The gear pump is a rotary pump in which two gears mesh to provide the pumping action. This type of pump is mostly used for cooling water and pressure oil to be supplied for lubrication to motors, turbines, machine tools etc. The gear pump is rotating machinery though flow of liquid to be pumped is continuous and uniform. Action of gear pump on liquid to be pumped is not dynamic; gear pump displaces the liquid from one side to the other.
Gear pump consists of two identical inter-meshing gears working in a fine clearance inside a casing. One gear is keyed to the driving shaft and other gear rotates revolve due to driving gear. Gear pumps have many advantages over other pumps like simplicity in construction, reliability, easy operation etc. Gear pumps are available as inside and outside meshing gears. Single stage two rotor gear pump with outside meshing gears is simplest in construction however inside meshing gear pumps are compact with wide applications.
Before using such a pump we should have some sort of idea about the working principle and parts of these pumps. The large exterior gear is known as the rotor and the interior gear which is small is known as idler. Liquid first moves between the rotor and the idler teeth. Then the liquid moves through the teeth of the gear. The crescent shape of the gear divides the moving liquid and also acts like a seal between the discharge and the suction ports. The head region of the pump is flooded and the liquid is forced out of the port meant for discharge. The inter meshing gears form locked areas so that volume of the liquid can be controlled.
Gear pumps have two moving parts and a single stuffing box. Pumps are noted for flexible and sturdy designs, high operational fluency, corrosion and rust proof surface, less power consumption and longer operational life. The maintenance cost of these pumps is negligible. Impeccable performance and ease of installation has made these products very popular in the market. It is a self-priming pump. These pumps provide steady delivery with or without little pulsation. These are made with utmost care to reduce noise and vibration. The pumps are used for handling furnace oil, clear fluid, mineral oil, petroleum jelly, solvents and alkalies. Most of these gear pumps are used in industries like fisheries, distillers and brewery and soap and detergent.