Obturator ring

For other uses see Obturator

Obturator rings are a specific type of piston ring used in World War I aero engines to compensate for warping of the cylinders.

Purpose

The rotary aircraft engines of World War I (engines with the crankshaft fixed to the airframe and rotating cylinders) were notoriously difficult to keep cool when operating. Thus, their very thin walled steel cylinders would become distorted to an unacceptable level. Obturator rings, made of brass, were fitted to compensate for this out-of-roundness in much the same way as a leather washer does in a bicycle pump. Wear on the rings was considerable and they only lasted a matter of hours. By the time the war ended, technology and materials had advanced sufficiently to do away with these obturator rings.

Mechanical components	Camshaft Connecting rod Crankpin Crankshaft Cylinder Cylinder head Gudgeon pin Hydraulic tappet Main bearing Obturator ring Oil pump Piston Piston ring Poppet valve Pushrod Rocker arm Sleeve valve Tappet

Electrical components	Alternator Capacitor discharge ignition Dual ignition Generator Electronic fuel injection Ignition system Magneto Spark plug Starter motor

Terminology	Air-cooled Aircraft engine starting Bore Compression ratio Dead centre Engine displacement Four-stroke engine Horsepower Ignition timing Manifold pressure Mean effective pressure Naturally-aspirated Monosoupape Overhead camshaft Overhead valve Rotary engine Shock cooling Stroke Time between overhaul Two-stroke engine Valve timing Volumetric efficiency

Propellers

Components	Propeller speed reduction unit Propeller governor Spinner

Terminology	Autofeather Blade pitch Contra-rotating Constant speed Counter-rotating Scimitar propeller Single-blade propeller Variable pitch

Engine instruments

Tachometer
Hobbs meter
Annunciator panel
EFIS
EICAS
Flight data recorder
Glass cockpit

Engine controls

Fuel and induction
system

Other systems

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Obturator ring

Purpose

See also