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SUPPORT TOOL USER GUIDE
FOR
PBS BLUEPRINT VEHICLE DESIGN AND APPROVAL
PRIME-MOVER AND SEMI-TRAILER COMBINATIONS
April 2013
Document Version: v0.1
Software Version: v0.6
Prepared by
Mechanical System Dynamics Pty Ltd
National Transport Commission
Support Tool User Guide for PBS Blueprint Vehicle Design and Approval
Report Prepared by: Mechanical System Dynamics Pty Ltd
CONTENTS
1. INTRODUCTION .................................................................................................. 1
2. INTENDED AUDIENCE ........................................................................................ 1
3. BACKGROUND TO THE TOOL AND SCOPE .................................................... 1
4. OVERVIEW ........................................................................................................... 2
5. TOOL SPECIFICS (WORKSHEETS) ................................................................... 3 5.1 A4_Drawing and Front Overhang Detail ................................................................. 3 5.2 Tool Lines 01 to 14 – Dimensions .......................................................................... 3
5.2.1 Lines 1 to 3 ................................................................................................................ 3 5.2.2 Lines 4a to 5b ............................................................................................................ 4 5.2.3 Lines 6 to 14 .............................................................................................................. 4
5.3 Tool Lines 15 to 23 – Tyres .................................................................................... 4 5.3.1 Lines 15 to 17 ............................................................................................................ 4 5.3.2 Line 18 ....................................................................................................................... 5 5.3.3 Lines 19 to 23 ............................................................................................................ 5
5.4 Tool Lines 24 to 39 – Powertrain ............................................................................ 5 5.4.1 Lines 24 to 35 ............................................................................................................ 5 5.4.2 Lines 36a and 36b ..................................................................................................... 5 5.4.3 Line 37 ....................................................................................................................... 5 5.4.4 Lines 38a and 38b ..................................................................................................... 5 5.4.5 Line 39 ....................................................................................................................... 6
5.5 Tool Lines 40 to 58 – Loads, CGs and Suspensions .............................................. 6 5.5.1 Part A – Axle Group Loads and GCM ....................................................................... 6 5.5.2 Part B – Tare and Sprung Mass CG Heights ............................................................ 6 5.5.3 Part C – Suspension Properties ................................................................................ 6
5.6 Tool Lines 59 to 68 – Semi-trailer Sprung Mass CG Height ................................... 7 5.7 Tool Lines 69 and 70 – Braking Specification ......................................................... 7
6. SUBMIT VEHICLE FOR DESIGN APPROVAL .................................................... 8
7. USER FEEDBACK AND REPORTING DIFFICULTIES ....................................... 8
APPENDIX A – EXAMPLE WORKSHEETS FROM SUPPORT TOOL ...................... 9
Support Tool User Guide for PBS Blueprint Vehicle Design Page 1
1. INTRODUCTION
This User Guide has been prepared to assist users of the spreadsheet-based Support Tool
for PBS 20 m prime mover and semi-trailer Blueprint vehicle design. The tool was
developed as part of a National Transport Commission (NTC) funded project and initiative.
The aim of the project is to make the design of heavy vehicles under the national
Performance-Based Standards (PBS) scheme and formal approvals issued under that
scheme more accessible to a wider segment of the road transport industry at little or no
cost. The tool and associated software is initially available free from the NTC, and later it
is expected to be available together with ongoing support through the National Heavy
Vehicle Regulator (NHVR).
The purpose of the tool is to provide a relatively simple means for users to confirm designs
of 6-axle prime mover and semi-trailer combinations with overall lengths of up to 20 m
operating at axle group loads under General, Concessional and Higher Mass Limits (GML,
CML and HML). The tool can also be used to lodge formal PBS applications, as described
herein, and obtain design approvals.
2. INTENDED AUDIENCE
The tool has been developed to assist users to test vehicle designs and reach a design
outcome that satisfies all of the PBS performance requirements and, ultimately, provides
all of the necessary technical information in a single spreadsheet file to support a formal
PBS application and design approval. It has been assumed that users of the tool will have
some engineering background. It is expected that in some cases a single user will have
sufficient engineering knowledge and access to the required information to perform the
design with little or no outside assistance; others may require engineering support in one or
more areas to complete the design.
