GEAR PUMP HYDRAULICS

GEAR PUMP

GEAR PUMP CONSISTS OF TWO SPUR GEARS CLOSELY FITTED IN HOUSING. ONE GEAR WHEEL IS CALLED DRIVE GEAR GETS THE POWER FROM AN ELECTRIC MOTOR OR DIESEL ENGINE AND DRIVES THE OTHER GEAR WHEEL. END PLATES ARE PROVIDED TO COVER THE SIDE OF THE HOUSING AND TO ACCOMMODATE THE GEAR WHEEL SHAFT BEARINGS. IN THE HIGH PRESSURE GEAR PUMP WEAR PLATES ARE USED IN BETWEEN THE END PLATE AND GEAR WHEELS. BEARING ARE USED TO SUPPORT THE GEAR WHEEL SHAFT.THE CLEARANCE BETWEEN THE MOVING PARTS AND STATIONARY PLATE IS VARY FROM 0.002” TO 0.005”. WHEN THE GEAR WHEEL ROTATES, THE OIL IS CARRIED AROUND THE PERIPHERY OF THE REVOLVING GEARS FROM THE SUCTION SIDE TO DISCHARGE SIDE.THE TEETHS ARE MESHING BETWEEN THE TWO GEAR AND THUS PREVENT RETURN OF OIL FROM THE DELIVERY TO SUCTION

GEAR PUMPS ARE BASICALLY HYDRAULICALLY UNBALANCED. THE PRESSURE THAT DEVELOPED AT THE DISCHARGE PORT HAS A TENDENCY TO CROWED THE GEAR WHEELS OVER AGAINST THE INTAKE SIDE OF THE HOUSING

            A SUCCESSFUL ATTEMPT HAS BEEN MADE TO BALANCE THE GEARS HYDRAULICALLY BALANCED PRESSURE IS CONDUCTED BY PASSAGES FROM THE PRESSURE PORT SUITABLE POCKETS DIAMETRICALLY OPPOSITE.

            GEAR PUMP DOES NOT EMPLOY GASKET,BUT BODY JOINTS ARE GROUND TO AN OIL TIGHT FIT AND ASSEMBLED WITH ‘O’ RING PACKING SERVICE HAVE BEEN BUILT IN CAPACITIES RANGING ACTION FROM A FRACTION OF A LITER TO 300 LITER AND ABOVE THE SPEED OF THE PUMP VARIES FROM 900 TO 3500 RPM AND IT CAN DEVOLOP200.KG/CM².PRESSURE.THE VOLUMETRIC EFFICIENCY OF A GEAR PUMP VARIES FROM 85% TO 90%. THE VOLUMETRIC LOSSES IN THE PUMP ARE CAUSED BY INTERNAL LEAK THROUGH THE MATTING SURFACE,LOSSES DUE TO THE JET ACTION AT THE LINE OF CONTACT OF THE TEETH AND LOSSES IN INLET PRESSURE DUE TO CENTRIFUGAL ACTION OF FLUID.

MATERIALS

• EXTERNALS (HEAD, CASING, BRACKET) - IRON, DUCTILE IRON, STEEL, STAINLESS STEEL, HIGH ALLOYS, CAST STEEL
• INTERNALS (SHAFTS) - STEEL, STAINLESS STEEL, HIGH ALLOYS,
• INTERNALS (GEARS) - STEEL, STAINLESS STEEL,HEAT TREATED OR NITRIDED
• BUSHING - CARBON, BRONZE, SILICON CARBIDE, NEEDLE BEARINGS
• SHAFT SEAL - PACKING, LIP SEAL, COMPONENT MECHANICAL SEAL,

 ADVANTAGES

1.ABILITY TO HANDLE A WIDE RANGE OF VISCOSITIES OF FLUID

2.LESS SENSITIVITY TO CAVITATION (THAN CENTRIFUGAL STYLE PUMPS)

3.RELATIVELY SIMPLE TO MAINTAIN AND REBUILD.

4.AS THE PUMPING ACTION IS QUITE FINITE, THE OUTPUT IS VERY CONTROLLABLE. DOUBLING THE SIZE OR SPEED, IN THEORY SIMPLY DOUBLES THE OUTPUT

 DISADVANTAGES

1.THE FLUID MUST BE FREE OF ABRASIVES.

2.THE DISCHARGE OF GEAR PUMPS MUST BE CONTROLLED VIA THE MOTOR SPEED. THROTTLING 3.THE DISCHARGE IS NOT AN ACCEPTABLE MEANS OF CONTROL.

4.GEAR PUMPS RELY ON PRECISION CLEARANCES AND HAVE SEVERAL ROTATING ELEMENTS. THIS 5.MAKES THEM MORE EXPENSIVE THAN A CENTRIFUGAL PUMP

6. GEAR PUMPS ARE LIMITED BY SIZE. WHEN LARGE BULK FLOW RATES ARE REQUIRED THEY     BECOME PHYSICALLY UNSUITABLE COMPARE TO OTHER PUMP TECHNOLOGY

TYPES OF GEAR PUMPS

 1. EXTERNAL GEAR PUMP

EXTERNAL GEAR PUMP

2. INTERNAL GEAR PUMP

INTERNAL GEAR PUMP

3. GEROTOR PUMP

GEROTOR PUMP

 

4. LOBE PUMP

LOBE PUMP