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White Paper on Powertrain Spec’ing January 2005 KENWORTH. The World’s Best.

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Page 1: White Paper on KENWORTH. Powertrain Spec’ing The … · 1 WHITE PAPER OVERVIEW This Kenworth White Paper on Powertrain Spec’ing was developed to provide useful information and

White Paper onPowertrain Spec’ingJanuary 2005

KENWORTH. The World’s Best.

Page 2: White Paper on KENWORTH. Powertrain Spec’ing The … · 1 WHITE PAPER OVERVIEW This Kenworth White Paper on Powertrain Spec’ing was developed to provide useful information and
Page 3: White Paper on KENWORTH. Powertrain Spec’ing The … · 1 WHITE PAPER OVERVIEW This Kenworth White Paper on Powertrain Spec’ing was developed to provide useful information and

1

WHITE PAPER OVERVIEW

This Kenworth White Paper on Powertrain

Spec’ing was developed to provide useful

information and recommendations on the new

generation of heavy duty engines, transmissions,

cooling systems, and related technology to ensure

maximum performance, fuel economy and

minimum vehicle life cycle costs.

There are seven major areas covered in this

Kenworth White Paper:

• Cummins Engines—page 1

• Caterpillar Engines—page 3

• Engine Cooling Systems—page 6

• Spec’ing Considerations for Powertrain

Lubricants—page 7

• Automated and Automatic Transmissions—page 8

• Axles and Drivelines—page 10

• Suspensions and Traction Control Options—

page 13

CUMMINS ENGINES

Technology OverviewCummins emission technology uses cooled

Exhaust Gas Recirculation, or EGR. This process

takes a small amount of exhaust gas from the

exhaust manifold, sends it through a cooler

to reduce the temperature, and

then blends it with fresh

intake air before it goes

into the combustion

chamber. This added

exhaust gas helps

lower the combustion

temperatures and

reduces emissions

while maintaining

power and efficiency.

A key feature of Cummins’ new engines is the

Holset Variable Geometry (VG) turbo. This design

constantly adjusts airflow based on engine load,

fuel quantity, ambient pressure, temperature and

other conditions to provide the exact amount of

boost needed at any engine speed. This unique

design uses a

single sliding

nozzle with only

one moving part in

the exhaust

stream. The Holset

VG turbo is proven

technology and is

more reliable and

durable by design than other competitive designs

due to fewer moving parts.

Most truck owners will see no change from their

current preventive maintenance intervals,

including engine oil and filter changes. The

Cummins ISX is designed to operate between

service intervals in normal service use up to

25,000 miles.

PowerSpec ToolCummins PowerSpec is an application available

from the Internet that allows users to establish

feature and parameter settings, gearing

recommendations and basic trip and fault

information. By selecting an engine application

and answering a few simple questions, PowerSpec

will provide gearing recommendations specific to

the intended service. Users can enter specific

component options to determine what

combination of tires, transmission and rear axle

will optimize the vehicle performance. Kenworth

dealers can work with customers using PowerSpec

to create and load feature settings prior to

delivery of the vehicle to the customer.

The Cummins ISX is

designed to operate up to

25,000 miles between

service intervals in normal

service use.

Visit www.powerspec.cummins.com to download PowerSpec

and learn more about spec’ing Cummins engines.

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Key PowerSpec features and parameters include:

• Road Speed Governor Setting determines how

fast the vehicle travels on level ground to ensure

optimum fuel economy. As a rule of thumb, fuel

economy decreases by 1/10 mpg for every mile

per hour above 55 mph, primarily as a result of

higher aerodynamic drag.

• Idle Control sets the engine shutdown time and

adjusts idle speed control to improve fuel

economy during inactive operation. Heavy duty

engines typically use 0.5 gal/hr at 650 rpm and

1.0 gal/hr at 1,000 rpm.

• Gear Down Protection promotes increased fuel

economy by encouraging the vehicle driver to

operate as much as effectively possible in top

gear where fuel consumption is lower. This is

accomplished by limiting vehicle speed in lower

gears. Maximizing time in top gear means the

engine runs in a lower rpm range, thus

producing increased fuel economy and

improved durability.

• Engine Brake Settings allow the operator to

customize the brake application and operation

to best suit the driving conditions. These

options include the rate of brake application

and the vehicle speed range in which engine

braking is allowed.

Additional Cummins Features to AchieveMaximum Performance and Fuel EconomyIt is crucial to ensure that vehicles are spec’d

properly to balance fuel economy and

performance needs. PowerSpec, in conjunction

with the driver’s experience, will help optimize

the vehicle gearing to achieve these objectives.

Cummins SmartTorque (ST) rated engines help

drivers to drive smarter by providing up to 200 lb-

ft of extra torque in the top two gears. Using ST

promotes top gear usage resulting in a higher

percentage of time in top gear that translates into

improved fuel economy. This is accomplished by

allowing added peak torque under conditions

where it’s needed when in either of the top two

HOW IMPORTANT IS SPEC’ING TRANSMISSION ANDREAR-AXLE GEARING ON FUEL ECONOMY?

