1. Review of Wheelset Flange Height and Thickness Limits in GMRT2466 (RIS-2766-RST)
Dr Gareth Tucker
4/12/17

2. Scope
Can flange height and thickness limits be changed to allow more wear?
What are the historic reasons for wear limits in GMRT2466?
What hazards are controlled by flange wear limits?
How does flange wear affect negotiation of obtuse crossings?
How do GMRT2466 limits compare with the LOC & PAS and WAG TSIs?
What additional controls might be required if flange wear limits were relaxed?
Is there a benefit in higher flange wear allowance?

3. Flange height and thickness limits in GMRT2466 issue 3
Can 24mm flange width and 36.5mm flange height be applied to all profiles?
Could wear allowance be extended further?
Do TSIs allow more wear than RGS/RIS?

4. Previous wheelset standards
Standard No
Issue
Date
Title
BR MT 288 1
Jan 1991
Wheelset tread standards and gauging
GM/TT0115 ?
Wheelsets: In-Service Safety and Maintenance Attention
GM/TT0089
Feb 1994
Geometric Interfaces Between Railway Wheelsets and Track
GM/RT2026
May 1994
Wheelsets: In Service Safety and Maintenance Attention 2
July 1996
GM/RT2466
June 2003
Railway Wheelsets
GM/GN2497
Dec 2007
Guidance on Railway Wheelset Tread, Gauging and Damage Identification
Aug 2008 3
Feb 2010
RIS-2766_RST
2017
Rail Industry Standard for Wheelsets

5. Origin of requirements?
New Tyre Profiles For British Railways, Railway Gazette, January 1968
Discusses development of RD4 wheel profile (=P8)
Suggests flange height limit of 1.44 inches = 36.6 mm
Suggested minimum flange thickness of 0.79 inches = 20 mm
These limits appear to be based on RIV (International Wagon Regulations) requirements
VDYN 209 Flangewear Limits, 1990
Suggest flange wear allowance of 5mm to limit amount of material removed at turning in order to restore full flange width
Current limits are 4 – 5 mm
BDYN 143 P10 Profile limits and UIC leaflet 510-2
Suggests P10 (an S1002 variant) for GB use should have same wear limits as P5

6. TSI and RGS wheelset limits
𝐵 10𝑚𝑖𝑛 = 𝑆 𝑚𝑖𝑛 − 𝐴 𝑚𝑎𝑥 2 =23.5 => 𝐵 13𝑚𝑖𝑛 =23
TSI (wheels > 840 mm ⌀)
RGS
Amax
1363
1363.3
Amin
1357
1358
Smin
1410 x
Bmin 22
24 (exc P9)

7. Back to back measuring point
GB Approach
Back-to-Back measurement with the axle unloaded, or level with the centre if loaded
VEHICLE LOAD
EN Approach
Back-to-Back and Front-to-Front measurement at rail level under vehicle load
Axle deflection:
Outboard bearings: Reduces
Inboard bearings: Increases

8. Hazards controlled by limiting wheel wear?
Flange back strikes open switch.
Flange back makes contact with check rail before checkrail entry point.
Flange back makes contact with wing rail before wing rail entry point.
Flange hits the end of a closed switch.
Flange makes contact with a closed worn switch blade with a low contact angle (relative to horizontal).
Wheel with high tread wear makes contact with a fish plate on rail at maximum headwear allowance.
High angle of attack in curves due to thin flanges.
Allowing wheels to run longer between turning cycles could lead to low (or high) conicity.
Flange strikes obtuse crossing nose.

9. Freewheel passage through open switches, checkrail entry points and wing rail entry points (hazards 1 – 3)
T783 Wheelset and switches and crossing compatibility investigation, 2009

10. Check rail and wing rail entry points Hazard 1 & 2
TSI maximum freewheel passage at check rail entry
1380 mm
TSI min flange front to flange back
1382 mm
NR/SP/TRK/001 maximum freewheel passage at check rail entry
1376 mm (113A vertical)
1357 mm (NR60)
GMRT2466 flange front to flange back
1382 mm
(P1, P6, P8, RD9, P11, P12)
1385 mm (P5, P10)

11. Freewheel passage through open switches Hazard 3
GMRT2466 min flange front to flange back:
1382 mm (P1, P6, P8, RD9, P11, P12)
1385 mm (P5, P10)
TSI min flange front to flange back: 1382 mm
TSI max freewheel passage
Through open point: 1380mm
GCRT5021 max freewheel passage through open points: 1375mm
For ‘historic’ designs (113A vertical) previously applied limits can be used (GIRT7004) : 1388mm
NR/L2/TRK/6100 max freewheel passage for 113A vertical points: 1382 mm

