this file consists precise information about various hydraulic machines used in our life and

1. HYDRAULIC
MACHINES
1
Presented By: Mohd Areeb Qureshi

2. Content
• Hydraulic Accumulator
• Hydraulic Press
• Hydraulic Ram
• Hydraulic Crane
2

3. Hydraulic Accumulator
• Hydraulic accumulators are energy storage devices.
• By storing the energy of fluid under pressure and make this
energy available to hydraulic machines such as presses, lifts
and cranes
• The main reasons that an accumulator is used in a hydraulic
system, is that the pump doesn’t need to be so large to cope
with extremes of demand and supply circuit can respond
quickly to any temporary demand.
3

4. Construction
• It consists of fixed vertical Cylinder, containing a sliding
ram/plunger.
• A load weight is placed on the top, to create pressure in the
Cylinder
• One side of the cylinder in connected to the pump and other
side to the machine(lift, crane).
4

5. Working
• An accumulator usually has a cylindrical chamber, which has a piston
in it.
• This piston is either spring loaded or some calculated weight is kept
on it or even pneumatically pressurized.
• The hydraulic pump pumps the fluid into the accumulator, which is
nothing but a sealed container.
• The volume of the container is fixed and cannot be changed. But the
quantity of hydraulic fluid being pumped inside the container is
increasing continuously. So the pressure of the hydraulic fluid inside
the container starts to increase.
• A heavy weight is placed on the ram. The inlet of the cylinder is
connected to the pump, which continuously supplies water or the
hydraulic fluid under pressure to the cylinder. The outlet of the
cylinder is connected to the machine (which may be a lift or a crane).
5

6. Expression for Capacity
• Maximum amount of hydraulic energy stored in the accumulator
is its capacity.
• Let,
A=Area of sliding ram
L= Stroke of Ram
p=Intensity of Pressure
W=weight placed on the ram
• Now, W=Intensity of pressure * Area of ram pA.
• Work done in lifting the ram=W*Lift of ram pAL.
6

7. ADVANTGES :
• Used to meet heavy industrial requirements.
• Extremely high capacity at low cost.
• Rugged and durable construction.
LIMITATIONS :
• Extremely bulky and heavy.
• Problem in sealing.
• In contrast to compressed gas Hydraulic engine accumulator,
this type delivers a nearly house, Bristol Harbor.
• In constant pressure, regardless of the volume of fluid in the
cylinder, until it is empty
7

8. Functions of Accumulator
• Emergency and safety: An accumulator which is kept constantly under
pressure is valuable in the event of an electrical power failure as it can
provide flow and pressure to perform an additional function or complete a
machine cycle.
• Shock or pulsation dampening: An accumulator can be used to cushion
the pressure spike from sudden valve closure, the pulsation from pumps or
the load reaction from sudden movement of parts connected to hydraulic
cylinders.
• Leakage compensation: An accumulator can be used to maintain pressure
and make-up for lost fluid due to internal leakage of system components
including cylinders and valves.
• Thermal expansion: An accumulator can absorb the pressure differences
caused by temperature variations in a closed hydraulic system.
• Noise reduction: An accumulator is effective at reducing hydraulic system
noise caused by relief valves, pump pulsations, system shock and other
circuit generated noises.
8

9. APPLICATIONS
• Accumulators are devices used to store fluid power to do the
following:
• Dampen pulsations and shocks of a periodic nature.
• Increase the speed of the operational circuitt.
• Clamping devices to hold the jaw vices and fixtures.
• Agricultural Machinery & Equipment.
• Oil Field & Offshore.
• Machine Tools and Off- Road Equipment.
• Mining Machinery & Equipment.
• Suspension in vehicles.
9

10. Hydraulic Press
• A hydraulic press is a mechanical machine used for lifting or
compressing large items(by much smaller loads).
• The force is generated through the use of hydraulics to
increase the power of a standard mechanical level.
• It is based on Pascal’s law, which states that when pressure is
applied on fluids in an enclosed system, the pressure
throughout the system always remains constant ie. transmited
equally in all the directions.
10

11. Construction
• There are two main parts in the hydraulic press assembly:
• One is called as ram having larger diameter.
• Second one is known as plunger having smaller diameter.
• Ram works as output medium where as plunger gives input.
• In between ram and plunger hydraulic fluid is filled in a closed
container which is responsible for the whole operation i.e.
force and pressure transmission. In practical situation both
plunger and ram have different area.
11

12. Working
• Ram is operated by the hydraulic pressure of fluid.
• When a small force f is applied on the plunger in the downward
direction, a pressure is produced on the liquid in contact with the
plunger.
• This pressure is transmitted equally in all the directions and ats on
the ram in upward direction
• Hydraulic accumulator stores the high pressure liquid when press is
at stationary position.
• If ,
o ‘A’ is the area of ram
o ‘a’ is the area of plunger
o then the mechanical advantage of the system is equal to A/a;
o F is the force applied to the plunger
o W is the load lift by the ram
• So according to the Pascal’s law pressure is
• P = F/a = W/A or W = F (A/a) 12

13. Applications:
• The major application of the hydraulic press is in industry
where big size metal objects transform into thin sheets by the
application of pressure force.
• Sheet metal operations such as drawing, deep drawing,
punching and blanking etc
• In crushing of scraps and old vehicles.
• In Packaging industry.
13

