Redesigning the Hydraulics on a CAT 735C dump truck - Halmahera Minerals

The Halmahera Minerals gold mine in the remote, rugged Gosowong region of Indonesia produces more gold per tonne of excavated materials than any other mine in the world.

The global average in gold mining is 20 ounces of the precious mineral per tonne. Gosowong can produce up to 7,000 ounces per tonne. This equates to a staggering 96,000 ounces per day with a market value of $AU115M! In fact, each load of fill being hauled from the mine is worth more than the truck carrying it!!

To improve underground safety the mine sprays the walls of each tunnel with concrete. To achieve that it has a fleet of small trucks equipped with concrete agitators. Management wanted less truck movements and larger carrying capacity so it decided to convert a six wheeled CAT 735C dump truck into an 12 cubic metre concrete agitator. The truck would be operating in a hostile environment – volcanic water in the mine is 80 degrees Celsius!

This was a custom project – it hadn’t been attempted in these conditions before. The Scope Of Works called for the re-design of the rear section of the truck, supplying of the hydraulic system, two pumps, electronics and driver’s cabin controls… overseeing fabrication and installation… product trials and commissioning.

With 25 years of international experience, including on-site work at an Australian gold mine, FPES (Excel Hydraulics) was commissioned to come up with the solution. FPES Hydraulic Engineer & Project Manager Kevin McCaffrey began by consulting with Caterpillar to get specifications on their hydraulics and pump drive. He designed the system, sourced the right products and had them shipped out to the jungle location.

Kevin then had to spend a couple of days in the air – flying from Sydney to Singapore, Singapore to Manado, Manado to Kabok, then in a small propeller driven plane from Kabok to the hot, steamy and humid conditions at Gosowong where the work was carried out in an open air workshop.

Things don’t always go to plan and this is where being solution-minded counts,

“I stripped out the CAT hydraulic hoist pump and fluid lines, and found that the drive gear which was expected to be symmetrical so that the SAE C drive spline could be utilised could not be turned around. I also found that the pump mounting flange only had a two bolt arrangement not the combination two and four bolt arrangement in the CAT drawings. The new pump for the agitator had a four bolt mount. I removed the steering and auxiliary pump in the hope that this drive could be found but discovered that the rotation direction of the pump was opposite to the information that had been provided to us. This drive couldn’t be used for installation of either new installed pump. I spoke to the fabricator and we designed a plate for the mounting of the reservoir, cooler matrix and filter assembly.”

The conversion followed this process… (1) Controller and reservoir tank mounted and electrically connected, (2) Designed and made a clamp to attach the 4 bolt flange to the 2 bolt interface, (3) Steering pump installed.

The machine shop was able to make modifications to truck components. A physical space had to be created to incorporate an additional agitator pump and this required cutting out sections of the steel framework with a grinder.

FPES remanufactured transmission pump suction pipework, machined the drive gear, made up hose assemblies, installed the drive gear, flange plate, agitator and hoist pumps, installed all hose assemblies, added lubricants, checked for leaks – none found, did all of the electronic connections, designed and installed remote controls to allow an operator to control the agitator and hoist from the rear of the vehicle.

The project took 10 days from arrival to commissioning and demonstrated FPES (Excel Hydraulics) ability to be the one stop shop – designing, sourcing products, manufacturing parts and assemblies, project management on site, assembly, testing and commissioning.