Suspension is the interface between occupants in the cabin and the road. The ride comfort and handling of a vehicle is directly dependent on the suspension. The longevity and safety of occupants and vehicle are dependent on the suspension and its integration with the vehicle. The relevance may appear to be indirect but, in fact, it is pretty direct.
High vehicle speeds in lighter vehicles and busier traffic patterns have made ride and handling, and safety an imperative. With growing consumer demand for better ride quality, handling and safety, suspension systems have become more critical in the mobility space. For the occupants and in a vehicle, suspension systems balance damping, spring co-efficient, weight, cost, carbon footprint and of course, vehicle handling attributes.
Not to be surprised. The evolution of suspensions from basic springs, shock absorbers to active and semi-active sub-systems, and the affiliated steering system of the chassis have had a positive radical effect on styling of vehicles, which in turn has affected manufacturing and its related costs. Many of the vehicles that were 'body on frame' have transformed into uni-body constructions lately. The onslaught of uni-body constructions and haute styling has helped reduce components, increase efficiency in manufacturing, shorten developmental time and lower overall vehicle carbon footprint.
Weight distribution in the vehicle amongst the four wheels is another aspect that is linked to suspension systems, as it strongly influences vehicle handling, driver fatigue and ride behaviour. It is important to integrate suspension development from the initial stages in vehicle engineering and manufacturing to ensure better vehicle attributes and minimise costs.
PROS & CONS
A poorly optimised suspension can increase discomfort, radial angulation and NVH in a vehicle and decrease component life due to operational fatigue. For example, tie rods are present in both rack and pinion and recirculating ball set-ups. If tie rod ends wear out, they may cause the steering wheel to loosen up. A vehicle with worn tie rods may also squeak as the steering wheel is turned and be out of alignment. If the vehicle dips or rocks, when going over tiny bumps on roads or drifts around corners even at low speeds, then it could be an issue with the shock absorbers or struts. It is the same with the bushings that interface between the struts and D pillar region of vehicle rear end. If worn out, these could cause fishtailing of the vehicle.
An un-optimised suspension affects wheel alignment, tyre wear and wobbles at low or high speeds and diminishes driver confidence. Non-aligned wheels can increase component wear, decrease gas mileage, increase driver fatigue and affect safe handling. Not to ignore the existence and effect of tyres. Radical improvements in rolling resistance, wet grip, load index and lesser weight have significantly enhanced safety, driver comfort and drivability in vehicles.
Stiffness and ride comfort could be actively adjusted by technologies such as Magnetic dampers. By sending electric current through a ferrous fluid, with or without nanoparticles, Magnetic Ride Control dampers can adjust their stiffness in response to driving conditions. Similarly in Hydraulic Roll Control, the hydraulic systems send fluid to the opposite side of the car instead of using the conventional suspensions that use steel antiroll bars to counteract body roll. There has also been concept research in capturing regenerative energy, when shock absorbers move during road undulations, to supposedly charge the batteries in EVs for increasing driving range.
The ingenious suspension contributes to a lower carbon footprint, ensures an elusive balance of a perfect ride coupled with race-worthy handling that enhances occupant safety confidence in a dynamic and hostile driving environment.