New life

A giant excavator at a Vulcan Materials operation gets a new engine with a little help from a California agency.

The 13-year-old diesel hydraulic Hitachi EX2500-1 excavator working at Vulcan Materials’ Reliance sand-and-gravel pit in Irwindale, Calif., easily met air-quality standards. However, when plant managers there learned of California’s South Coast Air Quality Management District’s (SCAQMD) offer to fund retrofitting of machines such as theirs to a level exceeding required standards, they decided to organize the excavator’s upgrade.

SCAQMD is the air pollution control agency for all of Orange County and urban portions of Los Angeles, Riverside and San Bernadino counties, documented as one of the smoggiest regions of the United States. The agency provides funding incentives and other opportunities to assist businesses – especially those willing to go above and beyond required regulations – in repowering or replacing older, high-polluting, off-road diesel vehicles with new, cleaner engines and equipment.

Hitachi’s EX2500-1 was first introduced to North America in 1996 when the first of the newly designed Japanese manufactured excavators was delivered to the Santa Fe Pacific Gold Corp. Lone Tree Mine in Winnemucca, Nev.

Radical

In its day, the EX2500-1 was described as a “radical design departure” from previous Hitachi mining machines, featuring a single engine and a very different physical layout. The engine and hydraulics had their own individual compartments. Mechanics appreciated easy access to filters and maintenance components.

The machine’s larger, more comfortable cab, in combination with a larger and 70-degree-angle bucket, made operators both more productive and more satisfied with the machine’s performance. It proved to enhance mining productivity to such a great degree that within two years Hitachi developed the larger EX5500.

Within the first four months of the EX2500-1’s operation at the Lone Tree Mine, it moved nearly 60 percent more material than the company’s Hitachi EX1800s. Because of its single-engine design, fuel usage – compared with the EX1800 – increased just 20 percent.

The original EX2500-1 engine was the Cummins KTA50. Cummins’ extraordinarily powerful and fuel-efficient QSK45, specifically developed for mining, was installed in later EX2500-1 models. In addition to being designed for strength, performance and durability, the QSK45 was known for low per-ton operating costs. In comparison to other similarly sized engines, it was found to be highly reliable, routinely achieving more than 95 percent uptime in mining operations with load factors exceeding 40 percent.

Robert Lee, an engineer with California-based Valley Power Systems Inc., who oversaw the EX2500-1 upgrade, says Vulcan Materials’ shovel featured the Cummins KTA50 engine. It took some time and interactive dialogue to identify and refine upgrade plans, which were the first of their kind for a North American EX2500.

“We started working on the plan about six months before we could begin taking the machine down,” Lee says. “MTU Detroit Diesel-Australia has done so many upgrades to EX2500s in recent years that they engineered a kit for the project. That made our job significantly easier.

“We estimated it would take about one month to disassemble the machine and install the new engine,” Lee adds. “In reviewing the excavator’s operation schedule with Vulcan, we determined that early January was the most optimum time to complete the repowering project.”

The MTU repowering kit consisted of the new engine, manual, radiator, motor mounts and more. All the pieces needed to mount the new engine in the original engine module.

“MTU fully designed and engineered the kit, which was very well done,” Lee says.

Before the upgrade was implemented, Vulcan Materials stockpiled extra product to compensate for the excavator’s downtime. The first step in the project was disconnecting the hydraulic system, which was refurbished by Coastland Equipment, headquartered in Long Beach, Calif.

Once the hydraulic system was out, the team prepared for removal of the engine module.

Removing the engine

“When we completed a routine inspection of the module prior to beginning the project, we discovered there were multiple fractures in the enclosure surrounding the module,” Lee says. “That raised some concern about lifting the module out without causing further stress fractures or engine damage. We worked out a detailed plan for removing the module while putting the least amount of undue stress on the fractured areas.”

Once the engine module was removed from the excavator, it was transported to the shop and the engine itself was removed from the module.

Over the next few weeks, the upgrade team welded in new engine mounts and created a new firewall to accommodate the slightly longer new engine.

“The new firewall had to have some curvature to it to accommodate the new engine shape,” Lee says. “The engine is pretty compact and tight to start with, but MTU’s kit was well engineered and the repower progressed well.”

During the engine repower, additional enclosure cracks were revealed. Some were ground out and welded. In a few instances reinforcements were welded in.

“Over the years, as an excavator swings back and forth, stress cracks can develop,” Lee says. “Painting will often bring out a new fracture.”

One of the major differences between the EX2500-1 and the EX2500-5 is in the enclosure.

One challenge the team faced was modifying the MTU engine repower kit (originally designed to repower the EX2500-5 for the KT50 engine) to work with the EX2500-1 model.

“This is where MTU’s experience was invaluable, as they had previous experience with the dash-5 features. Everything about the hydraulics was the same, most of the modification was with motor mounts,” Lee says. “It wasn’t a big change, just an additional step for us.”

With the engine facelift, the team had to complete minor upgrades to the electrical cab controls. New wire coming from the upgraded engine module was connected to controls just beneath the cab.

“There were a number of features on the old electrical panel that weren’t compatible with the new engine module,” Lee says. “The upgrade included installing a new electronic instrument display in the cab.”

Completing the project

The upgrade team completed its work within a five-week period. Once the module was dropped back into place and refurbished hydraulics were reconnected, they fired up the repowered excavator.

“We had one fuel line issue that required about five minutes to correct once we identified the problem, otherwise the machine was up and running fairly painlessly,” Lee says. “Manuals identified the fuel line problem, so it was a simple fix.”

Lee believes one element of the successful upgrade was the inclusion of an MTU-Australia engineer who assisted the team in interpreting kit instructions.

“In order to stay on track, we had to complete all our fabrication work in a two-week period,” Lee says. “We thought it was counterproductive to spend a disproportionate number of hours deciding exactly what the kit instructions called for. Having personnel that were familiar with the kit helped us tremendously.”

The upgrade kit included a repower kit installation manual developed by MTU, which documented the WX2500 components to be replaced or modified to accommodate the new engine. The kit also included a jig for locating the new engine mounts relative to the hydraulics, to ensure accurate and repeatable results.

Depending on the machine, Lee notes that repowering costs may or may not be cost effective. For large machines, such as excavators and cranes, repowering is a viable option. Replacing engines in trucks, which typically have a five-year life, generally doesn’t provide an economic advantage.

“There’s probably some 20 years of life left in this excavator,” Lee says. “Emissions in the Irwindale area are a major concern, so reducing emissions was one major benefit of the upgrade.”

Lee expects his company will be involved in a greater and greater number of repowering projects in the coming years.

“As emission standards evolve, standards are likely to be stricter,” Lee says. “Even without funding incentives, companies benefit from this kind of project. There is definitely potential to do more.

Take note

The upgrade kit included a repower kit installation manual developed by MTU, which documented the WX2500 components to be replaced or modified to accommodate the new engine.

Loretta Sorensen is a freelance writer in Yankton, S.D. She produces material on a variety of topics, serves as a ghostwriter, and has authored her own books.