Land Transport Rule
Heavy-vehicle Brakes 2006
This is Schedule 3 of the Heavy-vehicle Brakes Rule.
Land Transport Division
Ministry of Transport
ISBN 0-477 05252-5
The Ministry of Transport gratefully acknowledges the very substantial contributions made by the Chairman and members of the Heavy Vehicle Brake Code Committee, individually and collectively, in the preparation of this code and for the support given to committee members by their respective employers.
The Ministry is also indebted to the various organisations that have made vehicles, equipment and services available and without whose support, the production of this code would not have been possible.
©1991 Land Transport Division
Ministry of Transport
P O Box 27-459
Phone (04) 828-300 Fax (04) 855-699
Background to the New Zealand situation
In New Zealand, power driven vehicles are sourced from world markets, the majority coming from Europe, North America, Japan and Australia. The result is that the local powered vehicle population has variations of the braking systems common to the country of origin. Locally manufactured trailers generally use imported brake components and are only required to meet emergency stop and parking performances.
By legislation, New Zealand has lower individual axle loadings than are common in the countries from which the power driven vehicles and trailer components are sourced. The road tax on heavy vehicles is collected through a system known as Road User Charges and applies to vehicles over 3500 kg gross weight. It is allocated according to gross vehicle mass, axle configuration and distance travelled. This tax has created a situation unique to this country by encouraging operators to fit more axles to carry a given load than would otherwise be necessary. Braking problems therefore can arise because the axles used on these vehicles are designed for substantially higher loadings and are fitted with brakes sized accordingly.
This code has been developed to improve the braking performance of heavy vehicles in New Zealand by an industry based committee consisting of representatives from the MVMA, NZRTA, IRTENZ, DSIR, NZTTMF and MOT.The code is based on European brake performance requirements, namely the United Nation Economic Commission of Europe Regulation 13, (ECE 13). To facilitate its adoption into the brake code, some simplifications to the regulation have been made and special New Zealand requirements have been included. Every effort has been made to minimise the extent of modifications necessary or existing vehicles to meet the code requirements.
It is intended to Gazette this code as an acceptable alternative (under Regulation I6A(2) of the Heavy Motor Vehicle Regulations 1974) to the current Heavy Vehicle Braking Specification, effective from 1 July 1991, for vehicle combinations operating at more than 39 000 kg. The further intention, is that all vehicles with a gross mass exceeding 3500 kg, first registered after 1 July 1994, will have to comply with ECE 13 plus special New Zealand annexes; or an equivalent international regulation if developed in the meantime. As a minimum requirement, any vehicle used in combination with a new vehicle first registered after 1 July 1994, shall comply with this code.
Aims of the Code
The aim of this code is to improve heavy vehicle safety by standardising braking performance. Its provisions can be summarised as follows:
- • To ensure that certified individual vehicles in the fully laden state meet the required braking performance, at all levels of braking and axle loads permitted under the Heavy Motor Vehicle Regulations 1974.
- • To ensure the continuing compliance of certified vehicles to this code. This is the responsibility of the operator. It is essential that adequate records of work carried out, and components used on a vehicle are being kept.
- • To improve compatibility between powered vehicles and trailers to ensure that vehicles in a combination function in harmony, provide optimum brake performance and improve directional stability. The majority of brake applications are at low levels of braking, well before the limits of adhesion are reached. The braking performance at or slightly above the threshold levels is a very important factor in ensuring brake compatibility.
- • To introduce a brake control system with common characteristics on all vehicles. This ensures protection of individual vehicles, efficient emergency braking and safe parking of individual vehicles and vehicle combination.
Auxiliary brake equipment
The code sets out general guide lines for supplementary brake equipment that gives the driver greater control and improved brake performance. This equipment includes such items as, trailer hand control, anti-lock braking systems (ABS), load sensing devices and engine retarders. The addition of any of this equipment to a certified vehicle will be classed as a modification and will require the vehicle to be recertified.
This code applies to the braking of vehicles with a gross vehicle mass of more than 3500 kg. It applies to power driven vehicles individually and to trailers individually.
In this code the words ‘shall’ or ‘must’ indicate a requirement that is to be adopted in order to comply with the code, while the word ‘should’ indicates a recommended practice.
2.1.1 ‘Certifier’ means manufacturer, a group or a person who are recognised by the Statutory Authority as being experienced in the matter of Heavy Vehicle Braking.
2.1.2 ‘Drawing vehicle’ means a vehicle equipped to tow a trailer.
2.1.3 ‘Gross Vehicle Mass (GVM)’ means the maximum laden mass of a motor vehicle as specified by the manufacturer or the New Zealand regulations, whichever is the lesser. See Appendix E.
2.1.4 ‘Gross Combination Mass (GCM)’ means the sum of the GVMs of the drawing vehicle and trailers) used in a combination. It is the lesser of that specified by the manufacturer of the drawing vehicle or the New Zealand regulations.
2.1.5 ‘Manufacturer’ means an organisation acceptable to the Statutory Authority, engaged in the manufacture, assembly, or importation of vehicles with a GVM of more than 3500kg.
2.1.6 ‘Statutory authority’ means the Secretary for Transport or persons with authority duly delegated by the Secretary for the purposes of this code.
2.1.7 ‘Vehicle type’ means a category of vehicles which do not differ in such essential respects as:
- • The vehicle category (e.g. passenger vehicle or goods vehicle, power-driven vehicle or trailer).
- • The gross vehicle mass (as defined above).
- • The distribution of mass among the axles.
- • The type of brake system.
- • The number, relative position and arrangement of the axles and suspension types.
- • The effective tyre radius. Tyre radii of within 5% of the indicated tyre radius shall be held to be the same for the purposes of this code.
2.1.8 Unladen mass means the mass of the vehicle fitted with body and equipment, plus full fuel tanks.
2.2 Trailer definitions
2.2.1 ‘Trailer’ means a towed vehicle.
