The document discusses hydraulic actuators, detailing their function in converting fluid pressure into mechanical energy with a focus on hydraulic cylinders. It outlines the components and types of hydraulic cylinders, including single acting and double acting cylinders, along with their applications and mechanisms like cushioning. Additionally, it introduces telescopic cylinders, which are multi-stage units designed for compact spaces.

1. Mohammad Azam Khan
HYDRAULIC
ACTUATORS
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2. Mohammad Azam Khan
HYDRAULIC ACTUATORS
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• The fluid dischargedby the pump is directedto the ‘hydraulic
actuator’.The actuator convert the pressure energy of the fluid into
mechanical energy.There are 3 basic type of hydraulic actuator.
• The actuators convert the fluid pressure to a suitable linear or rotary
motion.
• Linear motion – Hydraulic cylinder
• Rotary motion – Hydro motor
• Rotary motion – Semi-rotaryactuator

3. Mohammad Azam Khan
HYDRAULIC CYLINDERS
• A hydraulic cylinder is a device, which converts fluid power into
linear mechanical force and motion. It usually consists of a movable
element, a piston and a piston rod operating within a cylindrical
bore.
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4. Mohammad Azam Khan
PARTS OF A HYDRAULIC
CYLINDER
• A hydraulic cylinder consists of the following parts
• Cylinder barrel
• Piston
• Piston rod
• Bush
• Cylinder head and cap
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5. Mohammad Azam Khan
TYPE OF HYDRAULIC
CYLINDER
Hydraulic
cylinder
Single acting
cylinders
Double acting
cylinders
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SINGLE ACTING CYLINDER
• In the case of a single actingcylinder, only the pistonside is pressurized
with hydraulic fluid.The cylinder can thus carry out work only in one
direction.
• The fluid which flows into the piston chamber causes a pressure to build
up the surface of the piston.
• The piston travels into its forward end position.The return stroke is
effectedby a spring, the dead weight of the piston rod or an external
load
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7. SINGLE ACTING CYLINDER.
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PLUNGER TYPE SINGLE
ACTING CYLINDER
• In the case of plunger cylinders,the pistonand
rod form a single component.
• Due to the design of the cylinder, the return
stroke can only be effectedby external forces.
The cylinders can therefore generallybe
installedonly vertically.
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PLUNGER TYPE SINGLE
ACTING CYLINDER
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PLUNGER TYPE SINGLE
ACTING CYLINDER
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APPLICATION OF SINGLE
ACTING CYLINDER
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DOUBLE ACTING CYLINDERS
• In the case of double acting cylinders, both piston surfaces can be
pressurized. A working movement can thus be performed in both
directions.
• With double acting cylinders with a single-sidedpistonrod, different
forces and speeds are obtained on the advance and returnstrokes due
to the difference in area between the piston surface and annular
piston surface.
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13. DOUBLE ACTING CYLINDERS
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14. APPLICATION OF DOUBLE ACTING
CYLINDERS
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DOUBLE ACTING CYLINDER WITH
END POSITION CUSHIONING
• Cylinder with end position cushioningare used to brake high stroke speeds
smoothlyand prevent hard impacts at the end of the stroke. Shortly before
the end position is reached, the cross- sectionfor the outflow of fluidis
reduced by the built-in cushioningpistons and then finallyclosed.The
hydraulic fluid is then forced to escape through a flow control valve.
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CUSHIONING CYLINDER
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END POSITION CUSHIONING
• The piston is a short distance
before its end position; the
hydraulic fluid on the piston- rod
side must escape via the
adjustable flow control valve
above the piston rod
• This type of end position
cushioning is used for stroke
speed between 6 m/min and 20
m/min. At higher speed,
additional cushioning or braking
devices must be used
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18. Mohammad Azam Khan
END POSITION CUSHIONING
• The piston rod is on its returnstroke;
in this flow direction,the non-return
valve below the pistonrod is
opened, thus by-passing the flow
control valve.The pistonrod retracts
at maximum speed.
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DOUBLE-ACTING CYLINDER
WITH CUSHIONING
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TELESCOPIC CYLINDER
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• Often cylinder & rod length does not fit in the machine. In that case
the piston rod is also used as a piston barrel and a second piston rod is
used.
• These kinds of cylinders are called telescopic cylinders. If we call a
normal rod cylinder single stage, telescopic cylinders are multi-stage
units of two, three, four, five or more stages.
• In general telescopic cylinders are much more expensive than normal
cylinders. Most telescopic cylinders are single acting (push). Double
acting telescopic cylinders must be specially designed and
manufactured.

21. Mohammad Azam Khan
TELESCOPIC CYLINDER
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