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3 Vehicle structure

3-2 Stability

Reasons for rejection

Mandatory requirement

1. A class TD trailer, other than one listed in Table 3-2-1, that is presented with a body capable of achieving a load height exceeding 2.8m from the ground does not have proof of Static Roll Threshold (SRT) certification at 0.35g.

Modification

2. A modification or repair since 1 July 2000 affects the vehicle stability and:

a) is not excluded from the requirements for HVS certification (Table 3-2-2), or

b) the modification is not for the purpose of law enforcement or the provision of emergency services, or

c) is missing proof of HVS certification, that is:

i. the vehicle was modified or repaired before the last CoF inspection and no LANDATA record has been entered, or

ii. the vehicle was modified or repaired since the last CoF inspection and no valid LT400 form from a Level 1 or Level 2 SRT certifier has been presented.

Note 1 Definitions

High-productivity motor vehicle (HPMV) means a heavy motor vehicle or heavy combination vehicle that carries a divisible load and with or without a load:

a) exceeds a gross mass of 44,000kg, or

b) varies from a dimension requirement in Table 2-2-3, section 2-2 (other than width, height or ground clearance), or

c) both (a) and (b), and

d) operates on an HPMV permit issued by a road controlling authority.

Road controlling authority means the authority, body or person having control of the road (eg the NZTA, a regional council or an authorized delegate).

Note 2

For the avoidance of doubt, a high-productivity motor vehicle must comply with minimum SRT requirements.

Note 3

When measuring the height of a tipper body any lifting ram extending above the rim of the tipper body should not be included in the calculation of the height of the body.

Table 3-2-1. Class TD trailers that are not required to comply with SRT
  • An overdimension trailer (other than a high-productivity motor vehicle) (Note 1) (Note 2)
  • A trailer operating under an overweight permit (other than a high-productivity motor vehicle) (Note 1) (Note 2)
  • A trailer first registered before 1 January 1940
  • A vehicle recovery service vehicle that is designed principally to transport a heavy motor vehicle.
Table 3-2-2. Requirements for HVS certification

HVS certification is required

HVS certification is not required

A modification affects the trailer’s SRT compliance (eg deck, body, suspension, different sized wheels or tyres).

Any repair or modification not listed in the left-hand column unless the vehicle inspector considers that certification is required because the modification or repair has affected the vehicle’s safety performance (a second opinion from an expert may be needed, eg the manufacturer’s representative, or a reputable workshop).

Summary of legislation

Applicable legislation
Mandatory requirement

1. A class TD trailer, other than one listed in Table 3-2-1, with a body or load height exceeding 2.8m from the ground must comply with a Static Roll Threshold (SRT) of at least 0.35g.

Specialist certification

2. Compliance with SRT must be certified by a person approved as a Level 1 or Level 2 SRT certifier.

Modification and repair

3. A modification or repair, on or after 1 April 2002, that affects the stability of a heavy trailer must be inspected and certified by an HVS certifier, unless the vehicle:

a) is excluded from the requirements for HVS certification (Table 3-2-2), and

b) has been inspected in accordance with the requirements in this manual, including those for equipment, condition and performance.

Page amended 1 June 2018 (see amendment details).