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 Vane pumps Gear pumps have a disadvantage of small leakage due to the gap between gear teeth and the pump housing. These limitations are overcome in vane pumps.  The leakage is reduced by using spring or hydraulically loaded vanes placed in the slots of the driven rotor.  Capacity and pressure ratings of a vane pump are generally lower than the gear pumps, but reduced leakage gives an improved volumetric efficiency of around 95%. Types: Vane pumps are available in a number of vane configurations including  sliding vane,  flexible vane, swinging vane,  rotary vane, and  external vane, etc.  Each type of vane pump has its own advantages.  External vane pumps can handle large solids.  Flexible vane pumps can handle only the small solids but create a good vacuum.  Sliding vane pumps can run dry for short periods of time and can handle small amounts of vapor.  The vane pumps are known for their dry priming, ease of maintenance, and...

 Hydraulic gear pumps: The gear pumps are robust and simple positive displacement pumps.  It has two meshed gears revolving about their respective axes. These gears are the only moving parts in the pump.  They are compact, relatively inexpensive, and have few moving parts.  The rigid design of the gears and houses allow for very high pressures and the ability to pump highly viscous fluids.  They are suitable for a wide range of fluids and offer self-priming performance.  Sometimes gear pumps are designed to function as either a motor or a pump.  This pump includes helical and herringbone gear sets (instead of spur gears), lobe-shaped rotors similar to roots blowers (commonly used as superchargers), and mechanical designs that allow the stacking of pumps.  Based on the design, the gear pumps are classified as: External gear pumps  Internal gear pumps Lobe pumps Gerotor pumps Generally, gear pumps are used to pump: Petrochemicals: Pure or fille...

Hydraulic Pumps The electric driving motor combined with the pumping is known as a hydraulic pump (in most pieces of literature, it is referred to as a  motor-driven pump also). The hydraulic pump takes hydraulic fluid (mostly some oil) from the storage tank and delivers it to the rest of the hydraulic circuit.  In general, the speed of the pump is constant and the pump delivers an equal volume of oil in each revolution.  The amount and direction of fluid flow is controlled by some external mechanisms.  In some cases, the hydraulic pump itself is operated by a servo-controlled motor but it makes the system complex.  The hydraulic pumps are characterized by its  flow rate capacity,  power consumption,  drive speed,  the pressure delivered at the outlet and  the efficiency of the pump.  The pumps are not 100% efficient.  The efficiency of a pump can be specified in two ways.   One is the volumetric efficiency which is the ...

Need for filters in fluid power systems Moving parts in fluid power systems are subject to wear from contamination. Neither atmospheric air nor hydraulic fluids are clean enough as supplied to avoid this and they both become more contaminated with use.  Therefore all fluid power systems require filters to remove contamination and thereby increase component life.  Normally, filters are used to prevent dirt or dust from entering important elements of the hydraulic system such as valves, seals, etc. Hydraulic filters:  Filters are used to remove very fine particles and can be installed in various places as shown in  Figure 1. The various types of filters are as follows: Inlet line filters or suction side filters: Inlet line filters or suction side filters are located before the hydraulic pump, these filters are designed to protect the pump from harmful contaminants that are within the hydraulic fluid. The filtering media within this type of filter is typicall...

Comparison of hydraulic and pneumatic systems It is important to consider various points for comparing pneumatic systems with hydraulic systems such as power level, noise level, cleanliness, speed, accuracy, temperature effects, etc. Principal advantages and distinguishing characteristics of pneumatic and hydraulic systems are listed below: Availability: Air is available everywhere in unlimited quantities. Transport: Air and hydraulic fluid can be easily transported over large distances through pipelines. Storage: Compressed air can be stored in a reservoir and removed as required. Hydraulic oil can be stored in accumulators. Temperature: Compressed air is relatively sensitive to temperature fluctuations, whereas hydraulic fluids are relatively insensitive. Explosion-proof: Compressed air offers minimal risk of explosion or fire.  Cleanliness: Any unlubricated air which escapes through leaking pipes or components does not cause contamination. Components: The operating compon...

The key elements of a typical hydraulic system consist of the following components: Tank/ Reservoir:  The reservoir holds the hydraulic fluid (liquid petroleum oils and synthetic oils, usually oil) required for the hydraulic system. Filter:  Filters are used to remove any foreign particles so as keep the fluid system clean and efficient, as well as avoid damage to the actuator and valves. Motor-driven Pump:  The hydraulic pump is used to force the fluid from the reservoir to the rest of the hydraulic circuit by converting mechanical energy into hydraulic energy. The hydraulic pump which is the heart of the hydraulic system converts the mechanical energy int hydraulic energy. The mechanical energy is delivered to the pump via a prime mover such as an electric motor.   Pressure regulator:  The pressure regulator, as the name implies, maintains the pressure level of the hydraulic fluid. Whenever excess pressure level is generated, excess fluid is dope...