The crankcase is the main fixed part of an internal combustion engine with the crankshaft at the bottom and the cylinder block at the top. The connection of the upper and lower parts of the crankcase is made by means of mounting bolts with the help of a sealing gasket. If it so happens that the engine crankcase, and with it the entire machine has become unrepairable, then turn it in for recycling:

Crankcase Construction

It is necessary to say, of course, that the crankcase is not only the engine, the gearbox, transfer case and other mechanisms have it. Often the crankcase is cast from a heavy-duty and reliable aluminum alloy.

From below the engine crankcase is protected by a special pallet, also made of aluminum alloy, or steel forging.

The main purpose of the sump is to reliably protect the crankcase from dirt and oil leaks. In addition it serves as an oil reservoir, so the lower compartment has a special hole with a small plug for draining and changing engine oil.

To increase the rigidity of the entire structure, the inner walls of the crankcase have cross-sections with recesses to which the main bearings of all crankshafts – crankshaft and camshafts – are mounted. The main bearings have removable covers connected to the crankcase by bolts or studs.

To prevent oil leakage, special grooves and seals made of oil-resistant rubber, felt, leather, or cork are provided on the crankshaft jutting out parts (rear and front).

Oil deflectors and drainage grooves are provided in the bearing caps and crankcase walls for timely drainage of oil that tends to escape.

The crankcase has special flanges for installing additional engine mechanisms, such as gasoline and water pumps, starter motor, and alternator.

In the sump of the crankcase, serving as a collector and temporary storage of oil, which at the moment is not involved in the engine process, in addition to oil accumulate and different metal particles – swarf, which is formed during the engine operation from the friction parts on each other.

Some modern engines are equipped with a crankcase ventilation system. This system is needed to remove gases from the crankcase. Gases in the crankcase is a mixture of exhaust gases (most of which escape through the exhaust system) seeping into the crankcase from the combustion chambers, gasoline vapor, and oil. As they accumulate, they adversely affect the properties and quality of oil and the condition of the rubber and metal parts of the engine.

To reduce the negative impact of crankcase gases, they are forcibly pumped out of the crankcase. This is exactly what the crankcase ventilation system is responsible for.

Features of the crankcase of a two-stroke engine

This type of crankcase is not just an engine housing, it is the main part of the fuel system of the vehicle. In this case, the crankcase is responsible for the preparation and timely supply of the fuel-air mixture into the engine cylinders. Thus, reliable lubrication of all major engine parts is ensured.

The front part of the crankcase of a two-stroke engine is equipped with a crank chamber, which takes part in the gas distribution process.

For reliable sealing of the chamber, a rubber gasket is provided on the left side of the crankcase to prevent oil from entering the chamber.

The right side of the crankcase has a sealing gland whose primary purpose is to prevent outside air from entering the chamber.

What is a Dry Crankcase

The name “dry crankcase” certainly didn’t appear by accident, and it’s easy to guess that since the crankcase is dry, it has no oil in it, just like a normal crankcase, which serves as a reservoir to collect and store oil.

This is partly true, but not quite. In an engine with a dry crankcase, the oil also flows into the sump, but it is prevented from staying there by pumps that immediately pump it into a special reservoir, which is moved outside the engine and can be, in general, anywhere, but usually not far from the engine or even directly on it, but outside.

This engine lubrication system is used on sports cars, racing cars, as well as on serious off-road vehicles.

The need for a dry crankcase arises because such cars experience increased dynamic and inertial loads, due to which the oil in a conventional crankcase would be very splashy and frothy.

In tight tight corners or when going up and down steep hills, the oil inlet can become exposed and the result is a lubrication problem that causes the engine to run overloaded and can lead to failure.

The dry-sump lubrication system solves this problem. Oil is supplied from a special reservoir under pressure, and engine lubrication is ensured under all operating conditions.

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