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Pneumatic valve springs are also found in several Moto GP motorcycle engines, debuting in 2002 with the Aprilia RS Cube. In 2005, Team Roberts was the first to use pneumatic valves full-time in their uncompetitive KTM powered bike.
The effective mass of a traditional valve with spring includes one-half of the valve spring mass for symmetric springs and all of the valve spring retainer mass. However, a desmodromic system must deal with the inertia of the two rocker arms per valve, so this advantage depends greatly on the skill of the designer.
The blue valve body is visible in-line with the pipe. The valve actuator opens or closes the butterfly disc of the valve based on electrical signals sent to the actuator. Another valve actuator is visible in the background, with windows to indicate the valve position. A valve actuator is the mechanism for opening and closing a valve. Manually ...
An automatic control valve consists of three main parts in which each part exist in several types and designs: Valve actuator – which moves the valve's modulating element, such as ball or butterfly. Valve positioner – which ensures the valve has reached the desired degree of opening. This overcomes the problems of friction and wear.
Partial stroke testing (or PST) is a technique used in a control system to allow the user to test a percentage of the possible failure modes of a shut down valve without the need to physically close the valve. PST is used to assist in determining that the safety function will operate on demand.
These are more specific types of valves, used only in particular fields or applications. Often they are subcategories of the classification by operating principle and by function: Aspin valve: a cone-shaped metal part fitted to the cylinder head of an engine; Ballcock: often used as a water level controller (cistern)
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Although this provides better heat transfer, it requires steel valve seat inserts to be used; in older cast iron cylinder heads, the valve seats are often part of the cylinder head. A gap of 0.4–0.6 mm (0.016–0.024 in) is present around the valve stem, therefore a valve stem oil seal is used to prevent oil being drawn into the intake ...