The document details hydraulic actuators used for controlling and transmitting power through fluid systems, highlighting the role of pumps and valves in managing flow. It categorizes hydraulic actuators into linear, rotary, and semi-rotary types, while also discussing various types of hydraulic cylinders, including single-acting, double-acting, telescopic, and tandem cylinders. Additionally, it discusses specific types of rotary actuators and the importance of cushioning in hydraulic systems to prevent impact during operation.

1. ME8694
HYDRAULICS AND PNEUMATICS
UNIT-2
HYDRAULIC ACTUATORS

2. Hydraulic Actuators
• Hydraulic systems are used to control and
transmit power.
• A pump driven by a prime mover such as an
electric motor creates a flow of fluid, in which
the pressure, direction and rate of flow are
controlled by valves.
• Hydraulic actuators are devices used to
convert pressure energy of the fluid into
mechanical energy

3. Types of hydraulic actuators
• 1. Linear actuator: For linear actuation
(hydraulic cylinders).
• 2. Rotary actuator: For rotary actuation
(hydraulic motor).
• 3. Semi-rotary actuator: For limited angle of
actuation (semi-rotary actuator

4. Types of Hydraulic Cylinders
Hydraulic cylinders are of the following types:
• Single-acting cylinders.
• Double-acting cylinders.
• Telescopic cylinders.
• Tandem cylinders.

5. SINGLE ACTING CYLINDER
According to the type of return, single-acting cylinders are classified as follows:
• Gravity-return single-acting cylinder
• Spring-return single-acting cylinder

6. • Gravity-Return Single-Acting Cylinder

7. Spring-return single-acting cylinder

8. Double-Acting Cylinder
• Double-Acting Cylinder with a Piston Rod on
One Side

9. Double-acting cylinder with a piston rod on both
sides

10. Telescopic Cylinder
• A telescopic cylinder is used when a long stroke
length and a short-retracted length are required.
• The telescopic cylinder extends in stages, each stage
consisting of a sleeve that fits inside the previous stage.

11. TANDEM CYLINDER
• It is used in applications where a large amount
of force is required from a small-diameter
cylinder.

12. 2005/2006 I. Hydraulic and Pneumatic Systems 12
Rotary hydraulic actuators
Swivel vane rotary actuator:
Limited angle in both directions
Maximum angle always smaller than 360°
The same torque in both directions
Piston rotary actuator:
With rack and gear coupling
Here maximum angle may be larger than 360°
Mindkét irányban azonosan
működő hengerrelésfogasléces
meghajtással működtetett
tolódugattyús lengőhajtás
Párhuzamdugatty
ús lengőhajtás
Forgódugattyús
lengőhajtás menettel
működtetett
meghajtócsappal
Limited angle rotary
actuator
Limited angle rotary
actuator
Parallel
piston rotary
actuator
??? ???

13. 2005/2006 I. Hydraulic and Pneumatic Systems 13
Rotary hydraulic actuators
Parallel piston rotary
actuator

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Rotary hydraulic actuators
???

15. 2005/2006 I. Hydraulic and Pneumatic Systems 15
Rotary hydraulic actuators
Rack-and-pinion piston-type rotary actuator:

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Semi-Rotary hydraulic actuators
Limited angle rotary actuator:

17. 2005/2006 I. Hydraulic and Pneumatic Systems 17
Semi-Rotary hydraulic actuators
Limited angle rotary actuator:

18. 2005/2006 I. Hydraulic and Pneumatic Systems 18
Semi-Rotary hydraulic actuators
Helix actuator:

19. Cushioning of cylinders:
• A hard impact of the piston at the end surfaces has
to be inhibited – kinetic energy has to be absorbed.
• This is done by increasing the hydraulic resistance at
the end of the stroke.