Seat belts                                        

A seat belt, sometimes called a safety belt, is a safety harness designed to secure the occupant of a vehicle against harmful movement that may result during a collision or a sudden stop. A seat belt reduces the likelihood and severity of injury in a traffic collision by stopping the vehicle occupant from hitting hard against interior elements of the vehicle or other passengers (the so-called second impact), by keeping occupants positioned correctly for maximum benefit from the airbag, if the vehicle is so equipped, and by preventing occupants being ejected from the vehicle.





 - If the seat belt is worn,ripped or it wont click in to the tounge then that mean the vehicle will fail warrant. All the bolts need to be tight and stable, make sure the belt goes back to place when you pull it towards the tounge, if it does not then that will fail warrant aswell.


HOW TO TAKE OFF A SEAT BELT

- When you are taking off a seat belt you first need to take off battery cable, as wires are connected to it which could cause damage. carefully take off the seat let cover and not to brake anything and undo the bolts. Clean all the dust. Take off the metal nail that is  in the belt and pull the belt out and replace it the same way you took it off.

WARRANT AND FITNESS 






W.O.F CHECK
- Steering, brake,hand brake secure
- Indicators and full beam working in dash board
- Check seat beat, should lock, check all belts in car
- No rust on structure
 - If it has a space saver/ spare wheel, make sure its secure.
- Inside and outside handles working
- Make sure gas cap is secure
- Check back and front lights
- Has to have reflectors working
- Make sure head lights are in center
- Make Sure the horn is working
- Wiper blades need to be in good condition
- Windows must have no cracks in front of drivers side about "30 cm"
- Shocks , tyres , steering boot and brake hose need to be in good condition.
- Speedo needs to be working
- Suspension, wheel bearing , steering rack need to be in good condition ( no excessive play )
- No exhaust leak , no rust and leak on manifold






-Every car has its own VIN ( Vehicle Identification Number)  number which is manly under the bonnet, if not then it would be by the door frame somewhere. You also need the make, modal , odometer and registration N.O as-well. Make sure all the numbers are correct so double check if you are not sure.

- When checking the vehicle , make sure you look carefully and not to miss out a problem on the car because its for the safety of the people and if an accident did happen after you have passed the vehicle, it might be your fault.

      <<<<<<<   VIN NUMBER


 - If there is a problem with the vehicle then you need to tell the person that owns the car to fix it before they get their warrant. They have 28 days to fix it so they can get a RE-CHECK, if they do not want to pay again for another inspection .

Suspension and steering systems!






A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication.When a spring is compressed or stretched, the force it exerts is proportional to its change in length. The rate or spring constant of a spring is the change in the force it exerts, divided by the change in deflection of the spring.

Suspension systems serve a dual purpose — contributing to the vehicle's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations,etc. These goals are generally at odds, so the tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the forces acting on the vehicle do so through the contact patches of the tires.




A shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. It is a type of dashpot.Shock absorbers are an important part of automobile and motorcycle suspensions, aircraft landing gear, and the supports for many industrial machines. Large shock absorbers have also been used in structural engineering to reduce the susceptibility of structures to earthquake damage and resonance.


What is a shock absorber?

A shock absorber is a suspension component that controls the up-and-down motion of the vehicle’s wheels.

Though the devices are called shock absorbers, the job of absorbing the jolts that result when the wheels pass over bumps or dips is handled mostly by the springs. Shock absorbers would more accurately be named dampers, as they are called in the United Kingdom. Their main job is to damp the motion mentioned above, keeping the vehicle’s body from bouncing down the road on its springs. In fact, the simplest shock absorber test is to push down on the vehicle’s bumper; a healthy shock absorber or MacPherson strut will allow the body to rebound but quickly come to rest. If the vehicle goes into a prolonged bounce cycle, the shock needs to be replaced. Bad shocks or struts aren’t safe because they fail to maximize tire contact with the road, which degrades handling and braking.


