1. Conference On Railway Engineering
Perth 7-10 September 2008
LABORATORY TESTING OF BOGIE ROTATION FRICTION
WITH APPLIED TRACK TWISTING FORCES
Scott Simson1
and Bruce Brymer2
BE, ME, RPEQ and A.D.M.Eng
1. Centre for Railway Engineering,
Central Queensland University,
Rockhampton, QLD 4701
2. Asset Management, QR National Coal
SUMMARY
Laboratory tests of bogie rotation friction using the Centre for Railway Engineering’s heavy test lab facility
have been completed for the Rail CRC Project 82 -Bogie Rotation Friction Management. These tests are
believed to be the first in the world to rotate a full three piece bogie with track twist loads applied to the
wagon-bogie system. The lab testing expands on the simulation studies reported at the last CORE.
The objectives of the project 82 laboratory test program were to validate the behaviours of centre bowl
friction force occurring during curve transitions as identified in previous simulation studies. The testing
included:
• Centre bearing longitudinal movement in transitions due to track twist loads, or the walking motion of
the centre bearing that generates rim contact and adds rim contact rotational resistance.
• Change in the effective radius of friction rotation for the centre bearing due to centre bearing tilt from
track twist, and the additional change in the rotational centre when rim contact occurs.
Results include the effective centre of rotation and frictional effective radius in the centre bowl as altered
with pitching force on the bogie. The testing results show that no sliding movement occurs at the CCSB’s
until large curving rotations of the bolster occur due to the low elastic stiffness of the CCSB resilient blocks.
This has implications for simulation modelling of hunting performance and future CCSB design.
1 Introduction
Rail CRC Project 82 has been investigating bogie
rotation friction management in 3 piece freight
bogies. Simulation studies of the effect of bogie
rotation friction done in project 82 have been
previously reported, [1], [2], [3]. The cost benefits
of managing bogie rotation friction levels come
through limiting bogie hunting and poor vehicle
curving performance, [4]. In both curving and
hunting, 3 piece bogie performances are not only
dependent on bogie rotation friction but are heavily
dependent on wheel rail contact profiles and
effects of the bogie suspension in warping
(lozenge) and steering.
Wheel wear implications of bogie rotation friction
were found to be the result of bogie warp
deflections [3]. The largest wheel wear impacts
occurred at medium radius curves and particularly
gentle and near tight curvatures where bogie
rotation friction is the cause of flanging contact on
the lead bogie, [3]. The definition of near tight
curve being that were flange contact occurs on
three of four wheelsets and gentle curves being
were one the leading wheelset of four is in flange
contact. Tight curves, all four wheels flanging and
tangent curves no wheels flanging, have no
change in the total wheel wear due to bogie
rotation friction.
Design of the curve transition was found to effect
the warping of the bogie [1] with improved curving
wheel wear possible from cant deficient transition
in gentle curves and over rotating transition curves
in near tight curves. Over rotating curve transitions
include a tighter curve radius in the transition to
rotate the bogie frame past the point for constant
curving allow the elastic wheelset warp deflections
to relax during constant curving.
The simulation study found further increases to
wheel wear rates can be attributed to lubrication
effects. Increases in the wheelset angle of attack
from bogie rotation friction cause a large increase
in lubricant removal at the gauge face [2].
The laboratory test program for project 82 aims to
verify some of the results found during the
simulation study

2. Conference On Railway Engineering
Perth 7-10 September 2008
2 Laboratory Test
2.1 Test Program Objectives
The objectives of the project 82 laboratory test
program are to validate the model behaviours
identified in the simulation program. Behaviours to
be tested and validated are:
• Centre bearing longitudinal movement in
transitions due to track twist loads. The
walking motion of the centre bearing that
generates rim contact loads and adds rim
contact rotational resistance.
• Change in effective radius of centre
bearing rotational friction resistance due to
centre bearing tilt from track twist, and the
additional change in the rotational centre
when rim contact occurs.
• Change in bogie rotation warp deflection
due to increased vertical movements of
the friction wedges.
• Identification of un-modelled factors
influencing bogie rotation resistance and
bogie frame warp.
