Skip to main content

Suspension system, springs, dampers, stabilizer bar

Short answer

Suspension isolates body from shocks, maintains tyre contact, and supports weight. Springs include leaf, coil, torsion bar, air, and rubber types. A telescopic hydraulic damper forces oil through orifices during bump and rebound, dissipating energy. A stabilizer bar connects left and right suspension arms, twisting to reduce body roll in corners.

State the purposes of a vehicle suspension system. Describe the types of springs used in suspension. Explain the working of a telescopic hydraulic shock absorber and the function of a stabilizer (anti-roll) bar.

Purposes of suspension

  • Isolate the body from road shocks for ride comfort.
  • Keep the tyres in contact with the road for good traction and braking.
  • Support the vehicle weight and carry loads.
  • Maintain correct wheel alignment and control body roll, pitch and squat.
  • Transmit driving, braking and cornering forces to the frame.

Types of springs

SpringDescriptionUse
Leaf springSeveral steel leaves of unequal length (semi-elliptic); damping by inter-leaf frictionTrucks, buses, rear axles
Coil springHelically wound steel bar; light, compact; needs links to locate axleMost cars (MacPherson, wishbone)
Torsion barSteel bar twisted when the arm movesSome light trucks and cars
Air springRubber bellows with compressed air; stiffness and height adjustableBuses, luxury cars
Rubber / hydro-pneumaticRubber block, fluid + gasSmall cars, special cars

Telescopic shock absorber (damper)

A spring stores energy and would keep oscillating, so a damper is fitted in parallel to convert oscillation energy into heat.

   top mount (body)
        |
   [ piston rod ]
   |  +--------+  | <- oil
   |  | piston |  |    valves in piston
   |  +--------+  |
   |   oil + gas  |
   bottom mount (axle)

The cylinder is filled with oil. During bump the piston moves down and oil is pushed through small orifices and valves into the upper chamber. During rebound it flows back through other valves, giving more resistance (higher in rebound than bump, typically 2:1). The restriction of oil flow creates the damping force. A gas-charged (monotube) design avoids foaming.

Stabilizer (anti-roll) bar

A U-shaped steel torsion bar connected between the left and right suspension arms. In a corner, the outer wheel moves up and the inner wheel moves down; the bar twists and resists this. It reduces body roll, improves handling and keeps both tyres on the road.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Automotive Technology chapter 6 questions →