Based on Cummins testing, an engine geared to run 1,450

rpm at 65 mph gets approximately 4 percent better mpg

than one geared to run 1,600 rpm at 65 mph.

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gears. SmartTorque minimizes shifts, which

enhances fuel economy and driver satisfaction.

Load-Based Speed Control (LBSC) is Cummins’

engine management system that helps save on

fuel while providing power when needed. LBSC

works intelligently to understand the vehicle’s

operating conditions to balance performance and

fuel economy based on the Gross Vehicle Weight

(GVW) and grade. When maximum performance

is not required, LBSC manages the operating

range of the engine for maximum fuel efficiency.

LBSC also automatically ensures that the full

operating capability of the engine is available

when additional performance and operating

flexibility is needed, including:

• When driving in the top two gears

• When climbing grades

• When making gear changes

RoadRelay 4RoadRelay 4 gives drivers the means to increase

productivity by reducing idle time and improving

fuel economy, delivery performance and more.

The display provides

information while

they are driving to

help improve driving

habits and fuel economy.

Key features include:

• Trip and Route: Information is displayed and

recorded, including fuel, miles and engine

hours spent in idle, PTO and other operating

modes.

• Vehicle Protection: RoadRelay 4 constantly

monitors the powertrain. If an unexpected

event happens, RoadRelay 4 will inform the

driver and advise how to minimize potential

damage. It also tracks customizable service

intervals for oil changes, filter changes and tire

rotations, notifying the driver when it’s time to

head for the shop.

• Anti-theft: RoadRelay 4 comes with anti-theft

capability. This feature protects the vehicle from

theft when enabled.

CATERPILLAR ENGINES

Cat® Heavy-Duty ACERT™ OverviewCaterpillar has developed ACERT to provide

optimal combustion efficiency and produce

minimal emissions. The technology utilizes two

turbochargers in series, fuel systems, variable

valve actuation, and exhaust after-treatment.

Electronic controls manage the system.

ACERT uses a cross-flow cylinder head with four

valves per cylinder. To achieve high performance

and low emissions, the objective of ACERT is

twofold: get more clean air into the engine and

provide more uniform dispersion of that air

charge. ACERT uses proven turbochargers with

mechanical waste gates for increased

performance. Series turbochargers (two standard

turbos in series) provide the low-end response of a

small turbo with the higher-speed air volume and

boost pressures of a large turbo. Improved fuel

economy is an added benefit of this approach.

Maintaining optimized conditions requires that the

right amount of fuel be delivered at the right time

under the right pressure. Caterpillar engineers have

found that by providing multiple injections, they

can better control emissions. Managing these brief

events requires the world’s best injector technology

from Caterpillar—the Mechanically Actuated and

Electronically Controlled Unit Injection system.

This multiple-injection system is proven technology

based on millions of hours of successful real-

world experience.

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Variable valve actuation, controlled by electronics,

provides precise delivery of cooled air for

efficient, clean combustion. This technology

provides air delivery to meet varying engine

demands based on a wide range of factors, such as

coolant temperature, engine speed, throttle

position and more. Controlled by Cat advanced

electronics, this system allows just the right

amount of air for efficient and clean combustion.

This system also uses components from proven

Caterpillar technology. Benefits of variable valve

actuation include low emissions and improved

fuel economy.

Diesel oxidation catalyst after-treatment converts

hydrocarbons into carbon dioxide and water. The

process is fast, efficient and reliable.

Achieving Maximum Performance and FuelEconomy—CaterpillarCaterpillar has developed new guidelines for

gaining maximum fuel efficiency and

performance from ACERT engines, which may

differ from previous Caterpillar engines. As with

all engines, engine fuel consumption changes

when operated at different engine speeds.

Caterpillar’s recommendation to “gear fast, run

slow” still applies on all Cat® Heavy Duty engines.

For most applications, there are some differences

in Caterpillar ACERT drivetrain specs that should

be followed to achieve the best balance between

fuel economy and performance in a Kenworth

truck. In most cases, ACERT engines will be spec’d

at lower engine rpm than prior generations of

Caterpillar heavy duty engines.

ACERT ELECTRONIC PARAMETERSProgrammable electronic parameters are available

to ensure proper engine operation. Setting

parameters correctly will maximize fuel economy

and control engine life cycle costs. Parameters

such as Vehicle Speed Limit, Low and Intermediate

Gear Limits, High Cruise Control Speed Limit, Gear

SPEC’ING TIPS FROM KENWORTH FORCATERPILLAR ACERT ENGINES

• A transmission with “close steps” in the top gears can

provide a closer match to recommended engine speed.

Double-overdrive transmissions should be considered.

• A transmission that provides “automatic shifting” in the

top two gears will assist the driver in maintaining the

proper engine speed over moderate-grade road terrain.

• To achieve optimum fuel economy, use direct or overdrive

transmissions with Gear Down Protection to ensure that

cruising speed can only be reached in top gear.

