Maintenance and awareness information is provided to maximize service life and uptime and avoid expensive failures.
Logging-on brings the first part of the Tigercat information on turbochargers in this issue. The final part will appear in the next issue of Logging-on. Turbochargers are standard on most forestry machines. The amount of exhaust on the hot side of the engine controls the speed of the turbo exhaust turbine. As the speed increases, a greater amount of air is forced into the engine and more horsepower is produced. A steel shaft mechanically links the turbine to the compressor wheel and effectively controls the volume of air going into the cool side of the engine. Turbocharger speeds can reach well over 100,000 rpm. With faster rotational speeds, there is little room for error. Proper maintenance and operating practices can prevent damage or premature wear. Tigercat assists us with the management and maintenance of turbo-chargers, and in this first article we examine air filtration and restriction.
A turbocharger relies on the cleanliness of the air intake system to work efficiently. Air filtration is the first line of defence for the turbo from dirty atmospheric air. The outside air enters the pre-cleaner and then circulates through the primary (outer) filter element. Then it passes through the safety (inner) filter and finally toward the turbo inlet. To keep this system working efficiently, any debris accumulation around the pre-cleaner such as branches, snow, dirt, mud or leaves must be removed at least every eight hours and more often if working in challenging conditions. This helps keep the turbo vacuum pressure within limits and lowers the longitudinal strain on the shaft at high speeds, preserving the life of the seals and internal parts of the turbo. A plugged filter will cause the turbo speeds to increase because there is no load on the compressor and this in turn can cause the turbo to fail.
The air cleaner element should only be replaced when indicated by the filter restriction indicator, as opposed to proactive replacement. Over-servicing may render the system less efficient, as it relies on some filter dust buildup to maximize the filtration capabilities. It is not recommended to clean the filter. There is a risk of contaminants reaching the clean side of the filter and risk of filter damage from high pressure compressed air. Any type of cleaning is only as good as the people, methods, tools and inspections used in the process. The secondary (safety) element should never be cleaned, only replaced.
If you decide to clean the filter, first do a visual inspection. If there is any damage to the filter body, gaskets or end plates, the filter should be discarded. Always clean the filter in a clean environment and repackage the filter immediately after the cleaning process. Limit cleaning to a maximum of three intervals and always refer to the filter manufacturer’s recommended cleaning practices to safely execute the task. Some key points to remember:
- Pressure should not exceed 30 psi when using air
- Direct the air from the clean side pointing out
- Do not allow the nozzle to contact the filter media
Keep the filter replacement procedure brief to prevent any contaminants from entering the intake system. A clean rag can be used temporarily to block the intake port, but it is crucial that it is removed before reassembly. The finest of dust, sand and dirt particles can have a severe impact on the turbo, causing pitting, scoring or even total fracture of the compressor wheel fins that could result in catastrophic failure. Turbos are finely balanced. The smallest of cracks to the assembly can unbalance the system and accelerate failures.
More information will appear in the next issue of Logging-on. The information was compiled by Jean-Marc (JM) Labelle, a service engineer at Tigercat. Source