Mil is doing well 'over there'
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by Steve Sturgess • Although the first Cummins Mll diesels won't be appearing in UK trucks until later this year, the new electronic 11-litre engines have been proving themselves on operational trials with US fleets covering high mileages on arduous duties.
In the American west high mileages are regularly combined with steep hills and high temperatures to give the engines a good workout. CM has spoken to two fleets based in Phoenix, Arizona which were early converts to the 11-litre Cummins.
"We're having great success. It's fantastic," says Ed Ring, workshop superintendent for Apex Bulk, whose fleet hauls cement, fly ash, lime and borax, serving customers in Arizona, Nevada and California. "We ran the L10 for two years, then we were one of the first fleets to get the M11. We've now run some of them 560,000km (350.000 miles) with no problems."
Apex is a tough test fleet for Cummins. It has 350 tractors pulling pneumatic bulk tanks, all running at at the US maximum gross weight of 80,000lb (36.4 tonnes). Many of them run "slipseat", switching drivers and operating 24-hours a day. The trucks cover 150,000-200,000 miles a year with the round-theclock trucks running twice that.
Mountainous terrain adds to the task. "The drivers like the pulling power when they hit the hills," says Ring. "We spec 330s with peak torque of 1,6501bft (2,237Nm) for good performance. They're in FreightlinersFLD112 conventionals—and they're specced out for light weight: one fuel tank and many are single-drive with a single rag axle (6x2). We haul 55,000lb (25tonne) payloads.
"We were with the Detroit Series 60 and Cat when we went to the L10 for the weight savings; we had good luck with the L10 and stayed with Cummins when the M11 came out."
The L10 proved light, reliable and fuel efficient with Apex, averaging 6.9 mpg (40.91iti 100km). However, the Freightliners' Ml Is are outperforming these older Cummins engines and are turning in better economy, with 7.8mpg (36.21it/ 100km). "We've had small prob
lems with sensors but haven't had any engine problems at all," says Ring. "All the new trucks have the Mll and the whole fleet will go to the Cummins as the trucks are traded out."
Knight Transport is a truckload carrier, set up in 1990 by family members who had been managers at Swift Transportation. It has grown from startup to a 275-trucks in only four years.
Chief executive officer is Kevin Knight: he oversees a fleet that has run Cummins, Caterpillar and Detroit Diesel engines in its Freightliners. The latest batch of 60 units are powered by Mll engines.
"We have been using the Mll in the 48in (1.2m) Raised Roof Sleepercab models," says Knight. "They're rated at 370hp (276kW), and with 3.90 axle ratios the engines are averaging 7.1-7.4 mpg." Those are US gallons, which gives his Mlls a spread of 8.5-9mpg (33.231.41it/1001un). With the gearing he has specified, and with the electronic engines limited to 61mph (98km/h), Knight says the trucks cruise right at the "sweet spot", 1 ,4501,50Orpm. Durability has been good and his drivers like the performance, response and driveability of the 11-litre Cummins.
Knight aims to take care of his drivers; that's one reason for specifying the cavernous Sleepercab-model Freightliners. He is particularly pleased with the weight savings of the 11-litre over the bigger N14 and the comparably sized Detroit Diesel Series 60 that the company had tried previously. "It weighs 600700 pounds (272-318kg) less than the Detroit 11.1," says Knight. Some of the trucks will be right up at 80,000lb (36.4-tonne GCW) but even when it isn't we like to give that flexibility."
Truckload
Knight serves the Western States with truckload service, with an average run of 765km (475 miles). While the Mll is fuel efficient, Knight says it is matched by Caterpillar's 3176, 10-litre but it beats any 14-litre unit.
Li Existing UK Cummins L10 users ERF, Foden and Seddon Atkinson will all switch to the Cummins M11 when it has been certified for Euro-2 in the UK. Seddon Atkinson plans to introduce the Mll in October and an Mll-powered Seddon could be at the Scottish IRTE Show in September. Foden will introduce the engine later this year but will offer the L10 up to October 1996. According to managing director John Bryant ERF will probably offer it in late July or early August. The company will continue to offer the L10 until the October 1996 Euro-2 deadline.