I was in Peoria on Tuesday for Caterpillar's official introduction of the D7E. They were announcing that the unit will go into production in October, ramping up to full production by mid-2010. That's when production of the D7RII will cease.
There are 18 pre-production (produced on the East Peoria TTT line) units in the field with customers getting real-life experience, and Cat arranged to have representatives of three companies in Peoria to talk about their experience. As you might expect, all were very positive. Some of the details were particularly interesting, and you can find some of them in this
ConstructionEquipment.com machine analysis. We're in the process of posting some short audio clips of customers' comments about the machines.
My summation of what those who are using the machine said goes like this:
Maneuverable and controllable enough to work on sites previously restricted to the D6, but powerful enough to do most of what a D8 can do.
Caterpillar has upgraded its estimation of the fuel-efficiency advantages. Back at Conexpo (March of 2008), they were saying 10 to 20 percent reduction in fuel consumption compared to the D7RII. Now they're saying 10 to 30 percent. And users are saying they see significantly more. As much as 50 percent less fuel consumption, particularly in lighter-duty work.
Cat's saying they will set the MSRP at 20% above that of the D7RII. That puts the D7E at about $600,000, or within 12% of the D8T.
Check out the D7E intro analysis for a comparison of the cost per hour of the 7RII and the 7E.
With its fuel-efficiency advantages and lower undercarriage and PM costs, the D7E should cost about 7 percent more per hour to operate than the D7RII. In hourly production terms, it delivers about 10% more yards of dirt moved. But 10% more hours per year won't bring the 7E's hourly rate down to equal the 7RII's. Owners are going to have to think differently at least about their D7 work to take full advantage of the hybrid bulldozer's efficiencies.
How many D7-sized-tractor users can expect to get enough additional work for a D7E by virtue of its productivity advantages to make it earn its keep?
The D7E's hourly rate is easily 20% below that of the D8T.
Users gathered in Peoria were all doing conventional dozer work with their machines -- pushing considerable distances doing reclamation in a lignite mine, gravel pit, and quarry. The loading supervisor from Dolet Hills Lignite, J.V. Ropollo, said he'd gone so far as to put the D7E in a job that is usually done by a D10. Ground got soft and the D10 was having trouble getting around. The D7E could handle the underfoot conditions better (the standard track puts as much track on the ground as a D7RII LGP). He said the 7E operator wasn’t happy about it (guess he had to work at it pretty hard), but he was very nearly keeping up the work pace he had done in better conditions with the D10!
The D7E had also pulled loaded 785 haul trucks out of the mud that Dolet Hills' D7RII couldn't budge.
Dolet Hills had 1,600 hours on the unit (they run two twelves). Its tracks are on pace to just out-last the tracks on their conventional dozers. Lots of sand down there, so they only expect about 2,200 hours to the first turn.
Plote Construction's gravel-pit reclamation sounded like it was pretty tough, too. They parked a D8T, and the D7E was stripping and filling with all kinds of reclaimed asphalt and concrete. Plote said it was doing some really long pushing, although he didn't give any specific distances. Had pushed some scrapers, too.
Crossfire, diversified heavy contractor in the Four Corners region with a lot of oil and gas business, sounded like they would be putting the 7E on some D6-sized projects. They'd done a lot of reclamation work in 500 hours, but were also sure it would perform on road and site development jobs.
The diesel drives a generator that produces up to 480 volts. HD, armored cables with mil-spec connectors carry the voltage to a propulsion unit with two high-speed electric motors. The propulsion unit drives pretty conventional Cat diff-steer units and final gear reductions.
The motor/diff-steer configuration does out-perform conventional transmission/diff-steer pairing in that the D7E electronic controllers are programmed to deliver lock-track turns. The stopped track will not freewheel, for example, if the tractor is on a slope when the operator puts the tractor into a turn that stops the inside track. The D7E drivetrain is also capable of counter-rotating the tracks.
In a side-by-side demonstration, the D7E clearly outworked the D7RII. Now, the Cat operators could have rigged that any way they wanted to, and surely the things they did with the tractors played to the D7E's strengths. But I have no doubt that the new tractor will deliver 10 percent more work per hour. Cat puts that with the fuel-efficiency advantage and says the 7E produces 25 percent more earthmoving per gallon of fuel.
One thing's for sure, they aren't exaggerating about the view from the operator's seat. I'm not a dozer operator (I did stay at Holiday Inn Express once . . . ) but I was in the cabs of a D6N, a D7RII, a D8T, and a D7E on Tuesday. There's no comparison. There just is not much to block your view. And it's quiet. Easily half the noise at high idle, as Cat claims.
It's far smoother than the D7RII, and every bit as nimble as the D6N (I was doing laps with them in an indoor arena at Cat's Edwards, Ill., demo grounds). You gotta keep your eyes open because the 7E doesn't really lug down under load. If you have the electronic ground-speed control set too high (as this greenhorn did), the tracks start to slip with no audible warning.
At max. 480 volts, mechanics don't need a certification to work on the drive train. There will certainly be some training required to keep these things up and running as they age. All of the accessories -- including the hydraulic pumps, water pump, air conditioning -- are run electrically. There are no belts off the front of the engine, no refrigerant hoses in the engine compartment, no alternator. Accessory power comes from an inverter over the right fender.
More D7E technical details.
Photo 1: "Look Ma! No belts!" Wide-open engine compartment is built to accommodate the aftertreatment that will take the C9.3 (pre-production only today) all the way to Tier 4i in 2011.
Photo 2: Inverter powers all of the hybrid dozer's accessories -- including the hydraulic systems, water pump, air conditioning.