Power Steering Pump


Power steering helps drivers steer vehicles by augmenting steering effort of the steering wheel. Hydraulic or electric actuators add controlled energy to the steering mechanism, so the driver needs to provide only modest effort regardless of conditions. Power steering helps considerably when a vehicle is stopped or moving slowly. Also, power steering provides some feedback of forces acting on the front wheels to give an ongoing sense of how the wheels are interacting with the road; this is typically called "rοad feel".
Representative power steering systems for cars augment steering effort via an actuator, a hydraulic cylinder, which is part of a servo system. These systems have a direct mechanical connection between the steering wheel and the linkage that steers the wheels. This means that power-steering system failure (to augment effort) still permits the vehicle to be steered using manual effort alone.






Steering Rack 



Rack-and-pinion steering is quickly becoming the most common type of steering on cars, small trucks and SUVs. It is actually a pretty simple mechanism. A rack-and-pinion gearset is enclosed in a metal tube, with each end of the rack protruding from the tube. A rod, called a tie rod, connects to each end of the rack.
The pinion gear is attached to the steering shaft. When you turn the steering wheel, the gear spins, moving the rack. The tie rod at each end of the rack connects to the steering arm on the spindle.




Part of the rack contains a cylinder with a piston in the middle. The piston is connected to the rack. There are two fluid ports, one on either side of the piston. Supplying higher-pressure fluid to one side of the piston forces the piston to move, which in turn moves the rack, providing the power assist.


What Is A Tie Rod?

The tie rod is part of the steering mechanism in a vehicle. A tie rod is a slender structural rod that is used as a tie and capable of carrying tensile loads only.

A tie rod consists of an inner and an outer end. The spokes on a bicycle’s wheels are tie rods. As the ratio of its length to the radius of gyration of its cross section is normally quite large, it would likely buckle under the action of compressive forces.

The tie rod transmits force from the steering center link or the rack gear to the steering knuckle. This will cause the wheel to turn. The outer tie rod end connects with an adjusting sleeve, which allows the length of the tie rod to be adjustable. This adjustment is used to set a vehicle’s alignment angle.

GEAR BOX!


How Manual Transmissions Work



A manual transmission, also known as a manual gearbox or standard transmission (informally, a manual, 5 speed, or the number of forward gears said with the word speed following i.e.: 4 speed with overdrive, 4 speed, 5 speed, 6 speed or standard, stick-shift, straight shift, straight, or straight drive (U.S.)) is a type of transmission used in motor vehicle applications. It generally uses a driver-operated clutch, typically operated by a foot pedal (automobile) or hand lever (motorcycle), for regulating torque transfer from the internal combustion engine to the transmission; and a gear stick, either operated by foot (as in a motorcycle) or by hand (as on an automobile).

CLUTCH


A clutch is a mechanical device that provides for the transmission of power (and therefore usually motion) from one component (the driving member) to another (the driven member) when engaged, but can be disengaged.
Clutches are used whenever the transmission of power or motion needs to be controlled either in amount or over time (e.g., electric screwdrivers limit how much torque is transmitted through use of a clutch; clutches control whether automobiles transmit engine power to the wheels).
In the simplest application, clutches are employed in devices which have two rotating shafts (drive shaft or line shaft). In these devices, one shaft is typically attached to a motor or other power unit (the driving member) while the other shaft (the driven member) provides output power for work to be done.


GEAR



A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, torque, and direction of a power source. The most common situation is for a gear to mesh with another gear, however a gear can also mesh a non-rotating toothed part, called a rack, thereby producing translation instead of rotation.
The gears in a transmission are analogous to the wheels in a pulley. An advantage of gears is that the teeth of a gear prevent slipping.

When two gears of unequal number of teeth are combined a mechanical advantage is produced, with both the rotational speeds and the torques of the two gears differing in a simple relationship.
In transmissions which offer multiple gear ratios, such as bicycles and cars, the term gear, as in first gear, refers to a gear ratio rather than an actual physical gear. The term is used to describe similar devices even when gear ratio is continuous rather than discrete, or when the device does not actually contain any gears, as in a continuously variable transmission.

If you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmission and a manu­al transmission:

There is no clutch pedal in an automatic transmission car.
There is no gear shift in an automatic transmission car. Once you put the transmission into drive, everything else is automatic.


