April 2008
Overview
This proposal concerns the development by ARTSA and interested associates of an Industry Code of Practice to help vehicle operators improve the brake balance of heavy vehicles within their fleets.
The Code is to provide an assessment tool for quantifying brake balance of specific trucks and in particular specific combinations. Brake balance in this context is the extent to which the braking effort is distributed according to axle weight.
Poor brake balance is known to promote vehicle instability and premature brake wear. Furthermore, poor brake balance detracts from short stopping distance performance and limits the performance of antilock brake systems.
The rationale for this proposal is that brake balance can be quantified and thereby modifications made in a scientific way.
The elements of the Brake Balance Code of Practice are:
- A definition of what constitutes a ‘good’ heavy vehicle brake system and brake performance.
- A computational tool available via the Internet that calculates a Figure of Merit for brake performance.
- A description of available brake balance technologies – both mechanical and electronic.
- A technology map that makes general predictions about the likely performance of different brake technologies when used in combination.
- Guidance notes on the application of various technologies.
- A statement of the procedure that should be followed to assess and modify heavy vehicle brake performance. In particular the setting of load-proportioning brakes and trailer ratio valves.
The Code of Practice will be developed by the ARTSA Braking and Stability College in consultation with industry experts and the Australian Trucking Association’s Industry Technical Council.
The Code is intended to build upon the Australian Air Brake Code of Practice that was developed by the Australian Trucking Association.
It is hoped that in time the Brake Balance Code will be an adjunct to the ADRs / AVSRs. It could be accepted as providing ‘approved computations’ that justify brake set-up changes on heavy vehicles.
The Code will deal with the base pneumatic brake system performance. It will not attempt to model electronic controls acting on top of the pneumatic system.
Purpose of the Code
To assist operators to determine and improve the brake balance on an individual heavy vehicle and specifically to assess the vehicle against a performance standard.
The Code should have levels that are directed respectively to:
- Drivers
- Operators / vehicle specifiers
- Mechanics
- Vehicle engineers
It is recognized that different levels of presentation are needed to cater for the range of interests and responsibilities that exist.
Elements
- A written Code of Practice document.
- Principles that define a Figure of Merit for heavy vehicle medium and high pressure brake performance.
- Low-pressure braking compatibility tests and guidelines.
- A software tool that is made generally available via the Internet. This tool facilitates the ranking of brake performance.
Aspects
- Will focus on combination vehicles but not exclusively so.
- Defines acceptable brake balance in the Australian context.
- Provides guidance about brake balance correction on heavy vehicles.
- Demonstrates how brake balance (and a Figure of Merit) can be calculated.
- Provide principles to ensure that changes to vehicle set-up will make things better rather than worse.
- Provides calculated assessment of ‘generic vehicles’ so that operators might compare their vehicle with the generic combination vehicle.
- Reviews work by other industry groups and regulators that inform about heavy vehicle brake performance (such as the IRTE Compatibility Guide and the NZ Brake Code).
- Modeling of air brake system performance. Valve crack pressures to be nominated. Selection from, say, three air system characteristics to be available.
- Foundation brake torque models to be based on published trailer SARN data and vehicle manufacturer’s published data.
Timeframe
Delivery by the end of 2008.
Funding
Needed for Brake Consultant(s) and Web Consultant(s).
A review stage will also be needed that may require resources.
Editorial Control
ARTSA group provides editorial and directional over-view.
Consultant to develop the draft Code (including software).
Editorial panel of three to oversee the project and review the draft output.
Validation
Selected operators are involved. Specific combination vehicles are studied and modified according to set criteria.
Deliverables
- A Code document in publishable form.
- A software tool written in Visual Basic on a CD.
- A library of vehicle computations that can be made available on the ARTSA website.
