Lack of hydraulic system maintenance is the leading cause of component and system failure, yet most maintenance personnel do not understand proper maintenance techniques of a hydraulic system. The foundation to perform proper maintenance on a hydraulic system has three areas of concern: corrective, preventative and predictive.
It takes place following failure or damage, that is, it only occurs when there is an error in the system. This maintenance entails the following consequences:
- Unplanned shutdowns
- At production, it affects production lines
- It means costs due to not budgeted repair and replacement
- The time the system will be out of operation is not predictable
Preventative Maintenance (PM)
Preventive Maintenance of a hydraulic system is very basic and simple and if followed properly can eliminate most hydraulic component failure. Preventive Maintenance is also a discipline and must be followed consistently to obtain results.
Consider a PM program as being “performance oriented” rather than being “activity oriented.” Many organizations have good PM procedures but do not require maintenance personnel to follow them or hold them accountable for the proper execution of these procedures. To develop a good preventive maintenance program, follow these steps:
1. Identify the system operating condition.
- Does the system operate 24 hours a day, 7 days a week?
- Does the system operate at maximum flow and pressure 70% or better during operation?
- Is the system located in a dirty or hot environment?
- Identify the system operating condition.
2. What requirements does the Equipment Manufacturer state for Preventive Maintenance on the hydraulic system?
3. What requirements and operating parameters does the component manufacturer state concerning the hydraulic fluid ISO particulate?
4. What requirements and operating parameters does the filter company state concerning their filters ability to meet this requirement?
5. What equipment history is available to verify the above procedures for the hydraulic system?
As in all Preventive Maintenance Programs it’s a good practice to write procedures required for each PM task. Steps or procedures must be written for each task and they must be accurate and understandable by all maintenance personnel from entry level to master technicians. Preventive Maintenance procedures must be a part of the PM Job Plan which includes
- Tools or special equipment required performing the task.
- Parts or material required performing the procedure with store room number.
- Safety precautions for this procedure.
- Environmental concerns or potential hazards.
A list of Preventive Maintenance Task for a Hydraulic System could be:
Preventive Maintenance is the core support that a hydraulic system must have to maximize component life and reduce system failure. Preventive Maintenance procedures that are properly written and followed will allow equipment to operate to its full potential and life cycle. Preventive Maintenance allows a maintenance department to control a hydraulic system rather than the system controlling the maintenance department. You must control a hydraulic system by telling it when you will perform maintenance on it and how much money you will spend on the maintenance for the system. Most companies allow the hydraulic system to control the maintenance on them, at a much higher cost.
Predictive maintenance consists of determining the real technical conditions (mechanical and electrical) of the equipment examined, while it is in full operation.
The cause of many breakdowns couldn’t have been prevented with routine maintenance, but could have been caught with a predictive model. In many cases, it doesn’t make sense at all to do PMs from both a cost AND a time perspective. Regarding the preventative maintenance model, there are 3 critical factors in preventative maintenance that you must consider:
- How bad is the worst-case scenario?
- What is the likelihood of a breakdown?
- How much will it cost?
So, how often should you PM? Should you do it every 6 months, every 8 months or maybe every 4 months? This is something that is a bit controversial and needs to be looked at from a cost perspective. At the end of the day, PMs can be expensive if you are over PMing something, but it can help prevent critical failures. However, you also need to consider the fact that even if you PM something, that doesn’t necessarily prevent all failures. You need to make sure you are PMing the right thing and the correct frequency.
So, which is the better, predictive maintenance or preventive maintenance?
At the end of the day, ideally you would like to move from reactive to predictive. You also need to be able to tell when something is close to breaking down, or when the efficiency of that machine goes down to a point where it makes more financial sense to replace a component.