Hydraulic Preventive Maintenance

A sudden and unpredicted failure of any machine component can be not just inconvenient, but catastrophic.

In particular the load bearing nature of hydraulic systems can lead to sudden failure being particularly damaging. Despite this reality being well known, lack of maintenance is still the leading source of hydraulic system and component failure.

A well planned and implemented hydraulic preventive maintenance schedule with associated procedures is not just a good investment, but will pay for itself many times over during the life of the equipment.

Defining Hydraulic Preventive Maintenance

Hydraulic Preventive Maintenance does not have to be complex, but it does have to be consistently undertaken. Consistency means both in terms of frequency and quality of the service.

It will come as no surprise to learn that ensuring consistency starts with documented procedures. However, of equal importance to the procedures, is the allocation of procedural responsibilities and supervision to make sure they are carried out correctly and on time.

Organisations with a formal quality management system (QMS) such as ISO 9000, will already have the structure of procedures, frequency of use and checks to make sure everything is carried out.

For organisations without a formal QMS then procedures will need to be built from scratch and so the following can be used as a guide.

Creating a Preventive Maintenance Schedule

The first thing to do when creating a new preventive maintenance schedule is to review the equipment to be maintained in terms of both its use and its operating environment.

There are 4 stages to this as follows:

Stage 1 – Usage and environment

Assess the operating hours of the hydraulic system. How long does the equipment operate on a daily or weekly basis, eg 24 hours, 7 days per week or 16 hours per day 5 days per week?

Next, assess the flow and pressure of the hydraulic system during its operations and how close it operates to its operational limits.

Finally, assess the operating environment of the equipment. Eg is it in an exceptionally hot or dirty location, or perhaps exposed to salt water.

With this information we can assess the overall demands on the equipment which will feed into an estimate on the level and frequency of checks.

Stage 2 – Original Equipment Manufacturer’s Recommendations

Look at the manufacturer recommendations for preventive maintenance both in terms of detail and frequency.

Check what the recommendations of the component manufacturer with respect to the particulates in the hydraulic fluid.

Manufactures should normally provide advice on the level and frequency of checks which can be adjusted according to the information gleaned from Stage 1.

Stage 3 - Component Manufacturer’s Recommendations

Check the filter manufactures documentation to ensure the particulate requirement discovered in stage 2 can be met.

This stage is especially critical if the filter has been changed in the past and is no longer the one supplied by the original equipment manufacturer.

This information may require you to further adjust the frequency, or detail of checks established at stage 2.

Stage 4 – Maintenance History

Check the past maintenance history on this equipment. If breakdown maintenance has been undertaken more than once then this information may provide a clue as to the maximum interval for preventive routines.

In particular, if you find that past breakdown frequency is greater than the preventive maintenance schedule estimated in the earlier stages, then a re-think will be required.

If the preventive maintenance frequency established is substantially greater in the light of past maintenance then it is possible the equipment is either operating outside of its design parameters, or else approaching the end of its life. Consideration should be given to a potential exchange, or upgrade.

Detailing the Procedures

hydraulic maintenanceHow preventive maintenance overall is managed and undertaken should be outlined as part of the overall Quality Management System. If a QMS does not exist then a procedure will need to be established that dictates how maintenance is scheduled and monitored.

For each individual piece of equipment or machinery where preventive maintenance will be undertaken a separate standard operating procedure will be required.

In outline, each of these procedures should contain the following:

Title of the procedure

A short description of what the procedure covers.

Objective of the Procedure

A brief overview of why the procedure exists and the expected outcome on its completion.

Responsibility for undertaking the procedure

The job title responsible for ensuring the procedure is carried out correctly as scheduled. Avoid using personal names as people can move on.

Authorised responsibility for the content and date

The authorised responsibility is the person who authorised the content of the procedure. Here a name can be used in conjunction with job title as, even if the authority moves on, we still need to know specifically who made the authorisation.

Ideally this authority should be a role above those responsible for undertaking the procedure, but compromises may be required for smaller businesses.

Authorisation should be confirmed with a signature and date showing when the authorisation was made.

Identity reference and version number

A unique identifier for this document - together with a clear indication of the version number.

This identifier should be traceable to a company record that shows revisions, details of changes (ie what, when and who) and the correct current version.

This information is vital to ensure any independent audit can establish that the current procedure being used is the most up-to-date authorised version.


This information should define the minimum frequency with which the procedure should be undertaken. For example, once every 6 months.

It will still be possible to schedule the procedure more frequently (eg once every 4 months) as long as the minimum frequency is complied with.

Tools or special equipment

Defining all of the tools and equipment required at the outset makes sure that everything is available before work begins. This reduces time wasted during the procedure. It will also minimise both down time and the risk of accidental damage when using the wrong tools or equipment.

Parts or materiel required

As with the tools and equipment identifying all parts or materiel required to be on hand at the outset minimises down time.

Identifying the storage location or source of replacement materiel also minimises preparation time and so the overall time required by maintenance personnel.

Safety precautions

Ideally highlighted at the start of the procedure.

All risks associated with the undertaking of the procedure should be identified, both directly to the maintenance personnel, or indirectly to others .

Steps should be included in the procedure to minimise all clear risks. These should take into account who will undertake the procedure – see detailed steps below.

Environmental concerns

Environmental concerns includes such things as disposal of fluids after changing. These concerns may also form some of the risks – see above.

Detailed steps to be undertaken

This is the detailed step by step procedure.

It is possible to overdo this and so a general rule of thumb is that the more inexperienced the person likely to undertake the procedure, then the more detail it should contain.

It is also worth defining at the start a minimum skill, or experience required to undertake the procedure.

Additional reference material

If good quality maintenance information is contained in the original equipment manufacturer’s manual, it will make more sense to reference it than try to reproduce it.

Reference may also be made to the overarching maintenance plan, or schedule and/or smaller sub-procedures.

More Information

Please see our technical section for more information on hydraulic troubleshooting and other resources to support your hydraulic preventive maintenance.