Car Brakes Are Important for safely operating a car – here is all you need to know – Car Brakes 101
How often do we give a thought to the brakes on our vehicles? such important components of the 100’s that make up an automobile.
Have you ever considered how it works and the effects it has on your safety on the road?
We take off we, drive and have to STOP, sometimes in an emergency due to road hazards, ranging from inconsiderate road users, road works and emergency response vehicles etc.
So let’s take a look at what makes up the average vehicle’s braking system and how it works (in simple terms.)
The Braking system is made up of these listed main components:
- Brake Master Cylinder
- Brake Discs (Rotors) and Pads
- Brake Drums, Shoes and Wheel Cylinders
- Hand Brake or Parking Brake (Emergency Brake)
- Brake Booster (Servo)
- ABS (Most Modern Cars)
Brake Master Cylinders
This is a hydraulic cylinder, which takes brake fluid in from a reservoir mounted to it.
By applying pressure to your vehicle’s brake pedal the master cylinder pumps brake fluid into reinforced brake pipes which is attached to the front and rear brake component systems. This pressure activates friction surfaced pads or shoes which in turn clamps down onto rotating brake discs or drums (made of metal) forcing it to SLOW/STOP.
Brake Discs (Rotors) and Pads
The front brake system accounts for the main braking force on modern vehicles. Most modern vehicles incorporate a front brake disc (rotors) and disc pad system.It is used on the rear of most modern automobiles too.
The system is made up of 3 main components namely:
- 1 Brake Calliper
- 1 Brake disc (rotor) 1 per side
- 2 Per Side Disc Pads
How it works
When the brakes are applied, the pressure sent to the front by the brake master cylinder and into the Brake Caliper, squeezes the two Brake Pads contained in the Brake Calliper together, onto the spinning Rotor to SLOW/STOP the Vehicle.
Brake Discs and Pad systems generate lots of heat (more than shoes and drum system). When a Brake Pad is heated by contact with a Rotor, it transfers small amounts of friction material onto the car’s rims, turning it dull grey. This is visible as brake dust on your car mags.
Brake Drums, Shoes and Wheel Cylinders
Most modern vehicles use brake discs (rotors) and pads at the rear also, but some SUV’s and most LDV’s ( Pickups) use a brake drum with brake shoes, system. Rear brakes account for much less of the vehicle’s brake force compared to the front brakes and generates less heat due to its design. The split could be as much as 30/70.
The rear brake system is made up of 3 main components namely:
- 2 Brake shoes per side, (leading and trailing)
- 1 Hydraulic rear wheel cylinder,
- 1 brake drum
How It Works
When the brakes are applied, the pressure sent to the rear by the master cylinder, forces 2 pistons in the rear wheel cylinder to push out and activate the friction lined rear brake shoes which pushes against the brake drum to SLOW/STOP the vehicle.
The small amounts of friction material produced here are not seen as with disc pads and rotors, due to the friction material being much less and contained inside the brake drum.
Disc Brake Advantages
Disc brakes offer better stopping performance than comparable drum brakes, including resistance to brake fade caused by the overheating of brake components, and are able to recover quickly from immersion (less effective when wet). Unlike a drum brake, the disc brake has no self-servo effect; the braking force is always proportional to the pressure placed on the braking pedal or lever.
Advantages Of Drum Brakes And Shoes
Drum brakes are used in most heavy duty trucks, some medium and light duty trucks, and few cars, drum brakes allow simple incorporation of a parking brake. Drum brakes are also occasionally fitted as the parking (and emergency) brake even when the rear wheels use disc brakes as the main brakes. The increased friction contact area of drum brake shoes on the drum allows drum brake shoes to last longer than disc brake pads.
Hand Brake Or Parking Brake (Emergency Brake)
The idea is that the system is fully mechanical and completely bypasses the hydraulic system so that the vehicle can be brought to a stop even if there is a total brake failure. Here the cable pulls on a lever mounted in the brake and is directly connected to the brake shoes. This has the effect of bypassing the wheel cylinder and controlling the brakes directly.
Brake Booster (Servo)
A vacuum servo is a component used on vehicles in its braking system, to provide assistance to the driver by decreasing the braking effort. It is commonly called a brake booster. The brake booster usually uses vacuum from the engine intake to boost the force applied by the pedal on to the master cylinder.
Brake boosters come in either a single diaphragm or tandem diaphragm (which is generally used for bigger vehicles and trucks). Without the engine running the brake pedal feels very hard and the brakes are ineffective.
ABS (Most Modern Cars)
An anti-lock braking system or anti-skid braking system (ABS) is a vehicle safety system that allows the wheels on a motor vehicle to maintain tractive contact with the road surface according to driver inputs while braking, preventing the wheels from locking up and avoiding uncontrolled skidding. It is an automated system that uses the principles of threshold braking and cadence braking which were practiced by skilful drivers with previous generation braking systems. It does this at a much faster rate and with better control than many drivers could manage.
ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces; however, on loose gravel or snow-covered surfaces, ABS can significantly increase braking distance, although still improving vehicle steering control.
Since initial widespread use in production cars, anti-lock braking systems have been improved considerably. Recent versions not only prevent wheel lock under braking, but also electronically control the front-to-rear brake bias.
This function, depending on its specific capabilities and implementation, is known as electronic brake force distribution (EBD), traction control system, emergency brake assist, or electronic stability control (ESC).
These fancy terms I will explore with you in some follow up posts in the future.
The five most important characteristics that are considered when selecting brakes are as follows:
- The material’s ability to resist brake fade at increased temperatures
- The effects of water on brake fade
- The ability to recover quickly from either increased temperature or moisture
- Service life as traded off vs. wear to the discs (rotor) or drums.
- The ability of the material to provide smooth, even contact with the rotor or drum and not break off in bits or chunks.
Have the brakes of your car checked as regularly as every 6 months, by
an Auto Mechanic.
Signs that you need your brakes checked or repaired are:
- Grinding sound coming from the front or rear wheels while braking
- Shudder on the steering wheel at high speed braking
- A pulsating sensation on the brake pedal while braking
- Vehicle veering to one side while braking
- Hard brake pedal, reduced stopping power.
- Brake pedal fading while idling at a stop
- Rapid loss of brake fluid
- Hand brake or Parking brake (Emergency Brake) ineffective, not holding.
- Fluid leaking from your vehicle’s wheels
Some brake repair procedures are simple and straight forward enough but, in my opinion, it is very important procedures which are best left to the skilled auto mechanic.
My aim with this post is to help you better understand how the brakes of your automobile works, I hope that I have succeeded.
What are your thoughts, was this post useful to you?
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Until Next Time “Safe Motoring” – Gary