A heavy machine cannot do without an auxiliary braking system on mountain roads. Exhaust brakes are not only installed on trucks and buses for safety reasons. It extends the life of the main brake.
Exhaust brake is an additional braking system. It allows the vehicle to move at low speed. Fits on trucks, road trains and buses.
Wear-resistant and safe
Heavy cars don't need speed records. But confidence when moving on mountain roads will not hurt. With their endless descents and ascents.
If the car is going downhill, it will gradually accelerate. When, in the opinion of the driver, the speed becomes dangerous, he slows down. But soon the speed picks up again.
On a long descent, you have to slow down repeatedly. Tires wear out. Brake linings get hot.
The coefficient of friction of the lining on the brake drum is reduced. This leads to a decrease in the effectiveness of the main brake. And, as a result, to an accident.
The exhaust brake allows the service braking system to rest while remaining cold. So that in a critical situation she does not refuse. She stopped the car. After all, a mountain brake cannot do this.
There are three types of auxiliary brakes: motor, hydraulic and electric. At idle speed, the engine itself can be used as a retarder. But its braking torque is only enough for a passenger car.
In the heart of the car
The engine brake is a special device that turns off the fuel supply. It is installed in the engine of the machine.
During braking, the flap closes the muffler pipe and moves the fuel pump rail. Gasoline is not supplied. The engine stalls, but the crankshaft continues to rotate.
The piston tries to push air out of the cylinders. He is experiencing strong resistance. Because of this, the rotation of the shaft and, accordingly, of the driving wheels slows down.
Wheels in oil
The hydraulic retarder consists of two paddle wheels. They are located in parallel. The distance between the wheels is small. There is no hard link.
One wheel is attached to the propeller shaft and rotates with it. The second is on the brake body. It is motionless.
The body of the hydraulic brake is filled with oil through a special pump. It is accelerated by the blades of a rotating wheel. Spills over to a stationary one and loses speed.
Once again falling on the first wheel, the oil slows down its rotation. The braking torque is transmitted to the drive wheels of the vehicle.
In an electric braking system, a rotor is connected to the shaft. And the stator windings are located in the housing.
When voltage is applied to them, an electromagnetic field appears. It also prevents the rotor from rotating at the same speed.