Tractor engine means an engine certified for use in tractors. Where an engine family is certified for use in both tractors and vocational vehicles, tractor engine means an engine that the engine manufacturer reasonably believes will be (or has been) installed in a tractor. Note that the provisions of this part may require a manufacturer to document how it determines that an engine is a tractor engine.
40 CFR § 1036.801
The following definitions apply to this part. The definitions apply to all subparts unless we note otherwise. All undefined terms have the meaning the Act gives to them. The definitions follow: