Chapter 4

Preventive Maintenance Program

Objectives (1 of 2)

• Explain the characteristics and benefits of a well-planned preventive maintenance program.

• List and describe the steps of the pre-trip inspection procedure.

• Describe the criteria for deadlining or out-of-service (OOS) tagging a vehicle.

• Implement a policy of preventive maintenance scheduling that conforms to federal inspection regulations.

Objectives (2 of 2)

• Describe inspector qualifications and record-keeping requirements.

• Select lubricants for the various tasks of preventive maintenance.

• Describe the operation of on-board chassis systems, both manual and automatic, for vehicle lubrication.

• Prepare trucks and trailers for cold weather by winterizing.

Preventive Maintenance• Advantages

– Lower maintenance cost– Maximum vehicle

availability– Better fuel economy– Reduced road failures– Better customer relations– Reduced incidence of

accidents due to defective equipment

– Fewer driver complaints

• Importance of Records– DOT requirements– Performance– Used to develop

maintenance programs– Useful as proof of

maintenance during accident investigations

Setting Up a PM Program• PM inspections

– Schedule “A”; a light inspection taking about 2.5 hours of labor

– Schedule “B”; a more detailed inspection taking about 5 hours of labor

– Schedule “C”; a more detailed inspection including service and adjustments requiring about one day’s labor

– Schedule “D”; a comprehensive inspection and adjustment often including component replacement or rebuilding

– Schedule “L”; a chassis lubrication

Driver Inspection

• Pre-trip and post-trip inspections are spelled out by DOT regulations.

• The inspection form is usually found on the back of the hours-of-service log.

Inspection Procedure• Step 1 Vehicle overview• Step 2 Engine compartment• Step 3 Inside of cab• Step 4 Front of cab• Step 5 Left side of cab• Step 6 Left fuel tank area• Step 7 Left rear tractor• Step 8 Left side of trailer• Step 9 Rear of trailer• Step 10 Right side of trailer• Step 11 Right rear tractor• Step 12 Right fuel tank• Step 13 Right side of cab• Step 14 Cab

Deadlining a Vehicle(Out-of-service)

• Anything mechanical that can either cause or prevent an accident is a safety item (FMCSR part 393).

Caution

• Do not confuse the out-of-service (OOS) specification with the OEM safe operation limits. – OOS limit indicates that the system has

become potentially dangerous.

PM Scheduling (1 of 3)

Shop Talk

• Remember that if the technician misses something or fails to repair a defect before an inspection, the inspectors may take the vehicle out of service. – That can be costly—in both downtime and

fines. – It can also hurt a fleet’s DOT safety rating.– Worse yet, the defect could cause an

accident.

Shop Talk

• It should be noted that off-highway vehicles rarely have odometers. – Most use engine service or the vehicle’s hour

meter to measure PM intervals, as opposed to distance traveled.

– One current trend bases PM timetabling on the amount of fuel consumed.

PM Scheduling (2 of 3)

• Federal inspection regulations• The following vehicles must be inspected:

– Any vehicle involved in interstate commerce with a gross vehicle weight over 10,000 pounds

– Any vehicle regardless of weight which is designed to carry more than 15 passengers

– Any vehicle, regardless of weight, carrying placarded hazardous materials

PM Scheduling (3 of 3)

• Record-keeping requirements• PM software

Shop Talk• When undertaking PM checks and servicing trucks,

it is sometimes necessary to raise the cab. – With most hydraulic cab-lift systems, there are two

circuits: the push circuit that raises the cab from the lowered position to the desired tilt position, and the pull circuit that brings the cab from a fully tilted position up and over the center.

– Remember that in most systems, whenever raising or lowering the cab, stop working the hydraulic pump once the cab goes over center.

– The cab falls at a controlled rate and continued pumping could lock up the tilt cylinders.

Lubricants (1 of 8)

• Engine oils • Additives– Oxidation inhibitors– Antirust agents– Detergents– Anticorrosion agents– TBN additives

Lubricants (2 of 8)

• SAE grade of engine oil– See Table 4-3 on page 98 of textbook.

