Quick conicity methods
Mark Burstow
Principal Vehicle Track Dynamics Engineer
October 2015
/
Quick conicity methods
Quick conicity and equivalent conicity?
Equivalent conicity is a function of wheel and rail shapes
Quantifies the geometric interaction of the profiles
► Requires detailed knowledge of shapes of wheels and rails
►
It is at the heart of the wheel/rail interface
The infrastructure manager cannot manage equivalent conicity
without knowing the shapes of the wheels running over the rails
► The train operator cannot manage equivalent conicity without
knowing the shapes of the rails on the routes operated over
►
Are ‘quick conicity’ methods a way out of the dilemma?
►
Can they lead to better understanding of conicity?
11-Nov-15 / 2
Quick conicity methods
What is equivalent conicity?
113a-20_br-p8
Flange
contact
5
Rolling radius difference (mm)
LEFT
RIGHT
113A rail and P1
wheel
4
113A rail and P8 wheel
3
2
1
0
-12
-10
-8
-6
-4
-2
-1
0
2
4
6
8
10
12
-2
-3
-4
-5
Wheelset displacement (mm)
Rolling radius difference graph describes how the wheel rolling radius changes as
the wheel moves over the rail
Equivalent conicity is defined from the gradient of the line
11-Nov-15 / 3
Quick conicity methods
Benefits and disbenefits
Equivalent conicity is good!
It is required to allow wheels to steer around curves
► Higher conicity allows vehicles to be guided round sharper curves
without flange contact- reduced wear
►
Equivalent conicity is bad!
►
High conicity leads to instability on
straight track and shallow curves
• Small perturbations in the track cause the
wheelsets to oscillate
11-Nov-15 / 4
Quick conicity methods
How do we calculate equivalent conicity?
Procedure is specified in EN 15302
This must be performed for each wheel/rail/track
gauge combination
11-Nov-15 / 5
Quick conicity methods
How do we calculate equivalent conicity?
For a given displacement the equivalent conicity is the
conicity of a cone which has the same wavelength
The EN provides ‘answers’ for reference profiles
►
Users can check their calculation methodology
11-Nov-15 / 6
Quick conicity methods
What does the TSI say?
For design case,
assessment is
relatively easy
Single calculation for
design rail profile and
track gauge, for a
specified set of
wheel profiles
► ‘Standard’ rail profiles
comply with the TSI a
priori, so no
assessment needed
►
11-Nov-15 / 7
Quick conicity methods
What does the TSI say?
For in-service conicity assessment is more complicated
Assessment required in response to allegation of problems
• Is the track or the train the main contributor?
► Assessment methodology is complicated
► ‘Joint investigation’ with train operator to identify problem
►
No easy method of monitoring or pro-active control of conicity
11-Nov-15 / 8
Quick conicity methods
‘Quick’ conicity methods
A method is needed to identify wheel and rail profiles which
could lead to high conicity
►
Allow infrastructure managers and train operators to pro-actively
manage equivalent conicity
Characteristics of high conicity rail profiles
Higher gauge corner =
Higher conicity
56E1
60E1
95BH
11-Nov-15 / 9
Quick conicity methods
Quick conicity methodAlternative track gauge measure
Rail profiles with higher gauge corners usually give higher
equivalent conicity
The gauge corner contacts further into the wheel flange root
► These rail profiles also have smaller gauge measurements (3mm
below the crown)
►
At 14mm below the rail crown there is very little difference
between the profile shapes
3mm
56E1
60E1
95BH
Gauge point
11-Nov-15 / 10
Quick conicity methods
‘Quick’ conicity
Data from DynoTrain
project
►
A ‘Quick conicity’
method for
infrastructure?
Conventional track gauge
‘Track gauge’ 3mm
11-Nov-15 / 11
Quick conicity methods
Quick conicity test site #1
Site on WCML site with instability issues
►
Miniprof measurements of rails
Showed area of high conicity for worn wheels
Rail grinding reduced conicity enough to control vehicle performance
0.9
0.8
Before grinding
0.7
Equivalent conicity
►
After grinding
0.6
0.5
0.4
0.3
0.2
0.1
0
0
100
200
300
400
500
600
Distance/m
11-Nov-15 / 12
Quick conicity methods
Quick conicity evaluation- #1
Quick conicity method correctly picks the step change in conicity
22
0.9
Equivalent conicity
0.8
0.7
Equivalent conicity
24
3mm track gauge
26
0.6
28
0.5
30
0.4
32
0.3
34
0.2
36
0.1
38
0
40
0
100
200
300
400
500
600
Distance/m
11-Nov-15 / 13
Quick conicity methods
Quick conicity test site #2
Calculation from measured profiles & gauge showed very high
conicities for some wheels
BS113A 2001
DO
BR109 FB 1955
Corus MSM 2008 95RBH
Bridge 545
1.4
RB95 2005 DO
Surveyed length
Surveyed length
1.2
Surveyed length
Conicity
1
0.8
0.6
0.4
0.2
0
4900
5000
5100
5200
5300
5400
5500
5600
5700
5800
Distance (m)
5900
6000
6100
6200
6300
new P8 Measured rails
142029 Measured rails
6400
6500
6600
6700
142063ws1 Measured rails
142068ws1 Measured rails
143621 Measured rails
11-Nov-15 / 14
Quick conicity methods
Quick conicity test site #2
Quick conicity results follow calculated equivalent conicity well
High conicity driven by rail profile (new 95BH rail)
Equivalent conicity
►
Rail grinding was the solution
0.8
20
0.7
22
0.6
24
0.5
26
0.4
28
0.3
30
0.2
142009 ws4 Measured rails
3mm below crown
0.1
0
4900
32
142009 ws1 Measured rails
34
36
5000
5100
5200
5300
5400
5500
5600
5700
5800
5900
6000
6100
6200
6300
6400
6500
6600
6700
Distance (m)
11-Nov-15 / 15
Quick conicity methods
Acceptable ‘Quick’ conicity limits?
