Hydraulic systems rely on a specialized fluid – typically oil – to power the pistons that make the machine work. In a truck crane, hydraulics are responsible for raising and lowering the boom, extending the boom in a telescopic crane, controlling the steering and outriggers, and for adding and removing counterweights.
Any degradation in efficiency of your crane’s hydraulic systems can have a negative impact on boom truck’s performance and reduce the overall life of the hydraulic components.
What is one of the greatest threats to your boom truck’s hydraulics? The cleanliness of the fluid.
About five years ago, the Association of Equipment Management Professionals studied the issue of particle contamination in hydraulic fluid and published the results in its journal Up and Running.
The study included some attention-getting statistics:
- Between 70 and 80 percent of hydraulic equipment failures can be attributed to hydraulic fluid cleanliness (or lack thereof).
- Particles as small as 2 microns can cause problems in a hydraulic system.
- The most damaging particles are between 3 and 20 microns in size. These tend to escape standard fluid filters.
The authors suggest that oil analysis testing, which is the standard method used to assess the cleanliness of hydraulic liquid, is not sufficient because it cannot detect “damaging non-ferrous materials” that enter hydraulic liquids through dirty fluid-handling equipment, damaged seals, assembly debris or residual fluid in contaminated equipment.
Instead of oil analysis testing, the report recommends particle count testing which can detect particles as small as 2 microns. Since particles less than 10 microns can cause 3 ½ more times damage than particles larger than 10 microns, it is important to use the more sensitive test on your hydraulic oil.
Some other interesting results emerged from the study. These results use numbers based on ISO charts for cleanliness. For each size of particle, a count is cross-referenced to an ISO chart and an ISO number is assigned. Lower numbers mean cleaner systems. For example, a hydraulic fluid that showed 14,000 particles in the 2+ micron range, 3,780 in the 5+ micron range and 335 particles in the 15+ micron range would get an ISO number of 21/19/16. Now consider those results I mentioned:
- For mobile hydraulic equipment, like cranes, the counts are usually 23/21/19 or higher.
- Hydraulic fluid in the 23/21/19 range could generate 7,000 pounds of dirt in the system in a year (depending on pump volume).
- If the count were reduced to 14/12/9, the amount of dirt in the system would be drastically lowered to 14 pounds per year. The end result is a 15-year extension of system life.
Cleaning Your Hydraulic Liquid
Clearly, one of the keys to keeping your hydraulic crane in good working order is keeping the fluid clean. Talk to your service provider about improved filtration and particle testing to ensure that you maximize the life of your truck crane.