This powerpoint presentation is for the mechanical engineering field and for the subject fluid power engineering. The topic covered is all the hydraulic machines used.

2.  Name: Achal Parekh : 150050119053
 Division : ME-1 Dept. : Mechanical Engineering
 Subject : Fluid Power Engineering
 Faculty Guide : Prof. Sunny Rach

3. Principle:
The hydraulic press depends on Pascal's principle:
“The intensity of pressure in a static fluid is transmitted
equally in all directions.”
One part of the system is a piston acting as a pump, with a
modest mechanical force acting on a small cross-sectional
area; the other part is a piston with a larger area which
generates a correspondingly large mechanical force.
Only small-diameter tubing (which more easily resists
pressure) is needed if the pump is separated from the press
cylinder.

4.  A fluid, such as oil, is displaced when either piston is pushed inward.
Since the fluid is incompressible, the volume that the small piston
displaces is equal to the volume displaced by the large piston.
 This causes a difference in the length of displacement, which is
proportional to the ratio of areas of the heads of the pistons, given that
volume = area × length.
 Therefore, the small piston must be moved a large distance to get the
large piston to move significantly. The distance the large piston will
move is the distance that the small piston is moved divided by the ratio
of the areas of the heads of the pistons.
 This is how energy, in the form of work in this case, is conserved and
the law of conservation of energy is satisfied. Work is force applied over
a distance, and since the force is increased on the larger piston, the
distance the force is applied over must be decreased.

5.  The weight that is to be lifted by the ram can be given
by :
 W= f*(A/a)

7.  A hydraulic accumulator is a pressure storage reservoir in
which a non-compressible hydraulic fluid is held under
pressure that is applied by an external source.
 The external source can be a spring, a raised weight, or a
compressed gas.
 An accumulator enables a hydraulic system to cope with
extremes of demand using a less powerful pump, to
respond more quickly to a temporary demand, and to
smooth out pulsations.
 It is a type of energy storage device.

8.  An accumulator is placed close to the pump with a non-return valve
preventing flow back to the pump. In the case of piston-type pumps
this accumulator is placed in the ideal location to absorb pulsations of
energy from the multi-piston pump. It also helps protect the system
from fluid hammer. This protects system components, particularly pipe
work, from both potentially destructive forces.
 An accumulator can maintain the pressure in a system for periods
when there are slight leaks without the pump being cycled on and off
constantly. When temperature changes cause pressure excursions the
accumulator helps absorb them. Its size helps absorb fluid that might
otherwise be locked in a small fixed system with no room for expansion
due to valve arrangement.

9. Capacity of Hydraulic Accumulator: It is defined as the maximum amount of hydraulic
stored in the accumulator.
The expression for the capacity of accumulator is obtained as:
Let A = Area of the sliding ram
L = Stroke or lift of the ram
p = Intensity of water pressure supplied by the pump, and
W = Weight placed on the ram (including the weight of ram)
= Intensity of pressure * Area of ram = p * A
The work done in lifting the ram = W ´ lift of ram = W *l = p *A*l
Work done, in lifting the ram is also the energy stored in the accumulator and energy stored
is equal to the capacity of the accumulator.
Capacity of accumulator = work done in lifting the ram = p * A*l = p *V

10. Towers type:
 The first accumulators for Armstrong's hydraulic dock machinery were
simple raised water towers. Water was pumped to a tank at the top of
these towers by steam pumps. When dock machinery required
hydraulic power, the hydrostatic head of the water's height above
ground provided the necessary pressure.
Raised weight
 A raised weight accumulator consists of a vertical cylinder containing
fluid connected to the hydraulic line. The cylinder is closed by a piston
on which a series of weights are placed that exert a downward force on
the piston and thereby pressurizes the fluid in the cylinder.This type
delivers a nearly constant pressure, regardless of the volume of fluid in
the cylinder, until it is empty.

