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Video Engine Management

Video Cylinder Head 1
Video Cylinder Head 2
Video Cylinder Head 3
Video Cylinder Head 4
Video Cylinder Head 5
Video Cylinder Head 6
Video Cylinder Head 7
Video Cylinder Head 8
Video Cylinder Head 9
Video Cylinder Head 10
Video Cylinder Head Repair
Video Cylinder Head Gasket

Video Exchange of Gases
Video Comb. Chamber Shape
Video Cam
Video Camshaft
Video Adjustable Camshaft 1
Video Adjustable Camshaft 2
Video Adjustable Camshaft 3
Video Cambelt
Video Cambelt (assembly)
Video Camshaft Timing Chain
Video Camshaft Timing Chain
Video Upright Shaft
Video Timing Diagram
Video Valves
Video Valve drive
Video Natrium Cooled Valve
Video Valve Spring
Video Valve Stem Guide
Video Valve Seat
Video Valve Seat Angle
Video Valve Stem Sealing
Video Valve Overlap
Video Valve Play Adjustment
Video Valve Contr. (desmo.)
Video Hydraulic Lifter
Video Operating Valves
Video Var. Valve Timing 1
Video Var. Valve Timing 2
Video Var. Valve Lift 1
Video Var. Valve Lift 2
Video Drawrod Engine

Video Engine Control 1
Video Engine Control 2

          A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Valve Control (desmodromic)

Greek: desmo dromos - controlled movement


The desmodromic valve control closes the valve without the help of a valve spring. Fluttering of the valves at very high revs is thereby avoided. Moreover, the acceleration and deceleration during the valve control are improved. The real reason for the implementation of this valve control system lies in the bad quality of the steel after the Second World War which caused the valve springs to break over and over again (in particular for racing engines).

How it works

Instead of one cam, the camshaft features one cam for opening (blue) and another for closing (red) the valve. The valve is directly attached to the rocker arm. An exact valve adjustment is especially essential, yet complicated. For example, the sleeves on the valve stem must be renewed or grinded off if the valve clearance is altered.


Motorcycles feature this valve control sporadically (Ducati). Even for racing engine cylinder heads with valves, very high revs are realised exclusively with valve helical springs and/or air-filled diaphragms. 06/08               Top of page               Index
2001-2015 Copyright programs, texts, animations, pictures: H. Huppertz - E-Mail
Translator: Don Leslie - Email:

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