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PLOW AND SANDER MANUAL
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TRUCK II MANUAL
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Last updated: October 2020
TRUCK II MANUAL
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Table of Contents LIST OF FIGURES .............................................................................................................................. 3
Overview ......................................................................................................................................... 5
Knowledge of an Employee ......................................................................................................... 5
Skills of an Employee ................................................................................................................... 5
OH&S Regulations ........................................................................................................................... 6
Introduction .................................................................................................................................... 7
Heat – Energy – Traction - Friction .............................................................................................. 7
Stopping Distance ........................................................................................................................ 7
Pre-Trip Inspection .......................................................................................................................... 8
Approach ..................................................................................................................................... 8
Under the Hood ........................................................................................................................... 8
Walk Around ................................................................................................................................ 9
In Cab Checks .............................................................................................................................. 9
Pre-Trip Procedure for Air Combination Unit ............................................................................. 9
Schedule 1 ................................................................................................................................. 12
Starting the Engine ........................................................................................................................ 13
Ether .......................................................................................................................................... 13
Hydraulics .................................................................................................................................. 13
Air Bags ...................................................................................................................................... 14
Diesel Particulate Filter (DPF).................................................................................................... 14
Diesel Exhaust Fluid (DEF) ......................................................................................................... 15
Air Brake System ........................................................................................................................... 15
Compressor ............................................................................................................................... 16
Reservoirs .................................................................................................................................. 17
Foot Valve .................................................................................................................................. 18
Service-Brake Chambers ........................................................................................................... 18
Long stroke vs. Short Stroke ...................................................................................................... 19
Brake shoes and Drums ............................................................................................................. 20
Air Brake Operation ...................................................................................................................... 22
Safety Valve ............................................................................................................................... 23
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One-Way check Valve ................................................................................................................ 24
Air Pressure Gauge .................................................................................................................... 24
Air Governor .............................................................................................................................. 24
Relay Valve ................................................................................................................................ 25
Quick Release Valve .................................................................................................................. 26
Front Axle Ratio Valve ............................................................................................................... 26
Air Dryer .................................................................................................................................... 27
Truck II Operation ......................................................................................................................... 27
Sand Seal ................................................................................................................................... 28
Pavement Marking .................................................................................................................... 29
Sign Replacement ...................................................................................................................... 29
Safe Operation .............................................................................................................................. 30
Fine ............................................................................................................................................ 27
Overweight Load ....................................................................................................................... 27
Wheel Safety ............................................................................................................................. 28
Preventative Maintenance ........................................................................................................... 28
Oil Changes ................................................................................................................................ 29
Slack Adjuster Maintenance ...................................................................................................... 29
Relatable SOP’s ............................................................................................................................. 30
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LIST OF FIGURES Figure 1: Stopping Distance ............................................................................................................ 8
Figure 2: DPF system decal ........................................................................................................... 14
Figure 3: Air compressor ............................................................................................................... 17
Figure 4: Typical reservoir drain valves ........................................................................................ 17
Figure 5: Dual-circuit foot valve .................................................................................................... 18
Figure 6: Clamp-ring type service brake chamber ........................................................................ 19
Figure 7: Long stroke and Short stroke brake chambers .............................................................. 20
Figure 8: S-cam brake assembly ................................................................................................... 20
Figure 9 - Disk Brake wear Indicator ............................................................................................. 22
Figure 10: Brake application ......................................................................................................... 23
Figure 11: Safety valves ................................................................................................................ 23
Figure 12: One-Way check Valve .................................................................................................. 24
Figure 13: Air Pressure Gauge ...................................................................................................... 24
Figure 14: Air governor ................................................................................................................. 25
Figure 15: Relay valve ................................................................................................................... 25
Figure 16: Quick-release valve ...................................................................................................... 26
Figure 17: Front axle ratio valve ................................................................................................... 26
Figure 18: Air dryer ....................................................................................................................... 27
Figure 19: 3-Point Contact Entry .................................................................................................. 28
Figure 20: Sand Sealing (Oil roll) ................................................................................................... 29
Figure 21: Pavement marking ....................................................................................................... 29
Figure 22: Sign Replacement ........................................................................................................ 30
Figure 23: Slack adjusters ............................................................................................................. 29
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NOTE TO THE READER
The information in this manual does not include each and every unique solution that you may
encounter while operating or working on the MHI equipment. In the event that a situation is not
addressed in this manual is encountered, contact your supervisor if in doubt before proceeding
Recognizing that some changes on the unit may be made in the future, the information,
specifications and illustrations in this manual are based on information that was current at the
time of publication. Note that some illustrations are typical and may not reflect the exact
scenario in which the employer will be faced.
This publication is intended for MHI internal use only. No part of this publication may be
reproduced, stored in a retrieval system or be transmitted in any form by any means including
(but not limited to) electronic, mechanical, photocopying, recording or otherwise for any other
purpose without the written permission of the MHI.
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Overview As an employer, the Ministry of Highways and Infrastructure (MHI) must ensure adequate training
exists. This manual along with training for new employees and coaching by supervisors will form the
foundation of the Ministry program. The course content and format to deem an operator competent
on Truck II operations will consist of:
Review of the Ministry of Highways & Infrastructure (MHI) Truck II Manual.
Review of specific equipment manuals,
Completing Truck II E-Learning Module,
Successfully passing Truck II LEARN exam, and
A practical evaluation of a pre-shift inspection and proper operation of the unit typically done
with the employee’s supervisor for a minimum of 16 hours. Some employees could take more
than 16 hours to be deemed competent based on prior experience and comfort level with
power mobile equipment.
Occupational Health and Safety (OH&S) Regulations states; an employer or contractor shall ensure that
only trained operators are required or permitted to operate powered mobile equipment (Section 154).
The OH&S definition of a “trained operator” means a worker who has successfully completed a training
program that includes all the elements set in Table 14.1 of the OH&S Regulations.
You as an employee must use the procedures outlined in the manual along with the material presented
during the training to ensure not only your safety, but those co-workers around you.
