Hydraulic Cylinders

Hydraulic Cylinders
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Hydraulic Cylinders

Product catalog summary
Overview of Veljan's Offerings
Veljan is a well-established provider of high-quality fluid power products, serving industries such as machine tools, mining, mobile machinery, and marine equipment for over 35 years. They offer a comprehensive range of pneumatic products and hydraulic systems through a joint venture, providing a single-source solution for customers.

Hydraulic Cylinder Series
  • Series-HT: Compact tie-rod square type cylinders rated for 160 bar, adhering to ISO standards for various bore sizes.
  • Series-HR: Non-tie-rod welded round type cylinders for medium series applications, also rated for 160 bar.
  • Series-HH: Heavy-duty cylinders rated for 250 bar, suitable for high-pressure applications.
  • Specials: Custom-designed cylinders for pressures up to 500 bar and bores up to 800mm.

Seal Types
Veljan provides a variety of seals for different applications, including elastomeric piston seals, low friction seals, PTFE U-cups, and cast iron piston rings, each suited for specific conditions like high temperatures or low friction requirements.

Selection Process for Veljan Cylinders
The selection process involves determining the required force, calculating cylinder areas based on system pressure, checking rod diameter for strength, and selecting appropriate mounting styles and accessories. Variations from standard options include different port types, cushion adjustments, and rod-end threads.

Application Engineering Considerations
Considerations include acceleration, deceleration, piston speed, and temperature extremes. The document provides formulas and examples for calculating forces required for acceleration and deceleration in both vertical and horizontal motions.

Cushioning in Cylinders
Cushioning is crucial for decelerating moving masses, extending cylinder life, and reducing noise and hydraulic shock. The document explains when cushions are needed, how they are implemented, and optional features like air bleeds and gland drains.

Optional Features
Veljan offers optional features such as air bleeds for self-bleeding cylinders, gland drains for oil accumulation, and stroke adjustment for precision in end positions. Single-acting cylinders can be configured from standard double-acting cylinders.

Specifications and Design Features
The document outlines various cylinder designs, including single-acting cylinders with spring return and multiple stroke cylinders. It emphasizes the importance of stop tubing to prevent excessive bearing wear and rod buckling in long push stroke cylinders, providing detailed steps to determine when stop tubing is necessary and how to calculate its length.

Rod Diameters and Column Strength
A table is provided to determine the appropriate rod diameter for different force and rod size combinations, using the Euler formula for buckling with a safety factor of 4. Guidance is given on using compressive strength formulas for low slenderness ratios and selecting oversize rods for specific applications.

Piston Speed and Fluid Flow
Piston speed in hydraulic cylinders is influenced by the fluid flow rate, with a standard velocity limit of 5 meters per second to minimize turbulence and pressure loss. A table lists piston speeds for standard and oversize ports, recommending larger pipes or oversize ports if necessary.

Mounting Styles
Various mounting styles are discussed, including fixed and pivot mountings. Fixed mountings are subdivided into center-line and off-center mountings, with specific recommendations for tensile and compressive loads. Pivot mountings are categorized based on pivot location, with specific styles like clevis/eye and trunnion mountings.

Standard Design Features
The document describes features to enhance performance, such as secured pistons, self-centering cushion collars, and high-strength tie rods. It also details the materials and construction of components like the piston rod, tube, and ports.

Dimensional Standards
Detailed dimensions for various mounting styles and cylinder configurations are provided, including bore and rod sizes, port dimensions, and mounting dimensions for different series and styles.
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Catalog excerpts

Hydraulic Cylinders-1

Veljan's reputation as the designer and manufacturer of fluid power products of utmost reliable quality is an established fact for over 35 years now. With the back-up of up-to-date & state-of-the-art production facilities and a clear-cut focus on design engineering and product development, Veljan effectively meets the demand for a very wide spectrum of applications, such as in : ♦ STEEL MILL EQUIPMENT ♦ ATOMIC ENERGY EQUIPMENT ♦ POWER PROJECTS EQUIPMENT ♦ STABILISERS AND STEERING GEARS ♦ FORGE AND FOUNDRY EQUIPMENT Besides hydraulic and pneumatic cylinders for every conceivable application, Veljan continues to engineer, manufacture and market a wide range of pneumatic products. To achieve, maintain and provide a "single source system" facility, Veljan's joint venture company manufactures high performance Hydraulic Pumps, Motors, Valves and Systems. This has enabled Veljan products and services to be reckoned as the benchmarks for quality. While this catalogue is intended as a brief guide to the selection of standard Veljan Hydraulic Cylinders, Veljan also offers customised equipment and the specials needed by its valued and satisfied customers drawn from various sectors of the industry who have been regularly sourcing their requirements of these cylinders and other fluid power products from Veljan. Veljan, with its proven track record, technical expertise, design and engineering capabilities in the realm of high quality products and prompt services is confident of satisfying the exacting

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Hydraulic Cylinders-2

HYDRAULIC TYPES OF HYDRAULIC CYLINDERS Veljan offers various types of Hydraulic Cylinders for different pressure ratings and applications : Series-HT Compact tie-rod square type construction Hydraulic Cylinders rated for 160 bar with mounting dimensions conforming to ISO:6020 part 2 for 40 to 200 mm bore and ISO:6020 part 3 for 250 and 320 mm bore sizes. Series-HR Non-tie-rod welded round type construction of 160 bar medium series Hydraulic Cylinders with mounting dimensions conforming to ISO:6020 - part 1, in bore sizes from 40 to 320 mm. The above HT and HR series cylinders are also suitable...

