Circuits for Closed-circuit Hydro-static Transmissions (HSTs)

In a closed-circuit hydrostatic transmission (HST) system, a hydraulic pump drives a hydraulic motor. In the closed-circuit HST system, the fluid discharged from the hydraulic motor outlet flows directly to the pump inlet, thus forming a power transmission loop. The transmission loop has a high-pressure side and a low-pressure side. The pressure on the high-pressure […]

A Comparative Study of Pressure Control Valves

Pressure control valves are used in hydraulic systems for obtaining pressure-related regulation and control tasks. The control tasks include limiting the maximum operating pressure in a hydraulic system, reducing the pressure in a part of a hydraulic circuit, unloading pumps, establishing the sequence movements of actuators, counterbalancing overrunning loads, and braking hydraulic motors while running […]

Essential Relations in a Pump–Cylinder Hydraulic System

The figure below gives the summary of useful relations (SI units) of a pump-cylinder hydraulic system for highlighting their correlations. Joji Parambath Author / Trainer joji.p@hotmail.com Note: Several essential mathematical relations are also given in books ‘(1) Industrial Hydraulic Systems and Circuits -Basic Level (In the SI Units), (2) Industrial Hydraulics -Basic Level (In the […]

Manufacturing Process of Hydraulic Cylinders – Salient Points

Hydraulic cylinders are used in many types of machines and systems for industrial and mobile applications. The manufacturing process of cylinders mainly involves the following steps: design, heat treatment, machining, coating, assembly, and testing.  The Design Phase, Cylinder Manufacturing In the design stage, the requirement specifications of the cylinder to be designed are transformed into […]

Environmental Effects of Hydraulic Fluids

In every hydraulic system, a tightly confined incompressible fluid medium is used to transmit energy from the power pack to the actuators in the system. The fluid medium is formulated from a base stock and additives. The base stock should possess all the essential characteristics to perform well in a particular class of hydraulic systems. […]

Filtration Principles of Pneumatic and Hydraulic Systems: A Comparison Study

This article is the third part of the following three-part series of articles: Filtration and Drying Principles in Pneumatic Systems Filtration Principles in Hydraulic Systems Filtration Principles of Pneumatic and Hydraulic Systems: A Comparison Study The filtration principles of pneumatic and hydraulic systems were given in the previous articles. The third part of the three-part […]

Filtration Principles in Hydraulic Systems

This article is the second part of the following three-part series of articles: Filtration and Drying Principles in Pneumatic Systems Filtration Principles in Hydraulic Systems Filtration Principles of Pneumatic and Hydraulic Systems: A Comparison Study A hydraulic power system transmits the power in a controlled manner using an incompressible oil medium. Remember, the fluid medium […]

Filtration and Drying Principles in Pneumatic Systems

This article is the first part of the following three-part series of articles on filtration: 1. Filtration and Drying Principles in Pneumatic Systems 2. Filtration Principles in Hydraulic Systems 3. Filtration Principles of Pneumatic and Hydraulic Systems: A Comparison Study A pneumatic power system transmits the power in a controlled manner using a compressed air […]

Compressed Air Dryers

The natural water vapor content of air is concentrated and is carried through the compression process in a compressor as a vapor in high temperatures. A proper means of dehydration must be incorporated in the conditioning of compressed air where demands of high quality compressed air are entailed. A dryer can be used to receive […]

Bladder Accumulators – Basic Constructional Features and Specification Parameters

This article can be downloaded by clicking the link here A bladder accumulator consists of a seamless cylindrical pressure vessel (shell), internal elastomeric bladder, poppet valve, fluid (oil) port, charging valve, and clamps and brackets. A schematic diagram of a bladder accumulator is shown in the figure below and the basic constructional features and specification […]

Mounting Configurations of 4-port Hydraulic Directional Control Valves

[This is an extract of the article on ‘Mounting Configurations of 4-port Hydraulic Directional Control Valves’ authored by Joji Parambath. Full article can be downloaded by clicking the link here] Table 1 presents the size designations, port sizes, and nominal flow rates for different sizes of 4-port hydraulic directional control valves according to the DIN […]

Constructional Features of Hydraulic Cylinders

Hydraulic cylinders are designed to operate at high pressures and handle high loads in demanding operating conditions. Therefore, they need to be constructed with materials of high strength, expert workmanship, and advanced features to provide ruggedness, high quality, maintenance-free operation, and long service life. Some of the features of cylinder construction are presented below to […]

Side Loads in Hydraulic Cylinders

A long-stroke hydraulic cylinder often experiences significant side-load forces while in operation, especially when it is fully extended. The side load in the cylinder is the force component that acts laterally across the axis of its bearings, piston-rod seals, or piston. Many reasons can be attributed to the development of side loads on the cylinder. […]

Troubleshooting Chart for Hydraulic Pumps

The preventive maintenance is carried out on hydraulic systems to keep them in a perfect working condition at all times. However, faults or breakdowns do occur in hydraulic systems, which have to be traced and corrected with minimum delay and expense. Table below gives pump malfunctions and their potential causes and rectification. Disturbances Possible causes […]

