At the working engine and the serviceable vacuum amplifier the brake pedal at braking should not reach a cab floor — the backlash between a pedal and a floor should be not less than 40 mm.

Working capacity of the vacuum amplifier is checked as follows: at the idle engine it is necessary to press a brake pedal 3—4 times, and then, by the subsequent pressing a pedal, keeping it with effort 300—400 Н (30—40 кгс) to start up the engine. At the serviceable amplifier the pedal will move to a floor a little, and hissing of air passing through the filter of the amplifier will be audible.

If the pedal does not move or its moving is complicated, the reason in malfunction of the amplifier or wrong adjustment of the engine idling.

Serviceability of system of the alarm system of emergency falling of level of a liquid in a tank of the main cylinder is checked by pressing a float core. Thus on the panel of devices the lamp of red colour should light up.