Port Authority officials then shifted their attention to 21 Valmet/Sisu straddle carriers. Average engine life before overhaul on these machines was 7200 operating hours, and their maximum life was 9000 hr. Engine oil was changed every 250 hr and had an average ISO cleanliness code of 19/16.

The target to extend engine and oil change intervals was determined be an ISO particle level of 15/12. We fitted the machines with new filtration systems, and the result was oil change intervals extended to 750 and 1000 hr.

Furthermore, such favorable performance and test reports prompted the Port of Tacoma to push the period between engine overhauls out to 21,000 hr. At the beginning of last year, the equipment's Volvo engines had reached 16,000 service hours and were expected to reach the 21,000-hr target set nearly six years ago. Some of the engines have lasted even longer. Officials attribute much of this success to maintaining particle counts at or below target levels. In fact, ISO levels of 14/11 and 13/10 now are common.

Investment pays off

Tacoma Port Authority's cost of replacement hydraulic components fell by 59% within four years of implementing the testing and filtration systems. The total cost of maintaining its fleet of 21 straddle carriers fell by $209,000/yr - and this is after including the costs for oil analysis and filtration system retrofitting. In addition, officials claim to have all but eliminated unscheduled downtime for these machines.

Preliminary tests are now carried out on site. A sample of hydraulic fluid is taken from a gauge tap adapter that is installed just before the return filter, Figure 2. The fluid sample flows through a microbore hose with swivel fitting. With oil at operating temperature, a 4-oz bottle is filled and examined by a technician, who has a small lab set up on-site. The oil is diluted with hexene and pulled by vacuum through a patch, which the technician subsequently views through a microscope. If anything out of the ordinary is observed, a second sample is taken and sent off for an accurate particle count and viscosity check.

We installed filters for the engine oil as well. Fluid enters from the cam galley and returns to the oil pan. Two samples of hot oil are taken. One is sent to an Exxon/Mobil lab for spectrographic analysis, and the other goes to our lab for particle counting. This procedure is conducted every 250 to 500 operating hr, and the oil and filter are changed every 1000 hr.

For more information, contact By Bruce Anderson, General Manager of Contamination Control Engineering Co. (CCECOLab & Filtration), Kent, Wash., at (253) 872-5500, or visit cceco.net.