3. BACKGROUND TO THE TOOL AND SCOPE
The tool is the outcome of a process and series of meetings convened and managed by
NTC involving a wide range of stakeholders with a broad range of interests. Stakeholders
included in the process were truck and trailer manufacturers, component suppliers,
transport operators and consultants, trucking associations, road authority representatives,
and regulators.
The aim of these meetings was to establish the key parameters to define the blueprint
design in the most general context in order to satisfy the needs of as much of the industry
as possible. That is, rather than specifying a single set of dimensions, for example, for one
or two designs, a range of dimensions was set that would cover as many possible
applications and vehicle designs. While the initial parameter sets were quite broad, some
constraints had to be imposed on them to make the task tractable. Through consultation
these boundaries were determined to be acceptable for general application of the tool.
Once parameter sets for dimensions, suspensions, tyres, some mass properties and
powertrain were established, they were tested in a large number of designs against the PBS
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standards in order to determine what would and what wouldn’t work. The outcome of this
task was a very general and complex formal PBS application that defined the blueprint
vehicle. This went through formal review and approval by the PBS Review Panel (PRP).
It is the formal PBS application that underpins the blueprint vehicle design and the
application in that (complex) form identified a clear need for this Support Tool.
It is important to note that the blueprint vehicle design is not expected to cover all possible
designs but a useful majority. Niche areas will most likely need to be treated separately
through a PBS Assessor. However, with exposure to wider industry and with actual use
and feedback there will most likely be a need for some adjustments to the tool. In the
longer term it is expected that changes in vehicle design and emerging trends will also lead
to the need to occasionally update the tool.
4. OVERVIEW
The Support Tool comprises seven worksheets contained in a single spreadsheet. The
worksheets are labelled as follows:
A4_drawing
Front Overhang Detail
Dimensions
Tyres
Powertrain
CGs, Loads and Suspensions
Sprung Mass CG Height
Braking Specification
The first two worksheets, “A4_drawing” and “Front Overhang Detail”, simply provide
summary drawings showing key dimensions, tyre sizes, axle group loads, semi-trailer
centre-of-mass (CG) height, and front overhang details for the prime mover and semi-
trailer. The purpose of the two drawings worksheets is to simply provide an easy reference
of user selected design values and selected options to assist the formal approval process.
The next four worksheets, namely, “Dimensions”, “Tyres”, “Powertrain” and “CGs, Loads
and Suspensions”, and the last worksheet “Braking Specification”, are the main work areas
for specifying the vehicle. Each of these comprise a combination of pull-down menus for a
selection of numeric values from a preset range and options, spinner buttons for dialling up
desired numeric values, cells for manual entry of numeric values, cells that report
calculated values for information. Assistance to the user is also provided by way of up to
three columns in each worksheet. These columns are headed as “Notes”, “Action
Required” and “Warnings”. Notes lists a short meaningful phrase to help the user, Action
Required simply prompts the user for an action (for example, “select from drop-down list”,
“Enter value”, etc), and Warnings are short messages that appear, usually in bold red type,
alerting the user to a problem with one or more input values.
When all the required data have been entered into a worksheet and there are no warning
messages on that sheet the tool has taken that part of the design to be acceptable. When all
five worksheets have been completed in this way, and there are no warnings on any
worksheet, then the vehicle design as a whole is taken to be an acceptable design. That is,
the vehicle if built is likely to satisfy all of the PBS performance requirements. In this
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form the spreadsheet can be submitted (by e-mail) to the NTC/NHVR for processing to
obtain a formal PBS design approval.
The second last worksheet “Sprung Mass CG Height” is available to the user if an
independent value for the semi-trailer sprung-mass CG height is not available. CG height,
which has a major influence on rollover stability, is usually calculated in the normal course
of a vehicle design by manufacturers. For non-manufacturers, this worksheet is intended to
provide an approximate estimate of the CG height using a relatively simple calculation
based on a flat-top semi-trailer carrying a uniform density load.
5. TOOL SPECIFICS (WORKSHEETS)
This section of the User Guide describes each worksheet in detail and provides specific
information on data ranges and data requirements. An example of each worksheet is
presented in Figure A1 to Figure A8 of Appendix A. For convenience and ease of reference
the rows in each worksheet have been labelled with a line number.
The following sections refer to the line numbers specific to each worksheet.
