Theory Questions
- A solid axle suspension has 4 degrees of restraints.
- During Jounce, the suspension spring compresses. In order that the wheel stays perpendicular to the road surface contact patch when the suspension is fully compressed, we want a negative camber to be developed as the suspension travels to its extreme position.
- If the roll center is at the-
- CG height- No rolling moment will be produced when the vehicle is taking a turn, since the CG and the roll center are at the same height.
- Ground level- Rolling moment would be produced and it would be given by the product of the centrifugal force acting on the car, and the distance between the roll center and the CG.
- Below ground level- Maximum amount of Rolling moment will be produced in this case as the distance between the roll center and the CG is maximum in this case. So, the rolling moment will be maximum.
- The Mcpherson strut suspension is not able to provide change in camber angle with suspension travel. Because of it’s orientation, the camber angle of the wheel can’t be changed, so the tyre does not remain perpendicular to the ground with wheel travel.
- One possible solution is to prevent the extension of the rear dampers from their Mean position, and only allow them to get compressed when the vehicle hits a bump and come back to their mean position. During braking the rear spring expands, so if the damper would not be allowed to expand then the spring too won’t expand.
- Wheel center rate is similar to spring rate but it is measured but it is measured at the wheel instead of the point where the spring attaches to the linkage. The relation between them is defined by, Wheel rate= (Spring Rate)*(Motion Ratio)^2
- In anti-ackermann steering the inner wheel has less steering angle than the outer wheel.
- Since the turn center does not lie on the projection of the rear axle of the vehicle and lies behind it, the percentage Ackermann in this case would be zero percentage.
- Negative caster causes high speed instability and reduces the steering return capability of the steering wheel.
- The revoknuckle geometry reduces the distance between the tire centerline and the steering axis which reduces the scrub radius of the system. Since the scrub radius decreases so the torque steer also decreases.