5 TyresTyres are the first point of contact for the suspension system. The rubber tyre flexes when it comes into contact with a bump in the road and the air inside the tyre will compress to absorb some of the shock and travel
6 Laminated or Leaf Springs The main leaf is rolled at each end to for eyes and has a number of leaves clamped to it.Leaves are graduated in length to ensure a constant stressRebound clips transfer the load to some of the lower leaves to reduce the need to add too many springsRubber mountings absorb shock and noiseA swinging shackle is fitted to accommodate the alterations in spring length.
8 Stiffness rate The lower the rate the softer the ride The force required to deflect the spring effects ride comfort and payload.Length – the shorter the spring the higher the rateWidth – the wider the higher the rateThickness – the thicker the higher the rateNumber – more leaves the higher the rateForce required, length, width, thickness , number
9 FrictionAs the leaves flex they rub against each other causing friction. Although this does have a desirable damping effect it does create a hard ride, noise and wear. In older vehicles the leaves would be periodically sprayed with penetrating oil. These days special features have been added to prevent the need for servicing.Various methods of reducing the friction
10 Friction reduction Synthetic rubber buttons Reducing the number of leaves or using a single tapered leafInter-leaf plates of low friction material
11 Transverse Leaf Spring Triumph Herald used a transverse leaf spring which had the effect of drawing the wheels in wards when the weight was taken off them.
13 Coil SpringUsually used with independent suspension and some rear axle assemblies.Although the coil is better at storing energy it does require more components to be fitted which can add to the weight.Rate is governed by thickness and length of the spring.The length is determined by the diameter and number of active coils.
15 Dampers Convert Kinetic energy to heat energy When a spring is compressed it stores energyWhen the energy is released the spring will extend beyond it’s normal lengthThis also stores energy which is released and compresses the springThis characteristic is known as oscillationA damper is fitted to reduce the oscillations and improve ride comfort and road holding.
17 Shock absorbers work in two cycles -- the compression cycle and the extension cycle. The compression cycle occurs as the piston moves downward, compressing the hydraulic fluid in the chamber below the piston. The extension cycle occurs as the piston moves toward the top of the pressure tube, compressing the fluid in the chamber above the piston. A typical car or light truck will have more resistance during its extension cycle than its compression cycle. With that in mind, the compression cycle controls the motion of the vehicle's un-sprung weight, while extension controls the heavier, sprung weight.
18 Torsion bars Behaves like a coil spring One end attached to the frame and the other to the control armThe control arm rises and falls with the road wheel and the torsion bar twists and untwists to absorb the movement.A damper is used to control the oscillations
20 Air SpringsA throwback again to the horse and carriage where leather bellows type airbags where used.Changed to rubber air springs in the 1930’sNot so much used at all today
21 Hydrolastic Suspension The front and rear suspension units have Hydrolastic displacersThese are interconnected by a small bore pipe.Each displacer incorporates a rubber springdamping of the system is achieved by rubber valveswhen a front wheel is deflected, fluid is displaced to the corresponding suspension unit.That pressurises the interconnecting pipe which in turn stiffens the rear wheel damping and lowers itThe rubber springs are only slightly brought into play and the car is effectively kept level and freed from any tendency to pitch
22 Hydragas SuspensionWith Hydragas, the rubber spring is removed completely. The fluid still exists but above the fluid there is now a separating membrane or diaphragm, and above that is a cylinder or sphere which is charged with nitrogen gas. The nitrogen section is what has become the spring and damping unit whilst the fluid is still free to run from the front to the rear units and back.
23 Beam Axle A dead Axle (non-driving) Designed to reduce the sprung-weight of the rear axle in front wheel drive carsA panhard rod is used to prevent lateral (side to side) movement of the assembly
24 Control BladeFord’s new suspension lowers centre of gravity and separates suspension components from handling components.
25 ConclusionA suspension system separates the payload of a vehicle from the variations in road surfaceIt maintains maximum contact between the tyres and the road surfaceAbsorbs and controls pitch and roll from accelerating, cornering and braking forces.
26 Useful Websites http://www.mgfcar.de/hydragas Homework research the following page hydropneumatic suspension.