Pneumatic actuator Pneumatic actuator A pneumatic control valve actuator converts energy (typically in the form of compressed air) into mechanical motion. The motion can be rotary or linear, depending on the type of actuator. A Pneumatic actuator mainly consists of a piston or a diaphragm which develops the motive power. It keeps the air in the upper portion of the cylinder, allowing air pressure to force the diaphragm or piston to move the valve stem or rotate the valve control element. Valves require little pressure to operate and usually double or "triple" the input force. The larger the size of the piston,
Dunlop Pneumatic Tyre Co Ltd v New Garage & Motor Co Ltd damages and not as a penalty’. The judge held the £5 sum was liquidated damages and enforceable. The Court of Appeal held the clause was a penalty and Dunlop could only get nominal damages. Dunlop appealed. The House of Lords held the clause was not a penalty, and merely a genuine preestimate of Dunlop’s potential loss, and so Dunlop could enforce the agreement. Lord Dunedin set out the following principles. Dunlop Pneumatic Tyre Co Ltd v New Garage & Motor Co Ltd It should not be confused with "Dunlop Pneumatic Tyre Co Ltd v Selfridge & Co Ltd", which held