2.2.2 ‘Full trailer’ means a towed vehicle fitted with at least two axle sets, and equipped with a drawbar which controls the direction of the front axle(s) and which transmits no significant static load to the drawing vehicle.
2.2.3 ‘Semi-trailer’ means a towed vehicle having one axle set positioned behind the centre of gravity of the vehicle (when fully laden) so that a substantial portion of the laden vehicle’s weight is superimposed on the drawing vehicle.
2.2.4 ‘Centre axle (simple) trailer’ means a towed vehicle (not being a full trailer or semi-trailer) equipped with a drawbar such that only a small static vertical load is transmitted to the drawing vehicle when uniformly loaded.
2.3 Brake terminology
2.3.1 ‘Air brake system’ means a system in which the brake requires the use of compressed air.
2.3.2 ‘Brake’ means the assembly in which the forces due to friction opposing the movement of the vehicle develop.
2.3.3 ‘Brake coupling’ (‘Coupling Head’) means the device for connecting the control and supply lines of the drawing vehicle to the control and supply lines of the trailer.
2.3.4 ‘Brake system’ means the combination of parts whose function is to progressively reduce the speed of a moving vehicle or bring it to a halt, or keep it stationary if it is already halted. The system consists of the control, the circuit and the foundation brake.
2.3.5 ‘Circuit’ means the combination of components between the control and the brake and linking them functionally. The circuit may be mechanical, hydraulic, pneumatic, electrical or mixed. Where the braking power is derived from or assisted by a source of energy independent of the driver but controlled by him, the reserve of energy in the device is likewise part of the circuit.
2.3.6 ‘Control’ means the part actuated directly by the driver to furnish to the circuit the energy required for braking or controlling it. This energy may be the muscular energy of the driver, or energy from another source controlled by the driver.
2.3.7 ‘Control (Service) line’ means the part of circuit along which the service brake signal is transmitted.
2.3.8 ‘Emergency braking’ - see 4.1.2
2.3.9 ‘Graduated braking’ means braking which, whether during application or release of the brakes, the driver can at any moment increase or decrease the braking force by acting on the control; and
If the control is actuated by the foot, or used for control of brake other than park brake the control must return to the ‘off’ position when released; and
- • the braking force varies proportionally to the action of the control; and
- • the braking force can easily be regulated with sufficient precision.
2.3.10 ‘Load Sensing Device’ means a device fitted to the brake system to regulate the braking effort on any axle(s) in proportion to the load carried by the axle(s). (See section 4.1.4 and Annex A7).
2.3.11 ‘Parking braking’ - see 4.1.3
2.3.12 ‘Service braking’ - see 4. 1.1
2.3.13 ‘Supply (Emergency) line’ means the path by which any stored energy required to actuate the brakes is supplied.
2.3.14 ‘Spring brake’ means a brake in which the energy required for braking is supplied by one or more springs acting as an energy storage device.
2.3.15 ‘Trailer hand control’ means a hand operated control capable of applying a graduated service braking action on the towed trailer(s) only.
2.3.16 Threshold pressure. See Appendix A, A8.
3.1 Initial compliance
Initial compliance with this code is the responsibility of the Certifier.
3.1.1 The Certifier shall provide the Statutory Authority on request with one copy of the statement of compliance for every vehicle type (with format as shown in Appendix C).
3.1.2 The Certifier shall supply, with every vehicle complying with this code, one copy of the statement of compliance (Appendix C). The operator of the vehicle shall be responsible for ensuring that the statement of compliance remains with the vehicle documentation, but not necessarily on the vehicle.
3.1.3 The Certifier will be responsible for the safe keeping of all the calculations, test reports and other documentation for each vehicle issued with a statement of compliance and also for making copies of such material available to the Statutory Authority on request. This material must include:
- (a) A set of calculations which shall demonstrate compliance as follows:
- • Service brake performance (Appendix A)
- • Emergency brake performance (clause 4.1.2)
- • Parking brake performance, only on vehicles with spring brakes fitted to more than half of the axles.
- (b) A test report demonstrating compliance with the following requirements:
- • Parking brake performance (clause 4.1.3), unless determined by calculation as above.
- • Energy sources and energy storage devices (Appendix F Paragraph 2), or Current New Zealand Compressor Requirements
- • Response time (Appendix B)
- • Brake torque reaction Test (Appendix A3.3.2(e))
- • Load Sensing Valve operation (Appendix A7)
- (c) The documentation shall also include a schematic diagram of the brake circuit including a list of the components in the braking system. Also, a plate shall be affixed to the vehicle, adjacent to the vehicle’s identification plate stating that this vehicle complies with NZHVBC, dated_______
3.1.4 If a Certifier ceases his involvement with design certification to this code, the above mentioned records shall be forwarded to another practising Certifier and the Statutory Authority shall be notified of this change.
3.2 Continued compliance
Continued compliance with the code is a responsibility of the vehicle operator.
3.2.1 Servicing the brake system:
- (a) Companies or individuals who service brake systems on any vehicle complying with this code are responsible for ensuring that work procedures and practices acceptable to the Certifier are followed. Full and detailed records must be kept of the work undertaken and of the parts supplied and installed. A copy of this information must be made available to a vehicle operator.
- (b) Only components which do not alter the performance and quality as originally specified by the Certifier shall be used when servicing the brake system. Replacement brake linings must be supplied with a compliance certificate in accordance with the details on the certificate of compliance and fitted in axle sets (See 4.1.5 and Appendix C).
3.2.2 Modifications to the vehicle or the brake system:
- (a) For every modification of the vehicle type or of its braking system, continued compliance with this code shall be ensured by a Certifier.
- (b) The Certifier must provide the Statutory Authority with the full details of the modification and complete the modification certificate (see Appendix C). A copy of this modification certificate shall remain with the vehicle records.
- (c) Where the modification is appropriate to all vehicles of a particular vehicle type, the Certifier may issue a certificate to this effect, which clearly defines the modification and the vehicles for which it is appropriate.
