Explain Suspension System

Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two.
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 a ride quality reasonably well isolated from road noise, bumps, and vibrations

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The components of the suspension consist of:

• Tires
• Wheels
• Shock absorbers
• Mcpherson struts
• Springs
• Sway bars
• Torsion bars
• A arms
• Lower control arms
• Axles
• Alignment
• Tire pressure

The various components of the suspension systems of every vehicle are designed to counteraffect the forces of gravity and inertia! Even though every car is different, every system accomplishes the same objective:-

•  Keeping tires on the road surface. Engineers call this "road holding". It's important for the tires to stay in contact at all times, because friction between the tires and the ground is what lets the car accelerate, stop and corner. The suspension keeps the weight centered to maintain the grip.
• Stable steering and handling. The suspension keeps the car or truck body from tipping or rolling in a corner.
• Passenger comfort. Keeps the cabin isolated from the bumps on the road. Suspensions absorb that up-and-down energy and disperse it without too many bobbles.

     How does the Suspension System work?

The suspension system connects your vehicle to its wheels. It is designed to counteract the forces of gravity, propulsion and inertia that are applied to your vehicle as you accelerate, slow down or stop in such a way that all four wheels remain on the ground!

The tires - which are mounted on your vehicle’s wheels (or rims) - are the most important and visible components of the system. They transfer the power of the engine to the ground when your vehicle moves and they counter that motion when it stops.

As you drive over a bumpy road, shocks are absorbed by the combined work of a shock absorber (or damper) and a coil or leaf spring mounted on each wheel. The spring is a device that stores energy in order to supply it later on. It is actually the spring that handles the abuse of the road by allowing the wheel to move up and down with respect to the frame of the vehicle. In return, the shock absorber softens the suspension moves entailed by the spring by “absorbing the shocks”. The shock absorber is a steel or aluminum hydraulic cylinder filled with oil and pressurized with nitrogen. As the suspension moves, a piston is forced to move through the oil-filled cylinder. The energy produced from the motion of the piston is dissipated as heat which in turn is absorbed by the oil.

   

  Types of suspension system for independent system

• MacPherson strut type
• Double wishbone type
• Semi trailing arm type
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MacPherson strut type :

This system is usually use for most widely in independent suspension system for small and medium sized cars.These type are so popular so in FF(Front engine and front wheel transmission)type of car,used as the rear suspension.
Characteristic for MacPherson: The construction of the suspension is relatively simple. MacPherson type,have small number of parts,so when it component is less,then less weight.The effects is unsprung can be reduce.

The space for the suspension is small,the usable space in the engine compartment can be increased. Since the distance between suspension support point is great,there is a little disturbance of the front wheel allingment due to installation error or part manufacturing error.Therefore, except for toe-in,allingment adjustment ordinarily unnecessary.

Double wishbone type:

This is usually used for front suspension for small trucks and for front and rear suspension for passenger cars. Characteristic for double wishbone: Wheels are mounted to the body via upper and lower arm. Suspension geometry can be designed as desired according to the length of the upper and lower arm and their mounting angles.

For example if upper and lower arm are parallel and have equal length,the tread and the tire-toe ground camber of the tire will change.As a result,it is not possible to obtain adequate conering performance.In addition, in the tread will cause excessive tire wear.

To solve this a design is normally employed in which the upper arm is made shorter than the lower arm so that the tread and the tire-to-ground camber of the tire fluctuate less.

Semi trailing arm type

 

Is used for the rear suspension in a few models.With this suspension,the amount by which the toe angle and camber change(due to the up-and-down motion of the wheels) can be controlled at the design stage, in order to determined the handling characteristics of the vehicle.

Signs of troubles related to the Suspension System:

• Excessive tire wear

• Poor steering control or off-center steering wheel

• Excessive bouncing over road bumps

• Loss of control during sudden stops

• Excessive swerving while changing lanes

• Front-end nose diving during quick stops

• Vehicle sag in front or rear
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• the source : mechanics tips

Book to explain the brake system

Hello to the website of auto Spedes Today I present
  to you this book my father explains the brake system and in order not to dwell upon  Download Link
 

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Manual gearboxes - what, why and how

    Manual gearboxes - what, why and how

From the Fuel & Engine Bible you know that the pistons drive the main crank in your engine so that it spins. Idling, it spins around 900rpm. At speed it can be anything up to 7,500rpm. You can't simply connect a set of wheels to the end of the crank because the speed is too high and too variable, and you'd need to stall the engine every time you wanted to stand still. Instead you need to reduce the revolutions of the crank down to a usable value. This is known as gearing down - the mechanical process of using interlocking gears to reduce the number of revolutions of something that is spinning.

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A quick primer on how gears work
Spur gearsHelical gears

In this case I'm talking about gears meaning 'toothed wheel' as oppose to gears as in 'my car has 5 gears'. A gear (or cog, or sprocket) in its most basic form is a flat circular object that has teeth cut into the edge of it. The most basic type of gear is called a spur gear, and it has straight-cut teeth, where the angle of the teeth is parallel to the axis of the gear. Wider gears and those that are cut for smoother meshing are often cut with the teeth at an angle, and these are called helical gears. Because of the angle of cut, helical gear teeth have a much more gradual engagement with each other, and as such they operate a lot more smoothly and quietly than spur gears. Gearboxes for cars and motorbikes almost always use helical gears because of this. A side effect of helical gears is that if the teeth are cut at the correct angle - 45 degrees - a pair of gears can be meshed together perpendicular to each other. This is a useful method of changing the direction of movement or thrust in a mechanical system. Another method would be to use bevel gears.
gearup

   
The number of teeth cut into the edge of a gear determines its scalar relative to other gears in a mechanical system. For example, if you mesh together a 20-tooth gear and a 10-tooth gear, then drive the 20-tooth gear for one rotation, it will cause the 10-tooth gear to turn twice. Gear ratios are calculated by divinding the number of teeth on the output gear by the number of teeth on the input gear. So the gear ratio here is output/input, 10/20 = 1/2 = 1:2. Gear ratios are often simplified to represent the number of times the output gear has to turn once. In this example, 1:2 is 0.5:1 - "point five to one". Meaning the input gear has to spin half a revolution to drive the output gear once. This is known as gearing up.