• Determination of bogie rotation laboratory
testing procedures required to assess liner
material properties.
2.2 Laboratory Test Rig
The test rig makes use of the Centre for Railway
Engineering, Heavy Test Lab facility in
Rockhampton. The previously existing wagon
suspension rig shown in Figure 1 is used to
provide the test wagon with a twisting
displacement to the suspension. The test wagon is
a former QR gondola coal wagon designed with an
Aluminium body. The wagon body mass unloaded
is 8.1 tonne.
Figure 1 Wagon Suspension Rig with the Test
wagon.
The opposite end of the wagon is has QR48 bogie
mounted on a turntable rig. The turntable is shown
in Figure 2. Figure 2 shows the test bogie on the
turntable prior to instrumentation setup.
Figure 2 Test bogie prior to instrumentation
The QR48 bogie is a Super Service Ride Control
bogie and has been installed with Constant
Contact Side Bearers (CCSB) in a pre-molded
bolster pocket. The CCSB have resilient blocks
and a metal roller stop. The wheel centres in the
bogie are a nominal 1600 mm and the centre bowl
diameter is a nominal 300 mm. The top centre
castings are a full cylinder and have no lateral cord
cuts to limit point loading or generate edge cuts on
the centre bowl plate. The bolster centre bowl was
as worn and rusty when fitted under the wagon.
Previous operation of the bogie did involve cord
cut top centre and wear pattern is evident in
testing (see section 3.1, Figure 7).
When loaded the wagon is weighted with 31.1
tonne of steel ballast near evenly distributed with
the test bogie experiencing approximately 16.1
tonne. Therefore the empty and loaded conditions
of the wagon are approximately a 4 tonne
unloaded and a 20.1 tonne load on the bogie. The
bogie is designed for an 80 tonne maximum gross
wagon weight and has a self weight of 3.5 tonne.
2.3 Program of Test Configuration
The testing covers a number of centre bearing
setups at the time of writing this paper not all the
centre bearing setups have been tested. The
centre bearing being the entire connection
between the bolster and wagon body including the
centre bowl and the CCSB. The full range of
vehicle setups are as listed below including
changes to the CCSB setups and to the centre
bearing liner with testing being performed with an
empty and a partial loaded wagon condition. The
eight centre bearing setups are:
Loaded
• Bare Centre Bowl, Set CCSB (5.5)
• Bare Centre Bowl, add greese to CCSB
(5.5)

3. Scott Simson, Colin Cole An Active Steering Bogie for Heavy Haul Diesel Locomotives
Centre for Railway Engineering
Conference On Railway Engineering
Perth 7-9 September 2008
• Product B Liner, no set CCSB (11)
• Product A Liner, no set CCSB (8.5)
• Product A Liner, set CCSB (5.5)
Empty
• Product A Liner, set CCSB (5.5)
• Product A Liner, no set CCSB (8.5)
• Bare Centre Bowl, Set CCSB (5.5)
The numbers above indicate the set up heights of
CCSB to the steel roller stop and are not to
manufacturers recommendations of 6.5 mm which
would give a preload of 1.5 tonne.
2.4 Program Test Motions
The testing for each set up covers the range of
motions possible from the test rig. Five types of
tests are performed in the rig. The Initial tests are
the straight rotation test and the straight twist test
to determine the responses to these
uncomplicated movements. The third test type is a
rotation test for various static wagon twist
deflections. The fourth test is termed the walking
tests the wagon is twisted to a set deflection
before rotating the turntable in a set arc with the
motions oscillating between tilt and rotation so that
the bolster walks backward under the wagon as
seen in vehicle simulations for curve transitions.
The fifth test type mimics the behaviour of a curve
transition. Twist is applied as rotation occurs. The
test is duplicated for smooth and rough track
where rough track test involves additional
fluctuation of the wagon twist to induce additional
movements of the bogie suspension friction
wedges.
