Conversion: How to Convert Reciprocating Motion into Rotary Motion?

Connecting Rod

In every utility machine, there are various parts, connected to each other. This is the basic need of engineering product. To convert reciprocating motion of piston into rotary motion of crankshaft, we have to connect, piston to crankshaft with the help of connecting rod and gudgeon pin. Here I am going to share some information of parts of internal combustion engine as I promised earlier. Below you will find details about connecting rod and gudgeon pin.

Connecting Rod: -

The load on the piston due to combustion 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 or cotter pin.

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

02) Gudgeon Pin: -

This pin connects the piston with small end of the connecting rod, and also known as piston pin. It is made up of case hardened steel and accurately ground to the required diameters. Gudgeon pins are made hollow to reduce its weight, resulting low inertia effect of reciprocating parts.

This pin is also known as "Fully Floating" as this is free to turn or oscillate both in the piston bosses as well as the small end of the connecting rod. There are very less chances of seizure in this case but the end movement of the pin must be restricted to score the cylinder walls. This can be achieved by using any one of the following three methods,

A) One spring circlip at each end is fitted into the groove in the piston bosses.

B) On spring circlip is provided in the middle.

C) Bronze or Aluminum pads are fitted at both ends of the pin, which prevents the cylinder walls from being damaged.

The gudgeon pin may also be semi-floating type, in which either the pin is free to turn or oscillate in the small end bearing but secured in the piston bosses or it may secured in the small end bearing and allowed a free oscillating movement in the piston bosses. This method provides more bearing area at the bosses and hence no need for providing bushes there in, is preferred.

Will the information is useful to you or not? What is your opinion?

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