It all starts in a place between the engine and the transmission with a component called torque converter, a large fluid turbine clutch, hidden inside the bell housing-the front part of the transmission bolted to the engine. The converter is actually a pump and turbine mechanism assembled together with a series of huge vain passages designed to create a strong centrifugal force using the oil going through them.

Once you start the engine, the torque converter begins to rotate at engine speed and waits for you to shift gears. When you go from Park to Drive, the converter turbine uses a shaft to engage a series of gear sets located inside their own drum cases. These gear sets are called planetary gearsets because their varied size gears mesh together in a planetary system-like configuration to rotate and provide different torque speeds.

The key characteristic of a torque converter is its ability to multiply torque when there is a substantial difference between input and output rotational speed, thus providing the equivalent of a reduction gear. Some of these devices are also equipped with a temporary locking mechanism which rigidly binds the engine to the transmission when their speeds are nearly equal, to avoid slippage and a resulting loss of efficiency.



BASIC PRINCIPLE 

- A vehicle has a transmission to have the ability to apply different RPMs to different driving speed rangers, This is done by having a number of different gears which each feature different gear ratios.Different gear ratios are needed for when the vehicle needs more power or speed as the road conditions change.

  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.

SERVICING UNIVERSAL CROSS JOINTS




Cardan universal joints allow power to be transferred at larger angles than traditional flexible couplings. They can transmit power at up to a 15° offset angle depending on the application. Cardan shafts are available in a wide variety of torque capacities from 4.4 ft-lb (5.9 Nm) to 11,071,745 ft-lb. (15,009 Nm). There are many different styles of cardan shafts. The cross and bearing, ear and pin and Cornay joints are a few. Cross and bearing joints are the most common and use needle bearings to allow movement of the flange. Ear and pin joints, also known as pin and block joints, are simpler in design and are used for smaller applications. Cornay joints allow torque to be transmitted at high angles, even up to 90°.


The cross joint is mostly used in a rear wheel drive because it has more power and larger as it can handle more horse power.

CV JOINT


Servicing Constant Velocity Joints


-Today the class and i removed a CV joint from the drive shaft.To remove the CV we use a tool called the sliding hammer, this tool is very useful to remove the CV joint. When the CV joint came off it had rust, cracks, scratches and hammer marks. The balls inside were very dirty as the grease was very black and needed to be cleaned, so we did. As we were using the hammer to removed the CV joint off, the drive shaft, we had overall,steal cap and glasses on for safety reasons.




The sliding hammer




CV Joint



Close up on CV Joint 



Things inside a CV Joint




CV Joint Cage 



Inside a CV Joint





-A CV joint, or constant velocity joint, is part of a drive shaft, the shaft that attaches to a car's transmission at one end and the wheel at the other. CV joints are designed to be able to bend in any direction while continuing to turn the drive wheels at a constant velocity. CV joints are primarily used in the drive shafts of front wheel drive cars.

-Due to bumps and uneven surfaces in the road, a car's wheels tend to move up and down continuously while driving down the road; as a result, drive shafts cannot be made up of a solid shaft. The CV joint's precursor, the universal joint, was used in the drive shafts of rear wheel drive cars because of its ability to bend in any direction. With the advent of front wheel drive cars, however, car manufacturers had a new problem: the joints in the drive shafts needed to account not only for the up-and-down motions of the wheels, but also for the back-and-forth motions of steering. The CV joint is used in front wheel drive cars because of its ability to maintain a constant drive force to the wheels despite the many different kinds of movements in the front end of the car. The CV joint is often used in rear wheel drive and four-wheel drive cars, as well.



-CV joints should be inspected periodically and may require replacement as a car ages. A CV joint is covered with a bulbous rubber boot that tends to deteriorate over time. When a CV boot cracks or tears open, the CV joint is left exposed to the elements, which will quickly damage the joint. If the CV axles are inspected periodically, torn boots can be replaced as needed, potentially extending the life of the joints; however, if torn boots are left unattended, the joint or the entire axle may soon need to be replaced.



CV Boot

The rubber part of the driveshaft assembly / CV Axle is known as the CV boot, which is secured with stainless steel clamps. We call it cv boot clamp. The purpose of CV boot is to protect the internal components of the CV joint by retaining the lubricant, and also acting as a dust shied.