Understanding Vehicle Suspension Systems
Crossbows
Crossbows are different overlays, long and elastic. Steel components are joined by central bolt clamps and sliding keys, allowing weight loading. They can be mounted longitudinally or transversally.
Torsion Bars
Torsion bars are solid bars made of elastic material, providing elasticity. The ends are striated, with one end anchored to the chassis and the other to a suspension arm. The arm swings, creating a torsional movement.
Blocking (Bump Stops)
Blocking components provide resistance and elasticity, placed between the vehicle and the suspension system. Their mission is to longitudinally join the chassis to the suspension, absorbing movement and acceleration forces.
Suspension Arms
Suspension arms connect the frame and wheel elements, serving as support for the spring and damper. They manage drag forces and are made of resistant material.
Types of Suspension
Rigid Suspension
With rigid suspension, the two wheels are mounted on a single axis. A drawback is that when one wheel encounters an obstacle, the car body does not maintain its horizontal position.
Semi-Rigid Suspension
In semi-rigid suspension, the wheels are attached to each other, transmitting fewer irregularities. The rotation received through the wheel axle shafts is attached to the differential, and the wheels are attached by an axle rigidly anchored to the chassis.
Independent Suspension (De Dion)
Independent suspension enhances comfort and stability, reducing oscillations and preventing them from passing from one wheel to another. It lowers body displacement and improves wheel grip.
McPherson Strut Suspension
McPherson suspension uses a wishbone united to the subframe and a steering knuckle. It serves as a vertical axis of rotation for the wheel.
Multilink Suspension
Multilink suspension has several wishbones anchored by elastic bearings, modifying wheel parameters like camber and convergence. When used on the rear wheel, self-steering can enhance stability.
Buffer (Shock Absorber) Issues
What happens when a shock absorber is in bad shape?
- Irregular tire wear
- High body roll
- The car pitches during acceleration and braking
- Strange noises on irregular surfaces and curves
- Feeling of instability
Check the following:
- The union areas between the shock and the car should not be broken.
- The piston should not halt or lock, and there should be no deformation.
- There must be no traces of oil leaks, though some damping loss is acceptable.
- The silent block should not have deformations that produce noise.
- The piston rod should not be rusty, as this rapidly deteriorates the joints, leading to oil loss.
Hydraulic Assistance (Power Steering)
The oil pump collects oil from the tank and, through a cross-flow regulator and pressure valve, sends it to the rotary valve. This valve controls the oil input and output, sending any surplus oil to the expansion tank. The movement of the rack is achieved through the steering wheel. When turning right, oil is introduced to the left of the piston, and the pressure is removed from the right side, sending that oil to the expansion tank.
Electric Assistance (Electric Power Steering – EPS)
The electric motor is powered by signals from the torque sensor, speed sensor, and engine RPM. With this information, it calculates the spin rate and direction, the force being applied, the RPM, and the vehicle speed. The electric motor analyzes this information in the control unit to adopt the most appropriate gear ratio for each situation.
One advantage is that the hydraulic system is used less, as it consists only of an electric motor placed perpendicular to the steering column. The electronic engine management system determines a variable steering ratio, able to closely match each situation. It functions through a Hall sensor and a pierced ring, which capture the angle and direction of turns. This information is sent to the control unit, which operates the electric motor responsible for managing the steering and screw or ball rack.