We all know that by pressing the middle pedal, the car brakes and the car starts to stop. The question is, is this process? How does it happen? How is the force of your foot transmitted to the wheels and most importantly, How this force is multiplied To be able to stop a heavy vehicle? Stay tuned to Digito to answer these questions.
When the brake pedal is depressed, the force of your foot multiplies and reaches the wheels. Several types of car braking systems such as Hydraulic, mechanical, pneumatic, vacuum, magnetic and electrical The most common of these is the hydraulic case, which is why we are examining it. Given that the force required to hold the car is much more than the power of the driver’s foot, this force must be much more than the initial state until it reaches the wheels. There are two solutions to this problem:
- Increase mechanical force (lever)
- Increase hydraulic force
The most important issue in stopping a car is friction. Brake force in the form Friction is transmitted to the wheels And then there is the friction between the car tire and the road that holds the car. As a result, to get acquainted with the way the brakes work, there are three concepts Lever, hydraulics and friction Let’s get acquainted.
We must first talk about the design of the brake pedal, which gives us a mechanical and lever advantage. This design is such that it takes the least force and then transfers more to the other side. Due to the length of its arm, this lever can increase the force even several times, and with the least pressure, it can cause more movement on the other side of the arm.
How does the hydraulic system of the brakes work?
The second concept is hydraulic. The definition of the hydraulic mechanism used in the brakes is very simple: the force is applied from the side and by An incompressible liquid It is transferred to the other side. This liquid is mostly an oil. Now if we increase or decrease the diameter of the fluid transfer chamber, we can increase and decrease this force many times over.
If Two pistons in two glass cylinders If we have them and connect them with a tube full of liquid, by pressing one cylinder, the second cylinder will also be displaced and since the liquid inside the tube is incompressible, the power transfer will be done very efficiently.
Come on Hydraulic system inside the brakes Check. When the brake pedal is depressed, the master cylinder piston is displaced and this force is transmitted by oil to the sub-cylinder. In each wheel to which the brake system is connected, there is a sub-cylinder which is filled with oil as it enters them and their piston moves. In manual brakes, power transmission by one or two wires Done.
Friction is the resistance force created by the movement of objects from the surface. This force is only in the opposite direction of slipping and opposes the slipping of objects. To create motion in objects, a force greater than the force of friction must be applied in the direction of motion. As a result, in order for an object to stop moving, the opposing force must increase.
By understanding these three concepts, the working mechanism can be found Hydraulic brakes He fully understood the car. For example, imagine that the distance from the bottom of the pedal to the hinge is four times the distance between the main cylinder and the hinge. So, Driver foot force to reach the main cylinder, Quadruples. Also consider that the level of the brake sub-cylinder is three times the level of the main pedal cylinder. Hence the force applied to this hydraulic system 9 times increase Finds. As a result, considering both mechanical and hydraulic advantages, the driver’s foot force reaches the brakes of each wheel, 36 times. That is, if the pedal is large 4 kg Be compressed, 144 kg of force to the brakes arrives.
Disc brake against disc
So far we have talked about the transmission of power by a system to the car brakes. Systems such as ABS can prevent the wheels from locking in severe braking. There are two general types of brakes installed on car wheels: Bowl (drum) and disc.
A bowl brake consists of a piece called a brake bowl that attaches to the wheel and rotates with it. Brake pads on two numbers Crescent shoes They are placed and when moving the car, they are placed a short distance from the brake bowl. As the pressure in the brake cylinder increases, friction is created between the brake bowl and the pads and the car stops. The advantage of bowl brakes Cheaper price and less weight They are. The big drawback of these brakes Rising temperature and poor performance It is in heat.
Disc brake Instead of a brake bowl, it has a rotating disk that moves with the wheel. These brakes have a pair of flat brake pads, and as the pressure increases, contact is made between the disc and the pad and the wheels stop. Price and Disc brake maintenance cost It is more than a bowl sample. Instead, the temperature does not rise too high, it cools down faster, and it is more suitable for continuous use.
In the brakes, using mechanical and hydraulic advantages, the power of the driver’s foot is multiplied and reaches the wheels. Then, the friction between the pads and the wheels and then the friction between the car tire and the road causes the car to stop.
The definition of the hydraulic mechanism used in brakes is very simple: force is applied from one side and transferred to the other side by an incompressible liquid. This liquid is mostly an oil. Now if we increase or decrease the diameter of the fluid transfer chamber, we can increase and decrease this force many times over.
The advantage of bowl brakes is cheaper price and less weight. The big disadvantage of these brakes is the increase in temperature and its poor performance in heat. The price and cost of maintaining a disc brake is higher than a sample bowl. Instead, the temperature does not rise too high, it cools faster, and it is more suitable for continuous use.