Driving The New Big Cat In KW's W900L
SWEET AND LOW
Steve Sturgess
Senior Editor
The big unknown at the back of last year was the performance and driveability of Caterpillar's advanced combustion emissions reduction technology (ACERT). We'd seen the engines, and talked about the technology, albeit with a lot of proprietary Caterpillar information not forthcoming. But driving ACERT power was more difficult to put together. Then, in a rush, we had an opportunity to drive the C9 at a Peterbilt off-highway truck demo, followed a month later by a pair of offers. One was a show 'n tell at Cat's headquarters with a chance to drive a Kenworth T2000 with a C15 435 Multi Torque. And then an equally appealing chance came to drive the W900L you see here — also with a C15 — but this time rated a straight 475 and with 1,850 lb.-ft. of torque.
We were looking at the KW from a driver's perspective and even though it was a customer truck — thank you Mr. Customer — Kenworth let me take it for a couple of days, and 638 miles, to really get the feel of the new big Cat and also to revel in the luxury of the latest Kenworth interior.
As always with a Kenworth drive, I was full of anticipation. There's something very special about the way these trucks drive that makes a KW especially appealing to a driver. There's a sort of underlying well-engineered feeling. Everything is designed and put together so the controls are especially responsive. And this W9 did not disappoint.
We wanted to put both the KW and the new Cat to the test, so loaded to gross 78,000 pounds, I headed out of the Renton, Wash., plant, taking I-405 north to pick up I-90 east while playing the 18-speed to keep the rpms down — something I'd learned at Cat a couple of weeks earlier. Immediately this route took the long climb to Snoqualmie and over the pass to Ellensburg. Here I swung south on I-82 through Yakima and on to Richland, across a route that has four or five pretty tough pulls. Taking old 395 north I was able to admire orchards and vineyards, cutting across on 17 to pick up I-90 at Moses Lake. From there it was west on the homeward leg, with the long descent to the Columbia and the long, long pull back up out of the gorge and back into Ellensburg and then down into the greater Seattle area again.
The route was long enough to familiarize me with the KW, but it was fortunate I'd spent time earlier finding out about the characteristics of the ACERT Caterpillar. Otherwise I wouldn't have had much of a clue how to drive it. One thing's for sure: If you're going to give a driver one of these new Cat engines, you'd better have someone take a familiarization course first and then train the driver.
ACERT ENGINE
A little background on ACERT technology is in order.
Caterpillar's advanced combustion emissions reduction technology is a systems approach to reducing NOx and particulate matter (PM) to the level demanded for EPA 2004.
The components of the Cat system are the electronic controls; the fuel system — the injector in particular; the air handling components; a unique variable inlet valve timing; and exhaust aftertreatment. These together reduce NOx in the combustion process by lowering the peak combustion chamber temperature — which addresses the NOx formation — and then cleaning up the PM in the exhaust stream using an oxidizing catalytic converter tucked, in this case, into the mufflers.
The injectors, while new for ACERT, are well proven in the Bridge engine. The mechanically actuated electronic unit injector (MEUI) for the C11, C13 and C15 engines allows for higher fuel pressure and a pilot injection, which initiates the combustion process. Further, the injectors also allow for rate shaping, which also contributes to the combustion control, as does the newly shaped piston bowl.
The air system on the bigger Cat engines features series turbocharging, with dual turbos that together raise the inlet charge pressure to as much as 42 psi. Series turbos are used because the two-step compression keeps pressure ratios and turbine speeds down — both contributors to longer turbo life. Air exiting from the high-pressure compressor feeds directly into a water/air pre-cooler, then through the chassis mounted air/air charge cooler to the inlet on the opposite side of the head.
An interesting feature of the twin turbos is the flexible steel couplings used to accommodate the differential expansion of the components making up the air system.
A component of the air system not obvious from the outside of the engine is the variable valve actuation (VVA) of the inlet valves on the C15. The inlet side is hydraulically operated to vary the inlet valve timing and duration. Undoubtedly, the ability to vary the valve timing contributes to the engine's good performance, especially at low rpms.