• Spec multi-torque engines for applications requiring less

than 1,650 lb-ft torque. These ratings provide additional

torque in the top four gears. With the additional torque,

the truck will have greater ability to crest a hill without

downshifting to improve fuel economy, reduce engine

wear and increase driver satisfaction.

For most applications,

there are some differences

in Caterpillar ACERT

drivetrain specs that should

be followed to achieve the

best balance between fuel

economy and performance

in a Kenworth truck.

Caterpillar has developed

ACERT to provide optimal

combustion efficiency and

produce minimal emissions.

The technology utilizes two

turbochargers in series, fuel

systems, variable valve

actuation, and exhaust

after-treatment. Electronic

controls manage the system.

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Gross Combination Line-Haul Cruising Speed Engine Weight (lb) for Maximum Fuel Economy Comments

C7 < 50,000 60 mph

2,000 rpm

> 50,000 60 mph

2,200 rpm

C11 < 60,000 65 mph

1,450 rpm

C13 Non Multi-Torque and < 80,000 65 mph

C13 Multi-Torque 1,450 rpm

410 hp 1,450/1,650 lb-ft

C13 < 80,000 65 mph

Multi-Torque 1,325 rpm

430 hp 1,550/1,750 lb-ft

C15 ≤ 80,000 Less than 1,750 lb-ft

Non Multi-Torque 65 mph

1,400 rpm

1,750 lb-ft and above

65 mph

1,325 rpm

C15 ≤ 80,000 65 mph

Multi-Torque 435 hp 1,325 rpm

1,550/1,750 lb-ft

and 475 hp

1,650/1,850 lb-ft

VSL should be set to prevent excessive speed.

Vocational Cruise Speed: Rear-axle ratio may need to

be spec’d at higher engine rpm to meet gradeability

and startability guidelines.

Vocational Cruise Speed: Driveline may need to be

spec'd at higher engine rpm to meet gradeability and

startability guidelines.

Vocational Cruise Speed: Driveline may need to be

spec'd at higher engine rpm to meet gradeability and

startability guidelines.

Heavy Hauler Cruise Speed:

1,500–1,650 rpm

Vocational Cruise Speed: Driveline may need to be

spec'd at higher engine rpm to meet gradeability and

startability guidelines.

Vocational Cruise Speed: Driveline may need to be

spec'd at higher engine rpm to meet gradeability and

startability guidelines.

Spec’ing Guides for Caterpillar ACERT Engines. Caterpillar ACERT Gearing Recommendation.

Down Protection and Idle Control can be set

during the vehicle order or pre delivery process.

StartabilityStartability is the ability of the vehicle to pull

away from a dead stop on a grade. Depending on

vocation, Caterpillar recommends following these

startability performance guidelines:

• 10% Pickup and Delivery

• 14% Line-Haul

• 20% On-Off Highway

• 25% Off-Highway

GradeabilityAt peak torque rpm in top gear, Caterpillar

recommends a minimum gradeability

performance threshold of 1.8%. At cruise speed in

top gear, 1.0% gradeability is ideal to achieve

best performance.

Gearing Recommendations for CaterpillarACERT EnginesThe chart above provides some general guidelines

to consider when spec’ing Caterpillar ACERT

engines.

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The following example compares a typical Owner

Operator gearing comparison (80,000 lb GCWR

and less) with the new Caterpillar ACERT engines.

Caterpillar MessengerIn 2003, Caterpillar introduced a new driver

message display for monitoring engine

performance and

operating

information. CAT

Messenger

graphically displays

and records fuel

usage and average

miles per gallon to monitor individual

performance in achieving fuel economy goals.

Messenger can also be enabled to alert drivers to

preventive maintenance inspections and oil

changes. Messenger displays the codes, indicating

a potentially serious engine problem

automatically by displaying diagnostic codes, with

both a number and a brief text explanation.

Security features of Messenger provide the

capability to allow or prevent engine starting, or

to shut the engine down by entering a 4-character

password into the display when the engine is at

idle. Other information that can be stored and

displayed includes:

• Vehicle trip information, including average

vehicle speed

• Cruise control set speed

• Fuel economy and fuel used

• Power Take Off (PTO) engine rpm set speed,

operation time and fuel consumed

• Percent idle time, fuel consumed

• Fuel temperature to the engine

• Boost and oil pressure

• Coolant temperature

• Intake manifold temperature

ENGINE COOLING SYSTEMS

All Kenworth radiators

and charge-air-coolers

are designed to

optimize the

performance of the

vehicle horsepower and

torque requirements to

the vocation, especially

when running at full

throttle at low speeds for

extended periods of time

in high ambient

conditions. Kenworth uses five basic sizes of

cooling modules:

Kenworth now offers a High Performance Engine

Cooling Ring Shroud to provide additional cooling

capacity with high horsepower and/or gross

combination weight ratings at or above 80,000

pounds. The High Performance Engine Cooling

Ring Shroud is mounted to the engine and

reduces fan blade tip clearance to promote more

efficient airflow over the cooling module.

