Cummins Teardown Shows Tier 4 Engine
as Durable as Tier 3
To assess durability and life-to-overhaul, Cummins tore down and inspected a Tier 4 engine, comparing it with a Tier 3 version. The disassembly and in-depth examination of a QSL9 Tier 4 engine at close to 10,000 operating hours revealed major components, fuel system, turbocharger and the block to be in near-perfect condition after three years of operation in a heavy lift-and-carry application, the company reported.
Cummins engineers conducting the teardown inspection concluded that the Tier 4 Interim (Stage IIIB) compliant QSL9 was capable of achieving up to 20,000 hours of operation before an engine overhaul may have been expected - equal to that of a Tier 3 version of the engine working on a similar duty cycle. Upon inspection, the QSL9 engine was in such good condition after nearly 10,000 hours of operation that it could have been reassembled and returned to service without any component change or maintenance intervention, the company reported.
The evaluation confirms that Tier 4 engines with low-emissions technology provide the same durability as demonstrated by their Tier 3 engine predecessors. "Cummins design philosophy is to utilize only proven technologies and components that we know will meet the in-service reliability and long-term durability demanded for the toughest equipment applications - and the advantage of taking this approach is reflected in the impressive results of the QSL9 Tier 4 teardown inspection," said Hugh Foden, Executive Director - Cummins Off-Highway Business.
The evaluation procedure included more than 230 measurements and values taken from the stripped-out components. Before the teardown inspection, the QSL9 was tested on a range of performance factors such as power delivery, fuel consumption, emissions and torque, to prove that the engine remained within acceptable tolerance levels of the original production specification.
Rated at 350 HP, the QSL9 engine selected for the durability assessment had required only standard servicing during the three years of operation, with no repair work or unscheduled maintenance ever needed. Cummins Tier 4 Final engines are designed with rebuild potential, to enable an easier and lower-cost overhaul.
Because the base 9-liter engine remained almost identical in transitioning from Tier 3 to Tier 4 interim, Cummins said it was an ideal platform for a durability comparison.The engine is used in demanding applications varying from excavators and wheel loaders to crawler cranes, snow groomers and reach stackers.
Technology enhancements for Tier 4 included an Exhaust Gas Recirculation (EGR) system and Cummins variable geometry turbocharger. For Tier 4 Interim, a Diesel Particulate Filter (DPF) system was used. For Tier 4 Final, a Selective Catalytic Reduction (SCR) system is used in combination with a Diesel Oxidation Catalyst (DOC). All of the aftertreatment systems function automatically, and require no operational intervention.
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