Knowledge of an Employee After attending training and then being deemed competent on Truck II, employees will be able to do the
following:
Identify hazards associated with the work, including the principles of operations and features of
the unit,
Understand the manufacturer’s specifications related to the operation and safe load handling
for the unit that the worker will be using,
Repeat workplace safety practices and procedures, and
Understand legislation applying to the work.
Skills of an Employee The skills to be learned are:
Pre-operation inspection and daily circle check,
Start-up and shut-down procedures,
General operation including starting, stopping, turning, driving forward and reverse, parking,
braking, lifting and operating around personnel,
Air Brake systems and service brake chambers
Operational maintenance such as servicing and refueling.
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OH&S Regulations This manual was based off of best practices, Ministry standards and of course, the Occupational Health & Safety (OH&S) Regulations. If you want to understand the reasoning or the legal obligations between both the employer and employee, we recommend you do further reading of the regulations that can be found at www.publications.gov.sk.ca. These are the Acts and Regulations that you need to understand and adhere to: The Traffic Safety Act;
The Commercial Vehicle and Drivers(Record-Keeping) Regulations
The Commercial Vehicles Hours of Service Regulations
The Vehicle Equipment Regulations, 1987
The Safety Fitness Regulations
The Trip Inspection Regulations
The Security of Loads Regulations, 2013
The Vehicle Weight and Dimension Regulations, 2010 National safety Code;
Standard 10
Standard 11 Truck II regulations (The OH&S Regulations, 1996);
o Section 12 – General Duties of Employers o Section 13 – General Duties of Workers o Section 14 – Employment of Young Persons o Section 17 – Supervision of Work o Section 24 – Identifying Mark of Approved Equipment o Section 25 – Maintenance & Repair of Equipment o Section 132 – Designated Signalers o Section 153 – “Hours of Darkness” Means o Section 154 – Trained Operators for Power Mobile Equipment o Section 155 – Visual Inspection o Section 156 – Inspection and Maintenance o Section 157 – Requirements for Powered Mobile Equipment o Section 157.1 – Construction, Repair, etc. of Powered Mobile Equipment o Section 158 – Use of Seat Belt o Section 160 – Warning of Reverse Motion o Section 161 – Roll-Over Protection Structure o Section 164 – Dangerous Movements o Section 165 – Transporting Workers
Training regulation (The OH&S Regulations, 1996);
o Table 14.1
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Introduction The study of the Truck II unit will make you aware of all possibilities you may encounter and
outline some of the main features of different systems. This manual will provide information on
basic air system and components, and key things to be aware of when operating the Truck II
unit. It will assist drivers in understanding the basic operation and function of an air brake
system.
Heat – Energy – Traction - Friction To move a vehicle, an internal combustion engine must convert its heat energy to mechanical
energy. This mechanical energy goes from the engine to the driving wheel tires by means of a
system of connecting rods, shafts and gears. The final factor that moves a vehicle is the amount
of traction its tires have on the road surface. Traction is the ability of a tire to grip the road
surface on which it rolls. The vehicle’s acceleration rate depends on the power the engine
develops and the amount of traction the tires has on the road surfaces. Friction is the force
which resists movement between two surfaces in contact with each other. To stop a vehicle,
brake shoe linings are forced against the machined surfaces of the brake drums, creating
friction. This friction produces heat. The distance required to stop a vehicle depends on its
speed and weight in addition to the factors of energy, heat and friction
Stopping Distance In addition to the factors that contribute to the movement of a vehicle, an operator must
understand what is meant by the term “Stopping Distance”. Stopping distance consists of three
factors; Reaction time, Brake Lag, Braking distance.
Reaction time, is the time it takes from the moment a hazard is recognized to the time the
brake is applied. Brake lag, is the time air takes to travel through properly maintained air brake
system. Braking distance, is the actual distance a vehicle travels after the brake is applied until
the vehicle stops. This distance depends on the ability of the lining to produce friction, the
brake drums to dissipate heat and the tires to grip the road.
Professional drivers never take breaks for granted. The braking system must be tested and
checked before placing the vehicle into service. Proper air brake testing and inspection
methods will be discussed later in this manual. Heavy vehicles such as the Truck II require
powerful braking systems that are obtained by use of mechanical leverage and air pressure.
Brakes must be used keeping in mind the heat generated by friction. If heat becomes too great,
braking effectiveness will be lost. The heavier the load and the faster the speed, the greater the
power needed to top. A professional driver is well aware that the vehicle, even with properly
adjusted brakes will not stop as quickly as a passenger vehicle.
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Figure 1: Stopping Distance
Pre-Trip Inspection A pre-trip inspection must be completed and documented at the start of each work day. This
includes a complete visual inspection of the equipment and the surrounding area to ensure that
no worker is endangered by the start-up of the equipment. If there are any defects or out-of-
service items, these must be reported immediately to your supervisor. Some examples of
legally mandatory items include a horn or other audible warning device, effective braking
system, seat-belts, etc. The Ministry expects that immediate steps are taken to eliminate
unnecessary risks with defective equipment.
Approach
Inspect the equipment for leaks underneath that may indicate a problem (coolant,
engine oil, transmission fluid or gear oil)
Inspect the unit for any act of vandalism
Ensure the tires are of good pressure and not flat
Wheels must be blocked and zero energy is used.
Under the Hood
Check Engine Oil Level and top up as needed
Check coolant level and top up as needed
Check all belts for proper tension and condition
Inspect differential and transmission for observable damages
Check fuel pump sediment bowl and fuel filters; if water is present, remove it
Make sure radiator is clear of obstruction
Inspect suspension, frame, steering components and brake stroke on front axle
SAFETY NOTE IS TO NEVER START AN ENGINE BEFORE DOING UNDER HOOD
CHECKS.
