04/19/23

Lake Area Tech

Diesel Technology

DT220 Truck Preventive Maintenance

Heavy Duty Truck Systems

Chapter 1

Introduction to Servicing Heavy-Duty Trucks

Without Trucks, America Stops

Trucking is vital to America

• General Information: The trucking industry is comprised of more than 500,000 for-hire, private and government fleets, including owner operators. It employs 9.7 million people, including 3.12 million drivers, and accounts for nearly 5% of the U.S. gross domestic product. Truly, trucking is an essential part of our economy and society.

Check out the American Trucking Association

• ATA

http://www.truckline.com/index

.

Weight Classifications

• Class 1 up to 6000 LBS GVW• Class 2 6001-10,000• Class 3 10,001-14,000• Class 4 14,001-16,000• Class 5 16,001-19,500• Class 6 19,501-26,000• Class 7 26,001-33,000• Class 8 33,001 and over

Major manufacturers

• Freightliner• Navistar• Kenworth• Mack• Sterling• Peterbilt• Volvo• Western Star

Cab ConfigurationsConventional • Cab-over-engine

Cab Configurations

• Short conventional • Low cab forward

Truck Classification

TRUCK TOTAL WHEELS

DRIVEN WHEELS

TOTAL AXLES

DRIVE AXLES

4X2 4 2 2 1

4X4 4 4 2 2

6X2 6 2 3 1

6X4 6 4 3 2

6X6 6 6 3 3

8X4 8 4 4 2

8X8 8 8 4 4

Truck and Trailer dimensions

Electrical systems

• Batteries

• Alternator

• Starter

• Series/Parallel switch

• Lighting

• Accessories

Clutches• Two plate clutch

• Push type

• Pull type

• Clutch brake

Transmissions

• Twin countershafts

• Triple countershafts

• Automatic (Allison)

• Auto-shift (2 or 3 pedal)

• Lubrication

• Oil coolers

Drive shafts

• End yoke

• U-joint

• 1610 size is 5.312” across the lugs

• 1710 size is 6.094” across the lugs

• 1760 size is 7” across the lugs

• 1810 size is 7.547” across the lugs

Axles

• Weight rating– Steering axle—8,9, 12, 14, 16K lbs– Single rear axle—14, 17, 19, 23K lbs– Tandem axles—34, 36, 38, 40K lbs

• Power divider

• Axle ratio– Find numbers on end of pinion shaft on rear-rear

axle

Steering

• Manual– Worm and roller, recirculating ball, cam and lever

types

• Hydraulic Power assist• Air power assist• Integral power steering (most common)

– TRW (Ross)– Sheppard

Suspension systems

• Hendrickson equalizing beam

Four Spring

• Four spring

Four air springs (bags)

Torsion barEight bag (Kenworth)

Wheels and Tires

• Cast spoke (Dayton)

• Steel disc (Budd)

• Aluminum disc

• Stud piloted

• Hub piloted

Brakes

• Hydraulic drum• Hydraulic disc• Air S-cam• Air wedge• Air disc• NHTSA• FMVSS 121• ABS senders/modules (6S/6M)

Retarders

• Jacobs engine brake

• Mack Dynatard®

• Cat Brakesaver®

• Exhaust brake

• Electrical retarder

Chassis Frame

• Rails

• Crossmembers

• Flange

• Web

Fifth wheel

• Stationary

• Sliding

• Air slide

• elevating

HVAC

• Cab HVAC

• Sleeper HVAC

• APU

Electronic controls

• Engines

• Transmissions

• ABS

• Safety radar

• multiplexing

Fleet operations

• Linehaul• JIT• LTL• P&D• Courier• DCC• Vocational

• Renting and leasing• O/O

Shops

• Fleets

• Dealerships

• Independent

• Specialty shops

• others

Jobs

• Service tech

• Specialty tech

• Service writer

• Parts manager

• Shop supervisor

• Service manager

As always, read the summary

Remember,

without trucks America stops