Extended Life CoolantExtended life coolants (ELC) are a popular option

which allow operators to run the latest generation

of heavy duty diesels to overhaul, with no

supplemental coolant additives or coolant

changes necessary.

Extended-life coolants offer cooling system

protection for up to 300,000 miles. ELC contains

no silicates, nitrates, borates, phosphates, amines,

or other abrasive dissolved solids that can

Cooling Module Size(square inches) Models

840 T300

950 W900S

1,200 T800, W900L, T2000 and T600

1,430 W900B, T800H

1,520 T800W

Pre-ACERT Cat Spec TypicalSpec Type Recommendation New Cat ACERT Spec

Engine Rating 550 hp 1,850 lb-ft 550 hp 1,850 lb-ft

Transmission RTLO 18913A RTLO 18913A

Rear-Axle Ratio 3.55 3.25

Tires 285/75R24.5 285/75R24.5

Cruising Speed 1,410 rpm at 65 mph 1,300 rpm at 65 mph

Gradeability at Cruise 2.0 1.7

Startability 1st Gear 29.3 25.9

Startability 2nd Gear 17.0 14.9

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contribute to water pump seal wear. It provides

long-term corrosion protection for all cooling

system metals, including copper, brass, steel, lead

solder, cast iron and aluminum. It also offers

exceptional protection against pitting for wet

sleeve cast iron cylinder liners in heavy duty

engines and eliminates the need for the addition

of traditional supplemental coolant additives

(SCAs). Unlike traditional coolants that require

SCAs at 12,000- to 20,000-mile intervals, long-life

coolant requires only one recharging with an

extender product at 150,000 miles.

SPEC’ING CONSIDERATIONS FORPOWERTRAIN LUBRICANTS

Engine Oil Specifications for LowEmission EnginesKenworth Truck Company and its supplier,

ChevronTexaco, have taken steps to ensure that

the new generation of engine oils is compatible

with engine manufacturer requirements for the

new engine emissions standards. In June 2003,

Kenworth manufacturing plants transitioned to a

new formulation of Delo 400 multigrade oil. This

new formulation was optimized to meet the

demands of Cummins EGR engines while at the

All Kenworth radiators and

charge-air-coolers are

designed to optimize the

performance of the vehicle

horsepower and torque

requirements to the

vocation, especially when

running at full throttle at

low speeds for extended

periods of time in high

ambient conditions.

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same time providing the highest level of

performance with Caterpillar ACERT engines.

Delo 400 multigrade provides excellent soot

control, acid neutralization capability, maximum

thermal stability, and wear control while

minimizing diesel engine piston deposits.

Synthetic Transmission and Axle LubricantsKenworth trucks come standard with factory-

filled synthetic lubricants. The products, which

include SAE 50 synthetic manual transmission

fluid, 75W-90 synthetic axle lubricants and the

optional 80W-140 synthetic axle lubricant, meet

the Dana/Eaton Roadranger® extended 750,000-

mile warranty and 500,000-mile extended

lubricant drain interval requirements.

Synthetic lubricants provide superior all-climate

performance. The high viscosity index, low pour

point and subzero fluid flow provide for easier

cold-weather shifting, less drag and less gear wear

because vital transmission parts are lubricated

quickly. Since it is highly stable when exposed to

severe heat, oxidation and shear conditions,

synthetic lubricants provide exceptional high-

temperature lubrication for extended drain

intervals.

Synthetic transmission and axle lubes also

provide several low costs of operation benefits.

They provide antiwear additive, as well as rust,

oxidation and corrosion inhibitors that protect

bearings and synchronizers, reduce component

wear and promote longer transmission and

lubricant life.

AUTOMATED AND AUTOMATICTRANSMISSIONS

Automated and automatic transmissions are a

growing trend in the

industry. There are two

primary types:

• Automatic

Transmissions

• Automated Manual

Transmissions

Automatic Transmissions from AllisonAutomatic transmissions use a torque converter in

lieu of a clutch. The torque converter can provide

strong starting power, especially on hills or in soft

terrain. The torque converter multiplies the

engine’s torque, so the first gear offers similar

ratio coverage as the first two or three gears of a

manual transmission. Another feature of

automatic transmission is no power

interruption between or during shifts,

which can provide better

acceleration, smoother ride and

reduced shock loading of the

drivetrain, compared to a

THE NEW FORMULATION FOR KENWORTH’SFACTORY FILL DELO 400 MULTI-GRADE MOTOR OILIS COMPATIBLE WITH OLDER ENGINES

Delo 400 multigrade heavy-duty motor oil provides out-

standing protection under both pre- and post-2002 EPA

standards. This product can also be used in EGR-equipped

engines from other diesel engine manufacturers as well as

in all pre- 2003 heavy-duty diesel engines. Packaged

product labels have been updated to reflect the new

Caterpillar ECF-1 claim and will appear in circulation

as older inventories are depleted.

