ocr: HYDRAULIC RAM PIPE. CYLINDER 4 - 4 * - - 49 PISTON- d - - - a - 14 HYDRAULIC ARM Machines such as excavators work by using hydraulic rams. Each ram consists ofa piston inside a cylinder. Pipes connect the cylinder to at reservoir of - hydraulic fluid. Controls in the driver's cab open valves that allow high- pressure fluid to enter either side ofthe piston. The - piston moves a part of the machine backand forth.
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