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Unit No.03 Suspension & system

Prepared by,

Prof. Santosh Kailas Chandole

ME (Design Engineering)

BE (Automobile Engineering)

Function Suspension System

•Supports the weight.

•Provides a smooth ride.

•Allows rapid cornering without extreme body roll.

•Keeps in firm contact with the road.

•Prevents excessive body squat.

•Prevents excessive body dive.

•Allows front to turn side-to-side for .

•Works with the steering system to keep the wheels in correct alignment.

Comparison of Rigid And System Types of Suspension System

1.Non-independent/Rigid suspension has both right and left attached to th same solid . When one wheel hits a bump in the road, its upward movement causes a slight tilt of the other wheel.

2.Independent suspension allows one wheel to move up and down with minimal effect to the other. Suspensions

Independent

Nonindependent Suspension System

Coil spring is the most common type of spring found on modern .

Leaf springs are now limited to the rear of some . Types of Springs

A. B. C. Air spring D. System Basic Parts

Control arm – movable lever that fastens the steering knuckle to the ’s body or frame.

Steering Knuckle – provides a spindle or bearing support for the wheel hub, bearings and wheel assembly.

1 Wishbone Suspension

The suspension must be designed in such a way as to keep the wheel upright for Upper wishbone maximum tyre contact (vehicle control) and to minimize tyre wear. The upper wishbone is short and the lower wishbone is longer. Both wishbones pivot points and lengths are calculated to provide the best operating angle for a given suspension movement. Lower wishbone 10 of 12 Advantages & Disadvantages of Wishbone type independent suspension

Advantages Disadvantages

•Ride quality is good. •Initial cost is more •Maintenance cost is •Improve the steering more. preciseness since the •Required frequent wheel movement are not link otherwise increase •Ground clearance tyre wear. increase

Applications:-SUV,CARS 2 MacPherson Strut

This is a very popular and efficient form of suspension. It has one control arm and a strut assembly. A coil spring and Strut will normally form parts of the strut assembly. assembly

Coil springs may be mounted on Frame the control arm instead of being around the strut. On this type, the shock absorber connects the Shock knuckle to the frame. absorber

This type of suspension strut is Knuckle often also used on rear suspension systems. Control arm Coil spring 12 of 12 Front Suspension (MacPherson Strut) MacPherson Strut Suspension

The top of the strut is bolted to a reinforced section of the Steering knuckle frame structure.

The lower end of the strut is attached to a steering knuckle. Strut

The control arm is also attached to the steering knuckle. Frame

The control arms are mounted on Control a cradle section of the frame. arm

An anti-roll bar links the two Cradle control arms together to reduce sway (body roll). Anti-roll bar 14 of 12 Advantages & Disadvantages of Macpherson strut suspension Advantages •Light in weight. Disadvantages •Camber does not •Not suitable for Heavy change due to up & motor vehicle. movement of wheels •Load caring capacity is •Maximum Engine less. compartment available. •Maintenance cost is less. •Initial cost is less. •Ride comfort is more. •Improve road safety. Applications:-CARS Solid Rear Axle Suspension

This type of rear suspension Shock absorber is typical for a rear-wheel drive vehicle. Coil The axle is inside a springs solid housing.

The shock absorbers are Axle housing Stabilizer bar mounted between the solid axle and the frame.

The springs are arranged between the axle housing and the frame of the vehicle. Trailing arm

Trailing arms, or links, hold the rear axle in position.

A stabilizer bar and track bar are included to add vehicle stability. 16 of 12 Independent Suspension System Parts Basic Parts

Ball Joints – swivel joints that allow control arm and steering knuckle to move up and down and side to side.

Springs – supports the weight of the vehicle; permits the control arm and Wheel to move up and down. Shock absorbers or dampeners – keeps the suspension from continuing to bounce after spring compression and extension.

Control arm bushing – sleeves that allows the control arm to swing up and down on the frame. Coil Springs Leaf Spring Assembly Air Springs Layout of System Schematic view of Air Suspension System

Location of Air bellows Advantages & Disadvantages of Air suspension Advantages Disadvantages • Variable space for wheel * Higher initial cost deflection is put for optimum * Occupies more space use for automatic height * Maintenance cost is more control. Head light alignment does not * Due lack of damping is vary due to different loading necessary due road shock condition. •It improve the ride comfort. •Reduce noise in suspension system.

Applications:- Volvo Buses

Torsion Bar

The bar resists twisting action and acts like a conventional spring Torsion bar (large spring rod)

•One end is attached to the frame and the other to the lower control arm. •Up and down of the suspension system twists the torsion bar. •It will then try to return to its original shape, moving the control arm to its original place. Advantages & Disadvantages of Torsion bar suspension Advantages Disadvantages •It does not take •Light in weight. accelerate & Braking •Less space occupies . thrust so required additional linkages •Its maintenance cost is less. •Due lack of friction damping is necessary •Initial cost is less. due road shock •Ride comfort is more.

