The Leading Cause of Breakdowns in Hydraulic Equipment, and How to Prevent it
The number one cause of breakdowns in hydraulic equipment is contamination. Luckily, in most cases it is very easy to prevent.
Advances in technology in the field of hydraulics has lead to powerful, reliable and very efficient machinery. With these advances, the necessary level of cleanliness of hydraulic oil has also risen, and keeping the hydraulic oil clean is now the most important maintenance task for hydraulic equipment.
Contamination can enter the system in many different ways, but the most common are built in contamination, ventilation, leaking seals and poor maintenance procedures.
Built in contamination is contamination from when the machine was initially built. This can range from very little contamination in machinery built in quality modern factories, through to large amounts in poorly managed factories in developing nations.
Most machine builders combat this by using quality procedures such as cleaning hydraulic lines and tubing before assembly, using highly trained assembly staff, and the fitment of efficient return to tank filters. Built in contamination is the main reason that hydraulic return filters must always be changed early in a machine's life, commonly at 50 working hours. This way any built in contamination is removed from the system after the machine is 'run in'.
Contamination through ventilation is another major cause of system contamination. This is through unfiltered air entering the system through normal use. As cylinders extend and retract, the hydraulic oil level in the hydraulic tank will raise and lower, drawing air from the atmosphere.
All hydraulic tanks that are open to the atmosphere should have a filtered tank breather fitted. This is especially important on mobile plants working in dusty environments. However many machines imported into Australia do not have filtered tank breathers fitted as a standard. If your machine does not have one we highly recommend to have one fitted to prolong the life of your equipment.
Leaking seals are a high cause of contamination. If oil can escape through a worn seal, contamination can enter the system through the same seal. A lot of contamination will enter the system through leaking cylinder seals as dirt and dust stick to the oily cylinder rod on extension. The dirt is then drawn into the system when the rod is retracted.
A leaking cylinder should always be a priority to be repaired, even on older machinery. It will cause a lot more damage then just leaking oil.
Poor maintenance procedures can be the most detrimental form of all contamination. There are three major causes of contamination from poor maintenance procedures.
Firstly, refilling the hydraulic oil tank with low grade oil. Low grade group 1 hydraulic oils are actually made to a lower cleanliness standard than group 2. Most modern machinery will specify a group 2 hydraulic oil as they result in superior performance due to additives and better cleanliness. Group 2 oils are so clean that they will generally be completely colourless.
The next common incorrect maintenance procedure is the use of the incorrect hydraulic filter, followed by the fitting of hydraulic lines that have not been cleaned prior to fitment. When new lines are manufactured, the lines need to be cut to length first. This will put dust and metal particles into the hydraulic hose. If it is not cleaned correctly then all the particles will end up straight in the system. We have seen many cases of pump failure due to this.