- (d) If major modifications are made affecting the vehicle type or the brake system the Certifier shall issue a new Statement of Compliance (see Appendix C).
4.1 Requirements of the brake system
The brake system as defined in 2.3.4 must fulfil the following functions:
4.1.1 The service braking must make it possible to control the movement and retardation of the vehicle or vehicles in combination. It must be possible to graduate this braking action. The driver must be able to achieve this braking action from the driving seat without removing his hands from the steering control.
Service braking shall meet the requirements of Appendix A (Braking distribution) and should meet the requirements of Appendix B (Time response) of this code. Service braking must be capable of stopping the fully laden vehicle within 7 metres from 30 kilometres per hour (equivalent to an average deceleration of 5 m/s 2).
The service braking must act on all wheels of the vehicle.
4.1.2 The emergency braking must be capable of stopping the fully laden vehicle or vehicle combination within 18m from 30 km/hr (equivalent to an average deceleration of 2m/s 2) in the event of failure of the service braking. The driver must be able to achieve this braking action from the driving seat while keeping at least one hand on the steering control. For the purposes of these provisions it is assumed that not more than one failure of the service brake system will occur at one time.
4.1.3 The parking braking must be capable of holding the fully laden vehicle on an up or down gradient of 20% on a surface sealed to highway standard. The working parts must be held in the locked position by a purely mechanical device. From the driving seat, the driver must be able to achieve this braking action on the vehicle and any vehicle that it is designed to tow, subject, in the case of a trailer to the provisions of 4.4.2 below.
4.1.4 Wear on the brakes must be capable of being easily taken up by means of either a system of manual or automatic adjustment. In addition, the control and the components of the circuit and of the brakes must possess a reserve of travel such that, when the brakes become heated or the brake linings have reached a certain degree of wear, effective braking is ensured without immediate adjustment being necessary.
4.1.5 All components and devices in the brake system (including hoses and air connections) shall comply with at least one appropriate and recognised international, national or association standard where such standards exist. Recognised can be taken as meaning SAA, SAE, BS, JIS, ECE EEC, ISO, and DIN standards, in addition to other standards recognised by the statutory authority.
Friction materials shall comply with one of the following:
- (a) ECE 13 Annex 4 (EEC 71/320 Annex 2) - Braking Tests and Performance; or, ECE 13 Annex 15 Inertia dynamotor test method for brake lining.
- (b) Friction material performance may be determined by one of the following tests providing that, when the vehicle is loaded to the gross vehicle mass (the maximum legally permitted in New Zealand), the retardation force versus control line pressure meet the requirements of this code (Appendix A, diagrams 2 and 3) prior to the test being conducted. Acceptable tests include:
- • SAE J667, Brake Test Code - Inertia Dynamotor.
- • SAE J786a, Brake System Road Test Code - Truck, Bus and Combination Vehicles.
- • ADR 35A, Commercial Vehicle Brake systems (applicable to power driven vehicles only).
- (c) The friction material shall maintain stable friction characteristics between 100°C and 315°C and between 30 km/hour and 100 km/hour. ‘Stable’ means that the friction coefficient does not vary above or below the nominated friction value by more than 0.025.
4.1.6 Vehicles fitted with load sensing devices shall only be used in combination with other vehicles also fitted with load sensing devices, however power driven vehicles and full trailers with a load sensing device fitted only to the rear axle set may be used in combination with vehicles without load sensing devices.
4.1.7 Vehicles to which anti-lock brake systems are fitted must comply with all the requirements of this code.
4.1.8 Traction control systems may utilise the brake system components provided the system is fail-safe and does not interfere with normal braking.
4.2 Air brake system
4.2.1 A pressure test connection complying with the dimensional requirements of Appendix D shall be fitted at the intake to the chamber of the least favourably placed brake chamber (or pneumatic device in the case of partly pneumatic brake systems) with respect to brake timing (Appendix B) on each independent circuit of the braking system. See also Appendix F, clause 3.0.
4.2.2 Spring brakes should be used for parking braking.
4.2.3 Compressed air braking systems incorporating load sensing devices or any valve which can be adjusted to modify the system pressure shall be fitted with pressure test connections in the pressure line upstream and downstream of the device.
4.2.4 Air connections between all drawing vehicles and trailers must be of the two line system, using a one piece coupling, e.g. a ‘duomatic’ coupling or when an auxiliary air supply - separate from the braking system - is required for a trailer, a ‘trimatic’ coupling.
4.2.5 All power driven vehicles first registered from 1 September 1991 shall be valved and piped to the rear cross-member, unless the manufacturer forbids the attachment of a trailer with a GVM of more than 3500 kg to a particular vehicle type.
4.2.6 The control (service) line shall be to the left side of the coupling and coloured blue or black, the supply (emergency) line shall be to the right side of the coupling and be coloured red or yellow, or identified, within 150 mm of coupling or junction.
4.2.7 The coupling block shall be situated close to the centre line, preferably to the right hand side of centre.
4.2.8 On drawing vehicle/semi-trailer combinations the hoses shall form part of the drawing vehicle or be detachable at both ends. On other combinations the hoses shall form part of the trailer and be securely attached to the drawbar. This requirement does not apply to combinations which are not uncoupled in the course of normal operation.
Caution: When fitting the female end to the front of a semi-trailer, only the trailer version without check valves shall be used.
4.2.9 Each reservoir in an air brake system shall be fitted with an automatic or manual condensate drain valve at the lowest point. Where an automatic condensate valve is fitted, the reservoir shall have provision for manual operation.
4.3 Power driven vehicles
4.3.1 The systems providing service, emergency and parking braking may have common components so long as they fulfil the following conditions:
- (a) There must be only two controls (however, see section 5), in addition to any trailer hand control which may be fitted (as defined in 2.3.15) independent of each other and readily accessible to the driver from the driving seat.