KENWORTH TRUCKS COME STANDARD WITHSYNTHETIC TRANSMISSION LUBRICANTS TOPROVIDE PREMIUM VALUE

• Superior Lubrication for Less Friction and Drag

• Better Fuel Economy

• Reduced Vehicle Downtime

• Lower Maintenance Costs

Kenworth Truck Company

and its supplier,

ChevronTexaco, have taken

steps to ensure that the

new generation of engine

oils is compatible with

engine manufacturer

requirements for the new

engine emissions

standards.

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manual transmission. Electronic controls

continuously monitor engine rpm, load and

terrain to keep the vehicle operating at peak

performance and optimum fuel economy.

Automated Manual Transmissions fromEaton Corporation With an automated manual, electronic controls

and electromechanical actuators take the place of

the manual shift lever. Some versions, such as the

all new Eaton Fuller UltraShift™, require no

clutch pedal for starting or stopping the vehicle.

Shifting is fully automatic once the vehicle is in

motion and managed by an onboard computer

which can provide fast and smooth shifts. The

transmission electronic control unit calculates the

vehicle load and, depending on the throttle

position and other inputs, provides the best gear

selection for the situation.

Eaton’s Top2 feature with the Lightning

transmission is another form of an automated

SMART TRANSMISSION SPEC’ING TIP FOR FLEETS

The Eaton Convertible Transmission is an innovative life

cycle cost solution targeted at fleet customers. The base

transmission is a 13-speed, which is operated as a 9-speed

for the truck’s first life operation. At resale, the Convertible

Transmission can be easily upgraded to a 13-speed for

higher resale. An excellent feature of the Eaton Convertible

Transmission is that it is available with a Top2 feature. As

with other Top2 models, the top two gears shift automati-

cally. In a convertible transmission, this means that the

Top2 gears are from a 13-speed transmission, providing a

17 percent gear step. This step size is ideal for the narrow

fuel economy rpm window of some new technology engines.

As an added incentive, the Eaton Convertible transmission

comes standard with a 5-year / 500,000-mile warranty.

When converted to a 13-speed, there is an additional one-

year / 100,000-mile warranty included with the conversion

kit upgrade.

Automated and

automatic transmissions

are being recognized for

higher productivity and

driver satisfaction.

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manual transmission designed specifically for

pickup and delivery and over-the-road

applications. The Lightning Top2 feature can

eliminate up to 80% of the shifts on highway and

urban roads. When shifting between 9th and 10th

gears, this solenoid, which is electronically

controlled by the transmission ECU, initiates the

shifting. As the terrain or vehicle speed varies, the

Top2 shift logic in the electronic control unit

determines which of the top two gears is best and

automatically makes the shift at the right time for

optimum economy and performance.

Features, Advantages and Benefits ofAutomated Manual and AutomaticTransmissionsAutomated and automatic transmissions are being

recognized for higher productivity and driver

satisfaction. With automated shifting, the driver

can more easily utilize both hands on the steering

wheel and focus their concentration on traffic and

the road.

Other benefits of automated and automatic

transmissions include:

• Automatic or automated shifting controls

driveline shock in components such as the

clutch, yokes, driveshaft and drive axle

components.

• Electronic fault management features alert the

driver of problems and carry out an automatic

fault analysis.

• Resale values for trucks spec’d with automated

or automatic transmissions can command a

premium ranging from $2,500–$5,000

compared to a manual 10-speed, depending on

the vehicle condition and age.

AXLES AND DRIVELINES

When spec’ing a truck,

careful attention must

be paid to the drive

axle, driveline and rear

suspension in order to

optimize the truck’s

performance and,

ultimately, its

profitability. The drive axle is one of the most

critical components in a truck. Ensuring that the

axle is appropriately specified could mean the

difference between a good performing truck and a

breakdown. Before choosing the rear axle,

information about the truck specification and

application must be known to identify the right

axle for the job.

Axle Spec’ing ConsiderationsAssessing the intended service of the truck is

critical for axle selection. Duty cycles of the

vehicle must be considered, including annual

mileage, distance between starts and stops,

percent of load going versus returning, road

surface type and grades. As the duty cycle is

uniquely different for each intended service, the

application guidelines for any one axle will vary

as well. In addition, the details of the truck

specification must be known, such as gross axle

weight rating, gross combination weight, gross

vehicle weight, engine horsepower and torque,

and the desired rear-axle ratio. In a number of

cases, the transmission low-gear ratio and tire size

are also required to accurately determine the

appropriate axle.

As the duty cycle is uniquely

different for each intended

service, the application

guidelines for any one axle

will vary as well.

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An axle that may be suitable with a 600-

horsepower engine in a line-haul application may

not be approved for a pickup and delivery (P&D)

application with even less horsepower because the

duty cycle is more demanding due to the frequent

starting and stopping associated with P&D.

For example, let’s take a look at the Dana Spicer

Application guidelines for the DSH40 tandem

axle. In a line-haul application, the axle is

approved for 600 horsepower and 2,050 lb-ft of

torque with a GCW of 125,000 lbs. But in the P&D

application, the maximum allowable is 550

horsepower and 1,850 lb-ft of torque and a GCW of

only 90,000 lbs.

