48.83. What must be done in advance before using a hydraulic jack?
UAЩо потрібно зробити заздалегідь, перед використанням гідравлічного домкрата?
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This is an exam question from the Traffic Rules of Ukraine concerning safety during stopping or parking, when the driver performs technical actions with the vehicle. The use of a hydraulic jack increases the risk of unintentional movement of the vehicle: the car partially loses stability, and even the slightest push, road slope, or sinking of the support can cause it to roll. That is why the traffic rules emphasize the driver's duty to prevent the unintended movement of the vehicle.
The question tests knowledge of the section of the Traffic Rules regarding stopping and parking, specifically point 15.12, which directly states that the driver must take measures to ensure the vehicle does not start moving on its own. In the context of the theoretical exam, it is important to understand that the jack does not lock the car from moving forward or backward; it only lifts the body at a certain point. Therefore, the advance use of wheel chocks is a logical and necessary measure to comply with the Traffic Rules requirements.
The analysis of the answer options comes down to practical safety. Checking the jack’s serviceability is useful, but does not address the main danger of the car rolling, and thus does not guarantee compliance with the requirement to prevent unintentional movement. The statement that using a hydraulic jack is prohibited is incorrect: there is no such ban, but there is an obligation to properly prepare the vehicle. The only option that directly prevents the car from moving during lifting and complies with the traffic rules is the prior securing of the wheels with chocks.
Clause 15.12
The driver must take measures to prevent the spontaneous movement of the vehicle during its stop or parking.
Explanation of application: the use of a hydraulic jack means that the vehicle is actually in stop/parking mode and partially loses stability. To fulfill the traffic rules requirement to prevent spontaneous movement, additional fixing devices are applied in advance — wheel chocks (wheel stops).
That is, the correct answer is "Install wheel chocks," considering that according to the definition of the traffic rules, the driver is obliged to take measures to prevent the spontaneous movement of the vehicle during stop or parking.
When lifting a car with a hydraulic jack, the main risk is that the vehicle may lose stability and shift from its place. The jack does not prevent the car from rolling forward or backward; it only raises the body at the support point. Therefore, before starting work, you must first eliminate any possible movement of the vehicle.
Safety requirements set out in the operating instructions and the general principles of the Traffic Rules regarding the prevention of spontaneous movement require the reliable securing of the car when stopping to perform technical actions. In practice, this means that the wheels remaining on the ground must be blocked with wheel chocks so that even on a slight incline or with a push, the vehicle does not start to roll.
Imagine the situation: you have lifted the car with a jack to change a wheel, but did not install chocks. A slight shift in the center of gravity, slippery surface, jack subsidence, or accidental push is enough for the car to start rolling. In such a case, the jack easily slips from the support point, and the vehicle moves uncontrollably, which creates a direct risk of injury and damage. However, if the wheels are secured with chocks, even if the jack subsides or tilts, the car will not be able to roll freely, and the situation will be much safer.
Therefore, the correct answer is "Install wheel chocks," because before using a hydraulic jack, you must first prevent the possible rolling of the car and loss of stability.