Shop Talk

• Both the SAE viscosity grade and API (American Petroleum Institute) classification are clearly displayed on the label of any oil container.

Lubricants (3 of 8)

• Diesel engine oil classifications– The first character describes the type of engine for

which the oil is designed.• C: compression ignition; for diesel engines• S: spark ignition; for gasoline engines• G: appropriate for gasoline engines

– The second character further describes the oil’s characteristics. Future classifications are added in alphabetical order.

• CI SH• CH-4 GF-2• CI-4 GF-3• PC-10 GF-4

Shop Talk

• Using the incorrect grade or type of oil in an engine can cause a variety of problems. – For example, the wrong viscosity oil can cause either

an oil consumption or low oil pressure problem, depending on the weather and driving conditions.

– Using an oil with the incorrect service rating can result in inadequate protection for engine bearings and other moving engine parts.

– Consult the engine manufacturer’s recommendations to ensure that the engine is using the correct grade and type of oil.

Lubricants (4 of 8)

• Used oil• Gear lubricants

– See Table 4-4 on page 100 of the textbook.

Lubricants (5 of 8)

• Chassis lubricants– See Table 4-5 on page 101 of the textbook.

Lubricants (6 of 8)

• On-board chassis lubricating system– Manual systems– Automatic chassis lube systems (ACLS)

Lubricants (7 of 8)

• Properties of greases– See Table 4-6 on page 102 of the textbook.

Lubricants (8 of 8)

• Trailer lubrication– See Table 4-7 on page 105 of the textbook.

Winterizing (1 of 4)

• Engine coolant– Inspection– Clean the cooling system– Antifreeze

• EG• PG• ELC

Winterizing (2 of 4)

• Checking coolant condition– Hydrometers– Refractometers– Litmus/chemical tests– Lab sample analysis– Supplemental coolant additive

• Disposal of antifreeze

Winterizing (3 of 4)

• Air system• Starting aids

– Electric block heaters– Fuel-fired heaters– Oil pan heaters– Glow plug systems– Grid heaters– Ether starting systems

• Cab comforts• Batteries and electrical system

Winterizing (4 of 4)

• Diesel fuel• Fuel-water separators• General winterizing tips

Warning

• Avoid using ether with glow plug-equipped engines.

• On engines with an air pre-heater, consult the engine owner’s manual.

Performing a Lube Job

• Greasing the chassis• Checking fluids

TECHTIP

• When preparing to perform a lube job, place a few zerk fittings in your pocket before beginning. – Zerk (spring-loaded ball) seals may seize and

prevent grease from entering; replace a failed zerk fitting with a new one.

Caution (1 of 2)

• Some spring hangers are manufactured from cast aluminum alloy: Never apply heat anywhere near cast aluminum suspension components.

Caution (2 of 2)

• Remember that grease is both difficult to remove and may permanently stain surfaces.– There is probably nothing that will enrage a

driver more quickly than grease on any part of a truck chassis other than where it is supposed to be.

– Work clean! Use floor mats and change coveralls before driving a vehicle after a lube job.

TECHTIP

• Remember that a hand-actuated grease gun actually develops higher pressure than an air grease gun and may open a zerk nipple that a pneumatic gun failed to open.

Summary (1 of 3)

• A preventive maintenance program involves the inspection and servicing of the vehicle as a whole. – The program’s success depends on careful planning.

• The maintenance program that is most effective is tailored around the needs and experiences of each individual operation.

• The driver identifies many repairs when performing pre-trip and a post-trip inspections.

Summary (2 of 3)

• A vehicle considered likely to cause an accident or breakdown because of mechanical conditions or improper loading should be taken out of service.

• It is the fleet’s responsibility to ensure that all personnel performing annual inspections are qualified.

• Maintenance managers and truck technicians are expected to be computer literate because service tracking is computerized.

Summary (3 of 3)

• Proper lubrication is important in reducing wear and preventing premature failure of truck components.

• Winterizing a heavy-duty truck is an important part of any PM program.

• Performing a lube job properly is a requirement of an entry level truck technician from day one on the job.