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Walk Around
Check tires for proper inflation, tread, cuts and rims
Check accessories such as tanks, hydra drum, box and pins
Check fire extinguishers are secure and charged
Steps and tool box security
Check under the vehicle from front to back checking frame, air tanks and lines, drive
shaft, brake chambers and brake stroke measurements/brake pad indicators suspension
and any other damage to the undercarriage
Check all lights, doors and mirrors
Check the glass and wipers
Check the security of the load
Check hydraulic levels
Ensure all guards and shields are in place
Grease high wear points daily; Note, ZERO energy must be used
In Cab Checks
Adjust the seat, mirrors and steering wheel
Remove/secure all loose objects
Ensure park brake is on before starting the engine
Check wiper and washer operation
Keep glass clean
Proper operation of all switches and gauges
Ensure an effective braking and parking device
Be familiar with transmission and controls
Ensure horn and audible back up alarm are functioning
Take the required PPE with you
Fasten your seatbelt
Check registration, SGI inspection, permits, Schedule 1 and certificate of fitness
Operators are required to give the white copy; of the pre-trip inspections, to their supervisors
at the end of each shift. The supervisor then reviews the pre-trip (in case repairs are required)
and then ensures the white copy is turned into the area office within 20 days. Carriers are
required to keep the reports on file for 6 months. Inspect your vehicle daily and document your
circle check.
Please note: If units have the white copy; of the Pre-Trip inspection, in the truck older than 20
days it could result in a fine of $160.00 per sheet past the 20-day mark.
Pre-Trip Procedure for Air Single Unit Park the vehicle on level ground with the park brake set, the wheels blocked and the air tanks
drained (if possible):
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1) Check security and condition of compressor, belts and air lines under hood.
2) Start the engine and let air pressure build up.
3) With wheels chocked, release park brakes.
4) Check brake adjustments (push rod travel) manually. Adjust if necessary. Note: If brakes
are out of adjustment perform 6 pack and recheck. If still out of adjustment repairs are
required.
5) Check governor operation (be sure spring brakes are released):
a. cut-out pressure between 120 and 145 psi (828 and 1000 kPa)
b. cut-in pressure; fan brakes until compressor cuts in, should be at a minimum of
100 psi (690kPa)
6) Start engine and let pressure build till compressor cuts out:
a. ensure park brake released
b. shut off engine
7) Make and hold full foot-brake application:
a. maximum air loss after initial application must not exceed 1 psi in 1 minute
b. listen for audible air leaks
8) With ignition key on, fan brakes to lower air pressure:
a. low warning system should operate at minimum 60 psi (414 kPa)
b. continue to fan brakes, truck park-brake valve may shut off although on some
vehicles the button may never close. Always ensure the spring brakes have been
fully applied.
9) Run the engine between 600 and 800 rpm and observe the time needed for air pressure
to rise from 85 to 100 psi (586 to 690 kPa). It should be less than 2 minutes.
10) Ensure park brakes are applied and remove wheel chocks.
11) Perform tug test:
a. apply park brakes and gently try to pull ahead; release brakes
b. move slowly ahead and make a foot brake application
Pre-Trip Procedure for Air Combination Unit Park the vehicle on level ground with the park brake set, the wheels chocked and the air tanks
drained (if possible):
1) Check security and condition of compressor, belts and airlines under hood.
2) Start engine and let air pressure build up.
3) With wheels chocked, release park brakes.
4) Check brake adjustments (push rod travel) manually. Adjust if necessary. Note: If brakes
are out of adjustment perform 6 pack and recheck. If still out of adjustment repairs are
required.
5) Check governor operation (be sure spring brakes are released):
a. cut-out pressure between 120 and 145 psi (828 and 1000kPA)
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b. cut-in pressure; fan brakes until compressor cuts-in, should be at a minimum of
100 psi (690kPa).
6) Charge trailer system and rebuild pressure. Release brakes and shut off engine.
7) Break service line (blue glad hand, no air loss should occur).
8) Break supply line (red glad hand):
a. trailer brakes should apply immediately
b. there should be no air loss from trailer line
c. air from truck should shut off at a minimum pressure of 20 psi (138 kPa)
9) Make and hold a foot brake application:
a. check gauge for any air loss after initial application
b. listen for audible air leaks
c. there should be no air loss from the service line
10) Reconnect lines, charge trailer and rebuild pressure.
11) At maximum pressure:
a. release park brake
b. shut off engine
12) Make and hold full foot-brake application:
a. maximum air loss after initial application is 4 psi (28 kPa) in 1 minute
b. listen for audible air leaks
13) With ignition key on, fan brakes to lower air pressure:
a. low warning system should operate at a minimum of 60 psi (414 kPa)
b. continue to fan brakes, trailer-supply valve should shut off air to trailer at a
minimum of 20 psi (138 kPa)
c. Truck park-brake valve may shut off although on some vehicles the button may
never close. Always ensure the spring brakes have been fully applied.
14) Run the engine between 600 and 800 rpm and observe the time needed for air pressure
to rise from 85 to 100 psi (586 to 690 kPa) on the truck only. It should be less than 2
minutes.
15) Ensure park brakes are applied, remove wheel chocks.
16) Perform tug test:
a. with trailer emergency brakes applied and truck brakes released, try to gently
pull ahead to test emergency application of trailer brakes
b. charge trailer, apply park brakes on the truck only and try to gently pull ahead
c. release park brakes, move slowly ahead and apply trailer brakes with hand valve,
if equipped
d. move slowly ahead and make foot-brake application
Note: Repeat hand and foot valve test on both sides of the unit checking for response and, in
winter, for frozen wheels.
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Schedule 1 Schedule 1 is required to be carried in all commercial vehicles registered over 11,794 kilograms
(RGVW), and any trailers or semi-trailers that they are toeing. The regulation states the vehicles
must be inspected by the driver or a qualified person every 24hrs (when in operation). The
carrier must supply a list of inspection items as per schedule 1 of the regulations, to the person
doing the inspection. Schedule 1 identifies defects and major defects in each inspection item
type. This document should help you to determine if your vehicle is safe to operate or if it not
safe. A major defect takes a truck out of service immediately. A defect will need to be repaired
before the next trip out. Please note your Safety and Training specialist will review a copy of
schedule 1, to help you understand how this document is used.
