IMTS Mechanical Eng. (Fluid mechanics & pneumatic)

Page 54

FLUID MECHANICS & PNEUMATICS

50

Applications of a hydraulic accumulator 

Dampens hydraulic shocks which may develop when pressure surges occur in hydraulic systems.

Adds to the output of a pump during peak load operation of the system, making it possible to use a pump of much smaller capacity than would otherwise be required.

Absorbs the increases in fluid volume caused by increases in temperature.

Acts as a source of fluid pressure for starting aircraft auxiliary power units

Assists in emergency operations.

Pressure Intensifiers (or) Boosters It gives an output pressure higher than the input pressure and used in hydraulic circuit to increase value above the pump discharge pressure. Pressure intensifiers consist of cylinders of different diameters with pistons that are connected by a common rod. In double piston-cylinder devices, fluid is pumped into the larger cylinder and then expelled from the smaller cylinder at a higher pressure. To maximize efficiency, the larger piston is fitted with an o-ring. The smaller piston is lapped to a close fit. Typically, pressure intensifiers that produce higher pressures are built with heavier cylinders and pistons. Though not designed with high volumetric capacities, pressure intensifiers provide a simple and economical way to raise fluid pressures. For low pressure input is given by pneumatic pressure to the larger piston side which is transformed into a higher hydraulic pressure on the smaller piston side.

Fig. 4.4 Air oil intensifier 4:3 HYDRAULIC RESERVOIRS

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