All this is orchestrated by the electronic controls, which gain several additional sensors on the engine.
The exhaust aftertreatment is an oxidizing catalyst that enables the burn of the PM in the exhaust stream. As such, it has to be mounted within a certain distance from the turbo outlet. In a dual stack configuration as here, the oxycat fits into the lower section of the standard-looking muffler. In operation there's no more heat, either, despite the oxidation of CO, hydrocarbons and other soluble organic fractions that make up PM into carbon dioxide and water.
Cat's aim in the development of ACERT has been to design a robust and durable system around proven components. To this end, the system has proven parts: The oxycat is already in use with 80,000 in service; the injectors are already running in Cat engines; turbos are off the shelf. What is new is their combination into the ACERT system, says Cat.
So that's the hardware. The result is an engine that breathes huge quantities of air and features a sweet spot at extremely low rpms, so tall gears are necessary and driving discipline is essential to keep the revs between 1,100 and 1,400 as much as possible.
THE TRUCK
This somewhat complex looking C15 fits easily under the long hood of the 130-inch BBC W900L. With its 1,850 pounds feet of torque it gets the beefy RTLO18918 Eaton Fuller transmission with a B ratio set, a double-overdrive transmission. With the top ratio of 0.73 to one and 3.55s in the Dana DSP40 rear ends, the engine's cruise speed is around 1,280 rpm at 60 mph. At 50 mph the engine has dropped to 1,060 rpm; a split down to the 0.86 17th gear in a climb brings engine speed back up to around 1,250 rpms. A whole gear at 50 mph is still OK, resulting in 1,450 rpms, though by the time the shift is completed, you're comfortably under the recommended 1,400 rpm max.
On any sort of grade, this whole gear is the best strategy, since it leaves the full recommended rpm band if the grade steepens, or the speed starts to roll off.
These numbers are with the 11R22.5 Bridgestone M726 drive tires on new Dura-Bright finished Alcoa wheels that are reputed never to need polishing to retain their like-new shine.
Suspension was the conventional 54-inch taperleaf spring up front with a Dana axle, and steering was the familiar TRW TAS65. Kenworth's latest AG400, eight-bag air-ride tandem was spec'd for the rear. This suspension has recently been optimized to improve performance and save several hundred pounds. Wheelends were low-maintenance Dana LMS with Dana brakes and Meritor WABCO antilock braking system.
There was plenty of dress-up shiny stuff, those big, external air filters and dual cab-mounted stacks to complement the KW 86-inch Studio sleeper. Featured on this unit were Kenworth's DayLite doors and the single-piece windshield for optimum visibility. As always, cowl-mounted mirrors made the most of the rearward view, allowing a driver to see to the rear with no more than a quick glance.
In keeping with its very traditional look, the W900 had little in the way of aerodynamic aids apart from cab extenders. There's no rooftop fairing to get in the way of the additional clearance lights mounted up there. And side fairings make no sense when you have big 150-gallon polished fuel tanks with additional polished toolboxes as steps and frame access.
The downside was the weight: this tractor, admittedly with around 200 gallons of fuel, tipped the scale at 20,760 pounds.
CAB & SLEEPER
The interior of the W900 was a treat, with subtle jet black and slate gray providing a very comfortable, restful dˇcor. Black carpets on the floor and Bostrom hi-back seats in "Ultra Leather" completed the rich feeling cab. The trim was a combination of stylish line and more traditional button diamond pleat completing the traditional feel.
The wheel featured buttons for cruise and Jake brake, a mixed blessing because you lose them while in a turn. On the plus side, a driver can drive all day without taking hands off the wheel — barring the odd gearshift — and a lot of the time without putting feet on the pedals by just using the cruise and retarder buttons.
Creature comforts like the electric window lifts and the pop-up sunroof, a unique Kenworth feature, make the driving environment extra special.