Tips for Safe Hydraulic Operation

Some essential precautions necessary for the safe operation of hydraulic systems are enlisted below: Design and build hydraulic systems with safety in mind, Select hydraulic components and fluid conductors that are rated for the highest system working pressure, Position valves, safety guards, and controls with the operator’s safety in mind, Know the hazards involved in […]

Troubleshooting Chart for Hydraulic Cylinders

Most of the hydraulic system failures are similar. That is there is a sudden or gradual loss of pressure or flow. Consequently, cylinders and motors in these systems may stop working. Any of the system components can be at fault. Possible causes of hydraulic cylinder faults and their rectification are highlighted below: Possible causes Rectification […]

Safety in Hydraulic Systems

Any hydraulic system is inherently dangerous, as an enormous amount of energy is transmitted through the high-pressure system. There are many hazards associated with hydraulic systems. The safety of personnel must be ensured while they are operating and maintaining hydraulic systems. Every operator of hydraulic systems has the right to know the hazards of his/her […]

PLC Communication Services

A PLC system is configured using several networked components, such as PLCs, computer, communication modules, and HMI, with communication interfacing capabilities. These components can exchange data between two or more communication partners through the network using specific protocols for handling the data traffic. A network is characterized by the type of hardware involved, communication procedure, […]

Proximity Sensor Circuit Technology

Discrete output proximity sensors are most important for industrial applications. They gain importance in such applications where it is necessary to record or count moving objects or work-pieces on machines or conveyors. Based on the way of connection of the final output amplifier transistor of a discrete proximity sensor to the power supply terminals, proximity […]

Maintenance of Pneumatic Systems

As you are aware, a pneumatic system is an interconnection of various components such a compressor, actuators, control valves, and other elements using fluid conductors. The operation of the pneumatic system is affected by the presence of heat, dust, moisture, leaks, loose bolts, and misalignment in the system. Lack of regular maintenance may result in […]

Hydraulic Seals

Seals (or packings) are deformable materials sandwiched between the mating surfaces to close of their small gaps. They retain fluid under pressure within the system and keep foreign matter out. They prevent the metal-to-metal contact of sliding surfaces. They are made from polymer materials that are flexible (rubber) and soft (plastics). The elastomeric quality enables […]

Electro-pneumatics and Automation

An electro-pneumatic system, in general, consists of an electrical or electronic control part controlling the pneumatic power part of the system. Integrating the power density of pneumatic systems with the controlling possibilities of the electric systems opens up a new world of opportunities for the high-performing pneumatic systems. In this hybrid technology, solenoid valves are […]

Hydraulic Fluid Cleanliness Standards

The cleanliness of hydraulic fluids needs to be monitored for maintaining the components of hydraulic systems at a satisfactory level. Many national and international organizations such as ISO, SAE, National Aerospace Standards (NAS), etc., have developed standards for specifying the particle size classification and contamination concentration levels in hydraulic fluids. All standards specify the contamination […]

Load Sensing Hydraulic System

The primary goal while designing a hydraulic system is to use less energy and do more work. A conventional hydraulic system with a fixed-displacement pump provides a constant flow through the system. The maximum system pressure is limited by the settings of a pressure relief valve in the system. When the load demands less flow […]

Electro-hydraulic Proportional Valves

The most common valve configurations used for hydraulic control systems range from the discrete valves controlled by the electromagnets to infinitely variable valves, controlled by the special proportional electromagnets (or torque motors). Proportional valves are devices for obtaining the finely variable flow and pressure controls using proportional electromagnets. They were developed as a low-cost alternative […]

Design of Industrial Hydraulic Systems

Design of Industrial Hydraulic Systems in the SI Units By Joji Parambath The book describes the design aspects of hydraulic systems systematically. It highlights the essential parameters and specifications of hydraulic components in SI units. Design Concepts in Industrial Hydraulic Systems in the English Units By Joji Parambath The book highlights the essential parameters and […]

Fittings for Hydraulic Fluid Conductors

Hydraulic Pipes Tubes and Hoses in the SI Units By Joji Parambath This book presents the necessary information about the configuration, performance specifications, and other details of pipes, tubing, and hoses and their fittings. The book uses the SI system of units. Pipes Tubes and Hoses in Hydraulic Systems in the English Units By Joji […]

Swing Clamp Hydraulic Cylinders

Hydraulic Cylinders in the SI Units By Joji Parambath This book deals with hydraulic cylinders of varying designs. The principles of operation, constructional details, and classification of the hydraulic cylinders are explained in detail. This chapter also covers the topics on the position transducers, swing clamp cylinders, applications, design aspects of hydraulic cylinders, advantages, and […]

Hydraulic Power Packs – Essential Features

Hydraulic Power Packs in the SI Units By Joji Parambath The book deals with power pack components such as hydraulic reservoirs, pumps, pressure relief valves, unloading valves, filters, accumulators, and power pack control units. It also presents the noise reduction techniques for hydraulic systems. Next, the book highlights power packs with standardized assemblies. The book […]

