• Connection rods are widely used in vehicles that are powered by internal combustion engines. All cars and trucks that use this type of engine employ the use of connecting rods. Farm equipment like tractors and combines also use connecting rods. Even construction equipment like bulldozers uses internal combustion engines, thus requiring connecting rods.
• When the spark plugs ignite the fuel-air mixture in the combustion chamber, the resulting explosion forces the pistons downward with tremendous force. The function of the crankshaft is to change the up-and-down motion of the pistons to a rotating motion. This is accomplished by having the connecting rods (which are attached to the pistons) connect to the crankshaft in an offset manner, so that as they go up and down their angle changes. This can be easily seen in the video link supplied
A short cylindrical bearing surface fitted between two arms of a crank and set parallel to the main shaft of the crankshaft.
Types of rocker arm
1 stamped steel rocker arm
2 rollers tipped rocker arm
3 full roller rocker arm
4 shafts rocker arm
Rocker arms are typically in between the pushrod and the intake and exhaust valves. They allow the pushrods to push up on the rocker arms and therefore push down on the valves. However, in over head cam applications the cam will ride directly on the rocker arm.
In addition to just changing the the direction of the motion from up on the rocker arm to down on the valve, the rocker arm changes the amount of motion transferred. Typically a rocker arm will "multiply" its motion by a rocker arm ratio by a factor of 1.45 to 1.7, meaning that for each .100" of pushrod motion
A camshaft's main job is to open and close the engine valves, via the lifters and rocker arms, in time to the piston's position in the cylinder. This causes the engine to take in air, burn fuel and expel exhaust gasses.