Certification of Safety Fitness The National Safety Code (NSC) is a set of national standards supported by provincial
regulations. The program establishes management and performance requirements for
commercial carriers.
To meet the Certification of safety Fitness, The Ministry of Highways has to ensure accurate
record keeping.
1. Retain documents of all, PM Inspections every 6 months, service intervals and what was
completed, inspections and repairs completed.
2. The Drivers of the fleet must submit a copy of their driver’s license as well as provide a
copy of their commercial drivers abstract.
All commercial vehicles have to meet the National Safety Code’s performance standards.
You have to keep a copy of your Certificate of Safety Fitness in all company vehicles registered
under the NSC program. The original certificate should be kept in your office records.
To qualify for a Certificate of Safety Fitness you need to:
Have a principal place of business in Saskatchewan.
Register a commercial vehicle
Provide proof you have the required liability and cargo insurance.
Provide all background information related to your previous commercial operations.
Any time you register a new or additional commercial vehicle, you have to provide your
NSC number on the Certificate of Safety Fitness to a motor license issuer
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Starting the Engine Most Truck II equipment’s start by simply turning the ignition key. There are some things to
check before attempting to start the engine:
Ensure park brake is engaged
Hydraulic controls are in neutral position
Make sure all is clear and anyone around you know you are starting the engine
The supervisor or trainer will show you the proper procedure for the truck you will be
operating
Start engine and check gauges
Allow ample time for engine to warm up. This is a great opportunity to fill out the pre-
trip documentation
SAFETY NOTE IS TO MAKE SURE YOU KNOW HOW TO SHUT DOWN THE
ENGINE IN CASE OF TROUBLE
Ether This is a volatile liquid that is highly flammable and used as a starting aid for different units,
most trucks do not require ether as they have pre heating devices. Check the operator’s manual
for cold weather starting. This liquid is usually used in extremely cold temperature when the
engine is having trouble starting; usually when it’s cranking. These are the things you should
know about ether as a starting aid
1. Always use ether in small quantities:
2. Use ether only when engine is cranking;
3. Never use ether after the engine has fired up, and
4. Never use ether on a hot engine.
There are also several types of pre-heating devices. Some heat the cylinder; others heat the air
entering the intake manifold. Most pre-heating devices get turned on by the key and you need
to wait for the indicator light to go out before attempting to start the engine.
Note: Most newer trucks have pre-heating devices and you should never use ether.
Hydraulics
Hydraulic fluids are used to power motors and lifting rams by a pump
Hydraulic tanks store and helps cool fluids
Cleanliness is a must when dealing with hydraulics
Use cardboard to check for leaks
Ensure all leaks are repaired with caution because hydraulics may be under high
pressure
Hydraulic fluid is flammable
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Before removing cap, shut down engine and make sure oil is cool
Use funnels with filters and screens
Do not overfill tank
Always treat hydraulic components with caution even when shut down
Air Bags
Exhaust air from air bags before end dumping material
Dropping air bags helps stabilize truck
Do not exceed 20km/hr with air bags dumped.
Refill air bags before travel
Before completing service on tandem make sure air bags are deflated
Diesel Particulate Filter (DPF) Environmental legislation was passed in 2008 to reduce emissions which led to the introduction
of the DPF system.
Key notes:
During a regeneration exhaust temp can exceed 1000°F or (540°C), ensure not to do a
parked regeneration where overhead obstacles exist such as trees or anything that
could start on fire.
Monitoring dash lights and following recommended procedures will help to keep your
truck running properly. If not followed properly it could cause damage to the truck.
Parked regenerations maybe required.
Please refer to the operator manual for specific instructions. Note, most trucks will have a
decal; as shown in figure 2, on or above the sun visor.
Figure 2: DPF system decal
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Diesel Exhaust Fluid (DEF) To further reduce emissions Diesel Exhaust Fluid is an addition to the DPF system. Note: review
the SDS on Diesel exhaust fluid.
DEF:
Is non-toxic, ultra-pure solution of urea and ultra-pure water
Is highly corrosive
Urea is injected into the exhaust system; after the DPF, and as it is heated it turns into
ammonia
Is a part of a system designed to further help prevent emissions
can freeze at -11ºC
Tank has a heater to help keep it from freezing
Pump will draw back the fluid to help prevent line freeze
Has a second fuel gauge
Has a 22L tank
IF YOU RUN OUT OFF DEF, THERE WILL BE A DEGENERATED POWER RATING.
DEF WILL HAVE A BLUE CAP ON THE TANK
Antilock Brake System (ABS)
An antilock brake system (ABS) is an electronic system that monitors and controls wheel speed
while braking. If it detects a wheel locking up during a brake application, the system releases
brake pressure to that wheel only. This keeps the wheel from skidding and increases vehicle
stability and control during emergency stops and in adverse situations; such as on wet or icy
roads, through curves or during lane changes. The air brake system remains the same with the
addition of the ABS components.
ABS indicator lights
ABS indicator lights are amber-colored and marked with the letters ABS. They are there to tell
you that the ABS is working properly. Know where the ABS indicator light is on every vehicle
you operate and how to check that it’s working properly. The lights are located on the
instrument panel of trucks and on the exterior of trailers near the red side marker on the left
rear side of the trailer. If the truck you drive was built after March 1, 2001, and is equipped to
tow a trailer, it will have two ABS lights on the dash, one for the towing vehicle and one for the
trailer.
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How ABS indicator lights work
When the ABS is working properly, each time the vehicle ignition switch is turned on and kept
in the on position the ABS indicator lights will turn on for a few seconds then turn off.
When power is supplied to the ABS controller the ABS indicator lights momentarily turn on as
the ABS automatically conducts a self-test. If the light does not come on at all there could be a
problem with the indicator light, the wiring or the ABS controller. When an ABS malfunction is
detected the ABS indicator light stays on. If no malfunctions are detected the light turns off
after a few seconds.
