Automobiles are most vulnerable to overheating. With the engine producing a lot of friction and burning fuel, stability and imperviousness are always at stake. And even if they hold up to the harshest of conditions, the passengers still have to worry about the rough situations on the road. The radiator and shock address these fears.
A radiator is a type of heat exchanger. It is designed to transfer heat from the hot coolant that flows through it to the air blown through it by the fan. Most modern cars use aluminum radiators.
Mercedes radiator, for example, are made by brazing thin aluminum fins to flattened aluminum tubes. The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flowing through the radiator.
The tubes sometimes have a type of fin inserted into them called a turbulator, which increases the turbulence of the fluid flowing through the tubes. If the fluid flowed very smoothly through the tubes, only the fluid actually touching the tubes would be cooled directly. The amount of heat transferred to the tubes from the fluid running through them depends on the difference in temperature between the tube and the fluid touching it. So if the fluid that is in contact with the tube cools down quickly, less heat will be transferred. By creating turbulence inside the tube, all of the fluid mixes together, keeping the temperature of the fluid touching the tubes up so that more heat can be extracted, and all of the fluids inside the tube are used effectively.
Radiators have at least two very important parts. The pressure cap increases the boiling point of the coolant by about 45 F (25 C). When the fluid in the cooling system heats up, it expands, causing the pressure to build up. The cap is the only place where this pressure can escape, so the setting of the spring on the cap determines the maximum pressure in the cooling system. When the pressure reaches a certain limit, the pressure pushes the valve open, allowing coolant to escape from the cooling system. This coolant flows through the overflow tube into the bottom of the overflow tank. This arrangement keeps air out of the system. When the radiator cools back down, a vacuum is created in the cooling system that pulls open another spring loaded valve, sucking water back in from the bottom of the overflow tank to replace the water that was expelled. The thermostat, on the other hand, is designed to allow the engine to heat up quickly, and then to keep the engine at a constant temperature. It does this by regulating the amount of water that goes through the radiator.
Despite popular thinking, conventional shocks do not support vehicle weight. Instead, the primary purpose of the shock is to control spring and suspension movement. This is accomplished by turning the kinetic energy of suspension movement into thermal energy, or heat energy, to be dissipated through the hydraulic fluid.
Shocks work on the principle of fluid displacement on both the compression and extension cycle. A typical car or light truck will have more resistance during its extension cycle then its compression cycle. The compression cycle controls the motion of a vehicle's unsprung weight, while extension controls the heavier sprung weight.
Shocks are basically oil pumps. A piston is attached to the end of the piston rod and works against hydraulic fluid in the pressure tube. As the suspension travels up and down, the hydraulic fluid is forced through tiny holes, called orifices, inside the piston. However, these orifices let only a small amount of fluid through the piston. This slows down the piston, which in turn slows down spring and suspension movement.
The amount of resistance a shock develops depends on the speed of the suspension and the number and size of the orifices in the piston. All modern designs, like the
Mercedes shock, are velocity sensitive hydraulic damping devices - meaning the faster the suspension moves, the more resistance the shock provides. Because of this feature, shocks adjust to road conditions. As a result, shock reduce the rate of bounce, roll or sway, brake dive, and acceleration squat.
Doubtlessly, radiators and shocks are critical automobile components that maintain engine condition in place and vehicle bounce under control, giving needed security and comfort.