12. Limits on flange wear to control Hazard 1 – 3 ?
Hazard 1 – 3 not directly affected by flange height
Network Rail standards control the maximum freewheel passage in 113A vertical points to 1382 mm
GCRT5021 (referring back to GIRT7004) effectively permits a maximum freewheel passage of 1388 mm
Based on the Network Rail limits, all profiles could be given a minimum flange thickness of 24 mm
This would allow the flange back to just touch an open switch (as is currently the case for P1, P6, P8, P11, RD9 & P12)
GCRT5021 should be updated to reflect the freewheel passage limits that are currently being used by Network Rail

13. Clearance with closed switch toe (Hazard 4)

14. Assumed worn wheel shape

15. Clearance assessment Max side wear 0.89 mm overlap 1.86 mm overlap
27 mm flange width, 33 mm flange height
24 mm flange width, 36.5 mm flange height
23 mm flange width, 36.5 mm flange height
New P5
Max side wear
0.89 mm overlap
1.86 mm overlap
1.86 mm overlap
1.86 mm overlap
Max head wear
0.93 mm overlap
0.93 mm overlap
0.93 mm overlap

16. Limits on flange wear to control Hazard 4?
Already possible for new wheels and worn wheels to scuff a switch toe (if the wheelset completely closed up stock rail)
Further reducing the flange width doesn’t increase the level of interference with a switch toe
Level of inference is dependent on flange angle
In the clearance assessment assumed worn flange angle is 76⁰
Is flange width an indirect control of flange angle?

17. Worn P5 flange angle vs flange width
468 worn P5 wheel profiles measured as part of T889

18. Contact angle with a worn switch blade (Hazard 5)
NR/L2/TRK/0053 Hazard 2
Maximum 3mm side wear on stock rail within first 500mm of switch
TGP8 does not make contact below 60⁰ line in first 500mm of switch
NB1 TGP8 is based on cross section of a new P8
NB2 Contact angle assessment is very sensitive to the assumed worn switch shape

19. Contact angle?     27 mm flange width, 33 mm flange height
New P5    

20. Limits on flange wear to control Hazard 5?
Reducing the minimum flange thickness for a P5 appears to increase the risk of low contact angle with worn switches
Also relevant to other wheel profiles with low flange heights (P10/S1002)
Assessment has been based on maximum flange wear with zero tread wear
Higher flanges (i.e. tread wear) reduce the risk
Might be beneficial to modify method to inspect worn switch rails
P1, 24mm worn flange width
P8, 24mm worn flange width
P5, 24mm worn flange width
P10, 24mm worn flange width

21. Clearance to fishplates (hazard 6)
Possible to increase flange height limits to 39 mm (with 0.5 mm clearance)
Or 38 mm (with 1 mm clearance)

22. Angle of attack in curves (Hazard 7)

23. Limits on flange wear to control Hazard 7?
A wider flange way clearance (narrower flange) can slightely reduce angle of attack because the increased flangeway clearance allows wheelsets to steer
This only works down to a certain, minimum curve radius

24. Link between flange width and conicity (Hazard 8)
468 worn P5 wheel profiles measured as part of T889

25. Limits on flange wear to control Hazard 8?
In the sample of wheels considered, wheels with thinner flanges are more likely to have a lower conicity
Flange width is not a direct control over conicity
35% of wheels with a flange width over 27 mm also have a conicity lower than (when combined with new CEN60E2 rail)
Lower flange widths could be permitted without creating wheels with conicities lower than the existing spread

26. Interaction with obtuse crossings (Hazard 9)
Reduced flange width increases clearances to the crossing nose
Increase flange heights reduce the effective unguided length
* T560 created a spreadsheet tool for investigating clearances in obtuse crossings

27. Summary   x                            No
Hazard/consideration
Give all profiles 24 mm min flange width?
Give all profiles mm max flange height?
Use TSI limits?
Further reduce flange width limit?
Further increase max flange height? 1.
Flange back hits open switch 2.
Flange back contact with check rail before entry point 3.
Flange back contacts wing rail before entry point 4.
Flange tip hits the end of a closed switch 5.
Interaction with closed switch ? 6.
Clearance to fishplate 7.
Angle of attack in curves 8.
Conicity 9.
Obtuse crossings   x                             

28. Conclusions and recommendations
The flange height limit for P5, P10 & P11 could be increased to 36.5 mm
Pending review of worn switch monitoring it may be possible to introduce 24 mm flange width for P5 and P10
A clearly defined maximum freewheel passage for 113A vertical points should be included in GCRT5021
Use of TSI flange width limit should only be used in combination with full TSI wheelset dimension controls
It appears existing flange width limits are based on maximising wheel life, with a flange wear allowance of around 5mm as suggested in VDYN 209
If flange width limits are reduced, wheels that reach those limits will require more material to be removed at turning
There may be some benefit at the last turning cycle or giving flexibility where there is limited lathe capacity