BRAKES

-The braking system converts "kinetic energy" into "heat energy".

Brake master 40mm
caliper 160mm                     3200N
wheel cylinder 20mm             400N
Brake master cylinder            800N

-Today in class we had to jack up a car from the front and the rear.I first checked around the car to find anything that could be a hazed. when it was clear i jacked up the car i placed a wooden block on the rear wheels so its more safe and secure,then i put the jack on the jacking point at the front of the vehicle. when the the car high enough for the stands to go under i lowered the jack slowly until it was safe to pull the jack out. I did the same for the rear. 

The master cylinder .

The master cylinder is a foot operated hydraulic pump that sends pressurized brake fluid through the brake lines and into the brake calipers/wheel cylinders.
In it's simplest form, the master cylinder consists of a housing, reservoir, piston, rubber cup, return spring and a rubber boot (manual only). A cylinder bore is machined into the center of the housing. The spring, cup and piston(s) slide in this bore and produce hydraulic pressure. The reservoir keeps the system full of fluid as the brake lining wears and the dust boot serves to keep contaminates from entering the rear of the master cylinder.




Bleeding 

- General principle kinetic to heat energy.
- Force on the brake pedal 
- Force the push rod in the brake booster which in turn
Forces the primary piston in the master cylinder forward 
, the fluid pressure presses on the secondary piston.
- The brake pipes carry the fluid pressure  to proportioning valve 
then to the brake calliper.
The piston forces the brake pad against the disc rotor.
The friction reduces the rotor speed.
The wheel being attached to the rotor is therefore slowed down 


How to bleed 

- Clean the reservoir 
- Top up with new fluid 
- Select Dot 
- Clamp the brake hose so pressure doesn’t go into the master cylinder
- Open bleeder nipple 
- Press the piston
- Close nipple 
- Place block under the pedal
- The guy in the car pumps about 6 times then he holds down
- Open nipple, then close again
- Pump 6 more times, hold down 
- Open nipple and close again 



How to adjust rear brake
- Undo the hand brake bolt.
- When you have replaced the brake shoes ,you tight up the drum by
        Turning the spreader to the right adjustment. To find out that it is tight enough
        You just turn the drum and see if it is not too tight or to loose.
- Then tight up the hand brake and pull the hand brake up to 5 clicks.

-Today in class we had to take off the brake shoes and put them back on, we had 2 hours to do it.

we had 4 people on a car, which was Shivy, Russel, Louis and I.Shivy and Louis took them off and Russel and i had to put them back.I personally found putting back the springs back on because they were being very difficult.

The Wheel cylinder 





-A wheel cylinder is a component in a drum brake system. It is located in each wheel and is usually at the top, above the shoes. Its responsibility is to exert force onto the shoes so they can contact the drum and stop the vehicle with friction. What connects these wheel cylinders to the shoes are usually small rods shaped like a birds beak. It is very similar to a master cylinder and functions in pretty much the same way, consisting of just a simple little plunger on the inside. On older vehicles these will begin to leak and hinder the performance of the brakes, but are normally inexpensive and easy to replace.


-The wheel cylinder consists of a cylinder that has two pistons, one on each side. Each piston has a rubber seal and a shaft that connects the piston with a brake shoe. When brake pressure is applied, the pistons are forced out pushing the shoes into contact with the drum. Wheel cylinders must be rebuilt or replaced if they show signs of leaking.



Note- never take the drums off when bleeding the front brakes because as you are pumping the brake.The brake shoes will push out will allow the seals to pop out and you may need to change the seal or sometimes even the hole wheel cylinder. Always keep the drums on and usual finish the back first then start doing the front.

The brake pads

Brake pads convert the kinetic energy of the car to thermal energy by friction. Two brake pads are contained in the brake caliper with their friction surfaces facing the rotor. When the brakes are hydraulically applied, the caliper clamps or squeezes the two pads together into the spinning rotor to slow/stop the vehicle. When a brake pad is heated by contact with a rotor, it transfers small amounts of friction material to the disc, turning it dull gray. The brake pad and disc (both now with friction material), then "stick" to each other, providing the friction that stops the vehicle.

What a good brake pad looks like: 100%






What a worn brake pad looks like: 20%





^ this is a uneven brake pad. This is uneven because the sliding pin was jammed and needs to be adjusted, with grease on it. or it could be the piston jammed up.