Automobile suspension—front suspension(1)

The job of a car suspension is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to ensure the comfort of the passengers.Car manufacturers have set out to baffle use with the sheer number of different types of suspension available for both front and rear axles. The main groupings are dependent and independent suspension types.

Front suspension - dependent systems

So-called because the front wheel's suspension systems are physically linked.There is only one type of dependent system you need to know about.It is basically a solid bar under the front of the car, kept in place by leaf springs and shock absorbers. It's still common to find these on trucks.They haven't been used on mainstream cars for years for three main reasons:
Shimmy - because the wheels are physically linked, the beam can be set into oscillation if one wheel hits a bump and the other doesn't. It sets up a gyroscopic torque about the steering axis which starts to turn the axle left-to-right. Because of the axle's inertia, this in turn feeds back to amplify the original motion.
Weight - or more specifically unsprung weight. Solid front axles weigh a lot and either need sturdy, heavy leaf springs or heavy suspension linkages to keep their wheels on the road.
Alignment - simply put, you can't adjust the alignment of wheels on a rigid axis. From the factory, they're perfectly set, but if the beam gets even slightly distorted, you can't adjust the wheels to compensate.

Front suspension - independent systems

So-named because the front wheel's suspension systems are independent of each other (except where joined by an antiroll bar) These came into existence around 1930 and have been in use in one form or another pretty much ever since then.

MacPherson Strut or McPherson strut

This is currently, without doubt, the most widely used front suspension system in cars of European origin. It is simplicity itself. The system basically comprises of a strut-type spring and shock absorber combo, which pivots on a ball joint on the single, lower arm. At the top end there is a needle roller bearing on some more sophisticated systems. The strut itself is the load-bearing member in this assembly, with the spring and shock absorber merely performing their duty as oppose to actually holding the car up.The steering gear is either connected directly to the lower shock absorber housing, or to an arm from the front or back of the spindle (in this case). When you steer, it physically twists the strut and shock absorber housing (and consequently the spring) to turn the wheel. Simple. The spring is seated in a special plate at the top of the assembly which allows this twisting to take place. If the spring or this plate are worn, you'll get a loud 'clonk' on full lock as the spring frees up and jumps into place. Thisis sometimes confused for CV joint knock.

Baby's Car Seat——spot and safety

Throughout the United States, there are laws that require car seat use for children.In Ohio, parents or guardians by law must use a car seat for all children under 40 pounds and under 4 years of age. Make sure you know the car seat law of any state you may travel to. Many states require that children stay in appropriate car seats through 8 years or up to 4 feet, 9 inches tall. Car seat belts are made for adults and cannot protect a small child.

Car crashes are the main cause of serious injury and death in children. Correctly using a car seat save a child's life or prevent a more serious injury.

The safest spot for a baby's car seat is in the center of the back seat rather than on the sides, according to a new study.

Although older passengers using seat belts can decide where they sit in a car, researchers point out that a child's seat is determined by where the child-restraint system is installed. For ease of access and keeping an eye on a baby, the most common spot for a baby's car seat is the rear passenger side.

But the study showed that children under age 3 seated in the center of the back seat had nearly half the risk of injury in motor vehicle crashes than children seated in either of the other positions.

"The center rear seating position is used less often by children restrained by a child-restraint system as they get older," writes researcher Michael J. Kallan, MS, University of Pennsylvania School of Medicine, and colleagues in Pediatrics. "Children seated in the center rear have a 43% lower risk of injury compared with children in a rear outboard position."

Researchers say current child restraint safety guidelines recommend the center position as long as a snug fit of the car seat can be achieved. But those recommendations are based on research that was conducted a decade ago.

Center Seat Safest for Children

In this study, researchers looked at whether those recommendations were still valid by analyzing data on child occupants of motor vehicle accidents from 1998 to 2006 based on insurance claims and a telephone survey.

The analysis included children from birth to age 3 who were seated in a child-restraint system in the rear seat of motor vehicles (model year 1990 or newer) that were?involved in a crash in 16 states.

The results showed that the passenger side rear seat was the most popular position for the baby or child's car seat (41%) followed by the left (driver's side) rear seat (31%) and center seat (28%).

Researchers also found use of the center position decreased as the child got older. For example, 39% of baby car seats for infants under age 1 were placed in the center rear seat vs. 18% of child car seats for 3-year-olds, regardless of any additional passengers in the rear seat.

Children seated in the center had a 43% lower risk of injury than those in either side position, which researchers say revalidates current child-restraint safety recommendations.

"Although placement in any rear seating position provides excellent protection," write the researchers, "those in the center have the lowest risk of injury.

Researchers say recommendations should continue to encourage families to install child and baby car seats in the center of the rear seat.

Car Seat Safety Tips

• Not all car seats fit in all vehicles. When installed correctly, the car seat should not move more than one inch from side to side.

• Attend a car seat safety check in your community. These may be offered by your local health department.• Keep harness straps snug and fasten the harness clip at armpit level. Harness straps should be at or below the shoulder level.

• When using a rear facing infant seat, recline the car seat to keep the baby's head from dropping forward. Put the infant car seat carrying handle down.

• Rolled towels or rolled receiving blankets can be placed along the sides of the child for extra support. Never place padding under or behind the baby.

• The child should not have a heavy coat on under the straps of the harness. If extra warmth is needed, use a blanket over the seat.