5.1 A4_Drawing and Front Overhang Detail
As described earlier, these two worksheets, “A4_drawing” and “Front Overhang Detail”,
simply provide summary drawings showing key dimensions, tyres, axle group loads, semi-
trailer centre-of-mass (CG) height, and front overhang details for the prime mover and
semi-trailers. The values shown in the drawings are not editable but instantly updated as
changes are made to the design through the other worksheets. An example of each is
presented in Figure A1 and Figure A2 of Appendix A.
5.2 Tool Lines 01 to 14 – Dimensions
5.2.1 Lines 1 to 3
Lines 1 and 2 – The prime mover wheelbase and front plan profile are selected by the user
on Lines 1 and 2, respectively, using the pull-down menu. For a square front profile the
wheelbase range is from 3550 to 5150 mm in 50 mm increments, for a tapered front profile
the wheelbase range is from 3550 to 5200 mm. The square and taper details are shown in
worksheet “Front Overhang Details”. When square is selected the details for square front
is shown, when taper is selected the details for taper are shown.
It is important to note that a dimension increment of 50 mm has been used as agreed with
stakeholders. Where a wheelbase is not an integer multiple of 50 mm then wheelbase
values should be used in the assessment either side of the actual wheelbase. That is, an
actual wheelbase of 3570 mm may require assessments for wheelbase values at 3550 mm
and 3600 mm.
Line 3 – The front overhang dimension is selected in Line 3 using the pull-down menu.
For a square plan profile the overhang range is from 700 to 1650 mm, for a tapered plan
profile the overhang range is from 1300 to 1500 mm.
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5.2.2 Lines 4a to 5b
Lines 4a and 4b (Option 1) and Lines 5a and 5b (Option 2) – The allowable semi-trailer S-
dimension and front overhang dimension corresponding to the selected prime mover
wheelbase and front planview detail appear in lines 4a to 5b in two groupings referred to as
Option 1 and Option 2. One or both options may be available depending on choice of
prime mover dimensions and front overhang plan profile detail. If one option only is
available then the other option becomes “not valid” with a message to that effect appearing
in the warnings column.
5.2.3 Lines 6 to 14
Line 6 – In this line one of the two options is selected from the pull-down menu. If one
option only is available then that option must be selected; if two options are available then
either one of the two can be selected. Once an option has been selected the S-dimension
range and forward projection dimensions for that option are available for the semi-trailer.
Line 7 – The S-dimension for the semi-trailer is entered in this line. The value must be
consistent with the option selection in Line 6. Depending on choice of other dimensions
the total semi-trailer wheelbase range available to the user is 9600 to 10500 mm. Values at
the long end of the range will generally only be valid for short wheelbase prime movers
with short front overhang dimensions.
Line 8 – The forward projection dimension for the semi-trailer is entered in this line. The
value must be consistent with the option selected in Line 6.
Line 9 – The coupling lead for the fifth wheel connection is entered in this line. The range
for this parameter is 600 to -100 mm. A positive value denotes a coupling location that is
forward of the centre of the drive axle group.
Line 10 – The rear overhang dimension for the semi-trailer is entered in this line.
Acceptable values are up to the lesser of 4600mm or 45% of the semi-trailer S-dimension.
Lines 11 and 12 – These two lines are for information and show the overall length of the
vehicle and the deck length. The values are automatically updated as other numbers on
this worksheet are changed affecting these two lengths.
Lines 13 and 14 – Axle group spread is defined in these two lines for the drive (tandem)
and semi-trailer (triaxle) axle groups. Acceptable values for the drive axle group are in the
range 1200 to 1600 mm, for the semi-trailer axle group the range is 2000 to 3200 mm.
5.3 Tool Lines 15 to 23 – Tyres
5.3.1 Lines 15 to 17
Lines 15 – Using the pull-down menu select tyre size for the steer axle. Two (2) tyres sizes
are offered, 11R22.5 and 295/80R22.5.
Lines 16 – Using the pull-down menu select tyre size for the drive axles. Two (2) tyres
sizes are offered, 11R22.5 and 295/80R22.5.
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Lines 17 – Using the pull-down menu select tyre size for the semi-trailer axles. Six (6)
tyres sizes are offered, 11R22.5, 295/80R22.5, 305/70R22.5, 275/70R22.5, 255/70R22.5
and 265/70R19.5.
