Fleet Maintenance - 42

ยป Available on the International LT Series,
Navistar offers two MPG Fuel Efficiency
Packages for specification. The Aerodynamics
package offers wheel covers, chassis
skirts, extenders, and roof fairings. The
Powertrain package provides a number of
improvements to optimize fuel usage and
system performance including the Eaton
Endurant AMT, high-efficiency axle ratios,
programmable parameters, and more.
Photo courtesy of Navistar

Multi-torque engine ratings
Multi-torque models allow the engine and
transmission to work together to select the
optimal torque curve. This improves fuel efficiency by only providing maximum torque in
the top two or three gears, which encourages
the driver to operate in the highest available
gear for the highest efficiency.

Specifying vehicles for
optimal fuel economy
Which powertrain components should be considered?
It's no surprise that fuel is often one of a
fleet's largest expenses, since a typical Class 8
truck can consume anywhere between $40,000
and $70,000 worth of fuel annually. One way
to mitigate fuel cost is to specify the vehicle to
strike a balance between fuel efficiency and
performance. Optimized specifying for heavy
duty commercial trucks could pay dividends
to a fleet's bottom line over the life of a vehicle.
Specifying a vehicle for optimal fuel efficiency is not a one-size-fits-all approach. Variables
such as type of load, length of haul, driver
behavior, and geographic operating area all
play a factor in specifying a truck that's right
for a fleet's unique application.
There are a wide variety of options to choose
from such as aerodynamic skirts and fairings,
low-rolling resistance tires, idle reduction technologies, and lightweighting specs. Additionally,

By Jim Nachtman

Navistar International Corporation is a holding company
whose subsidiaries and affiliates produce International
brand commercial and military trucks, proprietary diesel engines, and IC Bus brand school and commercial
buses. Nachtman is responsible for the International LT
Series, RH Series, LoneStar, and A26 Engine. He plays an
instrumental role in voice of customer activities, sales
support, dealer education, driver training materials, and
future market trend projections. With nearly 20 years of
experience in the commercial truck industry, Nachtman
joined Navistar in 2002 and has held multiple roles at the
company, including competitive engine benchmarking,
engine design engineer, and lead design engineer for the
International A26 Engine.

42 Fleet Maintenance | June 2019

all fleets can benefit from an optimized powertrain to help deliver top fuel mileage.
What powertrain components should be
taken into consideration when specifically
looking to run an engine at its most efficient
speed? Since the entire system works together - the engine, transmission, driveline, and
rear axles - it's important to look at the entire
system as a whole. Each powertrain component
is available in many different options that all
have trade-offs in fuel economy and performance. By specifying all the components that
make up the overall system, the maximum
synergy can be achieved.

Powertrain basics

There are a number of areas where the powertrain efficiency can be improved. Here are some
of those options:
Downspeed engine ratings
Downspeed engine ratings can easily boost fuel
economy. When the engine operates at a lower
rpm at the same vehicle speed, engine friction
and pumping losses are reduced. For example,
the amount of energy to pump coolant and oil
are less at lower engine speeds, reducing pumping losses.
Rear axle ratio
The rear axle ratio is absolutely critical for
attaining optimal fuel economy. A lower rear
axle ratio works in conjunction with a downsped
engine rating to maximize fuel efficiency.

Powertrain options

A good initial spec can help fleets operate more
profitably and efficiently, but understanding
the factors that affect fuel economy is critical
to achieving the best results.
Engine ratings
Engines are available in a wide range of horsepower and torque ratings. Certain ratings favor
fuel economy over performance. These fuel efficiency-focused ratings are typically available
at 400 and 450 hp, providing higher torque at
lower rpm.
On/off fan clutch versus two-speed
(for long haul applications)
Fan operation can significantly affect fuel economy. After all, the more time spent with the fan
on, the more power required from the engine,
and the less power the engine has to move. The
on/off fan clutch is recommended primarily for
fleets that spend roughly 80 percent of their
time on-highway, as it doesn't require torque
when the fan is off. Two-speed fan clutches
use engine torque, even when the fan is off.
Less frequent cycling of the fan clutch can also
extend fan clutch life.
FA-4 versus CK-4 engine oil
Lubricant maintenance is crucial to the
performance and functionality of an engine.
FA-4 is an available factory fill option on the
International A26 engine. In testing, FA-4
10W-30 oil improved A26 fuel efficiency by 0.7
percent over CK-4 10W-30 oil. For customers
looking to maximize oil drain intervals with
an oil sampling program, FA-4 oil can help to
achieve reduced maintenance expenses.
FA-4 is suitable for use in 2017 GHG-certified
engines. CK-4 is a high-temperature, highshear oil that can be used in both new and
existing engines. FA-4 and CK-4 are interchangeable while topping off and at oil changes, providing the same engine durability and
oil drain interval.
High-efficiency rear axles
High-efficiency rear axles are optimized to


Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance

Uptime: Planning for change
Considerations when selecting CMMS software
Vehicles: How fleets can benefit form electric axles
In the Bay: Making the case for retreads
Shop Operations: Predicting the future
Diagnostics: "Smart" technologies will help improve maintenance
Powertrain: Specifying vehicles for optimal fuel economy
Fleet Parts & Components
Tools & Equipment
Guest Editorial: Advancements in new filter media
Fleet Maintenance - 1
Fleet Maintenance - 2
Fleet Maintenance - 3
Fleet Maintenance - 4
Fleet Maintenance - 5
Fleet Maintenance - 6
Fleet Maintenance - 7
Fleet Maintenance - Uptime: Planning for change
Fleet Maintenance - 9
Fleet Maintenance - Considerations when selecting CMMS software
Fleet Maintenance - 11
Fleet Maintenance - 12
Fleet Maintenance - 13
Fleet Maintenance - 14
Fleet Maintenance - 15
Fleet Maintenance - 16
Fleet Maintenance - 17
Fleet Maintenance - 18
Fleet Maintenance - 19
Fleet Maintenance - 20
Fleet Maintenance - 21
Fleet Maintenance - Vehicles: How fleets can benefit form electric axles
Fleet Maintenance - 23
Fleet Maintenance - 24
Fleet Maintenance - 25
Fleet Maintenance - 26
Fleet Maintenance - 27
Fleet Maintenance - In the Bay: Making the case for retreads
Fleet Maintenance - 29
Fleet Maintenance - 30
Fleet Maintenance - 31
Fleet Maintenance - 32
Fleet Maintenance - 33
Fleet Maintenance - Shop Operations: Predicting the future
Fleet Maintenance - 35
Fleet Maintenance - 36
Fleet Maintenance - 37
Fleet Maintenance - 38
Fleet Maintenance - 39
Fleet Maintenance - Diagnostics: "Smart" technologies will help improve maintenance
Fleet Maintenance - 41
Fleet Maintenance - Powertrain: Specifying vehicles for optimal fuel economy
Fleet Maintenance - 43
Fleet Maintenance - Fleet Parts & Components
Fleet Maintenance - 45
Fleet Maintenance - 46
Fleet Maintenance - 47
Fleet Maintenance - Tools & Equipment
Fleet Maintenance - 49
Fleet Maintenance - 50
Fleet Maintenance - 51
Fleet Maintenance - Classifieds
Fleet Maintenance - 53
Fleet Maintenance - Guest Editorial: Advancements in new filter media
Fleet Maintenance - 55
Fleet Maintenance - 56