Vehicle Dynamics - High Capacity Transports · PDF fileBF72991, Niklas Fröjd,...

Volvo GTT

HCT = Combinations heavier than 60 tons and/or longer than 25.25 m, like this:

BF72991, Niklas Fröjd, SVEA-presentation 2015,

1 Date

Vehicle Dynamics - High Capacity Transports

Increased profit for transport companies

Decreased costs for transport buyers

Decreased over all fuel consumption and emissions (per ton and km)

Increased traffic flow

Volvo GTT

2 Date

Finland, October 2013

Increase of max weight from 60 to 76 tons within

25.25 meters - to strengthen the national

transport companies and reduce costs for the

industry.

Sweden Step 1: June 2015

Increase of the maximum weight on BK1 roads

from 60 tons to 64 tons within 25.25 meters

Sweden Step 2: 2017?

Heavier (74 tons) and/or longer combinations on

some Swedish roads. Investigations ongoing - BK4 roads and bridges

- Safety regulations

- Road versus rail consequences

- Weight reporting systems

HCT introductions in Finland and Sweden

BF72991, Niklas Fröjd, SVEA-presentation 2015

76T

64T

74T

Volvo GTT

3 Date

Some HCT dispensation tests on the road

Speed Ltd, 80T 2x45’ A-double 2013

UPM, 94T Timber A-double 2014 Schenker, 66T 3x7.81 CAT double 2015

SCA 90T Truck B-double 2009-2014 1.3 Mkm


Volvo GTT

4 Date

• Traction/Start capability: The heavy vehicle should be able to start motion, maintain

motion and attain a desirable level of acceleration.

• Off-tracking: The rear end of the vehicle and all the units within the vehicle

combination should follow the path of the front end of the vehicle with adequate

fidelity.

• Stability: The vehicle should be stable, attain directional control and remain upright

during maneuvering and braking.

• Braking: The vehicle should safely attain a desirable level of deceleration during

braking.


Safety areas related to vehicle dynamics

Volvo GTT

Foreseen Swedish regulations will probably be a mix of performance

requirements and prescribed technologies covering the safety areas, like

this:

A set of performance tests and measures to fulfill

A set of approved calculation procedures as alternative

A set of predefined vehicle combinations deemed to comply

A set of prescribed technologies (Electronic Brake & Stability Control…)

5 Date


Safety regulations to come for HCT step 2

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6 Date


Examples of performance tests

Volvo GTT

7 Date

Hill start capability

Hill start test on 90T Truck B-double

at Hällered 2013

ETT Hillstart.MTS


90T ETT hillstart.mp4

ETT Hillstart.MTS

90T ETT hillstart.mp4

Volvo GTT

8 Date

Hill start capability – results & factors

Slope and Friction

Gross vehicle weight

Drive axle/axles ground pressure

Differential systems

Gear box and final gear ratios

Clutch system

Engine power/torque curve

Engine/gearbox/brake control logics

Drivers skill and awareness

Fully laden units typically max 12% dry slope


Volvo GTT

9 Date

Low speed off-tracking – swept path

Swept path test on 80T A-double at

Asta Zero and Hällered 2014

DUO Svep.mp4


DUO Svep.mp4

Volvo GTT

10 Date

Low speed off-tracking – typical results

-20 -10 0 10 20 30

-10

-5

0

5

10

15

20

25

30

m

m

Tractor/Semi(13.6 m)/Dolly/Semi(13.6 m). Max off-tracking of last unit.

inner circle Ri=2.4486

reference path R=12.5

max sweep=10.0514 at -1.4871

front corner outboard off-tracking =0.1445

rear corner outboard off-tracking =0.19669

swept path = 𝑅 − 𝑅𝑖


Volvo GTT

11 Date

High speed stability – rearward amplification

Lanechange tests at 80m km/h on 90T Truck B-double

Hällered 2014

BF72991, Niklas Fröjd, PBS-presentation 2015,

ETT lanechange.mp4

ETT lanechange.mp4

Volvo GTT

12 Date

High speed stability – typical results


ETT Lanechange.MOV

ETT Lanechange.MOV

Volvo GTT

13 Date

Low speed off-tracking & High speed stability


Good for stability

Long wheel bases

Long drawbars

Tight rear coupling

Laterally stiff tyres

Good for tracking

Short wheel base

Short drawbars

Far rear coupling

Auxiliary steering

Volvo GTT

14 Date

Why rearward amplification is critical

Simulation performed on 90T Truck B-double

ETT_lanechange.mp4


ETT_lanechange.mp4

Volvo GTT

15 Date

Brake performance and stability on dry road

Max brake from 80 km/h - tests at Hällered 2014


DUO full brake.mp4

DUO full brake.mp4

Volvo GTT

16 Date

Max braking in dry conditions - results

Retardation: 5,9 m/s2

Stopping distance: 42 m

The vehicle combination is stable during the braking


204 205 206 207 208 209 210-10

0

10

20

30

40

50

60

70

8014w41 DUO2 80tons Full brake 80-0kph dry.xlsx

time (s)

ve

locity (

km

/h)

Volvo GTT

17 Date

Stability during braking on icy road

Max brake from 60-70 km/h - tests at Arjeplog 2015

curve driving 1,5 – 2 m/s2 lateral accleration


Full brake in icy curve.mp4

Full brake in icy curve.mp4

Volvo GTT

18 Date

Stability during braking on icy road - results

Stopping distance from 60 kph: 25 – 45 m dependent on ice friction

With fully operational brakes the vehicle combination is stable

There is no ECS intervention during the high speed braking

At ABS fail, the combination is unstable


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19 Date


In case of time

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20 Date

Rollover stability – SRT (Static rollover threshold)

From tilt tests on timber trailers

Göteborg, Lundby 2014


𝑆𝑅𝑇 𝑔 = tan 𝑣

𝑣

Volvo GTT

21 Date

Rollover stability – results & factors

BF72991, Niklas Fröjd, PBS-presentation 2015,

Track width and COG height

Roll stiffness in relation to ground pressure

Suspension geometry (roll centre position)

Structure compliance and backlash

Moving load

Fully laden units typically SRT = 0.4 g

Vehicle Dynamics - High Capacity Transports · PDF fileBF72991, Niklas Fröjd,...

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