14. Advantages :
• Built-in overload protection
• Greater versatility compared to the mechanical press
• It is compact
• It is quiet in operation
• It is safe compared to the mechanical press
• Lower initial and operating cost
• It offers a full-power stroke
• Lower tool cost due to built-in overload protection
Disadvantages:
• Handling of hydraulic oil can be messy
• There are chances of hydraulic fluid leakage
• Hydraulic lines could burst due to excess pressure
• Some hydraulic fluids can catch fire
• The system gets heated because the hydraulic fluid is forced through the
pumps
• It has a low operational speed
• They have relatively high energy consumption
14

15. Hydraulic Ram
• A hydraulic ram is a cyclic water pump powered by
hydropower. Its function as a hydraulic transformer.
• It is a device which raises small quantity of water without any
external power to higher level from large quantity of water
available at lower level.
• It works on the principal of water hammer or inertia force of
water in a pipe line.
15

16. Constructional Details
• The main part of hydraulic ram are listed below:
a) Supply tank
b)Supply pipe
c)Valve chamber
d)Waste valve
e)Delivery valve
f)Air vessel
g)Delivery pipe
h)Delivery tank
16

17. WORKING
• Hydraulic ram works on the principal of water hammer as when a flowing
water is suddenly brought to rest the change in momentum of water masses
causes a sudden rise in pressure. This rise in pressure is utilizes to raise a small
quantity of water to higher level.
• Initially, the waste valve is open and delivery valve is closed. The water
from supply tank start to flow under the force of gravity and picks up speed
and kinetic energy until it forces the waste valve closed.
• The momentum of the water flow in supply pipe against now closed waste
valve causes a water hammer that raises the pressure in chamber. The high
pressure of water opens the delivery valve and water enters into the air vessel
which further compresses the air already preset in the air vessel.
• The pressure in the air vessel raises which closes the delivery valve ,now
water from air vessel is forced to flow through delivery pipe.
• Under this condition waste valve and delivery valve both remains closed
• Slowly pressure in the valve chamber falls and waste valve again opens
allowing the water to flow through it.
• Now, under this condition, flow through the supply pipe begins again
producing water hammer in the valve chamber. The cycle is repeated.
17

18. EFFICIENCY
• Hydraulic ram has two types of efficiencies namely D’Aubuisson’s
efficiency and Rankine’s efficiency.
1. D’Aubuisson’s efficiency:
• Let,
o Q = discharge from supply tank to valve chamber
o q = discharge from valve chamber to delivery tank
o H = height of water in delivery tank raised above the chamber.
o h = height of water in the supply tank above chamber (supply head)
• Since, Energy supplied to/by the ram per second = weight of water supplied
per second to chamber × height of fall or rised.
• So, energy supplied from the supply tank = ρQg.h
= ωQh ( ⸪m =ρQ and W=mg=ρQg)
• Energy delivered to delivery tank= ρqg.H
= ωqH
• Efficiency of ram, η = Energy delivered Energy supplied =
• ρ𝑞gH /ρQgh = 𝒒𝑯/𝑸𝒉
18

19. continued….
2. Rankine’ s efficiency: If the water level in the supply tank is taken as
datum. Then the actual height raised is (H-h).
• Energy supplied to supply tank = ρ(Q-q)gh.
= ω(Q-q)h
• Energy delivered to the delivery tank = ρqg(H-h)
= ωq(H-h)
• Efficiency, η = (ωq H−h) / (ω Q−q h) = (𝐪 𝑯−𝒉) / (𝑸−𝒒 𝒉)
• This is known as Rankine’s efficiency and its value is always less than
D’Aubuisson’s efficiency.
Reasons for low efficiency:
o High friction and secondry losses in the supply pipe and the valves.
o Loss of kinetic energy associated with the liquid leaving the waste valve
19

20. ADVANTAGES
1. No prime mover is required because it runs it self.
2. Simple design
3. Low repair cost
4. Negligible running cost
5. No electricity consumption
6. Long life
7. Reliable.
DISADVANTAGES
1. Large amount of water wasted through waste valve.
2. Its working is noisy.
3. Only suitable for certain sites.
20

21. Application
• To lift the drinking water from spring to high ground
settlement.
• Use where flowing water is available.
• It is useful in “hilly area” where large quantity of water flows
at low level is needed to be raised for domestic or irrigation
purposes
21

22. Hydraulic Crane
• A crane is a type of machine, mainly used for lifting heavy
things and traloading and unloading of freight, in
the construction industry for the movement of material
transnsporting them to other places.
22

23. 23

24. Continued….
• The jib and tie are attached to the vertical post .jib is hinged
near the foot of the vertical post .
• Hydraulic jigger consist of a movable ram sliding in a fixed
cylinder.
• The sliding ram , one end is connected to set of movable
pulley block and other end is contact with water.
• One end of wire rope fixed with cylinder body is taken round
all the pulley of the two sets of pulley and at the end passes
round the guide pulley block.
• The free end of the wire rope is attached with a hook for
suspending the load.
24

25. Working
• During the lifting the load by crane, the high pressure water is
admitted into the fixed cylinder of jigger.
• The pressuriesed water forces the sliding ram to move right
with movable pulley bock.
• So that the distance between two pulley blocks increases
• Which causes the wire passing over the guide pulley is pulled
by the jigger and hence the load attached to hook is lifted.
• For lower the load, close inlet valve and open vast valve so
that water is forced out the cylinder hence ram moves towards
the left and distance between two pulley blocks decreases,
which release the wire rope and the load is lowering down
25

26. Effeciency
η= Output/Iinput
=Weight * distance moved by weight
Forcen * Distance moved by force
26