ABS on trailers also receive backup power through the brake light circuit. In some cases, certain
types of malfunctions can cause the ABS indicator light to turn on each time the brake is
applied. While the ABS may be partially working, in this condition it is not working properly.
Whenever the ABS indicator light turns on when you are driving there is an ABS malfunction
present that requires repair. Make sure you have the ABS problem fixed as quickly as possible.
Remember, if the light does not work you will never know if the ABS stops working.
Know your ABS is working – check it during your trip inspection!
Knowing your ABS is working can give you peace of mind and it can help you when you need it.
Always confirm your ABS is working – see that your ABS light(s) turn on then off when power is
applied during your pre-trip inspection. Failure to ensure the ABS system functions as
prescribed by the manufacturer will result in a defect being identified on a CVSA road-side
inspection.
Air Brake System The five main components of an elementary air brake system are compressors, reservoirs, foot
valve, brake chambers and brake shoes & drums. Air brakes are used as an alternative to
hydraulic brakes, which are used on lighter vehicles such as automobiles. Hydraulic brakes use
hydraulic fluid to transfer pressure from the brake pedal to the brake shoe to stop the vehicle.
Air brakes use pressurized air and are common in heavy commercial vehicles due to their
reliability.
Compressor The function of the air compressor as shown in figure 3 is to build up and maintain air pressure
required to operate air brakes and air powered accessories. Air compressors are either gear
driven or belt driven. Although most compressors use the truck’s lubrication and cooling
systems, some are self-lubricated and some are air cooled. Self-lubricated compressors must
have their oil checked and changed at regular intervals.
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The compressor’s intake system draws air from either its own air filter or from the engine’s
intake system. Compressors that have their own filtration system must be serviced on a regular
basis. All compressors run continuously while the engine is running, but air compression is
controlled and limited by a governor which “loads” or “unloads” the compressor. In the loaded
stage, air is pumped into reservoirs. In the unloaded stage (with two cylinder compressors), the
compressor pumps air back and forth between the two cylinders without supplying the
reservoirs. The governor must take the compressor out of its pumping stage when system air
pressure reaches 120-145 psi and also put it back into the pumping stage at a minimum of 100
psi.
Figure 3: Air compressor
Reservoirs Reservoirs are pressure-rated tanks which hold a supply of compressed air; until required, for
braking or operating auxiliary air systems. They must store a sufficient volume of air to allow
several brake applications if the engine stops or the compressor fails. The maximum air
pressure available for brake applications depends on how much air is in the reservoir. A driver is
not able to make a higher pressure brake application than there is air pressure in the reservoir.
Each reservoir is equipped with a drain valve as shown in figure 4. Fully opening the drain valve
allows reservoirs to be drained of moisture and other contaminants that build up in the system.
Figure 4: Typical reservoir drain valves
ALL RESERVOIRS MUST BE COMPLETELY DRAINED ONCE A DAY!
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Foot Valve The foot-operated valve as shown in figure 5 applies air to operate the brakes. The amount of
air delivered to the brakes is regulated by the driver according to the distance the treadle or
brake pedal is depressed. Releasing it exhausts air in the service breaks through its exhaust
port. Brake application valves can be divided into two types: single-circuit valves and dual-
circuit valves. Trucks built before 1975 are generally equipped with single-circuit brake
application valves. These valves are made in overhead styles with a foot pedal hanging down, or
a floor-mounted version with a foot “treadle.”
Figure 5: Dual-circuit foot valve
Service-Brake Chambers Service brake chambers; as shown in figure 6, convert compressed air pressure energy into
mechanical force and movement, which apply the vehicle’s brakes. When the driver applies
pressure to the foot valve, air pressure enters the pressure side of the brake chamber through
the inlet port and forces against the diaphragm, which moves the push rod assembly forward.
When air pressure is released from the service brake chamber, the return spring returns the
diaphragm and push rod to their released positions.
Note: Never try to disassemble a brake chamber as they can be under extreme pressure and
can cause severe injury.
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Figure 6: Clamp-ring type service brake chamber
Long stroke vs. Short Stroke The 3-inch long stroke brake chambers are becoming standard equipment on more and more
new trucks. It is important for service and maintenance personnel to understand and recognize
the different types of brake chambers they might run into if there is a need for replacement.
To separate 3-inch long-stroke chambers from the current 2.5-inch “standard” units, the
industry has established the following forms of identification for spring brakes:
square air-inlet ports;
diaphragm replacement instructions embossed into flange case;
a triangular shaped I. D. tag secured to the service-side clamp band bolt.
Although 2.5-inch stroke and 3-inch long-stroke chambers provide virtually the same force
output at 1¾-inches of stroke, the performance and operational characteristics beyond that
point are dramatically different. Three-inch long-stroke chambers provide greater braking force
at/or beyond the point where 2.5-inch-stroke chambers cease to function. For this reason,
standard and 3-inch long-stroke chambers should never be installed on the same axle.
The benefits derived from having a heavy-duty truck, tractor and/or trailer equipped with 3-
inch long-stroke chambers are well documented — i.e. improved braking efficiency, increased
reserve stroke and reduced out-of-adjustment citations — but unless they are properly
maintained and serviced, those benefits will never be realized
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Figure 7: Long stroke and Short stroke brake chambers
Brake shoes and Drums Figure 8 illustrates the common S-cam brake assembly used on truck and trailer axles. Front
brake assemblies have the brake chamber and slack adjuster mounted on the backing plate
because the steering action of the front axle would otherwise interfere. The diagram shows the
brakes in the applied position. The S-cam is rotated so the high points have acted against the
cam rollers and forced the brake shoes against the drum. When the brakes are released, the
brake cam shaft returns the brake cam to the normal position. The cam rollers roll down into
the crook of the S-cam as the brake shoe return spring pulls the shoes away from the drum.