2.5 Instrumentation
The test bogie is instrumented for movements of
the bogie frame relative to the ground and the
body. Tilt movements from the wagon test are
instrumented for the relative vertical movements
between the bolster ends and the wagon body and
the vertical movements at the spring nests
between sideframes and bolster. Movements in
bogie rotational plane, lateral, longitudinal and yaw
motions of the bogie parts are monitored on the
bolster and on each sideframe. The axle
movements relative to the turntable are monitored
with x and y movements of each axle box end. As
the vehicle body moves longitudinally with the
suspension test rig the movement relative to the
ground is monitored along with lateral movement
at the vehicle side sill.
Figure 3 shows the bogie instrumentation.
3 Results
Bogie rotational load verses deflection data for the
turntable actuator is shown in Figure 4 for the steel
on steel centre bearing with CCSB set of 5.5 mm
(approximately 110% of specified preload).
Frictional losses in the turntable are approximately
1.0 kN (A variation of 1.3-0.7 kN over 150 mm of
full travel of the turntable).
Figure 3 Bogie Instrumentation
In Figure 4 the maximum rotation resistance is the
total friction in the centre bearing and the turntable
friction. Centre bearing friction is due to friction in
the centre bowl and the friction at the CCSB.
Centre bowl friction occurs on plate at an effective
radius depending on the distribution of the vertical
load and due to rim contact at the nominal radius
of 150 mm. In the results shown in Figure 4 there
is no rim contact and centre bowl friction is due
only to the plate contact.
Turn Table
Load vs Deflection [KN / mm]
‐40
‐30
‐20
‐10
0
10
20
30
‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 40 50 60
Figure 4 Turntable Load Deflection: Test 2
(Rotation ±50 mm) for Set up A steel liner and
5.5 mm CCSB setup
In Figure 4 there is significant elastic deflection in
the resilient blocks of the CCSB prior to sliding this
being 45 mRad of the turntable rotation. For a
wagon having bogie centres at 10m, 45 mRad is
the rotation needed for a curve radius of 222 m.
Figure 5 shows the turn table load deflection for a

4. Scott Simson, Colin Cole An Active Steering Bogie for Heavy Haul Diesel Locomotives
Centre for Railway Engineering
Conference On Railway Engineering
Perth 7-9 September 2008
small rotation of ±20 mm (±18 mRad) which shows
reduced maximum rotation resistance moment as
the resilient blocks are not fully deflected.
From Figure 4 and Figure 5 it is estimated that the
rotational friction in the centre bowl is 16 kN or
~17.5 kN.m. The CCSB have a break out friction of
~26.5 kN.m. The CCSB breakout friction is with
spacing between the side bearers of 940 mm. The
stiffness of CCSB’s appears to be 0.5 MN/Rad for
large deflections with the initially over 8 -10 mRad
deflection of the turntable including deflections at
the axle boxes. That is a stiffness 530 KN/m for
longitudinal deflection of the CCSB.
Turn Table
Load vs Deflection [KN / mm]
‐40
‐30
‐20
‐10
0
10
20
30
‐30 ‐20 ‐10 0 10 20 30
Figure 5 Turntable Load Deflection: Test 2
(Rotation ±20 mm) for steel liner and 5.5 mm
CCSB setup
The CCSB longitudinal stiffness impedes the
effectiveness of the hunting stability provided by
the CCSB. Maximum yaw deflections of the bogie
during hunting motions are a maximum of
approximately ±5 mRad. It is hence desirable if the
longitudinal stiffness of the CCSB is much higher
consistent with rigid contact. So in setup A whilst
the centre bearing friction reaches maximums of
±22 kN.m at deflections of ±30 mm (27 mRad) at
maximum hunting deflections of ±5 mRad the
friction peaks are less than ±12 kN.m.
From the friction force results of setup A, estimates
can be made on the friction coefficient for the
CCSB and assuming steel on steel friction
coefficient of 0.5 the effective contact radius of the
centre bowl. The breakout friction coefficient for
the CCSB resilient blocks is thus estimated as
~0.59. The effective radius of centre bowl contact
is estimated as 94 mm. That effective radius is
smaller than 2/3 the maximum radius as expected
for a constant pressure distribution.