Limits of stability appear
consistent between the
two sites
0
0.8
5
0.7
Equivalent conicity
Gauge
measure
3mm
0.9
Quick conicity
limit
<28
10
0.6
15
0.5
20
0.4
25
0.3
30
0.2
35
Before grinding
0.1
9mm
<12
3mm
0
0
<3
100
200
300
400
500
0.9
40
6mm 600
9mm
Distance/m
142009 w s1 Measured rails
142009 w s3 Measured rails
3mm below crow n
9mm below crow n
1
142009 w s2 Measured rails
142009 w s4 Measured rails
6mm below crow n
-5
0
0.8
5
0.7
Conicity
6mm
Surveyed length
Surveyed length
0.6
Surveyed length
10
Bridge 545
0.5
15
0.4
20
0.3
25
0.2
30
0.1
0
4900
5000
5100
5200
5300
5400
5500
5600
5700
5800
5900
6000
6100
6200
6300
6400
6500
6600
35
6700
Distance (m)
11-Nov-15 / 16
Quick conicity methods
Quick conicity test site #3
Site shows large variation in equivalent conicity for different
wheels:
►
Does the same technique work for wheels?
New P8
New wheel
Worn60632
wheelws2
1
Worn60922
wheelws3
2
Equivalent conicity
0.8
0.6
0.4
0.2
0
32
32
Quick conicity/mm
0
33
33
34
34
Distance/miles 35
35
36
36
37
37
Distance/miles
10
20
30
40
11-Nov-15 / 17
Quick conicity methods
Wheel ‘quick’ conicity
Thicker flange measurements might be expected to equate to
higher conicity
►
Flange root will make contact with rail gauge corner sooner
Flange thickness needs to be combined with back-to-back
dimension
30
25
20
15
10
Quick conicity
3mm
5
0
0
-5
20
40
60
80
100
120
Tread datum, 70mm
-10
11-Nov-15 / 18
Quick conicity methods
Wheel conicity
Data provided by IRR (University of Huddersfield)
Proposed limit
11-Nov-15 / 19
Quick conicity methods
Quick conicity test site #3
Wheel profiles exhibit a range of quick conicity estimates
98
Quick conicity
96
94
60172
60252
60532
60632
60922
92
90
88
86
84
82
29
29.5
30
30.5
31
31.5
32
32.5
33
Flange height/mm
New P8
Equivalent conicity
0.8
60632 ws2
0.6
60922 ws3
0.4
0.2
0
32
33
34
35
36
37
Distance/miles
11-Nov-15 / 20
Quick conicity methods
Wheel and rail quick conicity
0.45
Choose wheel profiles for
‘low’ and ‘high’ quick
conicity
Equivalent conicity, 113A
0.4
0.35
0.3
Wheel 2
0.25
0.2
0.15
0.1
Wheel 1
0.05
0
80
82
Distance/m
84
86
88
90
92
94
Wheel quick conicity, 3mm, relative to 1360mm/mm
1400
1600
1800
2000
2400
2600
2800
2
22.5
Quick conicity/mm
2200
1.75
25
1.5
27.5
1.25
30
1
32.5
0.75
35
0.5
37.5
Equivalent conicity
1200
20
0.25
40
0
Quick conicity
Equivalent conicity (wheel 1)
Equivalent conicity (wheel 2)
11-Nov-15 / 21
Quick conicity methods
Wheel and rail quick conicity
0.45
0.4
Equivalent conicity, 113A
Some wheels have same
‘quick conicity’ value but
very different equivalent
conicity
0.35
Wheel 3
0.3
Wheel 2
0.25
0.2
0.15
0.1
Wheel 1
0.05
Wheel 4
0
1200
20
Quick conicity/mm
22.5
25
27.5
30
32.5
35
37.5
40
1400
1600
1800
82
Distance/m
2000
conicity (wheel
88
90 Equivalent92
941)
Equivalent
conicity
(wheel
2)
Equivalent
conicity
(wheel
3)
Wheel quick conicity, 3mm, relative to 1360mm/mm
conicity (wheel 4)
2200 Equivalent
2400
2600
2800
84
Quick conicity
86
2
1.75
1.5
1.25
1
0.75
0.5
Equivalent conicity
80
0.25
0
11-Nov-15 / 22
Quick conicity methods
Combinations of quick conicity wheels
and rails
Contour plots for combinations of quick conicity wheels and rails
Good correlation- quick conicity provides a useful way to classify
profiles
20
22
24
Rail quick conicity/mm
►
26
28
30
32
Eq>0.6
34
0.4<Eq<0.6
0.2<Eq<0.4
36
Eq<0.2
38
84
86
88
90
92
94
40
Wheel quick conicity/mm
11-Nov-15 / 23
Quick conicity methods
Conclusions
An indicator of equivalent conicity can be obtained from measurement of:
Track gauge 3mm below rail crown
► Wheel face-to-face 3mm above tread datum
►
Quick conicity methods can identify rails and wheels which may be
contributing to high equivalent conicity
Allow infrastructure managers and train operators to better monitor and
predict interventions
► May not eliminate the need for a deeper investigation, but quickly identifies
‘problem’ locations and vehicles
►
Simple addition to existing automated measuring systems
►
Trial currently taking place on infrastructure data of an additional track gauge
measurement for ‘quick conicity’
11-Nov-15 / 24
Quick conicity methods
Thank you
11-Nov-15 / 25