Creation of fluid flow : PumpObjectives :Distinguish between positive and non-positive displacement pumpsUnderstand the principle of operation of gear, vane and piston pumpsDifferentiate between fixed and variable displacement pumps, external andinternal gear pumps as well as axial and radial piston pumpsExplain how pressure-compensated pumps workIdentify the various types of pumps used in hydraulicsSelect and size pumps for various hydraulic applicationsCarry out basic maintenance activities on the pumps.

Principle of operation

Pump classification

Positive displacement pumps. Non-positive displacement pumps and

GEAR PUMP-INTERNAL-EXTERNAL-GEROTER

RESIPROCATINGPISTON PUMP

SCREW PUMP

ROTARY

VANE PUMP

FIXED DISP. VARIABLE

UNBALANCEBALANCED

RADIAL PISTON AXIAL

STATIONARY CYLINDER

STA. PISTON

BENT AXIS INLINE

VARIABLE SWASH PLATE CAMDRIVEN

Non-positive displacement pumps

hydro-dynamic pumpfluid is displaced and transferred usingthe inertia of the fluid in motionLow Initial Cost & maintenance costOperated quietlyAll types of fluid like sludge and slurriesHigh reliabilitySimplicity of operation

Positive displacementhydrostatic pumpspumps discharge a fixed quantity of oil per revolutionCapability to generate high pressuresHigh volumetric efficiencySmall and compact with high power to weight ratioRelatively smaller changes in efficiency throughout the pressure rangeWider operating range i.e. the capability to operate over a wide pressure andspeed range.

External gear pump

Internal gear pump

Lobe pump

Gerotor pump

Vane pumps

Balanced vane pump

Variable displacement vane pump

Pressure compensation in variable displacement vane pumps

Simple circuit with variable displacement pump.

Simple circuit with fixed displacement pump

Piston pumpBent-axis piston pumps