Q.1.List out any four criteria for selection of hydraulic pump in hydraulic system. Explain in brief.
Important criteria for selection of Hydraulic pump
1. Maximum operating pressure: This is determined by the
power requirement of the circuit, the particular application, availability of components, type of fluid and to some extent the environment and level of labor both using and maintaining the equipment
2.Maximum delivery: The pump
system selected must be capable of delivering the maximum flow rate
demanded by the circuit. If the circuit demand is constant, a fixed
displacement pump is chosen.
3. Type of control: Various types of pump controls are available such as manual servo control, pressure compensated control, constant power control and constant flow
control. The choice of control is dependent upon the circuit requirement such as complexity, accuracy of control, cost, type of machining operation, etc. The designer has to choose carefully the
type of control after a detailed study of system characteristics.
4. Pump drive speed: The fluid delivery rate is proportional to the speed of rotation. Each design has a minimum and maximum operating speed: the faster the pump runs,
the shorter its life
5. Type of fluid: Pumps are designed to operate within a particular range of fluid viscosity. Mineral oils of the correct viscosity work satisfactory with most
pumps provided the oil is clean
6. Pump noise: The actual efficiency depends on design, operating pressure, speed and fluid viscosity
7. Cost:The initial cost of a pump is usually of secondary importance to running and maintenance costs.Gear pumps are cheaper, vane and piston pumps are expensive.
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