Crankcase

De Dion-Bouton engine (Rankin Kennedy, Modern Engines, Vol III)

Two-Stroke Engine

4StrokeEngine Ortho 3D Small

Gardner 0 engine, Abergavenny steam rally, 2015

Crankcase is a fundamental component of internal combustion engines and serves as the housing for the crankshaft and other related components. It is designed to seal the bottom of the engine to prevent the leakage of oil and to keep contaminants out of the lubrication system. The crankcase plays a crucial role in the engine's ventilation system, often housing the oil pan where engine oil collects and is circulated to lubricate, cool, and clean the engine's moving parts.

Design and Function

The design of the crankcase varies significantly depending on the type and size of the engine. In most automobile engines, the crankcase is made from cast aluminum or iron and is split into two parts: the upper crankcase and the lower crankcase. The upper crankcase supports the crankshaft bearings and is bolted to the engine block, while the lower part, often referred to as the oil pan, collects and stores the engine oil.

Crankcases are designed to withstand the pressures and temperatures of the engine's operation. They often incorporate passages for oil and, in the case of two-stroke engines, fuel-air mixture. In addition to holding the oil, the crankcase also serves as a structural member of the engine, providing rigidity and support to ensure the precise alignment of the crankshaft and other components.

Ventilation

The crankcase contains a mixture of air, fuel, and combustion byproducts that can build up pressure during engine operation. To manage this, engines are equipped with a crankcase ventilation system, which removes these gases to prevent pressure buildup and potential damage. This system, known as the Positive Crankcase Ventilation (PCV) system in modern engines, also helps reduce emissions by routing the gases back into the engine's intake manifold for combustion, rather than releasing them into the environment.

Maintenance

Regular maintenance of the crankcase and its components is essential for the longevity and efficiency of an engine. This includes regular oil changes to remove contaminants that accumulate in the oil and inspection of the crankcase ventilation system to ensure it is functioning correctly. Leaks in the crankcase can lead to loss of oil and contamination of the engine, which can cause significant damage if not addressed.

Environmental Impact

The crankcase and its ventilation system play a significant role in controlling emissions from an engine. The PCV system helps to reduce the amount of unburned fuel and oil vapor released into the atmosphere, contributing to air pollution reduction efforts. Proper maintenance of the crankcase and PCV system is essential for minimizing an engine's environmental impact.

Crankcase Resources
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