5.3.2 Line 18
The vertical stiffness of the softest tyre is entered on this line. The softest tyre must have a
stiffness value of at least 750 N/mm measured at its rated load and at the recommended
inflation pressure.
5.3.3 Lines 19 to 23
The main cornering properties of the tyre with the lowest cornering stiffness are entered on
these lines. Cornering stiffness varies with vertical load so it is necessary to define tyre
characteristics for a range of vertical loads as defined in Lines 20 to 23. The tyres
cornering stiffness measured at zero lateral slip angle must be at least 0.7, 1.4, 2.1 and
2.8 kN/deg at vertical loads of 10, 20, 30 and 40 kN, respectively. These characteristics
are taken at the recommended inflation pressure.
5.4 Tool Lines 24 to 39 – Powertrain
5.4.1 Lines 24 to 35
Engine characteristics are entered in Lines 25 to 35. Engine torque values for engine speed
in the range 1000 to 2000 rpm are required. The worksheet includes a graph of engine
torque and power output versus engine speed, which overlays the engine torque (and
power) characteristics specified by the user and the minimum torque (and power)
requirement. This graph can be used to check if the specified characteristics satisfy the
minimum performance characteristics. Warning will also appear if the specified torque is
below the minimum requirement. Note that only engine torque characteristics are required
from the user and the power curve is derived from the torque curve.
5.4.2 Lines 36a and 36b
These two lines are for information and report peak torque and maximum power from the
user entered values.
5.4.3 Line 37
Use the spinner buttons to enter a value for clutch engagement torque or stall torque if the
transmission has a torque convertor. The range for this parameter is 100 to 1350 Nm.
5.4.4 Lines 38a and 38b
Gear ratio values for the lowest and highest gears are entered in these lines. For the lowest
gear a value not less than 9.16 must be entered, for the highest gear a value in the range
0.73 to 1.00 will be accepted.
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5.4.5 Line 39
Use the spinner buttons to enter a value for rear axle ratio. The range is 3.4 to 4.7 for this
parameter.
5.5 Tool Lines 40 to 58 – Loads, CGs and Suspensions
5.5.1 Part A – Axle Group Loads and GCM
Line 40 – Use the pull down menu to select axle group loading from GML, CML and
HML.
Line 41 – If the prime mover qualifies for an extra 0.5 t on the steer axle (compliant Front
Underrun Protection Device, etc) select “yes” from drop-down list.
Lines 42 to 44 – For GML and HML loading, axle group loads for the steer, drive and
semi-trailer are set values, for CML loading the spinner buttons can be used to adjust the
axle group loads.
Line 45 – The calculated value of Gross Combination Mass (GCM) is shown for
information on this line. This is a calculated value which is automatically updated when
the axle group loads are adjusted. GCM cannot be adjusted directly on this line.
5.5.2 Part B – Tare and Sprung Mass CG Heights
Line 46 – Select from the drop-down list the tare mass of the prime mover. The range is
from 7.5 to 12.5 t selectable in 0.5 t increments.
Line 47 – Select from the drop-down list the height of the prime mover’s sprung mass CG.
The range is from 800 to 1250 mm selectable in 50 mm increments. Sprung mass refers to the
portion of the prime mover’s total mass that is supported above the suspension.
Line 48 – Use the spinner buttons to set the height of the semi-trailer’s sprung mass CG.
The range is from 2100 up to 2440 mm set in 10 mm increments. The value set is an “up
to” limit, which means if an acceptable outcome is achieved lower CG height values are
also acceptable. Please note, the value entered in Line 48 is not linked to worksheet
“Sprung Mass CG Height” and the stability analysis is based on the value set in Line 48.
5.5.3 Part C – Suspension Properties
Lines 49 to 51 – Use the spinner buttons to set the total roll stiffness for the steer, drive and
semi-trailer axles. Total roll stiffness comprises roll stiffness due to the springs (air or
leaf) and auxiliary mechanisms from sources such as anti-roll bars, bushings, tie-rods,
locating rods, and “wind-up” of suspension components. Roll stiffness values in the
following ranges are considered:
Steer: 1.0 to 6.0 kNm/deg
Drive: 6.1 to 46.0 kNm/deg/axle
Semi-trailer: 7.7 to 44.9 kNm/deg/axle
Line 52 – This line checks that the ratio of semi-trailer to drive total roll stiffness falls
within an acceptable range and the suspensions are correctly matched. If there is a
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mismatch a warning message will appear with advice on whether this ratio should be
increased or decreased.