Brake lining material is attached to the face of the shoes. Lining material is selected according
to the type of service the brakes are subjected to. Linings must give consistent braking output
with minimum fade at high temperatures. Brake shoes generate heat through friction with the
brake drum surface. Drum thickness determines the amount of heat that can be absorbed and
dissipated to the atmosphere. Thin or distorted drums, weak return springs, improper linings,
poor adjustment, or grease or dirt on the lining, will all result in erratic, unpredictable and
potentially dangerous brake performance.
Figure 8: S-cam brake assembly
Long
Stroke
Short
Stroke
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Brake Pads and Rotors The Ex+ air-actuated disc brake has a direct-mounted air chamber. It is essential that the
correct service procedures are observed to ensure that the brake gives satisfactory service
throughout is working life.
Automatic Adjustment
The automatic adjuster adjusts the brake pad clearance to compensate for pad wear. Every
time the brake is applied, the system senses whether adjustment is required or whether the
running clearance of the brake pads to the brake rotor is still within the built-in tolerance and
does not need to be adjusted. The built-in tolerance is determined in the design by the
clearance between the ball-ended drive pin that is rigidly fixed to the operating shaft and the
fork on the end of the adjuster shaft. Adjustment takes place under very small clamping forces
only, therefore minimizing air consumption.
Manual adjustment of the brake must only be made at a pad change. No manual adjustment is
required between pad changes, and must only be done by a certified technician.
Intervals
For military on/off highway and military severe duty applications, refer to TP-10109. For a copy
of this technical bulletin, contact the Meritor OnTrac™ Customer Call Center at 866-
OnTrac1(688-7221).
Use the schedule below that gives the most frequent inspection of the brakes. Check the
caliper, torque plate, pads and rotor for signs of wear and damage. Also check for any loose or
missing screws. For additional roadside inspection information, contact the Meritor OnTrac™
Customer Call Center at 866-OnTrac1 (688-7221).
Fleet chassis lubrication schedule
Chassis manufacturer lubrication schedule
At least four times during lining life
At tire replacement
Wheels-On Inspections
Visual Wear Indicator
The visual wear indicator (VWI) alerts you as to when the braking system needs to be inspected
for wear on the pads and rotor. When the pads are new, the end of the visual wear indicator
stem will protrude past the edge of the housing casting. As the pads wear, less and less of the
indicator will be visible past the edge of the casting. The increments of the indicator equate to a
level of pad wear.
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If the indicator shows more than 75% wear: The pads require further inspection or
replacement. To get an accurate indication of lining wear, it is important to ensure that the VWI
is not seized in the hole. Check the VWI by grasping the VWI and rotating/pulling outward and
releasing. If the VWI does not move when you pull on it, move it by hand as necessary to free it
up.
Rotor
Visually inspect the rotor for signs of cracks, deep grooves, blue marks and heat checking.
Air Chamber
Inspect the air chamber to verify that the caliper mounting bolts and air lines are securely
fastened and are not damaged.
To prevent serious eye injury, always wear safe eye protection when you perform vehicle
maintenance and service.
Figure 9 - Disk Brake wear Indicator
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Air Brake Operation Air is pumped by the compressor to the reservoir. When air pressure reaches 120-145 psi, the
governor places the compressor into its unloaded stage. At this stage the air system is fully
charged. When the brakes are applied, air is delivered through the foot valve to the service
brake chambers as illustrated in figure 10. Air pushes against each service-brake diaphragm
causing the push rod to move the slack adjuster. The slack adjuster rotates the brake cam which
forces the shoes against the brake drum. When the driver releases the foot valve, air in the
brake chambers is exhausted through the foot valve, which releases the brakes. When reservoir
air pressure drops, the governor puts the compressor back into the pumping stage to keep
adequate air pressure available for future brake applications.
Figure 10: Brake application
Safety Valve The supply reservoir is protected from being over-pressurized and bursting by a safety valve as
shown in figure 11. This valve is pre-set (usually at 150 psi [1,034 kPa]) and will “blow off”
excess pressure. Once pressure is lowered, the safety valve will re-seal until an over-pressurized
condition exists again. If a safety valve “blows off” excess pressure, this indicates a problem
with the governor. The problem should be dealt with immediately by a mechanic.
Figure 11: Safety valves
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One-Way check Valve If the air compressor fails or a leak develops in the supply reservoir, a one-way check valve as
shown in figure 12 is installed between the reservoirs to keep air from bleeding back. The valve
is spring loaded. Pressure at the inlet side overcomes spring pressure and lifts a check ball or
disc off its seat. Air passes through the valve to the outlet. When pressure at the outlet
becomes greater than at the inlet, together with spring pressure, the check valve seats,
preventing air from flowing back through the valve.
Figure 12: One-Way check Valve
Air Pressure Gauge An air pressure gauge is installed in the dash (plumbed in after the service reservoir) so the
driver will know the amount of air pressure available for braking.
Figure 13: Air Pressure Gauge
Air Governor The governor, which is usually compressor mounted, operates in conjunction with the
compressor unloading mechanism and maintains reservoir air pressure between a
predetermined maximum and minimum pressure.
• cut-out pressure 120-145 psi
• cut-in pressure 100 psi minimum
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Figure 14: Air governor
Relay Valve On long wheelbase trucks and tractors and on trailers, the distance from the brake chambers to
the foot valve is too far to cause immediate application of the brake when the foot valve is
depressed. This is called brake lag. To correct this situation, a relay valve as shown in figure 15
is installed near the rear brake chambers. A large diameter pipe is connected between the
service reservoir and relay valve. The air line from the foot valve to the relay valve now
becomes a control line that signals to the relay valve the amount of air to be drawn from the
service reservoir.
Figure 15: Relay valve
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Quick Release Valve The function of a quick-release valve shown in figure 16 is to rapidly exhaust air from the
controlled device. It is normally located adjacent to the controlled device, rather than requiring
exhaust air to return and exhaust through the control valve. This decreases release time.
