Parts of a Car Suspension System

All 16 parts on the diagram

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Front suspension 11

Strut (MacPherson strut) A tube with the shock absorber built in. It links the wheel to the body, so this corner needs no upper arm.
Coil spring Spring steel wound into a coil. It holds the car up and squeezes shorter when the wheel hits a bump.
Steering knuckle It carries the wheel hub and joins the suspension to the steering. It swivels so the front wheel can steer.
Wheel hub The turning center the wheel is bolted to. Wheel studs stick out of it to hold the wheel.
Lower control arm A hinged arm between the car's frame and the knuckle. It lets the wheel move up and down.
Ball joint A ball-and-socket joint between the control arm and the knuckle. It lets the wheel steer and the arm swing.
Tie rod end The jointed end of the steering's tie rod. It pushes and pulls the knuckle's arm to turn the wheel.
Sway bar (stabilizer bar) A steel bar across the car, joining the left and right sides. It twists to resist the body's roll in a turn.
Sway bar link A short rod joining each sway bar end to the suspension.
Upper control arm A second arm that holds the top of the knuckle. Found in a double wishbone suspension. It is usually shorter than the lower one.
Bushing A rubber sleeve between two metal parts. It lets an arm pivot on the frame and keeps noise and vibration out of the car.

Rear suspension 5

Leaf spring Strips of spring steel stacked in a curve. Shorter ones sit under the long one. It holds the car up and keeps the axle in place.
Shackle A swinging link between one leaf spring end and the frame. It lets the spring get longer as it flattens.
U-bolts U-shaped bolts that clamp the axle to the leaf spring's middle.
Axle A solid axle joins the two rear wheels with one beam. That makes both move together.
Shock absorber A tube with a piston moving through oil inside. It damps the spring so the car does not keep bouncing.

How this list was compiled: Read 2026-09-30; a name is kept only where at least two of these use it. (1) US Army, TM 9-8000, Principles of Automotive Vehicles (1985, public domain), chapter 30, Suspension systems, figures 30-1 (leaf springs: shackle, spring leaves), 30-9 (upper and lower control arm, upper and lower ball joint, steering knuckle, coil spring, shock absorber, stabilizer bar, stabilizer link), 30-13 (MacPherson strut) and 30-14 (U-bolts), paragraphs 30-8 (the strut houses the shock absorber and links the wheel and body) and 30-20 (swaybars), and chapter 33 (tie rod ends), https://archive.org/details/tm-9-8000-principles-of-automotive-vehicles-1985 . (2) Virginia Administrative Code, Motor Vehicle Safety Inspection Regulations, 19VAC30-70-110, Steering and suspension, https://law.lis.virginia.gov/admincode/title19/agency30/chapter70/section110/ : shock absorbers, coil springs, MacPherson strut, tie rod end, ball joint, upper and lower control arm, bushing, stabilizer bars and links, shackles, U-bolts, axle. (3) Wikipedia, text only: MacPherson strut, Car suspension, Control arm, Ball joint, Steering knuckle, Anti-roll bar, Tie rod, Double wishbone suspension, Bushing (isolator), Leaf spring, Shackle, U-bolt, Beam axle, Shock absorber, Coil spring. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's car, nothing traced. Licence: own work

How it works

The parts of a car suspension in three drawings: a front corner with a strut, the same corner with a double wishbone, and a rear axle on a leaf spring. Tap a part to read what it does.

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Springs, shock absorbers and arms

Every corner has three jobs to do. A spring, either a coil spring or a leaf spring, holds the car up. A shock absorber damps the spring so the car does not keep bouncing; in a strut it is built into the tube the spring sits on. Arms hold the wheel in place: a control arm hinges on the frame through rubber bushings, and a ball joint lets the knuckle steer.

Front and rear

Struts are widely used at the front. A double wishbone has an upper and a lower control arm instead. On a leaf-spring rear axle, U-bolts clamp the axle to the spring, and a shackle at one end lets the spring get longer as it flattens.

A strut is more than a shock absorber: it also links the wheel to the body, so a strut corner has no upper control arm.

Questions and answers

What are the main parts of a car suspension system?

Springs (coil or leaf), shock absorbers or struts, control arms with their ball joints and bushings, the steering knuckle and wheel hub, and a sway bar with its links. A rear axle on leaf springs adds shackles and U-bolts.

What is the difference between a strut and a shock absorber?

A shock absorber only damps the spring's movement. A strut has a shock absorber built in, but it is also part of the structure: the coil spring sits on it, and it links the wheel to the body.

What are the parts of a rear suspension?

On a leaf-spring rear axle: a leaf spring each side, a shackle at one end of it, the U-bolts that clamp the axle to the spring, the axle and the shock absorbers. Other cars have coil springs and control arms at the rear.

What does a sway bar do?

It joins the left and right sides of the suspension. When the car leans in a turn, one side rises more than the other and the bar twists, which resists the lean. It is also called a stabilizer bar or anti-roll bar.