- (b) The control of the service brake system must be independent of the control of the parking brake system.
- (c) The control for the emergency braking system may be combined with either the control for the service braking system or the control for the parking braking system, however the emergency braking action on the vehicle must be capable of graduation. If the service braking system and the emergency braking system have the same control, the parking braking system shall be so designed so that it can be actuated when the vehicle is in motion without endangering the stability of the fully laden vehicle.
- (d) If the service braking force and circuit depend exclusively on the use, controlled by the driver, of an energy reserve, there must be at least two completely independent energy reserves each provided with its own circuit likewise independent; each of them may act on the brakes of only two or more wheels so selected as to be capable of ensuring by themselves or in associating with the emergency brake control the prescribed degree of emergency braking without endangering the stability of the vehicle during braking. It must be possible to graduate this braking action.
- (e) The braking systems must not compound their application forces.
4.3.2 Gauges shall be fitted to indicate to the driver the pressure in each independent service brake energy reserve (as defined in 4.3.1 (d)) and shall be visible to the driver in the normal driving position.
4.3.3 Where there are separate controls for the service brake system and the emergency brake system, simultaneous actuation of the two controls must not render both the service brake system and the emergency brake system inoperative, either when both brake systems are in good working order or when one of them is faulty.
4.3.4 Every vehicle equipped with a service brake actuated from an energy storage device (energy accumulator) must, where braking with the performance prescribed for emergency braking is impossible without the use of the stored energy, be equipped with an alarm device, in addition to any pressure gauge. The alarm device shall give an acoustical signal when the energy, in any part of the installation preceding the control valve, falls to a value which without refeeding the storage devices, guarantees that after four full-stroke actuations of the service brake control it is still possible on the fifth application to achieve the prescribed performance of the emergency brake (without failure in the service brake circuit). This alarm device must be directly and permanently connected to the circuit (See Clause 4.3.7(f))
This acoustical device may be rendered inoperative while the park-brake is applied and/or, at the choice of the manufacturer in the case of automatic transmission the selector is in the ‘Park’ position.
In verifying compliance with this clause, the vehicle’s brakes shall be correctly adjusted.
4.3.5 The auxiliary equipment must be supplied with energy in such a way that, even in the event of damage to the source of energy, its operation cannot cause the reserves of energy feeding the brake systems to fall below the level indicated in paragraph 4.3.4 above.
4.3.6 Retarders, other than exhaust brakes, shall not be capable of stalling the vehicle’s engine.
4.3.7 Power driven vehicles capable of towing a trailer of more than 3500 kg GVM shall meet the following requirements:
- (a) The braking system shall be capable of supplying the needs of the combination at GCM to comply with Appendix A.
- (b) The service braking system of the drawing vehicle shall incorporate automatic protection to preserve the drawing vehicle’s brake circuits in the event of a failure of the trailers brake system, whereby it shall be possible to brake the drawing vehicle with the effectiveness prescribed for emergency braking.
- (c) When the drawing vehicle’s emergency braking system comes into action, there must also be a braking action in the trailer.
If the requirements of the specifications section of this code are achieved by compliance with ECE 13, then when the drawing vehicle’s emergency braking system comes into action, there must also be a graduated service braking action in the trailer.
- (d) In the event of failure of the drawing vehicle’s service brake system, where that device consists of at least two independent parts, the part or parts not affected by the failure must be capable of actuating the brakes of the trailer. It must be possible to graduate this braking action.
- (e) In the event of a breakage of or a leak in one of the air connections (or of, or in such other type of connection as may be adopted), it must nevertheless be possible for the driver to actuate the brakes of the trailer by means either of the service brake control or the parking brake control, unless the breakage or leak automatically causes the trailer to be braked.
- (f) If the requirements of the specifications section of this code are achieved by compliance with ECE 13, then on air braked vehicles there should be an acoustic alarm device which is activated when the pressure at the coupling head of the supply line drops below 450 kPa. This alarm device may be combined with that described in clause 4.3.4 of this code.
4.4.1 The brake systems must be such that the trailer is stopped automatically, in a progressive manner, if the supply line breaks while the trailer is in motion, or when the supply line pressure falls below 310 kPa.
4.4.2 Parking braking must be ensured when the trailer is separated from the drawing vehicle or when the supply line pressure falls below 310 kPa.
A person standing on the ground must be able to release the parking brake at least three times after the trailer has been uncoupled. In the case of air brake systems, the pressure in the supply line shall be between 650 and 665 kPa before uncoupling. These conditions must be satisfied when the brakes are adjusted to normal clearances.
The auxiliary park release device shall be such that the system is restored to normal automatically on the resumption of supply from the drawing vehicle.
4.4.3 The braking systems shall not compound their application forces.
4.4.4 As an alternative to the system capacity requirements of Appendix F, trailers with air brake systems shall have a minimum air reservoir capacity in litres equal to three times the maximum mass in tonnes carried by the trailer axles.
5.1 Vehicles are exempt from clause 4.3.1(a) provided that the following requirements are met:
- (a) If there is a system park button it shall be coloured yellow.
- (b) If there are control buttons which apply the parking brakes on the drawing vehicle or trailer separately, they must be guarded to prevent accidental operation during an emergency.
5.2 If the requirements of clause A3.4.1, A 3.4.2, A3.5.3 and A8.1 cannot be met, the manufacturer may apply to the Statutory Authority for an exemption.
Distribution of braking among the axles of vehicles and requirements for compatibility between drawing vehicle and trailer
A1.1 This appendix relates to the retardation forces acting on the vehicle which are created by friction in the brakes; retardation forces which are applied through the drive axle do not form part of this appendix.
A1.2 The requirements of this appendix shall be met by vehicles when laden to the gross vehicle mass, EXCEPT in the case of vehicles fitted with load sensing devices, which must meet the requirements in all states of load. See Appendix E.
