Skip to main content

FP1: Introduction to hydraulic circuits and components

Find out more about this CPD course, including dates, prices and course content.


This course is run in conjunction with the IMechE.

This introductory course give you a good working knowledge of hydraulic circuits and components. You'll explore their principles of operation, their performance characteristics, and standard ISO symbol representation.

During the course, you'll learn how to draw circuit diagram and design simple circuits for linear actuators, hydrostatic transmissions and velocity control. We'll introduce you to the characteristics of hydraulic fluids, the need for contamination control and the functions of auxiliary devices such as accumulators and coolers. Tutorials and laboratory work strengthen your understanding of how to apply your theoretical knowledge in practice.

Who should apply

Our introductory course is for professional engineers, graduates, technicians, managers and supervisory staff who are new to hydraulic fluid power systems. The course content is mostly descriptive; however, you will need basic mathematical knowledge.

Prices and dates

All our course prices and dates are listed on our Centre for Power Transmission & control cpd courses for industry page.

Course objectives

When you complete the course, you should:

  • understand how a wide range of hydraulic components and circuits operate, and be aware of the underlying principles
  • be able to analyse hydraulic circuits from schematic drawings and draw diagrams using standard ISO notation
  • be able to design and analyse simple linear actuator and hydrostatic transmission circuits
  • understand different methods of velocity control, and evaluate circuits for given applications
  • be able to select hydraulic fluids based on their classifications and properties
  • be aware of the effects of contamination, and achieve, monitor and maintain appropriate system cleanliness levels
  • understand how auxiliary equipment including filters, oil coolers and accumulators are constructed, operated and used

Course Contents

Fundamental principles

  • comparison between hydraulic, mechanical, electrical, and pneumatic systems in 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

  • principle of operation and function of components in basic circuits, incl. 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

  • 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


  • linear actuator circuit computer animations
  • velocity control computer animations
  • velocity control tutorial
  • linear actuator circuit design exercise

Laboratory Sessions

  • velocity control circuits
  • proportional valves
  • relief valve characteristics
  • circuit design and build exercises
  • linear actuator circuits
  • gear pump characteristics


The University of Bath is regulated by The Office for Students (OfS). We continually improve our course by integrating feedback from academic staff and students.

Learning, assessment and final award

Our teaching is carried out by people experienced in the field, mostly academic staff and PhD candidates as well as select guest speakers. There is no formal assessment and to successfully complete the course and receive the certificate of competence, you must attend the course in whole and participate in the exercises.

Continue your professional development with us

Find out more about what other CPD courses we offer.


If you have any questions, please contact us.

On this page