Applications:-SUV Tata Safari, Tempo Trax Suspension System Shock absorbers

•Limits spring compression-extension movements to smooth the vehicle’s ride.

•Without shock absorbers, the vehicle would continue to bounce up and down long after striking dip or hump in the road. Shock Absorber Action Introduction of Brake

A is a brake in which the friction is caused by a set of shoes or pads that press against a rotating drum-shaped part called a brake drum.

The term "drum brake" usually means a brake in which shoes press on the inner surface of the drum. When shoes press on the outside of the drum, it is usually called a clasp brake. Main functions of braking system

To stop the vehicle safely in shortest possible distance in case of emergency. To control the vehicle when it is descending along the hills To keep the vehicle in desired position after bringing in at rest

CONSTRUCTION

The Break Drum consist of following components..

 Back Plate

 Brake drum  Wheel cylinder   Return spring  Piston WORKING

The drum brake stops the from rotating by using the hydraulic pressure transmitted from the to the wheel cylinder to press the brake shoe against that brake drum, which is rotating together with the tire. When the hydraulic pressure to the wheel cylinder disappears, the force of the return spring pushes the shoe away from the inner surface of the drum and returns it to is original position. ADV ANTAGES  Drum are smaller for the same brake force.  Drum brakes don't need a hydraulic system for activation.  Due to simple in construction it can be easiliy repair.  Due to the fact that a drum brake's friction contact area is at the circumference of the brake, a drum brake can provide more braking force than an equal diameter . DISADVANTAGES

 The use of many clips and springs makes overhaul of the brake drum assembly very time-consuming.3  Another problem with drum brakes is that if a vehicle is driven through water, it takes longer to get the brakes working effectively.

 When the drums are heated by hard braking, the diameter of the drum increases slightly due to thermal expansion, this means the brakes shoes have to move farther and the brake pedal has to be depressed further.

Applications: trucks, cars and in other automobiles. Disc Type Brake

CONSTRUCTION DISC Brake consist of cat iron disc bolted to the wheel hub and an stationary housing called “caliper”. The caliper is connected with some stationary part of position of vehicle, like stub or axle on of wheel of connecting rod . The piston rod is connected in between which has friction pad is being held by an piston pins, springs etc.

Working of Disc brake

The brakes are operated when friction is being created on friction pads by forced applying on it against the disc .the forces created on its is hydraulic pressure from master cylinder, thereby an engaging the braking system. When the hydraulic braking pressure is applied on piston will engaged an released bar due to pressure. When pressure is released piston will regain its original position. Here friction pad works on main fundamental working process. “CALIPER “ is added on system to balanced two calipers by diagrammatically opposite to each to other. In this way braking torque is reduced. Advantages of Disc Brake Better heat dissipation as braking torque on surface of exposed air. Adjustment of pads is automatic Renewal of pad is quick and easy.

Disadvantages of Disc Brake.

In comparison of brake drum of similar capacity, rate pad wear is more. The HAND BRAKE MECHANISM IS NOT SO CONVINENT.

ANTILOCKING BRAKING SYSTEM {abs} SOURCE: Internet

Anti-lock braking system (ABS) is an automobile 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 (ceasing rotation) and avoiding uncontrolled skidding. It is an automated system that uses the principles of threshold braking and cadence braking which were practiced by skillful drivers with previous generation braking systems. It does this at a much faster rate and with better control than a driver could manage

ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, ABS can significantly increase braking distance, although still improving vehicle control. Working of Anti Braking System

The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).

Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second. Because of this, the wheels of cars equipped with ABS are practically impossible to lock even during panic braking in extreme conditions

Modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated micro- controller. ABS is offered or comes standard on most road vehicles produced today and is the foundation for electronic stability control systems, which are rapidly increasing in popularity due to the vast reduction in price of vehicle electronics over the years

Construction of Anti Braking System

There are four main components of ABS: speed sensors, valves, a pump, and a controller. Speed sensors The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information. Valves There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions: In position one, the valve is open; pressure from the master cylinder is passed right through to the brake. In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder. In position three, the valve releases some of the pressure from the brake. Pump When the ABS system operates the brake lines lose pressure. The pump re-pressurizes the system. Controller The controller is an ECU type unit in the which receives information from each individual wheel speed sensor, in turn if a wheel loses traction the signal is sent to the controller, the controller will then limit the brakeforce (EBD) and activate the ABS modulator which actuates the braking valves on and off.