A1.3 A power driven vehicle not permitted to tow a trailer with a gross vehicle mass of more than 3500 kg is exempt from the requirements of this appendix provided that the vehicle is certified to an alternative standard that is acceptable to the statutory authority and:
- (a) The distribution of mass among the axles, when the vehicle is loaded to the gross vehicle mass (the maximum legally permitted in New Zealand), is the same (within 10%) as that to which the vehicle was originally certified; or
- (b) The vehicle is fitted with a load sensing device or an anti-lock device.
A1.4 No device shall be fitted into the cab of the vehicle which would allow the driver to alter the vehicle’s braking with respect to the requirements of this appendix.
E = wheelbase
fi= Ti/Ni, adhesion utilised by axle i*
g = acceleration due to gravity
h = height of centre of gravity of the laden vehicle
ho = height of centre of gravity of drawing vehicle
hs = height of the transverse pivot axis of the coupling on which the semi-trailer rests
i = axle index (i = 1, front axle; i = 2, second axle; etc.).
J = deceleration of the vehicle
M = weight of vehicle
Mi = reaction normal to road surface on axle i under static conditions
MM = total normal static reaction between road surface and wheels of drawing vehicles for trailer or semi-trailer
MM = Mo + Mso
Mo = unladen mass of vehicle
Ms = Mso (1 + 0.45z) used only in paragraph 3.1, diagram 1, Adhesion Utilisation Criterion
Mso = difference between the maximum laden mass of the drawing vehicle and its unladen mass
Ni = vertical reaction of road surface on axle i under braking
pm = pressure at coupling head of control line
MR = total normal static reaction normal to road surface on all wheels on laden trailer or semi-trailer
T = force exerted by the brakes on axle i under normal braking conditions on the road
TM = sum of braking forces at the periphery of all wheels of drawing vehicles for trailers or semi-trailers
TR = sum of braking forces at periphery of all wheels of a trailer or semi trailer
z = braking ratio of vehicle = J/g*
* = Adhesion utilisation curves of a vehicle means curves showing for specified load conditions, and adhesion utilised by each axle i plotted against the braking ratio of the vehicle.
** = For semi-trailers, z is the braking force divided by the static weight on the semi-trailer axle(s).
A3.0 Requirements for power driven vehicles
A3.1 Two axle vehicles
- (a) The following shall hold for fi values between 0.2 and 0.8:
- (b) For two axle vehicles, the adhesion utilisation curve of the front axle shall be situated above that for the rear axle for values of z between 0.15 and 0.3. This condition is also considered satisfied if, for braking ratios between 0.15 and 0.30, the adhesion utilisation curves for each axle are situated between two parallels to the line of ideal adhesion utilisation given by the equation fi = z + 0.08 as shown in Diagram 1.
- (c) In order to verify the requirements of paragraphs A3.1 and A3.2, the manufacturer shall produce the adhesion utilisation curves for the front and rear axles calculated by the formulas:
- (d) Where provision is made for several possibilities of load distribution, the one whereby the front axle is the most heavily laden shall be the one considered.
A3.2 In the case of a power driven vehicle authorised to draw trailers fitted with compressed air brake systems, the pressure at full application of the braking control must be between 650 and 800kPa at the coupling head of the supply line and between 600 and 750kPa at the coupling of the control line, upon full service brake application, irrespective of the load condition of the vehicle. These pressures must be demonstrably present at the coupling of the drawing vehicle.
A3.3 Vehicles with more than two axles
- (a) The adhesion utilised by at least one of the front axles shall be greater than that utilised by at least one of the rear axles for values of z between 0.15 and 0.3. This condition is also considered satisfied if, for braking ratios between 0.15 and 0.30, the adhesion utilisation curves for each axle are situated between two parallels to the line of ideal adhesion utilisation given by the equation fi = z + 0.08 as shown in Diagram 1.
- (b) For the calculation of the adhesion utilisation the effect of suspension geometry on the axle loads during braking (brake reactivity) may be neglected.
In cases where the suspension geometry has a significant effect on the axle load distribution, the Certifier shall verify, by performing an on-road test with the vehicle loaded to GVM, that no wheels on the vehicle lock up at a deceleration of 4.5 m/s2.
A3.4 Vehicles other than drawing vehicles for semi-trailers
- (a) In the case of vehicles fitted with an air brake system the permissible relationship between the braking ratio TR/MR or TM/MM and the pressure (pm) shall be within the areas shown in Diagram 2.
- (b) Vehicles first registered before I July, 1991 may, at the option of the Certifier comply with Diagram 3 as an alternative to Diagram 2.
A3.5 Drawing vehicles for semi trailers
- (a) The dynamic load of the semi-trailer on the drawing vehicle shall be represented by a static weight Ms applied at the coupling kingpin equal to:
Ms = Mso (1 + 0.45z)
- (b) In calculations of the effect of load transfer the following value shall be taken for h:
where M = Mo + Ms
- (c) In the case of vehicles fitted with air brake systems the permissible relationship between braking rate TM/MM and the pressure (pm) shall be within the areas shown in Diagram 3.
A4.0 Requirements for full trailers
A4.1 The requirements set out in Paragraphs A3.1 through to A3.4 inclusive shall apply to full trailers.
A5.0 Requirements for semi-trailers
A5.1 For vehicles with compressed air brakes the permissible relationship between the braking ratio TR/MM and the pressure (pm) shall lie within the shaded area shown in Diagram 2.
A5.2 The requirement of Paragraph A3.1(e) shall apply to vehicles with more than one axle if the suspension geometry affects the axle load distribution during braking (brake reactive suspensions).
A5.3 If the semi-trailer is itself a drawing vehicle for a second semi-trailer (i.e. the first semi-trailer in a B-Train), then the vehicle shall meet this requirement in the loaded condition specified in A3.5.
A6.0 Requirements for centre axle trailers
Centre axle trailers shall be subject to the requirements of A5.
