1)Camshaft:Camshaft is a type of rotating device or apparatus used in piston engines for propelling or operating poppet valves. Camshaft comprises of series of cams that regulates the opening and closing of valves in the piston engines. The camshaft works with the help of a belt, chain and gears.

2)    Crankshaft:

Crankshaft is a device, which converts the up and down movement of the piston into rotatory motion. This shaft is presented at the bottom of an engine and its main function is to rotate the pistons in a circular motion. Crankshaft is further connected to flywheel, clutch, main shaft of the transmission, torque converter and belt pulley.

To convert Reciprocating motion of the Piston into Rotary motion, the Crankshaft and Connecting Rod combination is used. The Crankshaft which is made by Steel Forging or Casting is held on the Axis around which it rotates, by the Main Bearings, which is fit round the main Journals provided.

There are always at least two such bearings,one at the rare end and other at front end.the increase in number of Main Bearings for a given size of the Crankshaft means less possibility of Vibration and Distortion.

But it will also increase the diffculty of correct alignment in addition to increased production cost. The Main Bearings are mounted on the Crankcase of the Engine. The Balance weight or Counter weight keep the system in perfect balance.

The Crank Webs are extended and enlarged on the side of Journal opposite the Crank Throw so as to from balance weights. The Crankshaft may be made from Carbon Steel, Nickel Chrome or other Alloy Steel.

3)    Connecting Rod:

Connecting rods are made of metals, which are used, for joining a rotating wheel to a reciprocating shaft. More precisely, connecting rods also referred to as con rod are used for conjoining the piston to the crankshaft. 

The load on the piston due tocombustion of fuel in the combustion chamber is transmitted to crankshaft through the connecting rod.One end of connecting rod known as small end and is connected to the piston through gudgeon pin while the other end known as big end and is connected to crankshaft through crank pin.

Connecting rods are usually made up of drop forged I section.In large size internal combustion engine,the connecting rods of rectangular section have been employed.In such cases,the larger dimensions are kept in the plane of rotation.

In petrol engine,the connecting rod’s big end is generally split to enable its clamping around the crankshaft.Suitable diameter holes are provided to accommodate connecting rod bolts for clamping.The big end of connecting rod is clamped with crankshaft with the help of connecting rod bolt,nut and split pin orcotter pin.

Generally,plain carbon steel is used as material to manufacture connecting rod but where low weight is most important factor,aluminium alloys are most suitable.Nickel alloy steel are also used for heavy duty engine’s connecting rod.

Connecting rods can be made of steel, aluminum, titanium, iron and other types of metals.

4)    Crank Case:

A crankcase is a metallic cover that holds together the crankshaft and its attachments. It is the largest cavity within an engine that protects the crankshaft, connecting rods and other components from foreign objects. Automotive crankcases are filled with air and oil, while Magnesium, Cast Iron, Aluminum and alloys are some common materials used to make crankcases.