Suspension Systems Questions and Answers

Answer: A

The suspension must both insulate the occupants from irregularities and maintain tyre contact so that steering and braking forces can be developed. The two requirements conflict, since a soft spring rides well but controls the wheel poorly. Every design is a compromise between them. The order in which the effects act is what decides the outcome, so it is worth establishing first. Tracing the requirement back to the physical constraint that produces it makes the answer follow.

Answer: B

Unsprung mass is everything not carried on the springs, and it must be accelerated by every bump in the road. Low unsprung mass improves both ride and grip. Independent suspension and inboard brakes both reduce it. Checking which component actually carries the load settles most questions of this kind at once. The shared behaviour explains why these belong together and the differences explain why both exist. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.

Answer: C

A light wheel assembly is accelerated more easily by the road, so it follows the surface instead of leaving it, which maintains grip. The body is disturbed less at the same time. It is the reason alloy wheels and aluminium suspension arms are used. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: D

Coil springs give a good ride for their weight and occupy little space, though they provide no location and must be used with links or a strut. Leaf springs locate the axle themselves. Air springs are used where levelling is required. The shared behaviour explains why these belong together and the differences explain why both exist. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: A

A semi elliptic leaf spring resists fore and aft and lateral forces as well as vertical ones, so no additional links are needed. That simplicity is why it persists on commercial vehicles. Its ride is inferior because of interleaf friction. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: B

The leaves rub as the spring deflects, and that friction prevents the spring from responding to small irregularities. Interleaf pads and single leaf springs reduce it. The effect is called stiction and it is why leaf sprung vehicles ride harshly when lightly laden. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: C

A torsion bar is anchored at one end and twisted by a lever at the other, giving a compact spring that fits along the chassis. The wire of a coil spring is also in torsion, which makes the second option a genuinely tempting distractor rather than a careless one. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.

Answer: D

Running the bar along the chassis frees the space a coil would occupy, and rotating the anchor raises or lowers the vehicle. The rate is essentially linear. Location must still be provided by the suspension arms. Naming what changes and what stays the same is the reliable route through questions of this shape. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. The order in which the effects act is what decides the outcome, so it is worth establishing first.

Answer: A

Adding or releasing air changes both the height and the rate, so a levelling valve or an electronic controller can hold the height constant under any load. A torsion bar anchor is a manual adjustment, not an automatic one. Air suspension is standard on buses and coaches. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. The order in which the effects act is what decides the outcome, so it is worth establishing first.

Answer: B

A spring alone would oscillate for many cycles, so a damper converts the energy to heat by forcing fluid through restrictions. The name shock absorber is a misnomer, since the spring absorbs the shock. An anti-roll bar is a spring, not a damper. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Framing the question as which quantity the change acts upon makes the answer follow without calculation.