Tractors - Scania Group

05:10-01 Issue 4 en-G

Tractors
General information on tractors
351

805

General information on tractorsTractors are intended to pull semi-trailers and are therefore equipped with a fifth wheel to make it possible to easily switch trailers.

In order to utilise the tractor optimally and not impair the vehicle's properties, it is important to follow national and international regulations when selecting axle dis-tance and fifth wheel position.

RecommendationsAxle distanceChoice of axle distance is affected by factors such as the following:

• The semi-trailer's front overhang

• National regulations on vehicle length and gross vehicle weight

These factors limit the possibilities to vary the longitudinal position of the fifth wheel. The shortest possible axle distance should generally be selected.

B 1 (13)© Scania CV AB 2014, Sweden

TractorsRecommendations

314

490

General guidelines for fifth wheel positioningIt is not possible to give exact recommendations for fifth wheel positioning since that is affected by many factors such as the chassis configuration, axle distances and, more importantly, legal requirements regarding both axle weight and vehicle meas-urements.

IMPORTANT!

Bear in mind the following when determining fifth wheel position:

• Always check the axle weight for each individual case when positioning the fifth wheel.

• Check that there is enough space between the semi-trailer and the rear of the chas-sis frame. There must be no risk of the semi-trailer striking the cab or rear end of the chassis frame.

• If the fifth wheel is positioned too far in front of the driving axle of a 2-axle vehi-cle, the following will occur:

– Driveability is impaired– The risk of exceeding the permitted front axle weight increases

• If the distance between the fifth wheel and the centre of the rear axle or bogie is short, the semi-trailer will displace the tractor laterally during skew (cornering or slippage), which is a danger on slippery road surfaces. The displacement varies depending on the load and road conditions and how great the acceleration or re-tardation is.

• To make best use of the maximum front axle weight on long tractors, the fifth wheel is often positioned far forward, which increases the risk of frame oscilla-tion.

© Scania CV AB 2014, Sweden

05:10-01 Issue 4 en-GB 2 (13)


The theoretical bogie centre is specified on the ICD (Individual Chassis drawing).

max 760 mm

351

801

The following fifth wheel position gives the vehicle combination good driving qual-ities and a relatively low front axle weight:

• On 2-axle vehicles: 10% of the axle distance in front of the rear axle.

• On 3-axle vehicles: 10% of the axle distance in front of the theoretical bogie cen-tre. Position the fifth wheel slightly farther forward to increase the front axle weight.

Position the fifth wheel max. 760 mm in front of the rear axle on 2-axle tractors as driving with a semi-trailer puts a highly concentrated load on the chassis frame.


05:10-01 Issue 4 en-GB 3 (13)


max 4 500 mm

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804

Special regulations to comply with EC directive 96/53/ECTo be able to transport a 13.6 m long EU semi-trailer with a total length of maximum 16.5 m, the distance between the front of the tractor and the centre of the fifth wheel must not exceed 4,500 mm.

On an EU semi-trailer, the distance between the trailer kingpin and the rear end of the semi-trailer is 12 m.

96/53/EC is an EC Directive (EC = European Community) with rules for weights and dimensions (Masses and Dimensions) that apply to vehicular traffic.


05:10-01 Issue 4 en-GB 4 (13)

TractorsAdaptable equipment for different transport types

315

590

315

591

Adaptable equipment for different trans-port typesTo be able to use the tractor for different types of transport, adjustable fifth wheels and replaceable lock mechanisms are used.

Adjustable fifth wheelA fifth wheel that can be adjusted along the longitudinal direction of the tractor ena-bles the following:

• Adaptation to the various countries' national regulations for axle weight and ve-hicle lengths

• Optimisation of weight distribution between the front and rear axle

• Adaptation to different types of semi-trailers

Replaceable lock mechanismA replaceable lock mechanism makes it possible to pull different types of semi-trail-ers.


05:10-01 Issue 4 en-GB 5 (13)

TractorsCombining vehicles and equipment in accordance with ISO 1726

A

343

247

A = Fifth wheel height above the ground

Combining vehicles and equipment in ac-cordance with ISO 1726ISO 1726 is an international standard covering the characteristics and positioning of the fifth wheel and clearance required by the semi-trailer.

Tractors and semi-trailers which comply with the standard can be combined with one another from a purely technical viewpoint.

IMPORTANT!

In addition to technical interchangeability, it is important to take regulations on the external dimensions and axle loads of the vehicle combination into consideration.

Vertical position of the fifth wheelThe following dimensions apply to the vertical position of the fifth wheel:

Road train Minimum MaximumLoaded tractor 1,150 mm 1,300 mm

Tractor without trailer - 1,400 mm

Loaded, bulk-adapted tractor 1,025 mm 1,100 mm

Bulk-adapted tractor without trailer - 1,150 mm

Loaded, bulk-adapted tractor with direct-mounted fifth wheel

900 mm 975 mm

Bulk-adapted tractor without trailer with direct-mounted fifth wheel

- 1,000 mm


05:10-01 Issue 4 en-GB 6 (13)


21 ωω

351

803

12

αα

351

800

Fifth wheel angles

Minimum angle of inclinationTo ensure sufficient clearance between the tractor and semi-trailer under all driving conditions, the tractor must permit the following minimum angles of inclination for the trailer:

• Forwards: 6° (ω1)

• Rearwards: 7° (ω2)

• Sideways: 3° (α1 = α2)

The following angles apply to tractors with low-mounted fifth wheel:

• Forwards: 3.5° (ω1)

• Rearwards: 4.5° (ω2)

• Sideways: 2° (α1 = α2)

Note:ISO 1726 specifies the angle of inclination ω as the clearance in relation to the tyres.


