chapter 4 preventive maintenance program. objectives (1 of 2) explain the characteristics and...
TRANSCRIPT
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.