Figure 16: Quick-release valve
Front Axle Ratio Valve Designed for use on dual-air system vehicles, the ratio valve as shown in figure 17 is installed in
the front axle delivery line. During normal brake applications, this valve automatically reduces
application pressure to the front axle brakes. As brake application pressure increases, the
percentage of reduction is decreased until about 60 psi (413 kPa) (depending on valve design)
when full pilot pressure is delivered. The valve is available with several different “hold-off”
pressures which prevent the front brakes from operating until this “hold-off” pressure is
exceeded.
Figure 17: Front axle ratio valve
OLDER TRUCKS MAY BE QUIPPED WITH A FRONT WHEEL LIMITING VALVE
CONTROLLED BY A SWITCH ON THE DASH. WHEN ACTIVATED, THIS VALVE
WILL REDUCE APPLICATION PRESSIRE TO THE STEERING AXLE BRAKES BY
50%
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Air Dryer The air dryer as shown in figure 18 is a desiccant-type in-line filtration system that removes
most liquid and water vapor from compressor discharge air before it reaches the air brake
reservoirs. This results in only clean, dry air being supplied to the air brake system, aiding in the
prevention of air-line freeze-ups. Air dryers utilize a replaceable desiccant material which has
the ability to strip water vapor from moisture laden air. The desiccant material is regenerative,
in that its absorptive properties are renewed each time the compressor is reloaded. The air
dryer end cover is equipped with an automatic drain valve, controlled by the air-system
governor, and is also equipped with an integral heating element.
Figure 18: Air dryer
AIR DRYERS DO NOT REMOVE ALL THE MOISTURE. THE RESERVOIRS STILL
NEED TO BE DRAINED DAILY.
Truck II Operation When entering and exiting the unit, use 3-point contact facing the machine (see related SOP).
Always use a three-point contact as shown in figure 19 to enter or exit the unit in order to
minimize the chance of slips and falls;
Always keeping 3 points in contact with the vehicle;
I. One hand and two feet;
II. Two hands and one foot
Always face the equipment
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Do Not Jump from unit
Scan ground for uneven surfaces
Always have the appropriate PPE
Figure 19: 3-Point Contact Entry
Sand Seal Sand sealing can be one of the best jobs at the ministry of Highways, but it can be very
dangerous as there is a lot of moving equipment in a restricted area travelling forward and
backward. Not to mention that the public will be in and out of our work area. Don’t forget to
watch for overhead obstacles such as power lines or maybe even overpasses. Reviewing current
SOP’s and completing your Take10 hazard identification will help you identify hazards.
Electricity can arc from a power line to the truck box, maintain a minimum of 3 meters’
separation between the box and power line. Refer to table 22 of the Occupational
Health and Safety Regulations, 1996.
Check for overhead lines or any other obstructions before raising the box.
Care should be taken to ensure that no sudden steering maneuvers or heavy braking
actions are applied while box is partially raised due to the extreme change in the center
of gravity of the unit.
Avoid coming too close to the shoulder while box is raised.
Do not gravel in center of road if line of sight is restricted.
Use caution when oncoming traffic is encountered.
Ensure the box is at the appropriate height to maintain steering control.
If visibility is obstructed due to dust, dust control may be necessary, otherwise wait for
the dust to dissipate before commencing spreading.
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Figure 20: Sand Sealing (Oil roll)
Pavement Marking This task requires 2 operators, 1 driving the truck and the second operator rides in the rear cab
of the truck. The operator in the rear cab controls the gun packs on the side of the truck to
determine what lines are being painted. Traffic again is a big hazard. Please note a TDG
(Transportation of Dangerous Goods) certificate is required to operate this truck (at certain
times of the year). Reviewing current SOP’s and completing your take ten hazard identification
will help you identify hazards.
Figure 21: Pavement marking
Sign Replacement Crew preparation is necessary for all sign replacement activities. Obtain load and secure all
necessary material, tools, personal gear, PPE and equipment to do the job.
Workers exit unit, remove equipment, material and tools.
Apply date decal sticker to back of sign, closest to the road.
Workers position ladder adjacent to sign.
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Do not lean against sign post.
One worker supports the ladder, while second worker climbs ladder to replace sign.
Worker removes the hardware from the existing sign and installs new sign.
Worker descends ladder and places old sign, hand tools and ladder into back of unit.
Be aware of the hazards posed by traffic volume, weather conditions, visibility, and time of day.
As you approach the Job Site, activate warning lights and begin to slow down. As you slow
down, assess the best position of the unit to complete the task. If traffic flow prevents you from
safely stopping on the road surface, proceed to the next approach and then return to the job
site. Signal your intentions when safe to do so, pull over and stop either on the shoulder or in
the ditch at the Job site. It is best to position the unit as far away from the traffic flow as
possible. Before entering the ditch, you must be aware of any physical hazards that are present,
such as slope of the ditch, culverts, rocks or holes, etc. See the specific SOP’s on practices and
procedure for sign replacement both manually and mechanically.
Figure 22: Sign Replacement
Safe Operation Prior to loading, visual inspection of the box inside and out is required. Operator makes all
necessary adjustments for the task being performed (e.g. spreader chains, conveyor covers,
hydra-drums, tailgate etc.) Operator must ensure that all material is loaded in accordance with
legal weights and load securement.
Be aware of the size of the truck and how it handles and stops.
Travel forward if possible as this will help ensure you reduce the chance of a backing
incident.
Check both mirrors while backing up and utilize your mirrors to be aware of your
surroundings.
Use a guide when possible especially in restricted areas.
Be sure you know what is behind you at all times (Get out and look if you’re not 100%
sure).
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Expect the unexpected at all times.
Read operator manuals.
Watch for other equipment and co-workers at all times!
Watch for overhead obstructions.
Ensure safety shields and guards are in place and used properly.
Make sure Hydra drums are secure.
Be aware of hydra drums, augers and conveyor chains as they are extremely dangerous.
Ensure the truck is equipped with a backup alarm.
Hydraulics are extremely dangerous and repairs should only be done by a qualified
person.
Use safety stands when completing repairs and remember the box must be empty and
lowered on to the safety stand.
Rotary lights are used on or near road surface.
