Which gear should you use in order to start moving a tractor on an icy surface?
Show the correct answer
Correct answer
C. The gear which requires you to apply the lowest possible driving force of the wheels.
Explanation
The question is about moving off with an agricultural tractor on an icy surface. You engage the gear in which you get the smallest driving force at the wheels that is enough to move off - answer C.
On ice a tyre transfers very little force before it starts to slip. First gear (answer A) multiplies the engine torque the most - the wheels easily start to spin, polish the ice under them, and instead of moving off, the tractor stays in place or slides sideways. That is why you move off in a higher gear, releasing the clutch slowly and pressing the accelerator very gently. Direct gear (answer B), usually one of the highest, on the other hand gives too little force - the engine will stall or the clutch will slip too much. Which gear is right depends on the tractor, the load and the slope of the road. If the wheels still spin, it will help to engage the front-wheel drive or to spread sand under the wheels.
Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)