How Brakes Work

       

                                                    

We all know that pushing down on the brake pedal slows a car to a stop. But how does this happen? How does your car transmit the force from your leg to its wheels? How does it multiply the force so that it is enough to stop something as big as a car?

When you depress your brake pedal, your car transmits the force from your foot to its brakes through a fluid. Since the actual brakes require a much greater force than you could apply with your leg, your car must also multiply the force of your foot. It does this in two ways:

• Mechanical advantage (leverage)
• Hydraulic force multiplication

­The brakes transmit the force to the tires using friction, and the tires transmit that force to the road using friction also. Before we begin our discussion on the components of the brake system, we'll cover these three :

How Car Suspensions Work new

  Suspension Types: Front

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So far, ou­r discussions have focused on how springs and dampers function on any given wheel. But the four

  wheels of a car work together in two independent systems -- the two wheels connected by the front axle and the two wheels connected by the rear axle. That means that a car can and usually does have a different type of suspension on the front and back. Much is determined by whether a rigid axle binds the wheels or if the wheels are permitted to move independently. The former arrangement is known as a dependent system, while the latter arrangement is known as an independent system. In the following sections, we'll look at some of the common types of front and back suspensions typically used on mainstream cars.

Dependent Front Suspensions
Dependent front suspensions have a rigid front axle that connects the front wheels. Basically, this looks like a solid bar under the front of the car, kept in place by leaf springs and shock absorbers. Common on trucks, dependent front suspensions haven't been used in mainstream cars for years.

Independent Front Suspensions
In this setup, the front wheels are allowed to move independently. The MacPherson strut, developed by Earle S. MacPherson of General Motors in 1947, is the most widely used front suspension system, especially in cars of European origin.

The MacPherson strut combines a shock absorber and a coil spring into a single unit. This provides a more compact and lighter suspension system that can be used for front-wheel drive vehicles.

The double-wishbone suspension, also known as an A-arm suspension, is another common type of front independent suspension.

While there are several different possible configurations, this design typically uses two wishbone-shaped arms to locate the wheel. Each wishbone, which has two mounting positions to the frame and one at the wheel, bears a shock absorber and a coil spring to absorb vibrations. Double-wishbone suspensions allow for more control over the camber angle of the wheel, which describes the degree to which the wheels tilt in and out. They also help minimize roll or sway and provide for a more consistent steering feel. Because of these characteristics, the double-wishbone suspension is common on the front wheels of larger cars.

Now let's look at some common rear suspensions

in the engine lubrication system

 Summary
The lubrication system is designed to keep the components in the engine lubricated and to reduce friction

All moving parts in an engine require lubrication, that is, the application of oil to moving parts to reduce

 friction between them.

A lubrication system distributes oil through the engine. A typical lubrication system consists of an oil sump, an oil pump, and oil galleries. The oil is stored in the sump, bolted to the bottom of the engine block. Oil is drawn from the sump by an oil pump. Oil galleries are small passages in the cylinder block that direct oil to the moving parts.

Oil that has been pumped to the crankshaft main bearings travels through oil-ways to the connecting rods.

Oil may also be splashed from the connecting rods onto the cylinder walls.

A filter is usually provided to remove particles of dirt from the oil, and the circulation of the oil assists with the cooling of the internals parts.

New cooling system and wonderful for your car

An intelligent cooling system for your car

Engineers at Dana Corp., Toledo, decided to add some intelligence to the cooling system and boost engine performance, fuel economy, durability, and passenger comfort, while cutting back on emissions and the overall size of the cooling system.

Traditionally, cooling systems relied on a water pump with flow dependent on engine speed, a wax thermostat, and a radiator big enough to meet rarely used peak demands. Dana’s system, dubbed Intelligent Cooling, relies on an electronic water pump, a multiport proportional flow valve to replace the thermostat, a variable-speed fan, and cylinder head gaskets containing temperature sensors. During engine warm-up, for example, the flow valve and pump act independently of the engine. They permit extremely low or even zero flow rates, which accelerates engine warm-up and minimizes heat losses. The pump and valve, as well as cooling fan and heat sinks, can also be mounted away from the engine, giving auto designers more flexibility in laying out the engine compartment. The gasket monitors temperature and has proven to have faster response to real-time thermal data than conventional cooling systems. The pump, valve, and fan can be controlled by the same unit or an Electronic Control Unit.

Common Rail Fuel System

Common Rail Fuel System

With a common rail fuel system, an extremely high fuel pressure is created in the supply pump and this is fed directly to the common rail which is located on the engine and is connected to the injectors.

 Compared to previous diesel engines, the Common-rail system supplies highly pressurized fuel injection even at low engine speeds. As the highly pressurized fuel exits the injector’s very small holes (which are about the same diameter as a human hair), the fuel is sent to the combustion chamber as an extremely fine spray (particle of fuel is small).

Fuel Injection

Fuel injection is controlled electronically by an ECU (Electrical control unit).

The ECU detects the driving conditions through the signals from various sensors and calculates the correct injection volume and timing. Then, the ECU sends a signal to the injector to operate for precise and accurate control in the same way electronic fuel injection functions on petrol engines.