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ROADEX Network Implementing Accessibility


Tyre Pressure Control

ROADEX IV final seminarRovaniemi, 25 April 2012

Pauli KolisojaTampere University of Technology


Outline of the presentation

• Basic idea of CTIS/TPCS• Historical development• Effect of TPC on wheel/road contact• Principle of operation to reduce tyre wear• Effect of TPC on road stresses• Effect of TPC on traction/mobility• Effect of TPC on driver’s health (by Johan

Granlund tomorrow)• TPC installation statistics in some of the

ROADEX countries


Basic idea of CTIS/TPCSCTIS = Central Tyre Inflation SystemTPCS = Tyre Pressure Control System


Historical development• 1942 US amphibious landing craft

Material borrowed from Allan Bradley, FPInnovations FERIC, Canada


Historical development• 1944 - 1960 widespread development and use

in military applications by Soviet Union• 1960 – 1970 also in many civil applications



Historical development• Widespread adoption by US and western

European militaries in 1990s; • By 1990, 30+ types of CTI used around world

• In 1982, USFS began CTI research program; applied to various forestry vehicles

• In 1993, first two TPCS for commercial trucks



TPCS components

ECM

+/-

ECM

+/-


Effect of TPC on wheel/road contact




Munro, R. & MacCulloch, F. (2008) Tyre Pressure Control on Timber Haulage Vehicles, ROADEX III report



Contact area

Stiffness and spring rate

Less impact energy

Lighter footprint, more tread

Contact stress distribution

Rut shape Wider, shallower rut




Less motion resistance in the direction on driving better mobility of the vehicle

Rut depth

Steep incline Shallow incline

High pressure Low pressure



Principle in the use of TPCS

Uncontrolled tires are over-inflated for 75% of the tripless tyre wear with the use of TPC

500

400

200

UNCONTROLLED TIRESTI

RE

PR

ESS

UR

E (k

Pa)

CONTROLLED TIRES

SECONDARY UNLOADED

80 km/h

SECONDARY LOADED 80 km/h

PRIMARY UNLOADED

100 km/h

PRIMARY LOADED 100 km/h

0

600

300



Effect of TPC on road stresses –Field trial at Stynie Woods, Scotland


Installation of the earth pressure gauges


Pressure distribution at full tyre pressure under the front wheel

Pressure distribution as a function of depth as expected.


Effect of tyre inflation pressure on road stresses

190

140

80

40

0

50

100

150

200

250

300

350

160 170 180 190

Pres

sure

, kPa

Drive path, cm

Low tyre pressure

P1_317 P2_317 P3_317 P4_317

235

170

90

45

0

50

100

150

200

250

300

350

160 170 180 190

Pres

sure

, kPa

Drive path, cm

Medium tyre pressure

P1_517 P2_517 P3_517 P4_517

300

185

90

50

0

50

100

150

200

250

300

350

160 170 180 190

Pres

sure

, kPa

Drive path, cm

High tyre pressures

P1_586 P1_690 P2_586 P2_690

P3_586 P3_690 P4_586 P4_690


Effect of TPC on road stresses

Stresses are reduced near to the road surfacebut much less deeper in the subgrade TPC helps on Mode 1 rutting, but not on Mode 2


Calculated effect of lowered tyre pressure

-1500

-1250

-1000

-750

-500

-250

00 100 200 300 400 500 600 700 800

Vertical stress, kPa

Dep

th, m

m

690 kPa inflation

450 kPa inflation

240 kPa inflation

AC

BASE

SUBGRADE

2045 kg = tire mass

Largest stress reductions occur in surfacing and

base layers



Effect of TPC on traction /mobility –Filed trial at Niinisalo, Finland


Effect of TPC on traction/mobilityField trial at Niinisalo, October 2011


Effect of TPC on traction/mobilityResults obtained on loose / soft surface



Effect of TPC on traction /mobility –Wintertime filed trial at Ivalo, Finland

10 %

17 %

23 %

200 m

160 m

50 m

Uphill profile at the Nokian Tyres test site:



10 %

17 %

23 %

200 m

160 m

50 m

Tyre inflation pressures(kPa)

Climbing distanace(m)

Full pressure in all tyres 370

’Medium’/350 kPa in driving wheels 380

Low / 220 kPa in driving wheels 379 - 380



A heap of show in front of the trailer wheels in the low pressure drive.


TPC installation statistics in some of the ROADEX countries

CountryYear of the first TPCS installation

Approximate number of

installations today

United Kingdom 2006 About 100

Sweden 2003 > 130

Finland 2009 >10


Questions ?

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