TMC updates lockout/tagout guidance for modern fleets

Today, more complex and higher energy systems have become commonplace in commercial vehicles of all vocations. (Palmer Trucks)

One challenge in fleet maintenance that has persisted across the 70-year history of ATA’s Technology & Maintenance Council is the control of energy sources inherent in medium- and heavy-duty commercial vehicles, especially when they are being maintained or repaired.

For veteran technicians, the term “lockout/tagout” (LOTO) meant securing the vehicle by removing the ignition key and placing it in one’s pocket or shop lockbox before any work began, then securing the vehicle itself so it didn’t roll away or move unintentionally. This approach worked well for legacy vehicles from a simpler time, but times change.

Today, more complex and higher energy systems have become commonplace in commercial vehicles of all vocations. With the advent of electric, hybrid and alternative fuels propulsion as well as new types of accessory drives and power takeoff systems, the methods and means to control these energy sources must evolve in kind.

Even in less-complicated times, accidents did happen with impactful consequences to people, equipment and operations, and as a result the Occupational Safety and Health Administration developed a regulation for LOTO of hazardous energy sources, which can be found in the Code of Federal Regulations (CFR) 29 CFR 1910.147, and accessed online at osha.gov.

Image

Legler 

Now, even the simple approach of turning off the vehicle, removing the ignition key, chocking the truck and disconnecting the battery would not be sufficient means of preventing LOTO incidents, as evidenced for example by a recent incident in western Pennsylvania involving the cutting of a brake line, which allowed the vehicle to roll away and crush the person attempting to perform maintenance. Unfortunately, since vehicles are often keyed identically in fleet operations, another person with a duplicate key could start the vehicle or release some other type of potential kinetic, chemical or thermal energy, putting the technician and others at risk of injury. A greater level of forethought is needed in these cases.

To address fleet maintenance application of the LOTO concept and assist with compliance with the OSHA mandates, TMC’s S.5 Fleet Maintenance Study Group developed a Recommended Practice, first published in 2018 and since revised as TMC RP 543A, Guidelines for Lockout/Tagout Procedures, for Classes 2-8 commercial vehicles.

Virtually all commercial vehicles present at least one source of energy that must be contained or controlled during maintenance processes, as well as in the shop itself. And since maintenance is rarely done by a single technician working in isolation, the maintenance team is made up of technician specialists (authorized to initiate LOTO) and shop supervisors, as well as others who may be affected due to possible exposure to those sources of energy.

TMC RP 543A helps fleet managers establish the structure of a LOTO program itself, define the roles of various personnel in the training processes, assess the various energy hazards present in fleet maintenance, set up devices to safeguard ignition and controls, and design a station where physical locks are maintained for use by employees authorized to lead the LOTO process on a particular job.

Image

 

The AI Summit at TMC

The Technology & Maintenance Council and Transport Topics will co-host a new event at TMC’s 2026 Fall Meeting, Sept. 20-24, to advance the conversation about artificial intelligence implementation in the trucking industry. Read more

The LOTO process involves updating the fleet’s assessment of vehicle types being maintained, as well as the facilities and equipment used in the maintenance process including mobile service vehicles. Alternative motive power fuels, such as natural gas and hydrogen, and electric vehicles — both battery (BEV) and fuel cell (FCEV) — must be thoroughly researched.

Of additional concern is the evolution of vehicle electronics and control systems and ever higher levels of automation, involving sophisticated sensors, advanced driver assistance systems, and even automated driving systems. When power is removed from the unit to make a repair, powering down the telematics device may cause loss of trip or other pertinent data, and affect the ability of automated control systems to maintain their level of function post-repair. Use of a constant power source/circuit may be required for these systems, at the same time protecting them against voltage overloads in the process of protecting the maintenance employee. Additionally, testing during maintenance frequently requires that energy be maintained or restored, which requires subsequent de-energization to proceed further.

Fleets must also review their personal protective equipment (PPE) as well as other shop equipment and related devices — utilization of which must be covered during initial and ongoing training. Since vehicle technologies are constantly evolving, periodic review and update of the LOTO program is critical. TMC, as well as other standards development organizations, addresses specific recommendations for controlling potentially hazardous energy sources encountered during maintenance processes.

TMC RP 543A describes what a LOTO program may need to entail for a modern fleet maintenance operation. For example, electric vehicles now feature much higher voltages than conventional vehicles for motive power and work-performing equipment/accessories. How electric vehicles may be addressed in a LOTO program is covered in both TMC RP 1619, Safety Aspects of Servicing Battery Electric Vehicles, and TMC RP 181, Solar Panel Installation, Safety and Preventive Maintenance Inspection Guidelines.

Similarly, when performing maintenance on tire and wheel assemblies, the pressure in a fully inflated tire presents a potential energy source of great impact if accidentally released. Various TMC RPs developed by the Council’s S.2 Tire & Wheel Study Group specifically address tire mounting and demounting procedures, frequently citing the use of a safety cage in the shop.

When a vehicle or its components are raised on a jack or shop lift/hoist, the sheer mass involved (aided by gravity) also represents a very large potential energy source. Proper lifting equipment procedures are, therefore, essential, and are discussed in TMC RP 1618, Vehicle Lifting Procedures and Equipment Guidelines. When hydraulically activated tailgates and liftgates are being serviced, sturdy blocking must be utilized, so that if a hydraulic line bursts or is intentionally disconnected, the potential for the gates dropping and crushing an employee beneath is controlled.

When working on or inside a tank vehicle the chemical energy contained in any residual cargo, such as gasoline or chlorine, must be controlled by evacuating the cargo and purging any hazardous atmosphere. Even then, working inside the tank may present the need for technicians to use a breathing apparatus and other PPE.

Finally, when working on pneumatic (air) brakes, the stored energy in the brake air system must be drawn down, and the tension contained in the spring brake chambers must be controlled through proper procedures, as discussed in, among others, TMC RP 607C, Preventive Maintenance and Inspection of S-Cam Foundation Brakes, and RP 652A, Service and Inspection of Air Disc Brakes.

While establishing an effective LOTO program may seem just a matter of documenting shop common sense, true success in the prevention of injuries and damage can only be attained from a disciplined approach as recommended in TMC RP 543A.