A7.0 Load sensing devices
A7.1 In air brake systems load sensing devices should not modulate the pressure below 70 kPa.
A7.2 Vehicles fitted with load sensing devices must be fitted with a prominent sign stating that either the rear axle set or all axle sets are equipped with load sensing devices.
A7.3 Requirements to be met in the event of a failure of the control of the load sensing device:
- (a) It shall be possible to stop the vehicle under the conditions specified for emergency braking.
- (b) Power driven vehicles authorised to tow a trailer fitted with an air brake system it must be possible to achieve a pressure at the coupling head of the control line within the range specified in Paragraph A3.2.
A8.0 Threshold pressure tests for combination vehicles fitted with air brake systems
A8.1 The braking at the wheels shall commence at a pressure between 55 kPa and 80 kPa, measured at the coupling head of the control line. Braking shall be deemed to have commenced when a brake torque of 100 Nm is first reached at the wheel. For trailers equipped to tow a trailer, braking at all the wheels shall commence at a pressure between 50 kPa and 85 kPa, this pressure measurement shall be made at the coupling head of the control line of the drawing trailer. If there are very good and reasonable grounds to grant an exemption to this clause, then the approval of the statutory authority must be obtained.
Adhesion utilisation criterion
(See Paragraph A3.1)
Drawing vehicles, semi-trailers and full trailers
(See Paragraphs A3.4, A4.1, A5.1) (See Diagram 3 for Tractors)
Tractors for semi trailers
(See Paragraph A3.5. Also existing drawing vehicles and trailers first registered before 1 July 1991 which cannot be made to comply with Diagram 2)
Requirements for measuring the response time on vehicles equipped with compressed air brakes
B1.1 The response times of the brake system shall be determined on the stationary vehicle, the pressure being measured at the intake to the cylinder of the least favourably placed brake and at the coupling head if present.
During the test the free stroke in the brake cylinders of the various axles shall be as specified by the Certifier.
The response times determined in accordance with the provisions of this Appendix shall be rounded to the nearest tenth of a second. If the figure representing the hundredth is five or more, the response time shall be rounded up to the next higher tenth.
B2.0 Power driven vehicles
B2.1 At the beginning of each test the pressure in the energy storage device shall be equal to the pressure at which the governor restores the feed to the system. In systems not equipped with a governor (e.g. limited maximum compressors) the pressure in the energy storage device at a beginning of each test shall be 90% of the pressure specified by the certifier.
B2.2 The time elapsing from the initiation of a full brake-pedal actuation to the moment when the pressure in the brake cylinder reaches 75% of its final value shall not exceed 0.6 seconds.
The time elapsing from the release of the fully depressed brake pedal to the moment when the brake pressure reaches 25% of its initial value shall not exceed 0.6 seconds.
B2.3 In the case of vehicles having a brake coupling for trailers the response time must be measured at the coupling head. During this test a volume of 385 + 5cm3 (which is deemed to be the equivalent to the volume of a pipe 2.5m long with an internal diameter of 13mm and under a pressure of 650 kPa) shall also be connected to the coupling head of the control and supply lines. Tractive units for semi-trailers must be equipped with flexible pipes for making the connection to semi-trailers. The coupling heads will therefore be at the extremity of those flexible pipes.
The time elapsing from the initiation of a full brake pedal actuation to the moment when the pressure measured at the coupling head of the control line reaches 75% of its final value shall not exceed 0.4 seconds.
The time elapsing from the release of the fully depressed brake pedal to the moment when the coupling head pressure reaches 25% of its initial value shall not exceed 0.6 seconds.
B3.0 Trailers, including semi-trailers
B3.1 The trailers response time shall be measured without the drawing vehicle. To replace the drawing vehicle it is necessary to provide a simulator to which the trailer’s control line and supply line coupling heads are connected.
B3.2 The pressure in the supply line shall be:
B3.3 The simulator shall have the following characteristics:
- (a) It must have a reservoir with a capacity of 30 litres which shall be charged to a pressure of 650 kPa before each test and which must not be recharged during each test. At the outlet of the braking control device the simulator must incorporate an orifice with a diameter of from 4.0 to 4.3mm inclusive. The volume of the pipe measured from the orifice up to and including the coupling head shall be 385 + 5cm3 (which is deemed to be equivalent to the volume of a pipe 2.5m long with an internal diameter of 13mm and under a pressure of 650 kPa). The control line pressures referred to in paragraphs B3.3(c) shall be measured immediately downstream to the orifice.
- (b) The braking control device must be so designed that its performance in use is not affected by the tester.
- (c) The simulator must be set e.g. through the choice of an orifice in accordance with paragraph B3.3.1 in such a way that, if a reservoir of 385 ± 5cm3 is joined to it, the time taken for the pressure to increase from 65 to 490 kPa (10% and 75% respectively of the nominal pressure of 650 kPa) shall be 0.2 + 0.01 seconds. If a reservoir of 1155 + 15cm3 is substituted for the above mentioned reservoir the time taken for the pressure to increase from 65 to 490 kPa without further adjustment shall be 0.38 + 0.02 seconds. Between these two pressure values the pressure must increase in an approximately linear way. These reservoirs shall be connected to the coupling head without using flexible pipes. The reservoirs and pipes shall have an internal diameter of not less than 10mm.
- (d) The layouts in Diagram 1 to this Appendix give an example of the correct configuration of the simulator for setting and use.
B3.4 The time elapsing between the moment when the pressure produced in the control line by the simulator reaches 65 kPa and the moment when the pressure in the brake actuator of the trailer reaches 75% of the asymptotic value must not exceed 0.4 seconds.
When releasing pressure the time elapsing between the moment when the pressure produced in the control line by the simulator reaches 490 kPa to the moment when pressure in the brake actuator of the trailer reaches 25% of its initial value shall not exceed 0.6 seconds.
B3.5 Semi-trailers laid out for towing a second (semi) trailer shall meet the following requirements:
- (a) The response time must be measured at the rear most coupling head. During this test a volume of 385 + 5cm3 (which is deemed to be equivalent to the volume of a pipe 2.5 m long with an internal diameter of 13 mm and under a pressure of 650 kPa) shall also be connected to the coupling head of the supply line.
- (b) The time elapsing between the moment when the pressure produced in the control line by the simulator reaches 65 kPa and the moment when the pressure in the rear coupling head of the trailer reaches 75% of its asymptotic value must not exceed 0.4 seconds.
- (c) When releasing pressure, the time elapsing between the moment when the pressure produced in the control line by the simulator reaches 490 kPa to the moment when pressure in the rear coupling head of the trailer reaches 25% of its initial value shall not exceed 0.6 seconds.
B4.0 Partly pneumatic brake systems
B4.1 For partly pneumatic brake systems the requirements of paragraphs B1, B2 and B3 pertaining to the coupling head shall be met. The requirements in paragraphs B1, B2 and B3, cornering the least favourably placed chamber shall apply to the least favourably placed pneumatic device which acts on the non-pneumatic part of the brake system.
Diagram 1 applies to Test Equipment A Supply connection with shut off valve.
C1 = Pressure switch in the simulator, set at 65 kPa and at 490 kPa.
C2 = Pressure switch to be connected to the brake actuator of the trailer, to operate at 75% of the asymptotic pressure in the brake actuator CF.
CF = Brake cylinder.
L = Line from orifice 0 up to and including its coupling head TC, having an inner volume of 385 ± 5cm3 under a pressure of 650 kPA.
M = Pressure gauge.
0 = Orifice with a diameter of not less than 4mm and not more than 4.3mm.
PP= Pressure test connection.
R1 = 30 litre air reservoir with drain valve.
R2 = Calibrating reservoir, including its coupling head TC, to be 385 ± 5cm3.
R3 = Calibrating reservoir, including its coupling head TC, to be 1155 ± 15cm3.
RA = Shut off valve.
TA = Coupling head, supply line.
TC = Coupling head, control line.
V = Braking control device.
VRU= Relay valve
1. Setting the Simulator
2. Testing the trailer
Statement of compliance with the New Zealand Heavy Vehicle Brake Code
|UNLADEN CoG HEIGHT:||WHEELBASE:|
|UNLADEN MASS, FRONT:||UNLADEN MASS REAR:|
|PAYLOAD CoG HEIGHT:||POSITION:||RANGE:|
|FIFTH WHEEL HEIGHT*:|
|FRONT SUSPENSION TYPE:||REAR SUSPENSION TYPE:|
|SYSTEM PRESSURE:||MAXIMUM OPERATING Pm………..kPa|
|GOVERNOR CUTIN Pg………...kPa|
|TIME Pg to Pm……….. secs|
| Brake Force
|Tyre Size||Friction Material|
|Axle||Brake Type|| Drum
|Chamber Size||Slack Length||Spring Force|
* Horizontal distance from front axle set
* See Fifth Wheel Standard NZS5450 (1989)
* Park brake spring force
|TRUCK OR TRACTOR|
|Primary Circuit Relay|
|Sec. Circuit Relay|
|Trailer Control Relay|
|Trailer Hand Control|
|Quick Release Valve|
A copy of the calculations, test reports, and other documentation which demonstrates that this vehicle complies with the New Zealand Heavy Vehicle Brake Code must be made available to the statutory authority on request.
I, the undersigned do hereby certify that the vehicle identified above complies with all requirements of the current New Zealand Heavy Brake Code.
Date: ___________________________ Signed: _________________________
Name: __________________________ Phone: _________________________
Postal address: ____________________ Fax: ___________________________
I, the undersigned, do hereby re‑certify the vehicle identified above, as modified complies with all requirements of the current New Zealand Heavy Brake Code.
Date: ___________________________ Signed: _________________________
Name: __________________________ Phone: _________________________
Postal address: ____________________ Fax: ___________________________
Pressure test connections for compressed air braking systems
Dimensions of the typical connection.
|valve position||dimension ‘a’|
Dimensions not specified are to be chosen according to the application.
Seals and covers shall withstand petroleum products.
Free space to be reserved around the pressure test connection
Dimensions in millimetres
Maximum vehicle and axle weights. (Feb. 1989)
1/2 axle limit plus 500 kg.
|Single standard tyred axle|
|Single standard tyred axle (tyres at least 330 mm (13 ins) width by 24 ins. diameter or 355 mm (14 ins.) width by 19.5 ins. diameter)|
|Twin tyred axle|
|Note: For weights on oscillating axles and other axle combinations not shown above, refer to the Heavy Motor Vehicle Regulations 1974. Amendment No. 5.|
|,000kgDistance from first to last axle of any axle group of the vehicle or combination|
|1.8m but less than 2.5m||15,500kg|
|2.5m but less than 3.0m||17,500kg|
|3.0m but less than 3.3m||19,000kg|
|3.3m but less than 3.6m||20,000kg|
|3.6m but less than 4.0m||21,000kg|
|4.0m but less than 4.4m||22,000kg|
|4.4m but less than 4.7m||23,000kg|
|4.7m but less than 5.1m||24,000kg|
|5.1m but less than 5.4m||25,000kg|
|5.4m but less than 5.8m||26,000kg|
|5.8m but less than 6.4m||27,000kg|
|6.4m but less than 7.0m||28,000kg|
|7.0m but less than 7.6m||29,000kg|
|7.6m but less than 8.2m||30,000kg|
|8.2m but less than 8.8m||31,000kg|
|8.8m but less than 9.4m||32,000kg|
|9.4m but less than 10.0m||33,000kg|
|10.0m but less than 10.8m||34,000kg|
|10.8m but less than 11.6m||35,000kg|
|11.6m but less than 12.4m||36,000kg|
|12.4m but less than 13.2m||37,000kg|
|13.2m but less than 13.5m||38,000kg|
|13.5m but less than 14.4m||39,000kg|
|14.4m but less than 14.8m||40,000kg|
|14.8m but less than 15.2m||41,000kg|
|15.2m but less than 15.6m||42,000kg|
|15.6m but less than 16.0m||43,000kg|
|16.0m and over||44,000kg|
(Reprinted from ECE 13, Annex 7)
Provisions relating to energy sources and energy storage devices ('energy accumulators')
Compressed-air devices braking systems
1.0 Capacity of storage devices ('Energy Accumulators')
1.1.1 Vehicles on which the braking device requires the use of compressed air shall be equipped with energy storage devices (‘energy accumulators’) of a capacity meeting the requirements of Paragraph 1.2 and 1.3 below.