Hydraulic Filters – Construction and Specification

Textbook on ‘Hydraulic Filters Construction Installation Locations and Specifications’ By Joji Parambath The textbook presents information on the construction, installation locations, and specifications of hydraulic filters, in detail. Please click on the image links to go to the Amazon Website Hydraulic filters need to be the integral parts of every hydraulic system to ensure the […]

Preventive Maintenance of Pneumatic and Hydraulic Systems

Textbook on ‘Maintenance Troubleshooting and Safety in Pneumatic Systems By Joji Parambath The book highlights all aspects of maintenance, troubleshooting, and safety in pneumatic systems, systematically. A section on energy saving highlights the steps that need to be taken for saving a substantial amount on energy costs. Textbook on ‘Maintenance, Troubleshooting and Safety in Hydraulic […]

Design of Pneumatic Systems

Textbook on ‘Design of Pneumatic Systems in the SI Units’ By Joji Parambath The book explains the design aspects of pneumatic systems systematically. The book also presents many typical examples of designing pneumatic systems using the SI units. Textbook on ‘Design Concepts in Pneumatic Systems in the English Units Please click on the image links […]

Electro-pneumatic Circuit Development for a stamping device

Electro-pneumatics and Automation Authored by Joji Parambath This book explains the functioning of single and double solenoid valves and various electrical control components such as pushbuttons, electro-magnetic releys, limit switches, reed switches, proximity sensors, timers, preset counters, and pressure switches. Many typical single-actuator and complex multiple-actuator electro-pneumatic circuits are also developed to illustrate various applications […]

Comparison of Power Transmission Systems (Part 2)

Textbook on ‘Pneumatic Systems and Circuits -Basic Level in the SI Units’ By Joji Parambath The book describes the topics on compressed air generation and contamination control, pneumatic actuators, and control valves, in detail. Many single-actuator control circuits are presented. Further, the book presents the maintenance, troubleshooting, and safety aspects of pneumatic systems. The book […]

Group Changing Pneumatic Circuit for Four Cascade Groups

Different positions of a group-changing pneumatic circuit for four cascade groups used for eliminating signal conflicts are illustrated in Figure below. Three pilot-operated 5/2 DC valves (reversing valves) are used to realize the group changing circuit. Figure | Different power supply positions of a four-group circuit Initially, the supply is in the last group, G4, […]

The Essential Parameters of Pressure Relief Valves

Some essential factors concerned about the operation of hydraulic pressure regulators are its set pressure, cracking pressure, full-flow pressure, pressure-override, closing pressure, overpressure, blowdown, and backpressure. These useful terms are defined in the following sections: Set Pressure It is the inlet pressure, under the specified service conditions, at which a PRV is set to open. […]

Applications of Hydraulic Pumps

Industrial Hydraulic Systems and Circuits Basic Level in the SI Units By Joji Parambath The textbook deals with the components and circuits of hydraulic systems. The fundamentals required to understand the core topics are given initially. The book describes the topics on power packs, hydraulic actuators, and control valves, in detail. Next, the book also […]

Hydraulic Motors – Essential Parameters

Some critical factors relevant to the operation and applications every hydraulic motor are its operating pressure, displacement, flow rate, input power, output power, torque output, and efficienOperating Pressure (P) It is the pressure in a hydraulic system that overcomes all resistances in the system, which includes both useful work and losses. The rated pressure of […]

Telescopic Cylinders

A multi-stage telescopic cylinder has many cylinder bodies inside one another. That is; the piston-rod of the first stage is used as the barrel of the second stage, and the second piston-rod is used inside the barrel of the second stage. Similarly, there can be up to six stages in the cylinder. Therefore, the total […]

Pre-charging of Hydro-pneumatic Accumulators

Textbook on ‘Hydraulic Accumulators and Circuits in the SI Units’ By Joji Parambath The textbook presents information on the classification, constructional features, working, and essential terms and definitions, sizing, and safety and maintenance aspects of hydraulic accumulators. The book uses the SI system of units. Textbook on ‘Accumulators in Hydraulic Systems in the English Units’ […]

Comparison of Power Transmission Systems (Part 1)

Pneumatic Systems and Circuits -Basic Level (in the SI Units) By Joji Parambath The book describes the topics on compressed air generation and contamination control, pneumatic actuators, and control valves, in detail. Many single-actuator control circuits are presented. Further, the book presents the maintenance, troubleshooting, and safety aspects of pneumatic systems. The book uses units […]

The Concept of Automation

The work process to carry out an industrial task usually involves many recurring steps. These steps can be carried out manually or automatically. In the manual system, an operator is always present to decide every process step. In the automatic system, the process controls itself, partially or entirely, by the feedback of its condition. Therefore, […]

Air Compression Process

The compression (or expansion) of air can be thought of as taking place under isothermal or adiabatic or polytropic conditions. Isothermal compression process takes place under constant temperature condition. When a volume of air in a system is compressed or expanded instantly, there is no time to add or dissipate heat into or out of […]