11. Compressed gas (or gas-charged) closed accumulator
 A compressed gas accumulator consists of a cylinder with two chambers
that are separated by an elastic diaphragm, a totally enclosed bladder, or a
floating piston. One chamber contains hydraulic fluid and is connected to
the hydraulic line. The other chamber contains an inert gas under pressure
(typically nitrogen) that provides the compressive force on the hydraulic
fluid. Inert gas is used because oxygen and oil can form
an explosive mixture when combined under high pressure. As the volume
of the compressed gas changes, the pressure of the gas (and the pressure
on the fluid) changes inversely.
Spring type
 A spring type accumulator is similar in operation to the gas-charged
accumulator above, except that a heavy spring (or springs) is used to
provide the compressive force. According to Hooke's law the magnitude of
the force exerted by a spring is linearly proportional to its change of length.
Therefore, as the spring compresses, the force it exerts on the fluid is
increased linearly.

14.  A device used to increase the intensity of
pressure of the water or oil by means of
hydraulic energy available from large quantity
of water at low pressure is known as
intensifier .
Construction : It consist of fixed ram
surrounded by a sliding cylinder which contains
high pressure water is supplied to the machine
through the fixed ram . The sliding cylinder is
enclosed in a fixed cylinder which contains low
pressure liquid supplied from main supply line .

15.  The valves v1 & v3 allow pressure water from the
supply line and valve v1 is for discharge and through
valve v2 ,high pressure water is supplied to the system .
 Working : At the beginning assume that the sliding
cylinder is at bottom most position and the fixed
cylinder is full of low pressure water .
 Then valve v2 & v3 are closed and valve v1 is opened ,
so the low pressure water from supply through valve v1
is admitted into the sliding cylinder .
 This permits the low pressure water from the fixed
cylinder to be discharged through valve v1 as it is kept
open and the moving cylinder moves up.

16.  When the sliding cylinder reaches its top most
position , the inside of the sliding cylinder is full of
high pressure water .
 Now the valves v1 & v4 are closed and valves v2 & v3 are
opened .
 Then low pressure water through the valve v3 enter at
top of sliding cylinder which forces the sliding cylinder
downwards and produces high pressure water in the
sliding cylinder which is supplied to the machine .
 The same cycle is repeated again and again.

18. Construction & Working
 Hydraulic crane is a device, used for raising or transferring heavy loads. It is widely used
in workshops, warehouses and dock sidings.
 A hydraulic crane consists of a mast, tie, jib, guide pulley and a jigger. The jib and tie are
attached to the mast. The jib can be raised or lowered in order to decrease or increase
the radius of action of the crane.
 The mast along with the jib can revolve about a vertical axis and thus the load attached
to the rope can be transferred to any place within the area of the crane's action. The
jigger, which consists of a movable ram sliding in a fixed cylinder, is used for lifting or
lowering the heavy loads.
 One end of the ram is in contact with water and the other endis connected to set of
movable pulley block. Another pulley block, called the fixed pulley
 The pulley block, attached to the ram, moves up and down while the pulley block,
attached to the fixed cylinder, is not having any movement.
 A wire rope, one end of which is fixed to a movable pulley (which is attached to the
sliding ram) is taken round all the pulleys of the two sets of the pulleys and finally
passes over the guide pulley, attached to the jib. The other end of the
rope is provided with a hook, for suspending the load.

19.  For lifting the load by the crane, the water under high pressure is admitted
into the cylinder of the jigger. This water forces the sliding ram to move
vertically up.
 Due to the movement of the ram in the vertically up direction, the movable
pulley block attached to the ram also moves upward.
 This increases the distance between two pulley blocks and hence the wire
passing over the guide pulley is pulled by the jigger.
 This raises the load attached to the hook.

20.  Hydraulic jacks are typically used for lifting heavy load
through small vertical distance by the application of
smaller effort.
 It is widely used for raising automobile vehicles in service
stations and to lift trolley in agriculture vehicles.
 Construction :
 It consists of a cylinder which is inverted and can move
downward on ram which is fixed with frame of jack.
 The top end of inverted cylinder contains a small
reciprocating pump operated by a lever outside the casing.

22. Working :
 When lever is working, Water is contained in the casing is forced out of into
the portion of the inverted cylinder above ram.
 Due to pressure, the upward force acts on the inverted cylinder.
 The cylinder therefore moves up and lifts load placed on the top of casing.

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