The automotive engine, sometimes named as the power plant or a motor, provides power necessary to move the vehicle. In most automobile engines, the burning of a mixture of air and fuel produces the power that moves the pistons down on the power stroke. The pistons turn a crankshaft to which they are connected. The crankshaft produces a rotary motion that is transmitted to the power train.
The power developed by the engine must be carried to the wheels and by so doing produce the torque that is required to move the vehicle. This is the function of a number of components grouped and arranged in a logical order and are named as the power train.
TORQUE, POWER, AND POWER FLOW
Torque is turning or twisting effort. When the burning of the air-fuel mixture takes place in the engine cylinders, pressure developed inside that cylinder pushes the piston and commenting rode which in turn forces the crankshaft to turn. The force that makes the crankshaft to turn is called torque. One of the major purposes of the power train is to increase the torque developed by the engine. When a mechanic uses a wrench to tighten a bolt, torque is applied to the bolt. The mechanic may continue to apply force after the bolt is tight. Even though the bolt does not turn any more, the mechanic is applying torque. Torque, then, is a force that produces, or tries to produce, rotation.
The term power I most of the time confused with torque. Power is the rate or speed of doing work while torque is a turning or twisting effort. Power involves the idea of tome. The more quickly work is done, the more power I involved. For example, we could tie a rope and pulley to a horse and make it move forward to lift a container full of water. It would take a certain amount of time for the horse to lift up the container. If we tie up the rope to two horses, we might be able to get the container up in less the time taken by one horse. If we assume that the two horses are equal in the work they perform, we might be able to get the water container up in half the time taken by one horse to do the same work. With two horses we have twice as much power.
As we describe the operation of components of the power train we will be concerned with the flow of power. The flow of power I the path the power takes from the engine to the wheels that drive the vehicle. Understanding the power flow though a power train component is basic to understanding how the power train component is basic to understanding how the components work. The mechanic must understand how a components work. The mechanic must understand how a component works in order to properly diagnose and repair a power train malfunction
