Diesel Engine Construction

In this post we will take a look at engine construction and learn about the different diesel engine parts and how they are constructed. We will take a look at 5 components in our first article to be followed by others later

Sole plate and Frame

Both Sole plate and Frame are of cast iron one block type with light weight and ample rigidity. They are specially designed not to generate stress concentration.

A water-Jacket is formed in between the upper part of the frame and the cylinder liner. The Crank Case is provided in between the lower part of the frame and the sole plate. The Crank Case has large inspection windows at its side enabling easy access to the main bearing shell, connecting rod and other main moving parts for their inspection and disassembling.

Frame and Sole Plate

Frame and Sole Plate

In accordance with Rules and Regulations each inspection window has Engine frame safety valves and also mist-gas outlet hole.

The sole plate standard type is that of the flat base type which does not store oil. But if the specifications does so require, a ship-bottom type sole plate which can contain oil in minimum necessary quantity is also available. In either cases it is necessary to keep enough oil for initial supply to the engine by providing a separate tank.

The sole plate and the frame are firmly jointed each other by means of tie bolts.


The crank shaft is made of high grade forged steel one piece type with a sufficient diameter and rigidity to cope satisfactorily with bearing pressure and tensional vibration at a high revolution, and the dimensions at each part are so designed as to meet various Rules and Regulations.

At the rear end of the crank shaft, it constitutes the power out put shaft coupling to which the flywheel is fitted with reamer bolts. If required by the special specifications, power take off from the front end of the crank shaft is possible.

Main bearing shell

The main bearing cap is made of cast iron. It is fitted into the sole plate and held down securely on to the engine frame by precise boring together with the sole plate, it constitutes the main bearing housing.

Main Bearing Shell

Main Bearing Shell

The main bearing shell is of white metal lined completed thin-shell type. It is provided with complete interchange ability. But be sure to replace the upper and lower bearing shells at the same time as a pair.

A claw on the bearing shell is provided asymmetrically on purpose so that the operator may not assemble the bearing shell reversing right and left at the time of re-assembly.

The bearing cap at the fly wheel side functions also as the receiver for thrust. Thus the thrust bearing is inserted in between the side of the main bearing housing and the crankshaft.

Piston, Piston Pin and Piston Ring

The piston is made of high grade cast iron suitable for high temperature and high pressure. The piston head is so shaped as to secure an good combustion. There are 4 piston rings at the upper part of the piston. The piston pin is inserted at its center and one oil ring each is equipped on its upper and lower side. The out side of piston is precisely finished by grinding process.

The piston pin is made of carburizing-hardening chrome-moribuden steel.

A full floating method, in relation to the piston boss hole and inside of piston pin bush, is adopted in fitting the piston pin, so that pressure surface and sliding surface change always, thus preventing local wearing.



At the both end of the piston pin the piston pin caps made of aluminium are inserted. These caps not only serve as the stoppers for pin but also prevent lubrication oil; from coming up through the gap between the piston pin and the piston pin boss.

Only the top piston ring is chromium placed so as to minimize the wearing of the cylinder liner and ring itself. If the cylinder liner is required to be chromium plated, the chromium plated ring cannot be used. Otherwise scuffing may occur due to the unison of materials.

Connecting Rod and Crank Pin Bearing Shell

The connecting rod is made of forged steel with a suitable shape for high rigidity. It has a piston pin bush at its small end and a crank pin bearing shell at its big end its cross section is I shape of which center runs an oil hole. The big end is split aslant into two with serrated surface and is fixed firmly by means of two connecting rod bolts. The piston pin bush is made of mild cylindrical steel babitted with lead bronze and is forcibly inserted into the small end. The crank pin bearing shell is of white metal lined completed thin-shell type. The characteristics are the same as mentioned about the main bearing shell.

Connecting Rod

Connecting Rod

The connecting rod bolts are made of nickel chromium steel with ample durability and reliability against the repeated inertia during operation and have strong tightening torque.

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