This is just one example of how a truck’s intended

service and application can impact the approval,

reliability and performance of the drive axle. It is

important to take the appropriate steps up front

in the truck spec’ing process to accurately identify

the intended service, application duty cycle and

drivetrain details. Doing so can help reduce the

potential for axle failure while also working to

optimize the performance of the drive axle in

terms of reliability, durability and weight

capacity. Your Kenworth dealer not only has access

to a powerful sales tool but can also work with the

Kenworth Application Engineering Department to

help spec the right axle to pull and support the

load, fine tune the driveline combination to

optimize performance and efficiency, answer

questions and offer spec’ing tips for your unique

truck application.

Double-Reduction AxlesConventional tandem axles achieve torque

multiplication by transferring torque through one

ring and pinion set. A double-reduction axle

transfers torque through a planetary or helical

gear set in the input carrier first and then

through the ring and pinion. By dividing the

torque multiplication between two gear sets

instead of just one, internal stresses on gears and

bearings are reduced. The result is an axle with

high resistance to shock loading and improved

vehicle startability, making it an ideal choice for

heavy-duty and off-highway applications.

Planetary Wheel End Reduction AxlesTypically used in mining, logging, oil field and

heavy-haul applications, planetary axles are the

choice for extreme heavy-duty and off-highway

applications requiring high gross weights. Similar

to a double-reduction axle, the planetary axle

achieves its torque multiplication with two gear

sets. However, instead of a gear set in the input

carrier, the planetary axle first transfers torque

through the ring and pinion and then through a

final planetary gear set in the wheel end. The

result is an axle with high tolerance for heavy

loads. Kenworth offers planetary axles with

GAWR’s ranging from 58,000 lbs up to 150,000 lbs

and GCW’s up to 1 million lbs. Traditionally,

planetary axles have been speed limited to 40–45

mph in order to avoid excessive heat buildup in

the planetary gear set, and this is largely true for

the axles in the high end of the capacity range.

However, Kenworth offers planetary axles with

GAWR’s ranging from 58,000 lbs to 70,000 lbs and

GCW’s up to 330,000 lbs that can operate at

highway speeds without exposure to overheating

of the planetary gear set. These axles make an

ideal choice for heavy-haul and prime-mover

applications that haul loaded at slow speed one

way and return home empty at highway speed.

Dual Range (Two-Speed) AxlesThere are applications that require a truck to not

only operate at normal highway speeds, but also

at very slow, steady speeds when pulling heavy

loads out of muddy job sites or maneuvering on

uneven terrain. A transmission with a wide ratio

coverage, such as an 18-speed, will often meet the

needs of most heavy-haul applications. But for

those who need extra reduction, a dual range axle

is an alternative to an auxiliary transmission that

deserves consideration. Dual range axles are based

upon the same technology used in double

reduction axles discussed previously. Like the

double reduction axle, the dual range axle utilizes

a planetary gear set in the input carrier to

compound the ratio of the ring and pinion. Unlike

the double reduction axle, the dual range axles

give the operator the capability to engage—via a

dash-mounted switch—the planetary gear set for

low-range slow-speed pulling, or disengage the

gear set for high-range highway operation.

Tridem Drive AxlesWhile not particularly suited for over-the-road

use, tridems offer a number of advantages for

truck applications that demand time and mileage

off the pavement, such as logging, oil field service

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12and mining, to name a few. With three axles

instead of two, tridems allow more load to be

carried on the drive axles, providing more tractive

effort. Additionally, the tridem axle provides

greater floatation and improved mobility in loose

surfaces. This is achieved by distributing the drive-

axle load over a greater surface area than a

tandem axle. Tridem axles are available on

Kenworth trucks in capacities from 58,000 lbs up

to 105,000 lbs.

Front Drive Axle–4x4, 6x6, 8x6, 8x8ConfigurationsIf your application demands the ultimate in

traction, a front drive axle is likely to be the

solution. When a front drive axle is added to a

truck, there are a number of drivetrain and

chassis components that are affected as a result.

First, a transfer case must be added to power the

axle. Transfer cases are available in a variety of

torque capacities and configurations. Second, a

front drive axle requires that the chassis be raised

approximately nine inches to provide adequate

clearance between the engine oil pan and the axle

housing. This usually requires the addition of a

rear suspension subframe to level the chassis. A

final consideration is insuring that the front and

rear axles turn at or very close to the same speed.

The speed at which the axles turn can be altered

by the axle ratio and tire size. A good rule of

thumb when spec’ing a front drive axle is to

There are applications that

require a truck to not only

operate at normal highway

speeds, but also at very

slow, steady speeds when

pulling heavy loads out of

muddy job sites or

maneuvering on

uneven terrain.

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ensure that the speed of the front and rear axles

are within 1% of each other. A truck that has

improper mismatch will encounter excessive tire

wear and potentially premature damage to

drivetrain components. Many truck

manufacturers outsource installation of front

drive axles to aftermarket up-fitters. The

Kenworth factory installs front drive axles to the

highest of engineering and manufacturing

standards and backs them with a Kenworth

factory warranty.

