Reciprocating Engine Construction

Crankcase

Crankcase

The foundation of the engine

Crankcase

Must support itself

Crankcase

Contains bearings in which the crankshaft revolves

Crankcase

Enclosure for lubricating oil

Crankcase

Provides mounting to the aircraft

Crankcase

Provides mounting for cylinders

Crankcase

Needs Strength and rigidity to prevent misalignment

Crankcase Material

Mostly made of aluminum alloys

Opposed-Engine Crankcases

Consists of two matching, reinforced aluminum-alloy castings

Opposed-Engine Crankcases

Castings are divided vertically at the centerline

Opposed-Engine Crankcases

Fastened together with studs and nuts

Lubricating System

Contained in the crankcase

Oil Passages

Drilled in sections of the case to supply lubrication to crankshaft bearings, camshaft bearings, and other parts that require lubrication

Radial-Engine Crankcase

Consists of multiple sections (3-7)

Front Section

Bell Shaped aluminum alloy housing

Front Section

Supports propeller thrust bearing and other propeller related components

Main Power Section

Usually consists of 1-3 pieces of high-strength heat-treated aluminum alloy or forged steel

Fuel Induction and Distribution Section

Also called blower section or supercharger section

Accessory Section

Provides mounting pads for accessory units such as fuel pump, vacuum pump, lubrication oil pump, starters, and magnetos

In-Line and V-Type Engine Crankcases

Four major sections: Front Section, Power Section, Fuel Induction and Distribution Section, Accessory Section

Power Section

May be one part or two part and supports crankshaft bearings

Plain Bearings

Low-power engines mainly designed to take radial loads

Roller Bearing

High-power applications made in a variety of shapes and sizes

Ball Bearings

Provides less friction than any other bearing types

Ball Bearings Components

Inner Race, Outer Race, Set of Polished Steel Balls, Ball Retainer

Bearing Race

Channel where rollers travel, made of hardened steel