The Studio sleeper is also a unique Kenworth feature and one that I particularly like, since it gives you a really comfortable sofa-like seat to relax on during when taking that 10 hours. When you need it as a bed, it converts quickly. Or, with the overhead bunk like the one in this truck, you can drop the bunk down and clamber up into it.
With the windows in the front, vents at the side and the big window in the sleeper door, there's plenty of light during daylight hours. At night, good lighting makes the sleeper a pleasant place to while away the hours. Those side windows are worth a second look. In part to eliminate leaks, they have no hinges. The windows open though, by deflecting the glass.
There's loads of storage because the TV shelf is high up, allowing for an additional closet. Oddly, the refrigerator sits on the right side of the sleeper where most truckmakers put it on the left.
ON THE ROAD
As expected, the Kenworth delivered all the usual tactile satisfactions. It is a very subtle feeling but it adds immeasurably to the satisfaction of driving the truck.
Of course, the 18-speed is a nice shifting transmission, such that a driver need not split the lower gear unless faced with a situation such as turning on to a freeway overpass while trying to grab gears. That's where the splitter really pays off.
In the high side, though, a splitter is almost required. While the engine is governed at 2,100 rpm, Cat says not to go there if you are to get good fuel economy. Driving the C15 ACERT as recommended, there's only a short 300 rpm band. Driving this way and keeping rpms low, I got 5.527 mpg, not anything to boast about, but the route was tough and the truck had only 150 miles on the odometer at the start.
So, you can guess that on this demanding test circuit, I spent quite a lot of time splitting up and down, and taking whole gears on the bigger grades. However, the lowest I had to go on any was to 11/12 or the lowest in the high side of the transmission. And that was — if memory serves — coming up off the Columbia River.
Don't think that the C15 is a weak-kneed power unit though. The amazing thing is the way you can lug it down and down and it stays smooth as silk. And the turbo boost stays right there with you, unlike previous engines that would die when you got down around 1,050 rpm. And you can take the ACERT engines down there, with full approval of the transmission manufacturers, says Cat.
This driving style may not be to everyone's liking, but a driver would get used to it quite quickly. For one thing, if this KW is representative, the engine is particularly quiet — likely a function of the pilot injection and rate-shaping of the new fuel system. The QuietCab package and the excellent sealing of the doors and windows help, too, so that cruising down the road at 60 mph you're in a hushed 72 dB(A) environment.
Open the windows, though, and you are in a whole different world. The air filters mounted up on the firewall are passing huge volumes of air to those series turbos and the rush of air makes a mighty sound. Some drivers might like it. I did for a while, but on the sound meter it reached 83 dB(A), which can be very wearing over time. Again, the grades I was on certainly accentuated this raucousness, but even cruising along 395 the noise through the open window was significant.
OPERATIONAL FACTORS
There were a load of things I got to like about this W900, the more time I spent with it. Little things like the red lights in the footwells and the logbook storage provision, and OSHA-oriented safety stuff like the courtesy lights that shine on the steps, the excellent step up to the cab or to the deck plate. There are good grab handles, wonderful forward (and rearward) visibility even though that big hood gets in the way in traffic somewhat. There's great flow-through ventilation using the sunroof and the sleeper vents to keep a driver from getting drowsy.
And there are things you don't see, like the low-voltage disconnect feature that prevents drivers running down the truck batteries to the point where the truck won't start.
Under the Metton material hood there are silicone hoses, constant-torque clamps, a radiator sight glass. Kenworth has synthetic lube factory fill for transmission and axles, extending change intervals to 500,000 miles and warranties to 750,000 miles. Low maintenance hubs and those Dura-Bright wheels keep the truck on the road and looking good.
CONCLUSION
There's no denying the W900L is a handsome truck. And it is a driver's truck, from the way it handles to the comfort in the cab and the fixtures back in the sleeper.
But with the ACERT Caterpillar C15, it's a truck the driver is going to have to drive — keeping the rpms down and using the multi-speed transmission's gears to keep it running in the sweet spot.
