Correct as at 18th April 2024. It may be superseded at any time.
Extract taken: from Vehicle Inspection Portal > VIRMs > In-service certification (WoF and CoF) > Tractors > Exhaust > Exhaust emissions
11-2 Exhaust emissions
Reasons for rejection
Performance
1. A vehicle with the engine at normal operating temperature emits clearly visible smoke (Note 2) from the exhaust tail pipe during a rapid acceleration test (Note 1).
Note 1 Test procedure
Rapid acceleration test
While the engine is accelerated quickly from idle to 2500rpm (or half the maximum engine speed if this is lower), observe the tailpipe emissions. To avoid engine damage do not over-accelerate the engine. A vehicle that passes this test below normal operating temperature is deemed to have passed with the engine at normal operating temperature.
Note 2
Visible exhaust smoke does not include:
- emissions that are largely water vapour, or
- smoke that is barely visible, or
- a moderate amount of smoke caused by turbo lag, or
- some normal visible smoke caused by the engine's design (with the engine in good condition and running the correct fuel). The inspector may require documentary evidence that the engine produces some visible smoke because of its design.
Note 3
The vehicle inspector may need to take into account information from the vehicle manufacturer or their representative or other appropriate expert, eg about older or unusual vehicles.
Summary of legislation
Applicable legislation
Performance
1. A tractor must not emit clearly visible smoke when the engine is running at its normal operating temperature, under the following condition:
- as the engine is being accelerated rapidly to approximately 2500 revolutions per minute or approximately half the maximum engine speed (whichever is lower).
Page amended 1 June 2013 (see amendment details).