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points and signal box (approximately 200-250 m) and a slow operating speed. It was common in Italy and France only. Pneumatic lever frames have an operating principle that is related to that of hydraulic lever frames, however, instead of a hydraulic liquid, compressed air is used. The two types also share the same disadvantages such as pressurized tubing having to run directly between the field appliance and the lever frame. Electric control of a hydraulic or pneumatic actuator in the field was far simpler and more reliable, allowing for

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