Suspension is an essential system of components, namely the system of shocks, tires, wheel chocks, linkages and retainers that connect a vehicle chassis to its wheels and enables vehicle flexibility and relative movement between the two. Suspension systems also have to support both ride quality and road holding/ Handling, which are in direct opposition with each other. These are the key ingredients to a high performance automotive system.
Generally, four-wheel drive vehicle suspensions employ independent rear suspensions with drive-by-wire actuation and PDS (Pre-spray Suspension) or spring loaded shock absorbers on all four tires. Independent suspensions enable high levels of suspension travel and actuation and dependable geometry, particularly with regards to shock absorption. Drive-by-wire systems send impulses to the control lines via a hydraulic motor which actuates the anti-lock braking system and the traction control system. Most drive-by-wire systems use hydraulic pressure or oil pressure to activate the control valves and anti-lock brakes.
In conventional truck and car suspensions, suspension is usually arranged as a coil over a drum that is hinged. Coil springs are typically made of iron, titanium, aluminum or steel. Coil springs are utilized for normal and emergency road vehicle applications, where greater tensile strengths are required due to the high loads they are subjected to on a regular basis. However, as suspension systems have evolved, so too have the materials used to manufacture them. New material discoveries have enabled suspension manufacturers to produce suspension systems with more elastic qualities, better resistance to wear and tear and enhanced stiffness and strength. One such revolutionary material is the Magnesium Alloys, which has been in use since the early 1960’s for truck and car suspensions.
Nowadays, it is imperative for manufacturers and consumers alike to pay close attention to vehicle suspension components. It is a proven fact that higher speeds lead to more vehicle accidents. This is attributed to the fact that the weight of the vehicle increases due to the increase in its wheelbase and its overall mass. In addition to the increased speed factor, vehicles with higher wheelbases tend to have larger tires and more powerful engine systems.
When shopping for a suspension system, you must first determine the spring rate, or the ratio of the instantaneous torque provided by the motor to that provided by the vehicle’s tires. The spring rate refers to the ratio of the instantaneous torque to the spring force developed during the wheel turning motion. The higher the spring rate, the better the torque transfer from the motor to the axle. The axle is able to absorb the torque that is applied through the tires, increasing the overall torque transfer as well. Therefore, the selection of the appropriate spring rate for a particular application is critical.
On the front end of vehicles, the drive train including the suspension system is designed to provide a smooth ride quality. Drive trains are composed of three parts – the suspension, the strut system, and the hydrostatic suspension. Most vehicles have one drive train system and two suspensions (one drive train and one suspension with a hydrostatic system). Front vehicle suspensions are typically independent of the vehicle’s main suspension and are often referred to as upper drive trains.
On the other end of the spectrum, trucks and SUV’s have radically different drivetrain requirements. Cars and SUV’s need to have a lower center of gravity to help reduce tipping, swivel, and transfer of weight to the tail. On the other hand, trucks and SUV’s need to have higher clearance rates to help improve safety and maneuverability. Most vehicle manufacturers now produce vehicles with a combination of both independent and tilt/tilt (also known as third-level) suspension systems.
Today, there are five common suspension types. The most traditional and reliable system is the conventional coil spring system that is found in high performance automobiles like sports cars and trucks. Coil springs are made up of a number of individual coils that are arranged in parallel to provide a smooth ride and adjustable damping. The advantages of using coil springs include their simple installation and reliable operation. On the downside, these coils tend to wear quickly, resulting in a need to replace them more frequently.