3.1 Wear Damage in Centre Bowl
The results of rotation resistance in other setups
are presented in Figure 6. Setups B to F have
CCSB resilient blocks lubricated reducing the
rotational resistance and the deflection at friction
breakout for the resilient blocks. The breakout
friction for lubricated CCSB resilient blocks
reduces ~6 KN or a friction coefficient ~0.15.
Turn Table
Load vs Deflection [KN / mm]
‐20
‐10
0
10
20
‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 40 50 60
Turn Table
Load vs Deflection [KN / mm]
‐12
‐8
‐4
0
4
8
12
‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 40 50 60
Turn Table
Load vs Deflection [KN / mm]
‐12
‐8
‐4
0
4
8
12
‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 40 50 60
Turn Table
Load vs Deflection [KN / mm]
‐12
‐8
‐4
0
4
8
12
‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 40 50 60
Turn Table
Load vs Deflection [KN / mm]
‐6
‐4
‐2
0
2
4
6
‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 40 50 60
Figure 6 Turntable Load Deflection: Test 2
(Rotation ±50 mm) for Set up B - F
Set up B
Set up C
Set up D
Set up E
Set up F

5. Scott Simson, Colin Cole An Active Steering Bogie for Heavy Haul Diesel Locomotives
Centre for Railway Engineering
Conference On Railway Engineering
Perth 7-9 September 2008
The considerable noise (see Figure 6) of dry
friction between less than smooth surfaces limits
the analysis results. Setup F in Figure 6 is an
empty load test and has a greatly reduced contact
load in the centre bowl. Surface roughness noise
on the rotational friction does not reduce with the
reduction in contact load.
In setup B to E beyond 40 mm of rotation (36
mRad) the rotational resistance increases due to a
wear pattern developed on the top centre. This is
further evidence by the wear patterns evident in
the centre bowl liners used in test setups C and D
(Figure 7). The friction performance differences of
the two centre bowl liner materials, setups C and D
are not distinguishable from the noise and the
more significant effect of changed CCSB preload.
Figure 7 Centre bowl liners from test setup C
and D
The use of the white liner in setup E compared to
metal on metal of setup B has significantly reduced
the centre bowl friction coefficient.
3.2 Longitudinal Movement of the Bolster
As the bogie rotates there is a longitudinal
movement of the bolster relative to the wagon
body depending on where the centre of rotation is
acting. As the wagon is twisted, and the tilt
between the wagon body and bolster changes, so
does the centre of rotation and the rate of
longitudinal movement. Figure 8 shows the bolster
movement with no suspension twist applied. As
rotation and the wagon twist oscillate for a wagon
travelling over transitioned curves this longitudinal
movement shifts the bolster until the centre
bearing rim contacts the top centre. The
longitudinal clearance at the centre bearing for the
test bogie is ~7.5 mm. Centre bowl rim contacts
are at 0.6 and 8.1 mm longitudinal shift.
Figure 8 Bolster movement: Test 2 (Rotation
±40 mm) for setup A
From the amount of longitudinal movement for
known rotation angle it is possible to estimate the
lateral centre of rotation. Results estimating the
lateral centre for rotation for the tilted rotation tests
of setup A case are given in Error! Not a valid
bookmark self-reference.. The zero wagon twist
position has a small lateral offset to rotation of
approximately 18 mm. This indicates a small offset
error in the wagon loading over the bogie and the
bogie position over the turntable centre and the
result is to be expected. The twist on the wagon
shifts the lateral centre of rotation for the centre
bearing.
3.3 Tilt Effects on Rotation Resistance.
Tilting the centre bearing with a wagon twist has
multiple effects on the centre bearing friction. The
most notable effect is as predicted in the
simulation studies, the effect being that of rim
contact friction. This is highlighted in Figure 9 and
Figure 10 which shows rotation tests with fixed
suspension tilts of ±22.5 mm of the suspension
test rig. For the positive tilt rim contact does not
occur the longitudinal travel being 4.7 of the
available 7.5mm. With the negative tilt the centre
bearing rim contact occurs at the end of each
rotation. Rotation friction increases by ~10 KN
because of this rim contact.

