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Video Cylinder - Crank Drive
Video Piston 1
Video Piston 2
Video Piston 3
Video Piston 4
Video Piston - history
Video Piston - in general
Video Piston - material
Video Piston - stress
Video Piston - dimensions
Video Piston - measuring
Video Piston - truck
Video Piston Pin
Video Piston Pin Offset
Video Piston Rings 1
Video Piston Rings 2
Video Piston Rings 3
Video Connecting Rod
Video Crankshaft-history
Video Crankshaft 1
Video Crankshaft 2
Video Crankshaft 3
Video Crankshaft 4
Video Crankshaft 5
Video V-2 Crankshaft 6
Video Crankshaft 7
Video Bearing Play Check
Video Forces crank mechanism
Video Rot. Vibration Damper
Video Equaliser Shafts 1
Video Equaliser Shafts 2
Video 5-cyl. Block
Video Fly Wheel
Video Cylinder Block 1
Video Cylinder Block 2
Video Cylinder Block 3
Video Cylinder Block 4
Video Cylinder Block 5
Video Cylinder Block 6
Video Measurements
Video Loop Scavenging
Video Classic Racing Engine
Video V8 Cylinder Block
Video V8 Crankshaft 1
Video V8 Crankshaft 2
Video V10 Cylinder Block
Video V12 Cylinder Block
Video W12 Cylinder Block
Video W8 Cylinder Block

Video CO2-Emissions
Video Torque
Video Gas Speed
Video Hollow Cylinder
Video Bore Stroke Ratio
Video Cubic Capacity
Video Output per Liter
Video Efficiency
Video Calc. Crank Mechan.
Video Pistin Force
Video Compression Ratio
Video Pistin Speed
Video Power (output)
Video Power (piston pressure)

Video Multi-cylinder engine 1
Video Multi-cylinder engine 10

          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

  Axial offset (gudgeon pin)

The picture above shows a slightly- and an exaggerated (on the right) axial offset. If you click on the button, you'll see that, through the shifting of the gudgeon pin, the right hand piston changes sides, before TDC. This is the case with the left hand piston as well, only after TDC, i.e, in the area of increased combustion pressure.

Of course, the picture above on the right, shows a greater shift than actually takes place. Mostly, it can hardly be seen with the naked eye, perhaps approx. 1 mm. This however, at the same time, is also the danger. Should one, when installing the piston/s, turn them around 180, which is possible with some pistons, exactly the opposite is achieved. After the installation, the engine, which needs the offset, could sound like it was suffering from piston damage.

Axial offset helps to prevent cavitation (pitting) on the cylinder sleeve walls.

Previously axial offset was used for the above described reasons. The mechanism for observing the processes in the cylinder area has now been refined. Perhaps the piston could simply be minimally tilted during the pressure phase, to allow the rings to seal perfectly. Either that or the piston first makes contact with the shaft instead of with the ring-zone.

Apart from the axial offset, there is also the skewing. Thereby, the crankshaft is moved away from the center-axis of the piston movement. VR-engines can mostly not get by without skewing, because there is too little space for the cylinders down in the cylinder-block. In certain circumstances an axial offset can compensate a little. Skewing is not only found in VR-engines. Toyota's three-cylinder e.g., is shifted 8 mm off-center to move the tilting point so that the connecting rod and the crank-pin are as straight as possible at the point of the highest working pressure, thus losing as little power as possible from the friction between the piston and the cylinder sleeve. 05/12               Top of page               Index
2001-2015 Copyright programs, texts, animations, pictures: H. Huppertz - E-Mail
Translator: Don Leslie - Email:

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