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Title / Describe tractor braking systems, and diagnose and rectify faults in wheel tractor braking systems
Level / 4 / Credits / 7
Purpose / This unit standard is for people in the automotive repair industry. People credited with this unit standard are able to: demonstrate knowledge of wheel tractor brake systems, servicing procedures, and fault diagnosis; demonstrate knowledge of tractor hand brake and emergency brake systems, fault diagnosis, and repair; demonstrate knowledge of tractor auxiliary braking systems; diagnose faults in wheel tractor brakes; carry out routine maintenance of wheel tractor braking systems; and repair faults in wheel tractor brakes.
Classification / Motor Industry > Vehicle Braking Systems
Available grade / Achieved
Explanatory notes
1The following legislation and amendments are to be consulted and followed where applicable:
–Health and Safety in Employment Act, 1992.
2Reference to 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 to a professional and competent manner with due regard to safe working practices.
3Because of the particular nature of this unit standard, it is essential that the practical assessment evidence is obtained from commercial jobs in the workplace under normal workplace conditions.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of wheel tractor brake systems, servicing procedures, and fault diagnosis.
Rangeoutboard slow axle brakes, high speed axle shaft brakes (dry), high speed shaft axle brakes (wet), high speed transmission brakes (dry).
Evidence requirements
1.1Safety requirements relating to workshop and field work are identified.
Rangepersonal safety, safe jacking procedure and jacking points, lifting equipment, slings and chains.
1.2Construction of wheel tractor braking systems is described according to tractor manufacturer's workshop manual descriptions.
Rangefeatures, identification of parts, layout of parts.
1.3Operation of wheel tractor braking systems is described according to tractor manufacturer's workshop manual descriptions.
Rangebraking action (combination, independent).
1.4Servicing and diagnostic procedures of wheel tractor braking systems are described according to tractor manufacturer's workshop manual instructions.
1.5Brake lining materials used for tractor braking systems are described according to manufacturer's specifications.
Rangeasbestos and non-asbestos linings, bronze and steel plate discs.
1.6Wet brake lubrication requirements are identified.
Rangemanufacturer's specified oils, oil company specified oils, compatibility and interchangeability of oils, oil requirements.
Outcome 2
Demonstrate knowledge of tractor hand brake and emergency brake systems, fault
diagnosis, and repair.
Rangehigh speed transmission shaft, transmission disc, main overriding system.
Evidence requirements
2.1Construction of tractor hand brake and emergency braking systems are described according to tractor manufacturer's workshop manual descriptions.
Rangefeatures, identification of parts, layout of parts.
2.2Braking action of a tractor wheel emergency braking system is described according to tractor manufacturer's workshop manual descriptions.
2.3Diagnostic procedures of tractor hand brake and emergency braking systems are described according to tractor manufacturer's workshop manual instructions.
2.4Repair procedures of tractor hand brake and emergency braking systems are described according to tractor manufacturer's workshop manual instructions.
Outcome 3
Demonstrate knowledge of tractor auxiliary braking systems.
Rangeoverriding drawbar brakes, operator controlled brakes.
Evidence requirements
3.1Construction of tractor auxiliary braking systems is described according to tractor manufacturer's workshop manual descriptions.
Rangefeatures, identification of parts, layout of parts.
3.2Braking action and operation of tractor auxiliary braking systems are described according to tractor manufacturer's workshop manual descriptions.
3.3Repair procedures of tractor hand brake and emergency braking systems are described according to tractor manufacturer's workshop manual instructions.
Outcome 4
Diagnose faults in wheel tractor brakes.
Rangeoutboard slow axle brakes, high speed axle shaft dry brakes, high speed shaft axle wet brakes, high speed transmission dry brakes, emergency brake systems, auxiliary systems.
Evidence requirements
4.1Safe working practices are observed throughout the task.
Rangepersonal safety, safety of others, equipment and tractor safety.
4.2Suitable tools and equipment are selected and used that enable faults to be diagnosed according to workshop manual instructions.
4.3The symptoms of the fault(s) are verified and recorded.
Rangecommunication with the customer and/or operator, operating the tractor to reproduce the fault(s).
4.4A diagnostic report on the braking system is completed and reported to the supervisor.
Rangevisual inspection of system following a logical systematic procedure, tractor operated and brake performance tested as specified by the tractor manufacturer, identifying and recording faults, estimating repair costs, recommending repairs and replacement of parts.
Outcome 5
Carry out routine maintenance of wheel tractor braking systems.
Evidence requirements
5.1Safe working practices are observed throughout the task.
Rangepersonal safety, safety of others, equipment and tractor safety.
5.2Suitable tools and equipment are selected and used that enables routine maintenance to be undertaken.
5.3Periodic and seasonal maintenance checks are carried out according to tractor manufacturer's and customer's requirements.
Rangecleaning, lubricating, inspecting, adjusting, testing, recommending repair work.
Outcome 6
Repair faults in wheel tractor brakes.
Rangeoutboard slow axle brakes, high speed axle shaft dry brakes, high speed shaft axle wet brakes, high speed transmission dry brakes, emergency brake systems, auxiliary systems.
Evidence requirements
6.1Safe working practices are observed throughout the task.
Rangepersonal safety, safety of others, equipment and tractor safety.
6.2Suitable tools and equipment are selected and used to enable repairs to be effected according to workshop manual instructions.
6.3The machine is cleaned in the area to be worked, to allow clean access when dismantling components.
Rangesteam machine cleaning, solvent and water hand cleaning.
6.4The machine is made safe before repairs are carried out.
Rangelevel surface, blocking, jacking.
6.5Brake housings are stripped down according to tractor manufacturer's workshop manual instructions.
6.6Brake parts are cleaned and made ready for inspection according to manufacturer's instructions.
6.7Repairs required to the braking system are identified, in comparison with manufacturer's specifications.
6.8The tractor braking system is repaired and reassembled according to tractor manufacturer's workshop manual instructions.
Rangereline and/or replace worn components, linkage operation, lubrication, adjustments.
6.9Field test is completed to ensure braking system operates to tractor manufacturer's specifications.
Replacement information / This unit standard has been replaced by unit standard 24416 and unit standard 24417.This unit standard is expiring. Assessment against the standard must take place by the last date for assessment set out below.
Status information and last date for assessment for superseded versions
Process / Version / Date / Last Date for AssessmentRegistration / 1 / 31 October 1995 / 31 December 2016
Review / 2 / 29 March 1999 / 31 December 2016
Review / 3 / 25 January 2008 / 31 December 2016
Rollover / 4 / 19 November 2010 / 31 December 2016
Rollover / 5 / 18 February 2016 / 31 December 2020
Consent and Moderation Requirements (CMR) reference / 0014
This CMR can be accessed at
Please note
Providers must be granted consent to assess against standards (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 granted consent to assess against standards by NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and which are assessing against unit standards must engage with the moderation system that applies to those standards.
Consent requirements and an outline of the moderation system that applies to this standard are outlined in the Conesnt and Moderation Requirements (CMR). The CMR 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.
NZ Motor Industry Training Organisation (Incorporated)SSB Code 101542 / New Zealand Qualifications Authority 2018