Assertion: tractor | /r/HasProperty | heavy
Facets:
value: for sufficient traction
type: PURPOSE
Source sentences:
text: The earliest tractors were huge, heavy and steam-powered.
text: Since tractors are heavy and often have to work on steep slopes and soggy, unstable ground, there's always a risk they might tip over so modern tractors generally have reinforced cabs fitted with anti-roll bars.
text: For sufficient traction the tractor must be heavy, and most models can have extra ballast added.
text: As cited before, the "tractor" needs to be heavy to aid traction.