1.1.2 However the energy storage devices shall not be required to be of a prescribed capacity if the braking system is such that in the absence of any energy reserve it is possible to achieve a braking performance at least equal to that prescribed for the emergency braking system.
1.1.3 In verifying compliance with the requirements of Paragraphs 1.2 and 1.3 below, the brakes shall be adjusted as closely as possible.
1.2 Power-driven vehicles
1.2.1 The air brake reservoirs of power-driven vehicles shall be so designed that after eight full-stroke actuations of the service brake control the pressure remaining in the air brake reservoir shall be not less than the pressure required to obtain the specified secondary (emergency) braking performance.
1.2.2 Testing shall be performed in conformity with the following requirements.
- (a) The initial energy level in that energy storage device or devices shall be that specified by the manufacturer. It shall be such as to enable the prescribed performance of the service braking system to be achieved.
- (b) The energy storage device or devices shall not be fed, in addition, any auxiliary servo energy storage device or devices shall be isolated.
- (c) In the case of motor vehicles to which the coupling of a trailer or semi-trailer is authorised, the feed line shall be stopped and an energy storage device with a capacity of 0.5 litres shall be connected to the control line. The pressure in this energy storage device shall be eliminated before each braking operation. After the test referred to in Paragraph 1.2.1, the energy level supplied to the control line shall not fall below a level equivalent to one-half of the figure obtained at the first brake application.
1.3 Trailers and semi-trailers
1.3.1 The energy storage devices ('energy accumulators') with which trailers and semi-trailers are equipped shall be such that after eight full-stroke actuations of the drawing vehicle’s service braking device the energy level supplied to the operating members using the energy does not fall below a level equivalent to one-half of the figure obtained at the first brake application.
1.3.2 Testing shall be performed in conformity with the following requirements:
- (a) The pressure in the energy storage devices at the beginning of each test shall be the maximum pressure specified by the manufacturer.
- (b) The feed line shall be stopped; in addition, any auxiliary servo energy storage device or devices shall be isolated.
- (c) The energy storage device shall not be appreciably replenished during the test.
- (d) At each brake application the pressure in the control line shall be the maximum pressure specified by the manufacturer.
2.0 Capacity of energy sources
The compressors shall meet the requirements set forth in the following paragraphs.
2.2.1 ‘p1’ is the pressure corresponding to 65% of the pressure p2 defined in Paragraph 2.2.2 below.
2.2.2 ‘p2 ’ is the value specified by the manufacturer and referred to in Paragraph 2.2.1 above.
2.2.3 ‘T1’ is the time required for the relative pressure to rise from 0 to p1 , and T2 is the time required for the relative pressure to rise from 0 to p2.
2.3 Conditions of measurement
2.3.1 In all cases of r.p.m. speed of the compressor shall be that obtained when the engine is running at the speed corresponding to its maximum power or at the speed allowed by the governor.
2.3.2 During the tests to determine the time T1, and the time T2 the auxiliary servo energy storage device or devices shall be isolated.
2.3.3 If it is intended to attach a trailer to a power driven vehicle, the trailer shall be represented by an energy storage device whose maximum relative pressure p (expressed in bars) is that which can be supplied through the drawing vehicle’s feed given by the formula p.V = 20R (R being the permissible maximum load, in tonnes, on the axles of the trailer or semi-trailer).
2.4 Interpretation of results
2.4.1 The time T1 recorded for the least favoured energy storage devices shall not exceed:
- (a) Three minutes in the case of vehicles to which the coupling of a trailer or semi-trailer is not authorised; or
- (b) Six minutes in the case of vehicles to which the coupling of a trailer or semi-trailer is authorised.
2.4.2 The time T2 recorded for the least favoured energy storage device shall not exceed:
- (a) Six minutes in the case of vehicles to which the coupling of a trailer or semi-trailer is not authorised; or
- (b) Nine minutes in the case of vehicles to which the coupling of a trailer or semi-trailer is authorised.
2.5 Additional test
2.5.1 If the power driven vehicle is equipped with one or more auxiliary servo energy storage devices having a total capacity exceeding 20% of the total capacity of the braking energy storage devices an additional test shall be performed during which no irregularity shall occur in the operation of the valves controlling the filling of the auxiliary servo energy storage device or devices.
2.5.2 It shall be verified during the aforesaid test that the time T3 necessary to raise the pressure from 0 to P2 in the least favoured braking energy storage device is less than:
- (a) Eight minutes in the case of vehicles to which the coupling of a trailer or semi-trailer is not authorised; or
- (b) Eleven minutes in the case of vehicles to which the coupling of a trailer or semi-trailer is authorised.
2.6 The test shall be performed in the conditions prescribed in Paragraphs 2.3.1 and 2.3.3.
3.0 Pressure connections
3.1 To facilitate the periodic inspection of vehicles already in use on the road, a pressure connection shall be fitted close to the least favourably placed storage device.
3.2 The pressure connection shall comply with Appendix 2 to Annex 6 to this Regulation containing the drawings according to ISO 3583- 1975.
Land Transport Rule - Heavy-vehicle Brakes - Rule 32015
Land Transport Safety Authority of New Zealand, Te Mana Marutau Waka Whenua o Aotearoa