World of Concrete (Jan. 23-26, Las Vegas Convention Center) stands to be the first major showing of heavy-duty mixer and dump trucks bearing engines and
World of Concrete (Jan. 23-26, Las Vegas Convention Center) stands to be the first major showing of heavy-duty mixer and dump trucks bearing engines and new exhaust systems aimed at Environmental Protection Agency 2007 diesel emission guideline compliance. In addition to requiring the ultra-low sulfur diesel that hit the retail market last October, the new power packages call for greater cooling system capability and diesel particulate filters (DPF) that oxidize soot. Flexible DPF placement, horizontal or vertical, in conventional chassis should mean limited changes in finished rear discharge mixers and dump trucks, although exhaust components and related engineering modifications will combine for premium north of $5,000 on 2007 trucks.
Comparable premiums are certain on front discharge mixers, where the 2007 engines’ new exhaust and cooling provisions have necessitated hood, radiator and hardware changes. Terex Advance Mixer in Ft. Wayne, Ind., has geared up its front discharge mixer design for Cummins ISM and Cat C13 power. Using Cummins-prescribed towed dynamometer units and thermal gauges, it confirmed suitability of its engine mounting and cooling system design with a beta version of an ISM 350-hp engine-equipped model last fall.
The beta version truck’s DPF is mounted vertically in the muffler rack structure, similar to current design. We have strengthened the structure and moved the air cleaner away from the DPF, and have finalized the mounting with the DPF on the road side and the Air Cleaner on the curb side, says Terex Advance Engineering Vice President Jim Yakel. It has been 24 inches on the test model, and we are considering relocating it a little closer, probably about a foot away.
Other modifications he and colleagues are finalizing for their Cat or Cummins 2007 engine-equipped front discharge models include:
The cover or hood has been widened about 12 inches, improving air flow around the engine and providing more clearance around the turbo charge and exhaust pipe routing. The addition of six inches to each side imparts needed breathing room. Staff from Indiana ready mixed market leader IMI looked at the Terex Advance beta model, noting how the wider hood improves a driver’s visibility of the hood corner. Critical when operating in reverse, corner visibility has typically been improved on narrower models with the use of brightly colored, angled plastic markers.
The charge air cooler and radiator are placed side by side, one factor requiring the wide engine hood. This design allows both components to see first-pass air Û versus one or the other Û and eases maintenance routines typical of overlapping cooler and radiator. It also affords optimal coverage area for the larger fan, a nine-blade, 36-in. model replacing previous trucks’ 30- or 31-in. versions. Terex Advance is standardizing the 36-in. model instead of offering two size options, and finds the new design to operate more efficiently and at lower noise levels than previous fans. The new model can contribute to fuel savings by operating at a fan speed-engine rpm ratio of 0.9:1 or 1:1, instead of a typical 1.1 to 1 level on pre-2007 engines.
A highly efficient cooling system requires a low tip clearance for the fan. In order to execute the new design with a ∫-in. clearance, Terex Advance had to use an engine-mounted ring shroud. Its seal allows the ring to float and move while ensuring the fan does not contact the shroud. The ring shroud is one-piece spun metal construction, while the shroud that moves with the frame is fiberglass. If the ∫-in. tip clearance between the fan and shroud is exceeded, noise level rises and cooling efficiency drops.
Not specific to 2007 engines, Terex Advance has timed another change for this year’s trucks, which will sport a larger hydraulic fluid reservoir located above the main hydraulic pump so the engine maintains constant fluid flow and prime. By increasing the capacity, engineers are able to allow the system to run cooler and cleaner because of improved filtration. This and the relocation of the hydraulic tank figure to lower hydraulic fluid temperature about 25_F.
Our plan will be to build a few 2007 engine-equipped front discharge mixers in January and February to prove out the production process and gain additional confidence in the design, says Yakel. We are looking at availability in mid-April for deliveries of trucks with the new power and exhaust packages.
At World of Concrete 2007 Booth #C5213, Terex Advance will feature a six-axle front discharge mixer with (Cat C13 or Cummins ISM) power, plus a rear discharge Bridgemax mixer with 10.5-yd. barrel mounted on a Peterbilt 357 chassis.