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FP1: Introduction to hydraulic circuits and components (by distance learning)

This self-guided version of our popular introductory fluid power course offers a solid foundation and enables you to attend our other in-house courses.



Our introductory, distance learning course gives you a good working knowledge of hydraulic circuits and components. We introduce you to their principles of operation, performance characteristics and standard ISO symbol representation.

You'll learn how to draw circuit diagrams and design simple circuits for linear actuators, hydrostatic transmissions and velocity control. When you complete the course, you'll have a detailed understanding of:

  • the characteristics of hydraulic fluids
  • the need for contamination control
  • the functions of auxiliary devices such as accumulators and coolers

Learning and assessment

This is a multimedia-based course. You will buy a secure download from us with lecture presentations, notes and exercises. This includes 16 sections and five examples/exercises. We expect that it should take you between 20 to 40 hours to work through the material. The course runs in all modern browsers. To take full advantage of the included Flash-based videos and interactive animations, we provide instruction on how to install a browser-plugin called "Ruffle" - a secure Flash emulator that runs on Chrome and Firefox. If you have any questions about this, simply contact the team, we'll be happy to help.

On the assessed course you'll complete and return a piece of independent work for your final exercise. If your submission shows an acceptable level of understanding, then you will be awarded a certificate of competence.

If you don't meet this level, then we will give you guidance on which subject areas you should work on before resubmitting.

Our full distance learning course includes support, assessment and a certificate of competence. These are not included if you only choose to buy the material. We continually improve our course by integrating feedback from academic staff and students.

Final award

To successfully complete the course and receive the certificate of competence, you must:

  • attend the course in whole
  • pass the assessment

Who should apply

Our course is for professional engineers, graduates, technicians, managers and supervisory staff, particularly anyone new to the field of hydraulic fluid power systems. Choosing the distance learning option gives you the flexibility to complete the course around any work or life commitments. You should have basic mathematical knowledge to take this course.

Prices and dates

You can start our course at any time. For prices, please visit the Course Overview

Course objectives

When you complete this course, you should be able to:

  • understand how a wide range of hydraulic components and circuits operate, including an understanding of their underlying principles
  • analyse hydraulic circuits from schematic drawings and draw diagrams using standard ISO notation
  • design and analyse simple linear actuator and hydrostatic transmission circuits
  • understand different methods of velocity control, and evaluate circuits for given applications
  • select hydraulic fluids based on their classifications and properties
  • understand the effects of contamination, and achieve, monitor and maintain appropriate system cleanliness levels
  • demonstrate knowledge of the construction, operation principles, and uses of auxiliary equipment, such as filters, oil coolers, and accumulators

Course content

Fundamental principles

  • comparison of hydraulic, mechanical, electrical, and pneumatic systems in terms of performance, reliability, efficiency and versatility
  • units for hydraulic and mechanical quantities
  • ISO symbol representation of hydraulic components and circuits
  • causes and effects of pressure generation, pressure losses, heat generation, fluid leakage, cavitation, noise, and vibration
  • mathematical relationships between:
    • linear actuators: pressure, piston area and transmitted force; flow rate, cylinder dimensions and rod velocity
    • valves: orifice area, pressure losses, fluid viscosity and flow rate; flow rate, pressure differential and thermal power
    • pumps: displacement, shaft speed and flow rate; flow rate, operating pressure and hydraulic power
    • hydraulic motors: pressure, displacement and motor torque; flow rate, displacement and motor speed

Hydraulic actuators

  • Construction of linear actuators: cylinder tubes, piston assembly, seals, bearings, end covers, mounting arrangements, cushioning, position transducers
  • Actuator sizing: force, velocity, buckling, side loading
  • Rotary actuator types (rack and pinion, vane, helical) and applications

Directional control valves

  • applications for 2-position 2/3/4-way valves and 3-position 4-way valves in open/closed/tandem centre configuration
  • construction of DCVs: stand alone, sub-base, stacking, cartridge designs
  • operating forces and valve actuation
  • logic elements, poppet valves

Pressure control valves

  • construction, characteristics, and applications of single- and dual-stage relief valves
  • description of sequence valves, unloading valves, and pressure reducing valves including practical circuit examples
  • use of counterbalance valves for braking overrunning loads and winch applications

Positive displacement pumps

  • types of pumps: external and internal gear pumps, fixed/variable displacement vane pumps, fixed/variable displacement radial and axial piston pumps
  • flow and pressure control, constant power compensators
  • limitations on pump performance: cavitation, mechanical strength, lubrication, bearings, heat dissipation
  • flow, power, and torque equations, pressure/flow characteristics

Linear actuator circuits

  • the principle of operation and function of components in basic circuits, including actuator, directional control valve, pump, and pressure relief valve
  • circuits for single and double acting actuators, incorporating 2-position 3-way and 3-position 4-way valves in open-, tandem-, and closed-centre configurations
  • methods for dealing with leakage: use of pilot operated check valves and counterbalance valves
  • over-run protection, dynamic braking and decompression

Velocity control circuits

  • the relationship between piston areas, pressure, and flow on retraction and extension to force/velocity for symmetrical and unequal area actuators
  • influence of relief valves
  • velocity control with simple restrictor valves: flow control and effects of load change
  • circuits with pressure compensated flow control valves
  • meter-in, meter-out, and bleed-off systems
  • deceleration control, transient behaviour

Modulating valves

  • characteristics and operating principles of proportional, direct drive and servo valves
  • spool characteristics (overlap, underlap) and valve flow ratings
  • valve actuation and open/closed-loop control, time responses
  • multistage valves

Hydrostatic motors

  • description and comparison of high-speed low-toque motors (e.g. axial piston swash plate, bent axis) and low-speed high-torque motors (e.g. orbit, radial piston, radial piston cam)
  • ideal motor equations
  • causes and effects of volumetric and mechanical inefficiencies
  • motor specifications and selection criteria

Hydrostatic transmissions

  • open and closed loop systems: example circuits for mobile and industrial applications
  • output speed control
  • performance: power availability and efficiency

Hydraulic oils and fluids

  • functions, properties, performance classification, and fluid selection
  • ISO viscosity grades, effects of temperature
  • fire resistant and biodegradable fluids

Contamination control

  • sources, types, and effects of solid contaminants; prevention of contamination
  • contamination related failure modes
  • specification and monitoring of system cleanliness levels; establishing, achieving, and maintaining cleanliness targets
  • filter types, rating, location, and performance

Oil coolers

  • construction and characteristics of oil-to-water and air-blast coolers
  • thermodynamic principles of surface heat exchange
  • energy losses, effects of oil temperature
  • cooler selection and circuit considerations


  • types and construction of pneumatic accumulators (piston, bladder, diaphragm)
  • application examples - supplementing pump flow, leakage compensation, emergency supply, shock alleviation, suspension, etc.
  • accumulator cycles

Interactive exercises

  • virtual velocity control laboratory session
  • velocity control tutorial
  • linear actuator circuit design exercise
  • assessed design exercise: velocity control (full distance learning course only)

Computer Requirements

The majority of the course runs in any standard browser and even less powerful devices will be able to handle it without problem. To play back our interactive animations, you need to have internet access (less than 10MB of animation data will be transmitted) and install the secure Ruffle Extension to the Chrome browser. If you have any technical concerns, please contact us.


The University of Bath is regulated by The Office for Students (OfS).

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