A well-maintained hydraulic system is essential to keeping your drilling rig running efficiently today and for years to come. It is far more productive to prevent breakdowns through regular maintenance than to deal with the downtime and increased cost associated with hydraulic system failures. The emphasis should therefore be on proactive, rather than reactive, maintenance.

An important step in proactive preventative maintenance is to have a clear understanding of the equipment’s operating conditions. No hard and fast rules can be established here because of the great variety of circumstances. However, one thing is for certain: Frequent maintenance will increase the life of the system. Some important considerations: How many hours is the rig operating per day and per week? What percentage of time is it operating at maximum flow and pressure? Is the environment extremely hot, cold, contaminated with dust and debris, etc.? This information will help you to follow the equipment manufacturer’s maintenance guidelines while tweaking those recommendations to your specific operating conditions. It is good practice to develop your own maintenance program that can be followed by all personnel. Make it specific and clear, and take good notes regarding what maintenance was performed and when. Have the required tools and parts easily accessible.

Some key components of your hydraulic system include the hydraulic fluid filter, hydraulic tank, air breather and hydraulic pump. Basic maintenance on these components includes replacing the filter, cleaning the inside and outside of the hydraulic tank, checking and recording hydraulic pressures and flows, and inspecting hydraulic hoses and fittings. The drilling rig manufacturer’s equipment manual should include hydraulic circuit diagrams. Being able to read and understand these diagrams is vital for performing maintenance and troubleshooting.

Hydraulic oil accomplishes two essential functions: lubrication and transmission of power. It is the lifeblood of the hydraulic system and it must be kept clean if the entire system is to operate properly. Precision parts are very vulnerable to the effects of contamination and debris. Contaminated hydraulic fluid causes wear, which can create leaks and cause heat to build up in the system. In turn, heat can decrease the lubricating properties of the hydraulic fluid and cause further wear. Another culprit is aeration or the formation of air in a hydraulic system. This can cause leaks and turbulence or vibration, which increases component wear. Never add hydraulic fluid to a system through a contaminated funnel or container that has previously had other types of fluids and lubricants in it unless that funnel or container has been properly cleaned.

If a hydraulic pump or motor does fail, the system can become contaminated by particles and debris from the damaged unit. While the component must be removed and repaired, this is often not the greatest expense. The tank must be drained, flushed and cleaned. All hoses, lines, cylinders and valves should be inspected for wear and debris. All components of the entire system should be flushed to remove any particles. Finally, filters should be replaced, the hydraulic fluid that was drained from the system disposed of and the tank filled with clean hydraulic fluid. All of this downtime and expense can generally be avoided by following a schedule of preventative maintenance.

Rig manufacturers recommend periodically draining the hydraulic system and re-filling with new fluid. Best practice is to remove all fluid from the system. Starting the system and heating the fluid first will decrease the time it takes to drain the system and allow impurities suspended in the fluid to be removed. If possible, bleeding the fluid at the lowest point in the system will also help. If deposits have accumulated and will not drain, flush with a light viscosity fluid that also contains a rust inhibitor to protect metal surfaces against rust formation after draining.

Leaks in the system can and should be corrected. Leakage can create fire and health hazards (clean up spills and leaks immediately), waste oil, increase machine downtime and decrease production rates. The minor cost of controlling leaks is negligible when compared to the long term costs of leakage. Leaks are most likely to occur where a hose has been kinked or bent sharply. Severe bends can often occur at the end of the hose next to the fitting. Hydraulic components and fluids can become very hot, so exercise caution. Do not try to detect the source of a leak with bare hands. A word of caution: When you notice the start of a leak, your first thought may be to tighten the connection. However, it’s quite possible that another problem in the system needs to be addressed.

When valves require replacing, confirm that they are the correct type. Many types of valves may appear to be the same; however they may operate in completely different ways due to different inner components. Fitting an incorrect valve can have serious consequences, including damaging the pump and other components.

Do not attempt any adjustment without first stopping the engine and placing all hydraulic moving parts in a locked position at rest. Hydraulic parts can be locked in position by oil pressure even when the engine is not running and the removal of hydraulic hoses could cause parts to move due to gravitational down force. Therefore, release all hydraulic pressure before doing any work on the rig. If a component requires repair or replacement, confirm that the hydraulic hoses are suitable for the working pressure and that the hose fittings and connections are the correct type. A hydraulic hose failure can cause serious injury, so do not use damaged, frayed or deteriorated hoses, and replace hoses at the first signs of damage. High-pressure fittings should only be replaced in the workshop where appropriate tools are available.

You don’t have to be at the mercy of hydraulic component failure or system breakdown. Develop your own maintenance program based on equipment use and site circumstances, and take control with a proactive approach.

Troubleshooting Tips
Common indicators of a problem with the system or a component include excessive noise or heat, incorrect flow or pressure, and incorrect operation.

Excessive noise from a hydraulic pump or valve can be caused by air in the system, a misaligned coupling, or a worn or damaged motor or pump.

Excessive heat may be the result of a relief or unloading valve set too high, system pressure that is too high, defective fluid cooling, or a worn pump, valve, motor, cylinder or other component.

Incorrect operation could include having no flow, which could be caused by a damaged pump or drive motor. Low or excessive flow could result from a flow control set too low or too high, or from a leak in the system. No movement, slow or intermittent movement, and extreme speed or movement are all indicators of system error.

Simple, Proactive Steps
Three simple maintenance procedures increase hydraulic system performance, efficiency and life:

1. Maintain a sufficient amount of clean hydraulic fluid of the proper type and viscosity/grade.
2. Change filters and clean strainers regularly.
3. Keep all connections tight to prevent aeration; but not overly tight to the point where the valve body is damaged, which can result in metal cuttings entering the hydraulic system.