Chapter 1

Introduction To Servicing Heavy-Duty Trucks

Objectives (1 of 2)

• Explain basic truck classifications.

• Define gross vehicle weight.

• Classify a truck by the number of axles it has.

• Identify an on-highway truck’s major systems and their related components.

• Identify various career opportunities in the heavy-duty trucking industry.

Objectives (2 of 2)

• Understand and explain the basic job classifications the heavy-duty truck industry offers to trained technicians with a sound understanding of truck systems.

• Understand the ASE certification program and how it benefits technicians.

Truck Classifications (1 of 2)

• Trucks are classified by their gross vehicle weight.– Light-duty

• Classes 1-3

– Medium duty• Classes 4-6

– Heavy-duty• Classes 7 and 8

• See Table 1-1 on page 2 of the textbook.

Truck Classifications (2 of 2)

• Trucks are also classified by their number of axles.

• The total number of axles is indicated first, followed by the number of driven axles.

• See Table 1-3 on page 3 of the textbook.

Heavy-duty Trucks (1 of 4)

• Engines– Heavy-duty trucks are

powered exclusively by diesel engines.

• More powerful• Less downtime for

repairs• More dependable

– Current highway diesel engines are electronically controlled.

• Electrical systems– Multiple batteries

– Heavy-duty charging systems

– Heavy-duty starting systems

Heavy-duty Trucks (2 of 4)

• Drive Shafts

• Axles– Steering axles– Differentials– Lift axles

• Steering

• Suspension systems– Leaf spring– Rubber cushion– Air suspension

• Wheels and tires

• Clutches– Push vs. pull-type clutches

– Two plate clutches

• Transmissions– Conventional

– Semi-automated

– Fully automatic

– Multiple countershaft designs

Heavy-duty Trucks (3 of 4)

• Wheels and tires– Cast spoke

– Steel disc

– Aluminum disc

– Wide base disc

• Brakes– Highway trucks use air

brakes exclusively.

– Current tractors and trailers are required to be equipped with antilock brakes.

• Vehicle retarders– Engine brakes

– Exhaust brakes

– Hydraulic retarders

– Electric retarders

• Chassis frame

• Fifth wheels– Fifth wheel

– Kingpin

Heavy-duty Trucks (4 of 4)

• Heating/air conditioning

• Electronic controls– Computerized control systems

• Engines

• Transmissions

• Climate controls

• Suspension

• Brakes

• Other systems

• Multiplexing

Career Opportunities

• The number of trucks in America is increasing while the number of qualified technicians is decreasing.

• Fleet operations• Fleet shops• Dealership shops• Independent truck repair shops• Specialty service shops• Other truck shops

Job Classifications (1 of 2)

• Service technicians– Certification– ASE

• Specialty technicians

• Service writer

• Parts manager

• Shop supervisor

Job Classifications (2 of 2)

• Service manager

• Advancement in the profession– Vocational/technical schools– Fleet training programs– Manufacturer training programs

Summary (1 of 4)

• Although the number of trucks and automobiles in America is increasing, the number of technicians available to service and maintain them is decreasing.

• Trucks are classified by their gross vehicle weight (GVW), the weight of the vehicle and maximum load, and by the number of axles they have. – Heavy-duty trucks have a GVW of 26,001

pounds or more.

Summary (2 of 4)

• The major systems in on-highway trucks are engines, electrical systems, clutches, transmissions, drive shafts, axles, steering, suspension systems, wheels and tires, brakes, vehicle retarders, chassis frame, fifth wheel, heating and air-conditioning, electronic controls, and accessories.

• Heavy-duty truck technicians are employed by fleet operations, fleet shops, dealership shops, independent truck service shops, specialty service shops, and other types of truck shops such as truck leasing and refuse haulers.

Summary (3 of 4)

• Job classifications in the heavy-duty truck industry– Service technician– Specialty technician– Service writer– Parts manager– Shop supervisor– Service manager

• Oversees the entire service operation of a large dealership, fleet, or independent shop

Summary (4 of 4)

• A successful heavy-duty truck technician must be able to maintain good customer relations and working relations; use effective communication skills; maintain a safe work environment; perform preventive maintenance; use tools and equipment properly; troubleshoot; correct problems by repairing or replacing; and upgrade skills and knowledge continuously.

• Training for heavy-duty truck technicians is offered by vocational/technical schools, fleet training programs, and manufacturer training programs.

• Heavy-duty truck technicians can obtain certification by the National Institute for Automotive Service Excellence (ASE) by passing written exams.