Lines 53 to 55 – Use the spinner buttons to set the suspension roll steer coefficients for the
steer, drive and semi-trailer axles. Roll steer values in the following ranges are considered:
Steer: -0.1 to 0.1 deg/deg
Drive: -0.1 to 0.25 deg/deg
Semi-trailer: -0.1 to 0.25 deg/deg
Lines 56 to 58 – Use the spinner buttons to set the suspension relative roll centre heights
(measured above the axle) for the steer, drive and semi-trailer axles. Roll centre height
values in the following ranges are considered:
Steer: -100 to 200 mm
Drive: -100 to 400 mm
Semi-trailer: -100 to 400 mm
5.6 Tool Lines 59 to 68 – Semi-trailer Sprung Mass CG Height
Line 59 – Use the spinner button to set the tare weight of the semi-trailer. The range for
tare weight is 2.5 to 11.25 t.
Line 60 – Use the spinner button to set the king-pin load of the laden semi-trailer. The
range for this load is 5.5 to 15.5 t.
Line 61 – In order to calculate the CG height of the semi-trailer sprung mass, the user must
specify the mass of the unsprung components, comprising complete axle assemblies (axles,
suspension, brake assemblies, wheels, etc.). Use the spinner button to set the unsprung
weight of a single (one) complete axle assembly. The range for axle unsprung weight is
750 to 1250 kg.
Lines 62 and 63 – Use the spinner buttons to set the floor/deck height and load height. The
range for floor/deck height is from 750 to 1750 mm, the range for overall load height is
from 2600 to 4600 mm.
Lines 64 to 67 – The values presented in these lines are for information and comprise the
Aggregate Trailer Mass (ATM), which is the sum of the kingpin load and the axle group
load, load mass (ATM less the tare), payload volume and payload density. The calculation
assumes uniform density over an assumed rectangular prism load shape.
Line 68 – This value is a simple estimate of the semi-trailer sprung mass CG height. This
value is not used in the stability calculations but is compared to the value set in worksheet
“Loads, CGs and Suspensions” which is used in the stability calculations. If the simple
estimate of the semi-trailer sprung mass CG height (Line 68) is greater than the set value
(Line 48) then a warning message is issued.
5.7 Tool Lines 69 and 70 – Braking Specification
Select the relevant option from the drop-down list for the prime mover and semi-trailer.
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6. SUBMIT VEHICLE DESIGN FOR APPROVAL
When the five worksheets labelled “Dimensions”, “Tyres”, “Powertrain”, “CGs, Loads
and Suspensions” and “Braking Specification”, have been completed and there are no
warnings on any of these worksheets then the vehicle design as a whole is taken to be an
acceptable design. That is, the vehicle if built is likely to satisfy all of the PBS
performance requirements.
In this form the spreadsheet can be submitted (by e-mail) to the NHVR at the address
shown below prior to commencing the vehicle build:
Les Bruzsa
PBS Administrator
National Heavy Vehicle Regulator
L9 / 515 St Pauls Terrace
Fortitude Valley QLD 4005
p: (07) 3309 8599
f: (07) 3309 8777
Upon confirmation from the NHVR, vehicle build can be commenced. Built vehicles must
be certified by an authorised PBS Certifier and submitted to the NHVR for a Final
(Vehicle) Approval.
7. USER FEEDBACK AND REPORTING DIFFICULTIES
User feedback and reporting of any difficulties is welcome and should be directed to the
NTC/NHVR at the address shown the previous section.
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APPENDIX A – EXAMPLE WORKSHEETS FROM SUPPORT TOOL
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Figure A1 - Worksheet “A4_drawing”
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Figure A2 - Worksheet “Front Overhang Details”
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Figure A3 - Worksheet “Dimensions”
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Figure A4 - Worksheet “Tyres”
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Figure A5 - Worksheet “Powertrain”
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Figure A6 - Worksheet “Loads, CGs and Suspensions”
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Figure A7 - Worksheet “Sprung Mass CG Height”
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Figure A8 - Worksheet “Braking Specification”