Sketch some examples of springs here
Sketch some examples of springs here
Dampers or Shock Absorbers The energy stored in the spring after a bump, has to be got rid of or else the spring would oscillate (bounce up and down). The damper damps down these oscillations by converting the energy Telescopic damper
from the spring into heat. If working correctly the spring should stop moving after just one bounce and rebound. Shock absorber is a term, which is often used, to describe a damper.
Strut The combination of a coil spring with a damper inside it, between the wheel stub axle and the inner wing, is often referred to as a strut. This is a very popular type of suspension.
Wishbone A wishbone is a triangular shaped component with two corners hinged in a
Front suspension wishbone
straight line on the McPherson strut vehicle body. The third corner is hinged to the moving part of the suspension.
Bump Stop When a vehicle hits a particularly large bump, or if it is carrying a heavy load, the suspension system may bottom out (reach the end of its travel). The bump stop, usually Rubber stop made of rubber, prevents metal-to-metal contact, which would cause damage.
Link A link is a very general term, which is used to describe a bar or other similar component that holds or controls the position of another component. Other terms may be used such as tie-bar or tie-rod.
Beam Axle This is a solid axle from one wheel to the other. It is not now used on the majority of light vehicles. However, as it makes a very strong construction, it is still common on heavy vehicles. Heavy vehicle axle
Gas/Fluid Suspension The most common types of spring are made from steel. However, some vehicles use pressurised gas as the spring, (think of a balloon or a football). On some vehicles, a connection between
Gas suspension unit
wheels is made using fluid running through pipes from one suspension unit to another.
Independent Suspension Independent front and rear suspension (IFS/IRS) was developed to meet the demand for improved ride quality and handling. The main advantages of independent suspension are as follows:
• When one wheel is lifted or drops, it does not affect the opposite wheel
• The unsprung mass is lower; therefore, the road wheel
stays in better contact with the road • Problems with changing steering geometry are reduced • More space for the engine at the front • Softer springing with larger wheel movement is possible.
Anti-Roll Bar The main purpose of an anti-roll bar is to reduce body roll on corners. The anti- roll bar can be thought of as a torsion bar. The centre is
Shape of an anti-roll bar
pivoted on the body and each end bends to make connection with the suspension/wheel assembly. When the suspension is compressed on both sides, the anti-roll bar has no effect because it pivots on its mountings. As the suspension is compressed on just one side, a twisting force is exerted on the anti-roll bar. Part of this load is transmitted to the opposite wheel, pulling it upwards. This reduces the amount of body roll on corners.
Panhard Rod The Panhard rod was named after a French engineer. Its purpose is to link a rear axle to the body. The rod is Rear axle with Panhard rod pivoted at each end to allow movement. It takes up lateral forces between the axle and body thus removing load from the radius arms. The radius arms have now to only transmit longitudinal forces.
Summary A wide variety of suspension systems and components are used. Engineers strive to achieve optimum comfort and handling. However, these two main requirements are often at odds Suspension continues to with each other. As is common with all
develop
vehicle systems, electronic control is one-way developments are now being made.
State the main advantages of independent suspension.
Look back over the previous section and write out a list of the key bullet points here:
SPRINGS
Introduction The requirements of the springs can be summarised as follows:
Absorb road shocks from uneven surfaces Control ground clearance and ride height Ensure good tyre adhesion Support the weight of the vehicle Transmit gravity forces to the wheels. There are a number of different types of spring in use on
modern vehicles. Coil Springs Although modern vehicles use a
number of different types of spring medium, the most popular is the coil (or helical) spring. Coil or
Coil spring in
helical springs used in vehicle suspension systems, position are made from round spring steel bars. The heated
bar is wound on a special former and then heat- treated, to obtain the correct elasticity (springiness). The spring can withstand any compression load but not side thrust. It is also difficult for a coil spring to resist braking or driving thrust. Suspension arms are used to resist these loads.