Suspension Systems Questions and Answers

Answer: C

Motion ratio is the spring displacement divided by the wheel displacement, and the wheel rate is the spring rate times its square. Damper motion ratio is a distinct quantity applying to the damper. Both must be known to predict behaviour. The order in which the effects act is what decides the outcome, so it is worth establishing first. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: D

Natural frequency follows from the square root of stiffness over mass, and a comfortable car sits around one hertz. Unsprung mass governs the much higher wheel hop frequency instead. Damping controls the decay rather than the frequency. Checking which component actually carries the load settles most questions of this kind at once. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: A

One hertz corresponds roughly to the rhythm of walking and is the frequency the body accepts most readily. Sports cars run higher, around one and a half to two hertz. Wheel hop occurs near ten to fifteen hertz. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Naming what changes and what stays the same is the reliable route through questions of this shape. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: B

The wheel and tyre form a second mass spring system that resonates around ten to fifteen hertz, and at that frequency the tyre loses contact intermittently. Damping controls it. Body float is the low frequency equivalent. 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. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: C

The roll centre is found geometrically from the instantaneous centres of the linkages, and the distance between it and the centre of gravity determines the rolling moment. Raising it reduces roll but increases jacking. It is not fixed and moves as the suspension deflects. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. A symptom that appears under one condition and not another is what narrows the diagnosis quickly.

Answer: D

A high roll centre gives a large geometric load transfer component that pushes the body upward, which is the swing axle problem. It does reduce roll, so the second option inverts the relationship. Designers keep it low and controlled. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. The order in which the effects act is what decides the outcome, so it is worth establishing first. Checking the units of each quantity catches a wrong formula before the arithmetic begins.

Answer: A

The line joining the front and rear roll centres is the roll axis, and the vehicle rolls about it. Its inclination affects the front to rear balance of load transfer. Pitch is a separate motion controlled by anti-dive and anti-squat geometry. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Checking which component actually carries the load settles most questions of this kind at once. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: B

Inclining the suspension arms so that the braking force produces a component opposing the deflection reduces dive without stiffening the spring. Anti-squat does the same at the driven axle under power. Both are geometric rather than spring solutions. Naming what changes and what stays the same is the reliable route through questions of this shape. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Working one numerical case through both cases side by side fixes the distinction better than any rule of thumb.

Answer: C

Because the geometry couples longitudinal force into the vertical motion, a bump taken under braking is transmitted more harshly. Full anti-dive is therefore rarely used, and figures around fifty per cent are typical. Every geometric solution has a cost. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. The shared behaviour explains why these belong together and the differences explain why both exist. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: D

Rubber bushes at every pivot and mounting break the metal path and absorb high frequency vibration. Their compliance also allows a controlled deflection under load. Stiffer bushes sharpen the response and increase the noise. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. 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.