Braking assist mechanisms used in the trailer.
The effectiveness of the hydraulic brakes is limited by the physical abilities of the driver. To brake a large truck or bus, the driver must use a lot of force, sometimes exceeding his physical abilities To facilitate the driving of heavy vehicles equipped with hydraulic brakes, Assistants have been introduced in some trucks and buses.
The booster is most effective when the crankshaft speed is high and the carburetor throttle is closed, when there is a high vacuum in its cylinder, e.g. when going downhill.
Some vehicles use hypertensive support mechanisms.