6. Scott Simson, Colin Cole An Active Steering Bogie for Heavy Haul Diesel Locomotives
Centre for Railway Engineering
Conference On Railway Engineering
Perth 7-9 September 2008
Table 1 Estimated lateral centre of rotation
Test
Twist
[mm]
Longitudinal
Movement
[mm]
Test
Rotation
[mm]
Measured
Bowl Tilt
[mRad]
Estimated
Centre
[mm]
45.5 1.9 10 9.6 105
22.5 4.7 40 5.9 65
22.5 1.2 10 5.8 66
11.25 0.8 10 3.7 44
0 0.35 10 1.9 19
0 1.3 40 1.5 18
‐11.25 ‐0.7 10 0.1 ‐39
‐22.5 ‐1.9 10 ‐1.3 ‐105
‐22.5 ‐7.5 40 ‐1.3 ‐1041
‐45.5 ‐2.2 10 ‐6.1 ‐122
Figure 9 Test 3 (Rotation ±40 mm) for steel
liner and 5.5 mm CCSB setup, tilt +22.5 mm
If a steel on steel friction coefficient is assumed to
be 0.5 we can calculate the effective rotational
radius of the centre bowl contact. Table 2 shows
that as the wagon twist is increased to higher
levels, the centre bowl contact effective radius
becomes smaller. The maximum effective radius
occurs with a small positive twist and is consistent
with a constant pressure distribution over the
entire centre bowl.
Figure 10 Test 3 (Rotation ±40 mm) for steel
liner and 5.5 mm CCSB setup, tilt -22.5 mm
The reduction of the centre bowl plate contact load
distribution and the resulting effective radius of
1
Test: twist -22.5 rotate 40 had rim contact on
both sides of the centre bowl.
rotational friction reported in Table 2 has
implication for stability. Table 2 results show a
reduction in the plate contact rotation friction of up
to 50% due to pitching loads whilst rim contact has
approximately doubled the rotational friction in the
centre bowl. As bogie hunting motions excite sway
of the vehicle body tilt loads at centre bearing will
affect centre bowl rim contact. If tilt motions in
hunting are in phase with the bolster yaw rotations
and the bogie will walk forward (or backward) until
rim contact is made and rim friction will contribute
the centre bearing friction. If tilting motions are out
of phase with yaw rotations then bogie rotation
friction will be dominated by the centre bowl plate
contact friction.
Table 2 Test 3 estimated effective radius of the
centre bowl contact and rim friction results
Tilt
[mm]
Turn
Table
Historicis
e [kN]
Friction
Moment
[kN.m]
Rim
Friction
[KN]
Estimate
Effective
Radius
[mm]
45 10 4.4 12 54
22.5 13 6.1 10 74
11.25 14 6.6 80
0 16 7.7 94
‐11.25 17.5 8.6 104
‐22.5 13 6.1 10 74
‐45 8 3.3 12 40
3.4 Yaw and warp deflections of bogie frame
components
Yaw movements of the wheelsets relative to the
turntable were negligible at maximums of ±0.2
mRad. Wheel rail contacts had been lubricated to
enable sliding of the wheelset to give a yaw angle
to the rails. In the results collected it appears the
lubrication has been insufficient to permit
movement at the wheel rail contacts. A final test
setup is required with the bolster rotation
restrained to complete the test program.
The bolster and sideframe yaw movements
relative to the turntable are significantly greater
showing that movement in the bogie frame is
occurring principally at the wheelset sideframe
connection. Figure 11 show the movements
calculated for the sideframe and bolster yaws
plotted against turn table actuation force. In Figure
11 the bogie is being rotated through ±10 mm or
±9 mRad and a large relative movement is evident
at the zero load point indicating slack movement at
the wheelset sideframe connection. Further elastic
extension appears to occur at the wheelset
sideframe connection for increasing forces seen in
Figure 11. Note: The wheelsets used are fitted with
axle boxes containing spherical roller bearings.
The wheelsets and axle boxes have not been
operationally used with the bogie previous to the
lab testing.