DrivelinesKenworth trucks are standard with the proven

Dana Spicer 10-Series driveline yet are also

available with the low-maintenance Dana Spicer

Life XL-Series. Featuring a lightweight design and

improved sealing technology, the first lube is not

required until three years or 350,000 miles for on-

highway applications.

While it may appear to be simple, the proper

installation of a driveline involves a careful

balance of drivetrain and chassis component

location combined with rigorous calculations to

ensure that drivetrain vibrations are minimized.

Variables in the chassis specification, such as the

engine, transmission, wheelbase, suspension, axle

and even tire size, contribute to driveline design.

Every Kenworth drivetrain is custom designed to

provide optimum performance and not only meet

but exceed the requirements of

driveline manufacturers.

SUSPENSIONS AND TRACTIONCONTROL OPTIONS

SuspensionsFor many years, air suspensions have been

regarded as strictly on-highway suspensions due

to their relatively low level of axle articulation

and propensity for getting stuck in off-road

conditions, leaving vocational duty to mechanical

walking-beam or spring-type suspensions. As

demand for smoother riding and better handling

trucks has been increasing over the years, so too

has the demand for air ride suspensions.

Kenworth, one of the pioneering companies in air

suspension technology, has continued

development of air suspensions since the

introduction of its proprietary AirGlide 100 in the

1970s.

Today Kenworth offers an extensive lineup of

proprietary air suspensions from its ultra

lightweight AG380 to its family of 8-bag air

suspensions, including the AG400, AG460

tandems and the AG690 tridem suspension. The

AG400/460/690 suspension family’s 8-bag design

yields a smooth, stable ride and features a

lightweight yet durable one-piece swaybar that

provides up to 6" of axle travel and allows for high

axle cross-articulation. Unlike competing air

suspension designs, the AG400/460/690

suspension does not use the axle housing as a

torsional member, improving the life of the axle.

The result is an air suspension that minimizes

stress in the frame and cross-members and

provides outstanding traction in off-highway

conditions. The Kenworth AG400, AG460 and

AG690 are excellent choices for a number of

on/off-highway applications, including logging

and heavy haul.

Inter-axle Differential LockKenworth provides the inter-axle differential lock

as a standard feature and also provides an option

that restricts use of this feature while the

transmission is in high range. When engaged

(locked), the differential is inoperable and the

available input torque is distributed to both axles,

ensuring the vehicle maintains traction. This

feature is typically used at slow operating speed to

minimize the potential differential damage to the

forward axle.

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14

Wheel Differential Cross-LockFor vocational trucks that traverse off-road

surfaces, Kenworth offers a wheel differential lock

(also known as a cross-lock) that, when engaged,

distributes the available torque to all wheels,

ensuring the power is delivered to keep the

vehicle moving.

Central Tire Inflation SystemDana Spicer Central Tire Inflation System (CTIS)

provides enhanced mobility through improved

flotation and traction by the adjustment of tire

pressures. In off-road vocational applications, CTIS

has grown in popularity as an effective alternative

to all-wheel drive, providing good off-road

performance with far less weight, cost and a lower

overall vehicle height. CTIS features operator-

controlled inflation and deflation of all the

vehicles’ tires based on terrain, speed and load.

Automatic Traction ControlAutomatic Traction Control (ATC) is an optional

feature of Kenworth’s Antilock Brake System (ABS).

When a difference in speeds between wheels

occurs during acceleration, the ATC is activated,

controlling wheel spin to provide improved

traction. Other features of ATC are noted above.

Feature Advantage and Benefit

Automatic Differential Braking Reduces potential of powering into a

jackknife caused by wheel overspin

during acceleration or in curves. Provides

primary control when drive wheels are

operating on different surfaces; when

one wheel spins, ATC momentarily

applies the brake on that wheel to gain

traction.

Electronic Engine Control If both wheels on the sensed axle are on a

poor-traction surface, ATC automatically

reduces engine power to attain optimum

tire-to-road traction.

ATC Light on Dashboard Indication of slippery road conditions.

Automatic Traction Control

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15

SUMMARY

Proper spec’ing of the vehicle’s powertrain is

crucial to achieve high productivity and low life

cycle costs. The Kenworth Dealer Network of

nearly 300 locations in the U.S. and Canada

provides assistance in selecting the optimum

powertrain for your application through a state-of-

the-art, Kenworth PROSPECTOR® vehicle spec’ing

system. Kenworth dealers are backed by the

World’s Best engineering organization, which can

provide a wide range of technical and

applications assistance.

Spec’ing Guidelines for Air Suspensions

Kenworth Air SuspensionAG380 AG400 AG460 AG690

Configuration Tandem Tandem Tandem Tridem

Ride Height 8.5" 9" 10.5" 10.5"

Rated Capacity 38,000 lbs. 40,000 lbs. 46,000 lbs. 69,000 lbs.