05:10-01 Issue 4 en-GB 7 (13)


G

BEP-L078 BEP-L079

315

616

For more information on measurement designations, see the Measurement designa-tions document.

Clearance for semi-trailer front overhangIn order to be able to operate the tractor freely, the diagonal dimension of the semi-trailer front overhang (BEP-L078) must not exceed 2,040 mm.

The rear section of the tractor must also have sufficient clearance. The minimum per-mitted distance from the trailer kingpin to the semi-trailer supporting leg is shown as G.

Leave 100 mm extra space between the radius described by the distance from the kingpin to the tractor's most rearward obstacle (BEP-L079) and radius G to allow for any angle differences between the tractor and the semi-trailer. Check the dimension at a steering angle of +/- 45°.

BEP-L078: Max. 2,040 mm

BEP-L079: Maximum 2,200 mm

G: Minimum 2,300 mm


05:10-01 Issue 4 en-GB 8 (13)


G

R

Y

P

315

617

Check interchangeability between the tractor and semi-trailerA coupling profile has been devised and can be used to ensure that the semi-trailer has enough clearance in relation to the tractor. The coupling profile indicates the most important measurement limits which guarantee interchangeability between the vehicles.

All tractors and semi-trailers built in accordance with ISO 1726 follow these meas-urement limits.

• P = Minimum 750 mm

• Y = Maximum 4°

• R = Maximum 450 mm

• G = Minimum 2,300 mm


05:10-01 Issue 4 en-GB 9 (13)

TractorsCalculation of D value according to directive UN-ECE R55

T

U

R

351

802

Calculation of D value according to direc-tive UN-ECE R55UN-ECE R55: Regulation on type approval of coupling devices.

The D value defines a theoretical horizontal reference force for towing units in the vehicle's longitudinal direction.

The selected towing unit must have the same or a higher D value than the D value of the intended road train.

D = g ·0.6 · T · R

(kN)T + R - U

T = Technically permitted gross tractor weight in tonnes

R = Technically permitted gross semi-trailer weight in tonnes

U = Vertical load in tonnes on fifth wheel

g = Gravity (9.81 m/s²)


05:10-01 Issue 4 en-GB 10 (13)

TractorsHeavy-haulage tractor

Heavy-haulage tractorA heavy-haulage tractor is a road train with a gross weight from the maximum per-mitted weight to a maximum of 250 ton.

A heavy-haulage tractor has a limited service life regarding the powertrain and re-quires more frequent maintenance intervals than other vehicle types.

General information on heavy-haulage tractorsScania defines the heavy-haulage business according to the following conditions:

• When the cargo is large and bulky, for example components for power stations, construction equipment and suchlike.

• When transportation is done on very hard road surfaces

• When a special permission from the transport authorities is required due to size and weight of the vehicle combination.

Vehicle for a gross train weight of up to 250 ton can be delivered complete from the factory.


05:10-01 Issue 4 en-GB 11 (13)


250

200

150

100

50

3 6 9 12 % X

Y

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799

Y = Max gross road train weight , X = Inclination

RecommendationsScania recommends that vehicles with a gross laden train weight between 150 and 250 ton are driven on roads with an inclination of less than 3%. Vehicles with a gross laden train weight of less than 150 ton can be driven on roads with up to 12% incli-nation. The weights are independent of the engine's performance and apply with Sca-nia's standard equipment and rear axle gears.

Contact a Scania dealer for more information.


05:10-01 Issue 4 en-GB 12 (13)


More information on subframes for tractors, fitting of the fifth wheel and information on the installation of winches or cranes is found in the Fitting the fifth wheel docu-ment.

More information on fifth wheels and their installation is found in the Fitting the fifth wheel document.

More information is found in the document Controlling Power take-offs and engine speed.

MountingGenerally, a subframe is recommended for heavy-haulage tractors. The fastening an-gle can be used if the following conditions are fulfilled:

• Favourable road conditions

• Moderate speeds

• Experienced driver

Crossmembers and side membersWhen cornering, lateral forces from the semi-trailer need to be distributed between the frame side members. If only one frame member is loaded by the lateral forces, it could become deformed. The subframe should, therefore, be equipped with cross-members in front of and behind the fifth wheel attachments.

Engine torqueFor heavy-haulage tractors, torque limitation is recommended to protect the clutch.

The following preparations and options can be obtained from the factory:

• Opticruise

• Protective mode for coupling actuator

• Clutch wear protection

• Hill hold

• Retarder


05:10-01 Issue 4 en-GB 13 (13)

Documents

Tractors - Scania Group