Camshaft: Definition, Operation, Types and Faults
Most followers of the motor world or simply drivers have ever heard of the camshaft . It is one of those mechanical components about which some doubts arise and that can bring more than a headache in the event that it breaks. So we are going to talk about this element and to clear all the unknowns about what it is, its operation, the types that exist and the breakdowns that it may suffer.
What is the Camshaft?
The camshaft is a mechanism formed by an axis in which a series of cams are placed. The objective is that when that axis rotates, the cams activate different mechanisms at repetitive intervals. In the case of car engines, what they control is the opening and closing of the intake and exhaust valves. The number of cams will depend on the number of valves that the mechanics have.
The axis that forms the camshaft is usually a single piece of cast iron or forged steel that presents a high level of resistance. It is necessary to be able to withstand the passage of time without wear, as this could lead to a modification of the distribution and even a serious breakdown. This element is lubricated by means of a circuit of conduits that lubricate each of the supports on which it rotates.
How does the Camshaft Work?
The operation of the camshaft depends to a large extent on its type and its placement. As we already said, with its rotation it will actuate the valves through a rod or rod system. The most common thing today is that this component goes in the stock , although we will review it later. Also to be mentioned is the possibility that the engines employ several camshafts one for the intake valves and one for the exhaust valves.
Types of Camshafts:
As we introduced, years ago the camshaft was in the engine block, but nowadays it is usually located in the cylinder head: in the cylinder head. Although as there are several provisions of the valves we are going to review the different types of camshafts that we can find.
- SV System: Known as the "side valve" system because these elements are placed on one side of the cylinder, inside the engine block. It was used years ago but was scrapped because it forced to have a larger compression chamber and the size of the valve heads was limited by the little space available.
- OHV System: It also has the camshaft in the engine block, although the valves go in the cylinder head. In this way, the crankshaft moves the camshaft using sprockets or a chain, so it has very little maintenance. Although it has the disadvantage that it has many components to compensate for the distance between the camshaft and valves, so that at high revolutions and at high temperatures it can suffer clearance in the tappets (the «thrusters between valves and camshaft).
- OHC System: It is the most widely used today and has both the camshaft and the valves integrated in the engine cylinder head. With this it manages to reduce the number of components and to have a more precise opening and closing, allowing the engines to reach a higher number of revolutions. The downside is that crankshaft motion transmission is more complicated and requires longer timing belts or chains, which will require more maintenance. There are two types of OHC variants: the SOHC that has a single camshaft that actuates the intake and exhaust valves, and the DOHC that has two camshafts, one for intake and one for exhaust.
The faults in the camshaft are not as frequent as in other mechanical elements, but may occur and are usually expensive. The main reason would be improper lubrication , which could cause premature wear and even breakage if the problem persists. We have also mentioned the clearance of the tappets, although their repair is easier and does not require changing the entire part.
Camshaft failure can be detected through some symptoms the car makes while driving. One of the most striking is an obvious loss of power experienced by the engine. Also of noises, because it is manifested through rattles that come from the engine or loud squeaks that can be caused by this component. Finally, if the car does not start directly it could be due to the breakage of the camshaft.