This document provides information about hydraulic cylinders. It defines a hydraulic cylinder as a mechanical actuator that uses pressurized hydraulic fluid to provide linear force and motion. The key components of a hydraulic cylinder are described, including the cylinder barrel, bottom/cap, head, piston, piston rod, and seals. Equations for calculating the required diameter of the piston rod and thickness of the cylinder barrel based on the load and pressure are also presented. The document concludes with dimensions for an example hydraulic press cylinder and references additional resources.

1. BY
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Hydraulic Cylinder

2. Definition Hydraulic Cylinder
 A Hydraulic cylinder (also called a linear hydraulic motor) is a mechanical
actuator that is used to give a linear force through a linear stroke.
 It has many applications, notably in engineering vehicles.
 Hydraulic cylinders get their power from pressurized hydraulic fluid
(typically oil).
The hydraulic pressure acts on the piston to do linear work and motion.
This pressure build in the cylinder with the help of the pump acts on the
piston head and force is created by the piston.

3. Cylinder barrel:-
 In which a piston connected to a piston rod moves back and forth.
 The barrel is closed on each end by the cylinder bottom. These ends are
known as the cap end. The cylinder head where the piston rod comes out
of the cylinder.
 The piston has sliding rings which prevent the hydraulic oil to move from
one side of the cylinder to the other.
 The seal provides protection to the oil from coming out of the cylinder.

4. Cylinder Bottom or Cap:-
 In most hydraulic cylinders, the barrel and the bottom portion are welded
together. This can damage the inside of the barrel if done poorly.
 Therefore some cylinder designs have a screwed or flanged connection from
the cylinder end cap to the barrel.
 In this type the barrel can be disassembled and repaired in future.

5. Cylinder Head :-
 The cylinder head is sometimes connected to the barrel with a sort of a
simple lock (for simple cylinders).
 In general however the connection is screwed or flanged. Flange
connections are the best, but also the most expensive.

6. Piston:-
 The piston is a short, cylinder-shaped metal component that separates the
two sides of the cylinder barrel internally.
 The piston is usually machined with grooves to fit elastomeric or metal
seals.
 These seals are often O-rings, U-cups or cast iron rings. They prevent the
pressurized hydraulic oil from passing by the piston to the chamber on the
opposite side.
 This difference in pressure between the two sides of the piston causes the
cylinder to extend and retract.

7.  Piston seals vary in design and material according to the pressure and
temperature requirements that the cylinder will see in service.
 Generally speaking, elastomeric seals made from nitrile rubber or other
materials are best in lower temperature environments
 The best seals for high temperature are cast iron piston rings.

8. Piston Rod
 The piston rod is typically a hard chrome-plated piece of cold-rolled steel
which attaches to the piston and extends from the cylinder through the rod-end
head.
 In double rod-end cylinders, the actuator has a rod extending from both sides
of the piston and out both ends of the barrel.
 The piston rod connects the hydraulic actuator to the machine component
doing the work.
 This connection can be in the form of a machine thread or a mounting
attachment such as a rod-clevis or rod-eye.

9. 𝑪𝒂𝒍𝒄𝒖𝒍𝒂𝒕𝒊𝒏𝒈 𝑫𝒊𝒂𝒎𝒆𝒕𝒆𝒓 𝒐𝒇 𝒑𝒊𝒔𝒕𝒐𝒏 𝒓𝒐𝒅 𝒖𝒔𝒊𝒏𝒈 𝒃𝒖𝒄𝒌𝒍𝒊𝒏𝒈 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏
 𝑷𝒂𝒄𝒕 =
𝑷
𝒄𝒐𝒔𝜽
 𝑷𝒅𝒆𝒔𝒊𝒈𝒏 = 𝑷𝒂𝒄𝒕 × 𝑭𝑶𝑺
 𝑭𝒄𝒓 =
𝒏𝝅 𝟐 𝑬𝑰
𝑳 𝟐
 𝑰 =
𝝅𝒅 𝟒
𝟔𝟒
 𝑫 = 𝟐. 𝟓𝒅 𝑬𝒎𝒑𝒊𝒓𝒊𝒄𝒂𝒍
 𝑫𝒊 = 𝑫 + 𝟓(𝑬𝒎𝒑𝒊𝒓𝒊𝒄𝒂𝒍)
Design Calculation
Pact=load acting on inclined cylinder
𝜃 = 𝐴𝑛𝑔𝑙𝑒 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑣𝑒𝑟𝑡𝑖𝑐𝑎𝑙 𝑎𝑛𝑑 𝑎𝑥𝑖𝑠 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟
E=Youngs Modulus
I=Moment of inertia of circular rod
d=Diameter of piston rod
D=Diameter of piston
Di=Internal diameter of cylinder barrel

10.  CALCULATING THE THICKNESS OF THE BARREL
The lame's equations are:-
 𝝈 𝒓 =
𝒃
𝒓 𝟐 − 𝒂
 𝝈 𝒄 =
𝒃
𝒓 𝟐 + 𝒂
 𝝈
𝒓 =
𝑷 𝒅𝒆𝒔𝒊𝒈𝒏 × 𝒈
𝝅 𝑫 𝟐
 Barrel must be strong enough to absorb all the stress such that the stress at the
outer surface of the barrel must be zero.
 𝝈 𝒓=𝟎 (at radious ro)
 𝒕 = 𝒓 𝟎 − 𝒓𝒊
σr = The radial stress
σc = The circumferential stress
a and b = constants
t=cylinder barrel thickness

11. Industrial Visit

12. Hydraulic Press Cylinder

14. Dimensions
 d=Diameter of piston rod=22mm
 D=Diameter of piston=55mm

15. Video

16. Matlab Code

17. Reference:-
 Design data handbook
 Shigley
 V.B Bhandari
 http://www.mechanicalhero.com/2012/09/design-calculation-
analysis.html