Refer to the operator’s manual to better understand differential locks and inter axle
locks and how to use them.
Be familiar with all the controls and note that any additions to the truck should have a
manual, contact your supervisor of fleet.
Ensure Zero Energy is used at all times when servicing or completing any repairs.
Fines
Operators are responsible for the safe operation of the vehicles they operate; this means any
tickets that are issued; while you are operating, are your responsibility. Please understand what
these tickets could cost you, if you operate outside of the law.
Fines will be given for:
Brake out of adjustment (base) = $150
Per additional brake = $100
Lights (head, signal, brake, etc.) = $150
Load security (plus 1 point on your licenses) = $175
Pre-trip inspection sheet not filled out or white copies older than 20 days= $160 per
copy
Overweight Load
Base fine of $100 + $10 per 50kg if under 1000kg
Ex: truck RGVW 24,500kg
truck loaded 25,000kg
over by ,500kg = $200
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Base fine of $100 + $15 per 50kg if over 1000kg + a victims of crime surcharge
Ex: truck RGVW 24,500kg
truck loaded 27,000kg
over by 2,500kg = $750
Wheel Safety One of the most important safety critical components on cars, trucks, and aircraft is the
pneumatic tire. Vehicle tires primarily control stopping distances on wet and dry roads or
runways and strongly influence over-steer/under-steer behavior in handling maneuvers of cars
and trucks. The inflated tire-wheel assembly also acts as a pressure vessel that releases a large
amount of energy when catastrophically deflated. The tire can also serve as a fulcrum, both
directly and indirectly, in contributing to vehicle rollover.
Under inflated tire causes the side wall to flex and generates excessive heat and promotes a tire
to blow and will be identified by outside edges on both sides of a tire being worn. Over inflated
tires will roughen the ride and can be identified by the center tread being worn. Lug nuts must
be torqued to a specific number depending on the style of rim, do not over torque as this can
cause studs to stretch and remember to torque after 80KM. A torque tag will have to be
submitted to fleet. Cracked or rusted rims can be very dangerous, make sure to inspect inside
and out and ensure proper washing.
Spacers are used with demountable rims and may collapse over time due to rust or over
torqueing. If this occurs, it is likely your tire will separate from the truck. Wedges can be
dangerous when removing the rim from the truck as they are under high pressure. Never repair
a demountable rim as they have been known to come apart and severely hurt or even kill
people. Brake shoes and drums have a backer plate installed on the back side of the drum, the
idea is to keep dirt and sand from enter the brake shoe and drum. If dirt does enter, it will
cause the brakes to not function properly, which will cause automatic slack adjusters not to set.
Front wheels use oil or grease to lubricate bearings. This is a sealed unit, so if the fluid is going
down it will indicate a wheel seal leak, which means oil has likely come in contact with the
brake shoe and will take it out of service. Final Drives are where the axle bolts to the hub on the
drive axle, this will need to be inspected for leaks as well.
Preventative Maintenance Preventative maintenance are planned maintenance actions aimed at the prevention of
breakdowns and failures before it actually occurs. Any time you use equipment, the key to a
good day's work is proper maintenance of your equipment. Your first task, at the beginning of
your shift, is to check your unit and make sure that it is ready to go. Make sure that your truck
can put in a day's work by attending to little problems before they become larger problems. If
you don’t schedule preventative maintenance, your truck will schedule it for you.
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Oil Changes
Units before 2009 = 250 hrs.
Units after 2009 = 350 hrs.
Grease spring pins and box pins daily.
Grease every 40 hrs.
Slack Adjuster Maintenance Slack adjusters are mechanical links between the brake chamber push rod and the camshaft on
cam type brakes. Slack adjusters are used to manually or automatically to maintain proper
brake chamber stroke and lining-to-drum clearance during normal operation. Slack adjusters
are available in a variety of arm configurations, lengths, torque ratings and spline types. The
entire slack adjuster operates as a unit, rotating with the brake camshaft as brakes are applied
or released. The most efficient braking occurs when push rod travel is held to a minimum,
therefore it is important that brakes are maintained to proper specification daily.
Figure 23: Slack adjusters
The number 1 reason that an air brake system fails is due to brakes out of adjustment, for
your safety and the safety of the people around you check your brakes. (This is a part of your
daily responsibilities).
In order for automatic slack adjusters to work properly there is some routine maintenance that
must be completed.
1. Grease and rotate the pins located on the slack adjuster and the clevis. If these pins are
seizing, it will cause automatic slack adjusters not to properly travel the required
distances needed to set up.
2. Check to ensure the push rod travels back to the brake pot fully when brakes are
released, if it is identified that push rod does not fully return it can be an indicator of
many different issues within the brake components.
To properly set automatic slack adjusters, wheels must be blocked to prevent unwanted
movement, spring brakes are in the released position (Minimum of 100PSI must be in the air
Manual Automatic
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system). You will make 6 to 12 applications of a minimum of 90 PSI. It will be important to
ensure 90 PSI is achieved on the application gauge and hold the application for 1 second and
release, watch the application gauge return to 0PSI and wait 1 second. Repeat this process up
to 12 applications and verify brake stroke is within prescribed limits.
If the Brake stroke is not within prescribed limits the truck is out of service and must be
inspected by a fleet technician. Front brakes have a maximum travel of ¾ of an inch, if manually
pulled or a maximum of 1 ¾ inches, if using an application of 90psi minimum. Rear brakes have
a maximum of 1 inch, if manually pulled or maximum of 2 inches, if using an application of 90psi
minimum. Note; due to an automatic slack adjuster being able to maintain 2 inches of travel,
even if a long stroke chamber is used, we expect that 2 inches is the maximum measurement by
application and anything beyond that would require further investigation from fleet.
Relatable SOP’s Visit the MHI website (www.mhisafety.ca) and review the following SOP’s or any others that
pertain to the work you do.
Tandem Truck
Washing
Winter clean up
Entering Exiting Units
Safe Lifting
Backing up
Sand sealing
Pavement marking
Sign replacement