Axle Spacing 52" 52", 54" 52", 54", 60" 54"

Intended Service Line-haul Line-haul Line-haul Line-haul

Local P&D Local P&D Local P&D Local P&D

EMT/Rescue/Fire EMT/Rescue/Fire EMT/Rescue/Fire

Heavy Transport Heavy Transport Heavy Transport

Wrecker* Wrecker* Wrecker*

Crane/Picker* Crane/Picker* Crane/Picker*

Oil Well Servicing Oil Well Servicing Oil Well Servicing

Loggers Loggers Loggers

Agriculture* Agriculture* Agriculture*

Construction* Construction* Construction*

Snowplows Snowplows Snowplows

Dump Dump* Dump*

Body Type Van All except All except All except

Beverage Mixer Mixer Mixer

Tanker Refuse Refuse Refuse

Flatbed Roll Off* Roll Off* Roll Off*

Road Usage 95–100% A&B 90–100% A&B 90–100% A&B 90–100% A&B

≤5% C ≤10% C ≤10% C ≤10% C

≤0% D ≤0% D ≤0% D ≤3% D

* Review required by Kenworth Application Engineering.

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16

Drivetrain Spec’ing - General Recommendations

Electronic Minimum EnhancementEngine Minimum Gradeability* Minimum Traction

Intended Service Parameters Horsepower (Cat Only) Startability† Transmission Drive Axle Suspension Features

Line-haul 400 1.5%–18% at 14% 9-Spd 40K Air Traction

peak torque in top Convertible, Control

gear, 1% at cruise 10/13-Spd

in top gear

P & D 305 1.5%–18% at 10% Automatic and 21K - 40K Air or Traction

peak torque in top Automated; Leaf Spring Control

gear, 1% at cruise 10-Speed

in top gear Manual

Dump 350 1.5%–18% at 16%–20% 10/11/13/18-Spd 40K-46K Walking Wheel

peak torque in top Manual or Allison Thick Wall Beam Diff-locks

gear, 1% at cruise Automatic Housing

in top gear

Mixer 305 1.5%–18% at 16%–20% 11-Spd 40K-46K Walking Wheel

peak torque in top Manual or Allison Thick Wall Beam Diff-locks,

gear, 1% at cruise Automatic Housing CTIS, 6x6

in top gear

Logger 430 1.5%–18% at 16%–20% 13/15/18-Spd 40K-46K Air or Wheel

peak torque in top Thick Wall Walking Diff-locks

gear, 1% at cruise Housing Beam

in top gear

Refuse Packer / 400 1.5%–18% at 11-Spd 40K-46K Walking Wheel

Roll-Off peak torque in top Manual or Allison Thick Wall Beam Diff-locks

gear, 1% at cruise Automatic Housing

in top gear

Refuse Transfer 430 1.5%–18% at 15% 10/13/18-Speed 40K-46K Walking Wheel

peak torque in top Thick Wall Beam Diff-locks

gear, 1% at cruise Housing

in top gear

Construction 400 1.5%–18% at 16%–20% 10/11/13/18-Spd 40K-46K Air or Wheel

peak torque in top Manual or Allison Thick Wall Walking Diff-locks,

gear, 1% at cruise Automatic Housing Beam CTIS, 6x6

in top gear

Heavy Haul 475 1.5%–18% at 15% 18-Spd 46K - 52K Air or Wheel

110K - 140K peak torque in top Tandem, Walking Diff-locks,

gear, 1% at cruise 58K-78K Beam Traction

in top gear Tridem Control

Heavy Haul 500 1.5%–18% at 15% 18-Spd or 46K - 52K Air or Wheel

140K - 185K peak torque in top with Auxiliary Single or Walking Diff-locks,

gear, 1% at cruise Double Beam Traction

in top gear Reduction Control

Heavy Haul 550 1.5%–18% at 15% 18-Spd or Planetary Air or Wheel

185K peak torque in top Automatic Walking Diff-locks,

gear, 1% at cruise with Auxiliary Beam Traction

in top gear Control, 6x6

Multi-torque ratings;

Idle shutdown timer;

On/Off fan controller;

Gear down protection;

Driver reward;

Duty cycle monitor

Idle shutdown timer;

ON/OFF fan controller

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

Gear down protection;

Idle shutdown timer;

ON/OFF fan controller;

PTO parameters

* In order to meet gradeability requirements, vocational cruise speed may need to be spec’d at higher engine rpm.

† Operation on rough, soft, poorly maintained or unimproved surfaces adds 3% to the above values.

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J.D. Power and Associates 2004 Heavy Duty Truck StudySM. Study based on 1,596 responses from principal maintainers of heavy duty trucks. The Vocational truck segment is defi ned as heavy duty trucks operating in typically rugged business environments such as construction, specialized heavy hauling, sanitation/refuse, forestry, mining, or utility services. Also included in this segment are dump trucks, concrete mixers, cranes, and other related vehicles. www.jdpower.com. ISO 9001. © Kenworth Truck Company, A Division of PACCAR. For more information, please call or visit your local Kenworth dealer or go to www.kenworth.com.

KENWORTH.The World’s Best.

“Highest in Customer Satisfaction among Vocational Segment Class 8 Trucks.”

Kenworth sets the standard for customer satisfaction.

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