7. Scott Simson, Colin Cole An Active Steering Bogie for Heavy Haul Diesel Locomotives
Centre for Railway Engineering
Conference On Railway Engineering
Perth 7-9 September 2008
Figure 11 Relative Yaw Movement: Test 2
(Rotation ±10 mm) for steel liner and 5.5 mm
CCSB setup
At high rotational resistance as the CCSB
deflection is increased (Figure 12) a hysteresis
loop becomes evident with differences between
the side frames and bolster. Again this appears to
be predominantly movement at the axle box side
frame connection with some movement at the
friction wedges. It must be noted here that the lab
test rig of the turntable generates lateral forces on
the wheelsets where as in track on a track curve,
large yaw forces on the wheelsets are generated
by longitudinal creep forces and combine with
lateral wheelset forces in yawing the bogie.
Figure 12 Relative Yaw Movement: Test 2
(Rotation ±40 mm) for steel liner and 5.5 mm
CCSB setup
The presence of a hysteresis loop indicates that
there is sliding friction at the bearing adaptors.
Figure 13 shows that for higher turn table yaw
forces the yaw movements of the bolster and
sideframes continue as elastic deflections.
The friction breakout at bearing adaptors is
consistent at 12-17 kN or 13.5-19 kN.m. The slack
action is consistent at 1 mRad the friction
movement is 1.8-2.5 mRad depending of the test.
The results indicate an equivalent stiffness at the
bearing adapters of ~10 MN/m is present and is
likely to be pendulum movements of the bearings.
As such the result may be unique to the axle
boxes and sideframes used in the test and are not
necessarily generic. The deflections though are
very significant to the low angles in hunting
motions. Yaw movements at the bolster sideframe
connection have been negligible.
Figure 13 Relative Yaw Movement: Test 3
(Rotation ±40 mm) for steel liner and 5.5 mm
CCSB setup, tilt -22.5 mm
4 Conclusions
Further analysis of the bogie rotation lab testing is
continues. Bogie frame warping results are as yet
inconclusive and will require restraint of the bolster
rotation to free the sliding movement of no rotating
wheels. However several of the test programs
objectives have already been meet.
The walking motion of the centre bowl due to the
combination of pitching loads and bogie rotation
has been measured. The effective centre of bolster
rotation under the vehicle body has been found to
change with centre bearing pitch load. It was also
found that the neutral position of the wagon can
have a significant lateral shift in the centre of
rotation compared to the vehicle centre line.
The presently installed CCSB provides little
rotational resistance to hunting motions due to the
low elastic stiffness of the resilient blocks to
longitudinal movements, the CCSB rotational
stiffness being determined as 0.5 MN/Rad. For
CCSB to provide rotational friction during hunting a
longitudinally very stiff design is required.
Deflections at the axle box sideframe connection in
the lab test have been significant to hunting. This
result though does not necessarily represent the
behaviour of operational bogies.
5 Acknowledgement
This research work has been conducted by CQU
at the Centre for Railway Engineering with the
support of the Rail CRC and its industry partners
principally QR.
6 References
[1] Scott Simson, Michelle Pearce, (2006),
Centre Bearing Rotation Forces During
Curve Transitions, Conference On
Railway Engineering May 2006,
Melbourne RTSA/RTAA, pp68-74.

8. Scott Simson, Colin Cole An Active Steering Bogie for Heavy Haul Diesel Locomotives
Centre for Railway Engineering
Conference On Railway Engineering
Perth 7-9 September 2008
[2] Scott Simson, Bruce Brymer, (2006),
Gauge face contact implications of bogie
rotation friction in curving, International
Conference on Contact Mechanincs and
Wear of Rail/Wheel Systems (CM2006)
Brisbane, Australia 25-27 September
2006, pp 549-554.
[3] Scott Simson, Michelle Pearce, (2006),
Wheel Wear Losses from Bogie
Rotational Resistance, Effects of Cant
and Speed, ASME/IEEE Joint Rail
Conference, 2006, American Society of
Mechanical Engineers, Rail
Transportation Division (Publication) RTD,
v 31, p109-114
[4] Wu, H., (2002), Effect of center plate
lubrication on vehicle curving and lateral
stability, Research Report R-959,
Association of American Railroads /
Transport Technology Center, Inc, Pueblo
Colorado