If he does, the Cat ACERT/KW combination should delight both the owner and the driver.
Test Vehicle Specs
Tractor: Kenworth W900L, longnose conventional
Engine: Caterpillar ACERT 475; 475 hp @ 2,000 rpm; 1,850 lb.-ft. @ 1,200 rpm
Clutch: Eaton Solo 15.5-inch two-plate ceramic
Transmission: Eaton Fuller RTO-18918B, 18-speed
Drive Axles: Dana DSP40, (40,000 lb. gawr); 3.55:1 ratio
Front Axle: Dana Spicer E-1322I (13,200 lb. gawr)
Front Suspension: Kenworth 54-inch Taperleaf, rated 12,000 lb
Rear Suspension: Kenworth AG400, rated 40,000 lb.
Foundation Brakes:
Front: Dana 15" x 5"
Rear: Dana 16.5" x 8"
Steering Gear: TRW TAS65
Wheels: Forged aluminum Alcoa Dura-Bright, hub pilot; 22.5" x 8.25"
Tires:
Front: Bridgestone R227 11R22.5 G
Rear: Bridgestone M726 11R22.5 G; 493 revs/mile
Fifth Wheel: Holland FW-35 Sliding, 48-inch height
Fuel Tanks: Dual aluminum, 150 U.S. gallons each
Cab: AeroCab w/DayLite doors; Studio 86-inch integrated sleeper
Cab Aero Options: Side extenders
Cab Interior Trim: Diamond VIT Multi-Tone
Seats:
Driver: Bostrom T915 Ultra Leather, air susp.
Passenger: Bostrom T915 Ultra Leather, air susp.
Paint: Imron 6000 Blue base coat/clear coat
|
Vital Statistics
Wheelbase: 282"
Bumper to Back of Cab (BBC): 130"
Overall Length: 370"
Overall Height: 138" (cab roof)
Overall Width: 102"
Turning Circle: Left: 100.25' Right: 100.25'
Driver's View To The Road: 32'
Weights:
Tractor: 20,760 lb. (with 3/4 tanks, approx 1,300 lb. fuel)
Combined Vehicle As Tested: 78,000 lb.
Interior:
Floor height from road: 52"
Luggage compartment liftover height: 45"
Width (window to window): 66"
Height (floor to ceiling): 60"
Driver's Seat to Ceiling: 39-46"
Width between seats (armrests down): 11"
Driver seat to firewall: 14-19.5"
Driver footwell width: 26"
Passenger seat to firewall: 22-29"
Passenger footwell width: 26"
Sleeper ceiling height: 85" next to bunk (in stand-up area)
Sleeper depth: 82"
Sleeper width: 84"
Trip Length: 473.0 miles
Fuel Used: 85.58 gal; mpg = 5.527
Noise Levels:
Full throttle, 50 mph (1,500 rpm): 72 dB(A)
Steady cruise, 60 mph: 69.5 dB(A)
Coasting, 60 mph: 68.5 dB(A)
Idle, parked: 59 dB(A)
Retarder on, 60 mph (1,500 rpm): 72 dB(A)
|
Additional Equipment: Aluminum crossmembers; Horton Drivemaster fan drive; Silicone coolant hoses;
Caterpillar/Jacobs engine retarder; Delco 33/34-SI 115-amp alternator; 4-battery system; Lo-voltage disconnect;
Delco 42-MT Type 450 starter; dual stacks; FS 1000 fuel filter; block heater; Additional tool boxes; Heated power mirrors;
Power windows; central locking Semi-auto-reset circuit breakers; Cat Messenger; Tilt/tele steering column;
Full complement gauges; Curbside peeper window; 42 x 78 sofa bed; Sunroof; Premium AM/FM/WB cassette/CD radio;
front-loading refrigerator; TV and cellular antenna prep kits; aluminum deck plate; Kenworth cut-out Texas bumper;
Chrome window beading; Sleeper-mounted marker lights; Stainless steel permit panels; Perlux fog lights; Panelite cab accents.
|
