23932 version 1
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Maintain and repair heavy trailers and semi-trailers
Level
4
Credits
13
Purpose
This unit standard is for people in the automotive heavy repair industry.
People credited with this unit standard are able to: determine the need for
service and repair of drawbar trailer and semi-trailer air braking and steering
systems; rectify drawbar trailer and semi-trailer air braking system faults;
service and repair trailer and semi-trailer suspensions; and check and adjust
semi-trailer wheel alignment.
Subfield
Motor Industry
Domain
Automotive Trailers
Status
Registered
Status date
21 September 2007
Date version published
21 September 2007
Planned review date
31 December 2012
Entry information
Recommended: Unit 23931, Demonstrate knowledge of
heavy trailer systems, or demonstrate equivalent
knowledge and skills.
Replacement information
This unit standard and unit standard 23931 replaced unit
standard 2341.
Accreditation
Evaluation of documentation and visit by NZQA and
industry.
Standard setting body (SSB)
NZ Motor Industry Training Organisation (Incorporated)
Accreditation and Moderation Action Plan (AMAP) reference
0014
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
 New Zealand Qualifications Authority 2016
23932 version 1
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Special notes
1
Legislation and publications relevant to this unit standard may include but are not
limited to – Health and Safety in Employment Act 1992; Goods Service Vehicle
(Constructional) Regulations 1936; Heavy Motor Vehicle Regulations 1974; Traffic
Regulations 1976; Land Transport Rules: Heavy-vehicle Brakes 2006, Rule 32015;
Heavy Vehicles 2004, Rule 31002; Vehicle Repair 1998, Rule 34001; Vehicle
Standards Compliance 2002, Rule 35001/1; New Zealand Standards NZS 4711:1984
Qualification tests for metal-arc welders; NZS 5446:1987 Code of practice for heavy
motor vehicle towing connections: drawbar trailers; Vehicle Inspection Requirements
Manual (VIRM) – In-service certification.
2
Land Transport Rules are produced for the Minister of Transport by Land Transport
New Zealand. These rules are available online at
http://www.landtransport.govt.nz/rules/.
New Zealand Standards are available from Standards New Zealand, Private Bag
2439, Wellington; phone 04 498 5990; or website http://www.standards.co.nz.
The VIRM is published by Land Transport New Zealand and is available online at
http://www.landtransport.govt.nz/certifiers/virm-in-service/index.html.
3
Definitions
Company requirements refer to instructions to staff on policy and procedures which
are documented in memo or manual format and are available in the workplace.
These requirements include but are not limited to – company specifications and
procedures, work instructions, manufacturer specifications, product quality
specifications, and legislative requirements.
Service information may include but is not limited to – technical information of a
vehicle, machine, or product detailing operation; installation and servicing
procedures; manufacturer instructions and specifications; technical terms and
descriptions; and detailed illustrations. This can be accessed in hard copy or
electronic format and is normally sourced from the manufacturer.
Suitable tools and equipment means industry approved tools and equipment that are
recognised within the industry as being the most suited to complete the task in a
professional and competent manner with due regard to safe working practices.
4
All trailer repairs and alterations must conform to the requirements of the Land
Transport Rules.
5
All welding to towbars, drawbeams and drawbars must conform to NZS 5446:1987
Code of practice for heavy motor vehicle towing connections: drawbar trailers and be
performed by a person holding a current NZS 4711:1984 Welding Certificate.
6
Brake equipment, repairs and alterations to equipment and replacement parts must
conform to the requirements of the Land Transport Rule, Heavy-vehicle Brakes 2006,
Rule 32015.
7
For this unit standard, it is essential that the practical assessment evidence is
obtained in the workplace under normal workplace conditions.
 New Zealand Qualifications Authority 2016
23932 version 1
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Elements and performance criteria
Element 1
Determine the need for service and repair of drawbar trailer and semi-trailer air braking
and steering systems.
Performance criteria
1.1
Safe working practices are observed throughout the task in accordance with
legislative requirements.
Range
personal safety, safety of others, equipment safety.
1.2
The operation of the trailer and semi-trailer air braking system are checked in
accordance with service information, and any faults found are noted.
1.3
The brake shoes, springs, backplates, operating mechanisms, brake drums,
slack adjusters, and brake chambers are inspected in accordance with service
information, and any faults found are noted.
Range
1.4
The air brake components are inspected in-situ in accordance with service
information, and any signs of air leaks and damage are noted.
Range
1.5
includes but is not limited to – condition of pipes and hoses, joints,
cylinders and valves.
Drawbar steering and turntable self-steering system maintenance schedules are
checked in accordance with company requirements. The steering systems are
inspected for wear and damage, and the results noted.
Range
1.6
includes but is not limited to – wear, scoring, runout, distortion,
condition of friction linings, spring brake operation.
drawbar coupling, turntables, friction plates, steering links,
turntable kingpins, locking device.
Castering axle self-steering is checked for wear and damage and any faults
found are noted.
Range
includes but is not limited to – king pins, tie rod, damping control,
reverse lock, wheel alignment.
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23932 version 1
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Element 2
Rectify drawbar trailer and semi-trailer air braking system faults.
Performance criteria
2.1
Safe working practices are observed throughout the task in accordance with
legislative requirements.
Range
personal safety, safety of others, equipment safety.
2.2
Suitable tools and equipment are selected and used that enable the rectification
work to be carried out in accordance with service information.
2.3
Faults noted in the air-operated brake equipment are rectified to meet the
Heavy-vehicle Brakes Rule, service information, and legislative requirements.
Range
spring brake, tractor protection valve, relay-breakaway valve,
automatic drain valve, air hoses and lines.
2.4
The wheel stations are disassembled, repaired, and reassembled to full
serviceability in accordance with service information and legislative
requirements.
2.5
The brake shoes and slack adjusters are adjusted in accordance with service
information.
2.6
The braking system is tested to ensure no faults remain in accordance with
service information.
Element 3
Service and repair trailer and semi-trailer suspensions.
Performance criteria
3.1
Safe working practices are observed throughout the task in accordance with
legislative requirements.
Range
3.2
personal safety, safety of others, equipment safety.
The trailer and semi-trailer suspensions are checked for misalignment, wear
and damage in accordance with service information, and any faults are noted.
Range
leaf springs, air springs.
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23932 version 1
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3.3
Any misalignment, wear and damage to the suspension system is repaired by
replacement with manufacturer approved replacement parts in accordance with
service information and legislative requirements.
Range
spring leaves, shackles, hangers, equaliser bars, torque rods, air
bellows, levelling valve and associated equipment, shock
absorbers.
Element 4
Check and adjust semi-trailer wheel alignment.
Performance criteria
4.1
Safe working practices are observed throughout the task in accordance with
legislative requirements.
Range
personal safety, safety of others, equipment safety.
4.2
Suitable tools and equipment are selected and used that enable the semi-trailer
wheel alignment to be checked in accordance with service information.
4.3
Semi-trailer wheel alignment is checked in accordance with service information,
and any misalignment is noted.
4.4
Adjustments are made to the wheel alignment to return it to full serviceability in
accordance with service information.
Please note
Providers must be accredited by NZQA, or an inter-institutional body with delegated
authority for quality assurance, before they can report credits from assessment against
unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by NZQA before they can register
credits from assessment against unit standards.
Accredited providers and Industry Training Organisations assessing against unit standards
must engage with the moderation system that applies to those standards.
Accreditation requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the NZ Motor Industry Training Organisation (Incorporated)
janet.lane@mito.org.nz if you wish to suggest changes to the content of this unit standard.
 New Zealand Qualifications Authority 2016