Economic Tyre Turning: Wheel Wear
Predictions
V/T SIC Seminar 2015
Julian Stow
Dr. Yousif Muhamedsalih
Institute of Railway Research
What is ETT?
Economic Tyre Turning (ETT): re-profiling wheels to the design
profile using a thinner flange within RGS limits
2.5 mm
6.2 mm
Benefits
• Profile restored with smaller reduction in wheel diameter
• Can extend wheel life (sometimes significantly)
– Useful when the wheel is nearing scrapping diameter
• Provides flexibility – delay / plan wheelset change
• No cost at time of turning
– Is already an option on most modern wheel lathes
But:
• Benefit can only be achieved once in the wheelset’s life
• ETT not permitted by RGS GM/RT2466
Background
• The potential for ETT was highlighted during RSSB research
project T963 (‘Wheel Tread Damage Guide’)
• Mark Burstow (NR) examined thin flange profiles turned on scrap
wheelsets at several wheel lathes
• The resulting profiles contravened both GM/RT2466 & EN 13715
– The shapes of the flange faces produced are the same as the design P8, for
which a thinner flange is not permitted
– The method of blending the profile between the flange and tread datum
changes the radii of the tread profile
– The lathe can produce profiles thinner than those permitted in the EN
without any warning!
• NR issued a National Incident Report in October 2014, reminding
maintainers that turning thin flanges is not permitted
Evidence to support change
• RSSB T641: Cost Effective Turning of Flange Worn Wheel
Profiles
– Thin flanges don't “compromise derailment safety or have significant
detrimental effects on vehicle dynamics”
– Construction method consistent with EN 13715
– Option should be available at final turning
• IRR Report 110/81: Business case for ETT on GB railways
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–
–
–
–
Statistical model investigated various turning strategies
Considered realistic wear and damage trajectories
ETT could save 1% to 4.4% of wheelset maintenance costs
Tentative benefit £0.8M - £5M p.a. for UK passenger rolling stock fleet
May be significant variation between fleets
• Anecdotal evidence that ETT widely used in Europe
Further investigation – aims
To help build a case for standards change by investigating:
• The difference in wear rates/patterns between thin flange and
design case wheel profiles
• The effect of using the thin flange profiles on rail RCF & damage
The project has been undertaken under the Strategic Partnership
between the University of Huddersfield and RSSB
Institute of Railway Research
Wear Modelling
Wheel profile damage model
Vehicle, routes & rail
profiles
Route characterisation
Vehicle dynamic simulation
Wheel – rail contact forces
Wheel wear prediction: using Archard method
Worn wheel profile
Repeat to
desired
mileage
Vehicles and routes
• Class 444
• Class 390
• Bulk cement tank
• Euston to Manchester
• Hounslow Loop
Piccadilly
• Waterloo to Woking
• Waterloo to Windsor & • Crewe to Glasgow
Central
Eton
• Rugby to
Wolverhampton
• Lafarge Cement –
Earles Sdgs
• Hope Valley –
Stockport
• Stockport – London
via WCML slow lines
• P8, P12 profiles
• P6 profiles
• P8, P12 profiles
Measured thin flange wheel profiles
• Thin flange profiles supplied by NR from Leeds Midland Rd lathe
• Ft in 1mm intervals from 28mm to 25mm
Both pictures courtesy of M Burstow
Wear model validation:
Class 444
Wear model validation:
Class 390
Results
Flange wear: P8, P12 profiles
Cl390
30
30
Flange Thickness, mm
Flange Thickness, mm
Cl444
29
28
29
28
27
27
26
26
25
25
24
24
23
23
0
20000
40000
60000
Mileage, mile
80000
100000
120000
0
20000
40000
60000
Mileage, mile
80000
100000
120000
Tread wear: P8, P12 profiles
Cl390
33
33
32.5
32.5
32
32
31.5
31.5
31
31
Flange Height, mm
Flange Height, mm
Cl444
30.5
30
30.5
30
29.5
29.5
29
29
28.5
28.5
28
28
0
20000
40000
60000
Mileage, mile
80000
100000
120000
0
20000
40000
60000
Mileage, mile
80000
100000
120000
Flange wear – P6 profiles
2-axle tank wagon
32
31
30
29
Flange Thickness, mm
28
27
P6_L_and_T
26
27mm-P6v
25
26mm-P6v
25mm-P6v
24
Upper limit ( 1SD(25mm_fth)]
23
Lower limit ( 1SD(25mm_fth)]
22
21
20
19
20
10020
20020
30020
Mileage, Mile
40020
50020
60020
Conclusions
Conclusions
What is the difference in wear rates/patterns between the thin
flange and design case P8 and P12 profiles?
• Thin flange profiles have almost a same wear pattern as full flange P8
and P12 profiles
– The tread wear rate was almost identical to design case profiles
– The flange wear rate was marginally lower
• Results same for low conicity (P6) profiles
Do thin flange profiles affect rail RCF damage?
• RCF damage similar to full flange P8 and P12s
• There is no clear trend within the thin flange profiles
• 25mm flange thickness generates some additional damage most
notably for radii between 800-1400 m
Conclusions
• There is now a substantial body of evidence to support a
change to RGS that shows:
–
–
–
–
–
An economic benefit exists
Wear rates and patterns are the same as full flange wheels
No significant impact on rail damage and wear
Safety against derailment is not compromised
No significant detrimental effect on vehicle dynamics
• Note that:
– RGS would have to mandate thin flange profile construction
– Maintenance and inspection practices must ensure that wheels turned with
thin flanges don’t subsequently infringe RGS limits as the profile wears
– Wheel lathe staff need training to ensure thin flange profiles used correctly
to maximise wheel life
IRR Bogie Dynamics, Rolling Contact,
Adhesion and Braking Rig
•
•
•
125mph (200 km/h) max speed
25t axleload limit
110kNm torque reaction, 0.45MW
(continuous power)
•
•
•
•
Bogie max. yaw 6° w.r.t.
rollers
•
In-situ roller re-profiling
128 analogue data channels at up to 10kHz
Precise w-r creep control (resolution of <0.1%
20
creep)
3-axis wheel/rail contact force measurement
IRR Bogie Dynamics, Rolling Contact,
Adhesion and Braking Rig
IRR Bogie Dynamics, Rolling Contact,
Adhesion and Braking Rig
Thank You
Institute of Railway Research
Comparison P8:P12
Class 444
Contact conditions
Rolling radius difference & equivalent conicity (56E1 rail)