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Hydraulic Cylinders-3

SEALS offers differ ferent Veljan offers the following variety of seals to suit different applications : PISTON SEALS ROD SEALS ELASTOMERIC Piston seals with integral anti-extrusion Rings are fitted as a standard for 160 bar application.Compact seals with bearing rings conforming to ISO:6547 dimensions and leak-tight under normal operating conditions are optional. These are suitable for speeds upto 0.5 m/s and holding loads in position. POLYURETHANE internally lubricated Rod Seals LOW FRICTION Piston Seals conforming to ISO:7425-1 grooves employ an elastomer energised PTFE ring and may be used...

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Hydraulic Cylinders-4

ELASTOMERIC PISTON SEAL POLYURETHANE LOW FRICTION PISTON SEAL PTFE ROD SEAL LOW FRICTION ROD SEAL PTFE CAST IRON PISTON RINGS 7 SEAL ROD U-CUPS WIPER

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Hydraulic Cylinders-5

HOW TO SELECT A VELJAN CYLINDER : APPLICATION ENGINEERING The following simple steps ensure that principal factors are considered while selecting the cylinder : Application 1. First Establish : -Force (F) needed or weight to be moved -Stroke or distance to be travelled. Check the following Acceleration Check whether the calculated and force is sufficient to accelerate/ Decelaration decelerate the load within prescribed distance. Check back-pressure rise during cushioning is within limits. 2. Based on the available or selected system pressure P, calculate the cylinder areas required by using the...

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Hydraulic Cylinders-6

ACCELERATON ACCELERA TON & DECELERATION DECELERATION IN CYLINDERS : It is often necessary to determine the Force F required to accelerate or decelerate a given mass. The maximum velocity `V’ attained by a mass `m’ over a distance `s’ is dependant on the force `F’ related as 2 follows : F=ma where a= v 2S These forces will help in selecting a proper size cylinder, pump pressure etc. They will also help in checking the safety of various system components by finding out the pressure rise when a moving load is stopped by means of internal cushions. The following examples well help in understanding...

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Hydraulic Cylinders-7

CUSHIONING In power cylinders, cushioning means deceleration of moving masses. Cushioning extends cylinder life and reduces undesirable noise and hydraulic shock. 1. When Cushions are required. Cushioned cylinders should be used whenever the piston is required to move heavy loads or travel at high speeds, say more than 0.1m/sec. Under both these conditions, the piston will pound the head and cap causing heavy damage to the piston and also heavy deceleration forces will be set up on the moving members. To minimise these effects, a back pressure or resisting force must be built up inside the cylinder...

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Hydraulic Cylinders-8

FEATURES OPTIONAL FEATURES AIR BLEEDS Hydraulic cylinders vertically mounted or horizontally mounted with ports on top are self bleeding when cycled full stroke and do not require air bleeds. When required or called for, bleed screws can be optionally provided at either end of the cylinder. Location of bleed screws must be specified to suit the accessibility in a particular application. The bleeder port of 1 /4” BSP is standardized for cylinders of 50mm bore and above. 1/8” BSP is provided for 40mm bore cylinders. Minimess type bleed screws are optional. AIR BLEEDS STANDARD TYPE MINIMESS TYPE...

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Hydraulic Cylinders-9

STOP TUBING Stop tube is ideal for preventing excessive bearing wear and rod buckling on long push stroke cylinders. A stop tube is a tubular spacer positioned between the piston and the cylinder head in the extended condition. The increased distance between the piston and the Rod bushing reduces bearing reactions. Stop tubes are useful to prevent buckling of horizontally mounted, long stroke cylinders on push stroke. These are more effective, less costly, and lighter in weight than oversize piston rods. When to specify stop tubing for your cylinder. The following simple steps give you the answer...

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Hydraulic Cylinders-10

STOP TUBE GROUP A STOP TUBE IS NOT REQUIRED. TO CHECK FOR ROD DIAMETER SHORT GUIDE LONG GUIDE LOAD PIN - CONNECTED & GUIDED LOAD SUPPORTED & GUIDED ANY FIXED/MIXED MOUNTING (HORIZONTAL/VERTICAL) GROUP B VERTICAL MOUNTINGS GROUP C HORIZONTAL MOUNTINGS

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