Mack Defines The 'Sweet Spot'
Jim Winsor
Executive Editor
As Mack began doubling production at Volvo's New River Valley plant to 36 trucks a day, the company hosted a press briefing to update trucking editors on the Mack CH and CX (Vision) models. The briefing took place at D.M. Bowman's headquarters in Williamsport, Md., about 12 miles south of Mack's engine and transmission plant in Hagerstown.
The briefing was called to update truck editors on Mack progress just five months after the company moved production to New River Valley from Mack's Winnsboro, S.C., plant.
Don Bowman, owner of the 400-tractor regional LTL and flatbed fleet, is a major customer of Mack Vision tractors.
Bowman started his company in 1963, hauling gravel in a used B-61 Mack tractor. Five years ago he bought back that same tractor and restored it. It is now part of his truck and antique car collection.
His company has been operating early '02 low emission Mack ASET AC engines with external cooled EGR. Bowman shared his company's experience with four engines — two with 150,000 miles and two at 90,000 miles. He also made the two high-mileage tractors with loaded trailers available for test drives.
Sam Kennedy, Bowman's chief maintenance officer, said the new engines have been trouble-free — other than a failed turbocharger that was replaced quickly under warranty. He said fuel mileage was running 4% behind the fleet's pre-'02 engines in the same type of service. And he said the trucks were performing extremely well and the drivers like them, adding they are particularly impressed with the quick throttle response, largely attributable to the use of variable geometry turbochargers.
Senior driver Charles Buffington, who regularly drives one of the high-mileage units, said that while the engines carry the same 427 hp ratings as pre-'02 engines, acceleration for merging into traffic was noticeably better. He also said engine noise in the cab was decreased substantially, an observation I found to be true during a 45-minute test drive.
In discussions about fuel economy, Mack's Dave McKenna said the 427 hp rated engine and "Maxicruise" models give the best fuel economy. He pointed out that the "sweet spot" — the rpm giving the best fuel efficiency — is now at 1,700 rpm, up from 1,650 rpm on pre-'02 engines. He also said Mack will be adding an indicator, probably an LED light or a light bar, to tell drivers exactly when they are operating in the "sweet spot."
Mack has increased oil capacity to 40 quarts from 32 with a pan that is three inches deeper. The company now recommends a 25,000-mile drain interval — down from the 30,000 miles on older engines. But the chassis lubrication interval has been increased to 25,000 miles from 15,000 miles, which means oil, filter and lube service can be combined into one service instead of two.
Full-flow oil filter capacity has been increased 40% with a 30% increase in efficiency. An integrated fill spout has been added to the centrifugal by-pass filter to make it easier to add oil.
The water pump has been separated from the fan drive, making it easier to position fan clearance with tight-fitting shrouds.
Tom Davis, Mack's highway products marketing manager, discussed Mack's on-highway truck line. He said the CH model is now offered only in an axle-forward version, designed for fleets needing tractors designed to meet bridge formula dimensions.
The CX Vision is now available as an axle-back day cab model for the first time. In other changes, he said orange seat belts have been added for visibility and to help determine if drivers are belted or not. A Mack "Performance Seat" with a 22-inch-wide seat cushion (19 inches is standard) is now offered. It's built by Bostrom to Mack's specs. Five-temperature seat heaters are also new.
As of mid-April, Mack had manufactured 3,896 ASET engines — 3,443 as AI versions (internal EGR engines for vocational trucks) and 453 AC versions (cooled external EGR).
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