

road topography

road surface (rolling resistance)

engine power

axle ratio

tire size

road speed

A low axle ratio (fast vehicle) means that the input torque to the axle gear mustbe higher than with a higher ratio for equal output torque to the wheels.Choosing the correct axle ratio is important for several reasons:

Suitable engine speed at cruising speed. The vehicle shall be able to run intop gear at cruising speed at an engine rev. within the economic range.Important for fuel consumption and engine life.

Good gradeability in bottom gear. Enables the vehicle to cope easily with

the steepest hills on the run.


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Good startability. The total ratio, of the axle gear and the bottom gear of thegearbox, must, together with the tire size, give a lowest driveable speed that islow enough to avoid excessive wear on clutch when starting.

The life of the axle bridge depends primarily on the vertical forces that arepresent.

The static axle load that is caused by the weight distribution on the vehicle.

The dynamic axle load which is caused by irregularities in the road surface

and the speed at which they are encountered.

Market conditions

The idea of the SCOP program is to give guidance when choosing a powertrain,so that users easy can compare alternatives and avoid mistakes when specifyingvehicles.It is important to remember that there are mostly several combinations that aremore or less equivalent and that you can not say that this is the only correctsolution.It is, as pointed out before, important to remember that the SCOP program is acalculation tool that has to be used in combination with your knowledge andexperiences.In fact there may be several reasons for departing from the first found solution,for example:Product rangeIt is by no means certain that the powertrain combination first found even existsas a selectable combination for the market in question or for the chassis type you

of other reasons want to specify. However this is not a serious problem since it isvery easy to make modifications in the program to find a permitted combinationthat gives more or less equal results.Local experienceYou also have to consider local conditions such as the climate and the standardof the roads when specifying the powertrain. This means that local experiencesmight be a reason for not specifying according to what is considered to be the'best' solution by the program.Servicing

If a particular engine or type of vehicle has never operated in a given market it isa good idea to think seriously before introducing it. An 'odd' vehicle may causeproblems with servicing and spare parts supplies.

Local conditionsIn some markets there are deeply ingrained views about what is the right type ofvehicle for certain transport tasks. This may be due to conservative attitudes butmay also be based on special operating conditions and real life experiences.As a general rule it is advisable to proceed with caution when tempting toovercome such attitudes and try to find the real reasons behind.


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What about the driver?There are many kinds of driver and as many different driving techniques. Thismust be taken into account when choosing a powertrain for the vehicle.It is also very important to know the drivers expectations of the vehicle.For example if a driver expects a sporty vehicle, there must be sufficient powermargin at cruising speed and the engine revs. at cruising speed when in top gearmust not be too low, otherwise the driver will be dissatisfied and treat the vehicle

accordingly. The service life of the vehicle will be shortened if a less powerfulengine is chosen in such a case.However if the diver aims to keep down the fuel consumption and knows howmuch can be gained by economical driving, an engine with a smaller powermargin and lower engine revs. at cruising speed can be chosen, but it isimportant never to go below the 'minimum' specification gradeability =0.8%. Thisshould be regarded as the definite bottom limit when specifying the powertrain fora vehicle.


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Troubleshooting and feedbackOne very important part of making a program like this is to get feedback from the users. Thismeans that if you have any problem when using the program please let us know.We are of course also very interested to know if you have any ideas about enhancements thatmight be added to the program and make it more useful to you.

If you have access to CREAM (available from Sail) you can see which improvements arescheduled and add your own suggestions. If you dont have access, you can contact:Scania CV. ABMikael Curbo / YDAS-151 87 SdertljeSwedenTelephone: + 46 8553 820823E-mail: [email protected]

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