Tips to jack up commercial truck, tractor or trailer
AKRON — In Greek mythology, Atlas was a Titan condemned to hold up the sky for eternity after he and his brother sided with the Titans in their war against the Olympians. When the Titans were defeated, Zeus condemned Atlas to stand at the western edge of the Earth and hold up the sky on his shoulders.
A common misconception today is that Atlas was forced to hold the Earth on his shoulders, which was probably founded in classical art that shows Atlas holding the celestial spheres, not a globe.
People confused the use of the marble globe in the renowned Farnese Atlas sculpture with the Earth, which eventually resulted in the usage of the word atlas to describe a collection of maps.
In the commercial truck tire service world, you don't have to be as strong as Atlas to lift a commercial truck, tractor or trailer. There are tools to help you with that endeavor, but like Atlas, there is confusion regarding how to hold up a vehicle correctly and the proper way to jack and lift these vehicles.
This is a big issue since, according to Occupational Safety and Health Administration (OSHA) data, the process of jacking, lifting and supporting tractors and trailers has resulted in more fatal accidents than any other aspect of truck tire and wheel service.
Most of these accidents were the result of technicians' failure to use the proper procedures and/or equipment (specifically jack stands).
To address this accident rate, the Technology & Maintenance Council (TMC) of the American Trucking Associations undertook the task of writing Recommended Practice (RP) 262 Guidelines for Jacking and Lifting Tractors and Trailers.
• This column appeared in the March 13 print issue of Tire Business
This RP provides technicians with guidelines for properly lifting, jacking and supporting Class 8 tractors and trailers with hydraulic jacks and jack stands using generally accepted lifting points. There's a lot of good information in it you should know.
Since equipment problems were the cause of most of the accidents, let's look at jacks and jack stands first. There are two types of lifting devices commonly used for commercial vehicles: hydraulic jacks and air-over-hydraulic jacks.
Hydraulic jacks, usually referred to as bottle jacks, are very portable and come in various heights to accommodate almost every type of vehicle.
When they are used to support a load for a period of time, excessive stress is placed on the seal at the bottom of the cylinder. Since the seal is actually supporting all the weight, when it fails, the load will crash to the ground instantly.
Air-over-hydraulic jacks require compressed air and typically are housed in a wheeled carriage to make them easier to move. They generally have different height adapters to accommodate both tractors and trailers.
No matter what type of jack is used, technicians should ensure the lifting capacity of the jack is greater than the weight of the axle being lifted. The jack also should be inspected thoroughly to ensure there are no oil leaks, particularly around the fill plug and release screw.
The release screw should be tightened and loosened to ensure smooth operation, and if the ram has an extender, it and the saddle should be checked for damage.
The most important thing to remember is that both types of jacks are designed to lift vehicles and are not designed to support a load by themselves.
Jack stands are designed to support the load and include some type of mechanical lock (usually a pin) that prevents the vehicle from being raised or lowered. They are adjustable and rated for a specific load that must be clearly indicated somewhere on the jack stand. They are rated and designed to be used in pairs on opposite sides of the same axle.
If the stand's rating is not visible or present, the jack stand should not be used. Their load rating must be greater than the weight of the axle being lifted.
It is vital to understand that when the capacity of a support stand is exceeded, it can fail with catastrophic results. Jack stands are not designed or rated to be shock loaded, so placing them under the axle or frame to act as stops in case the jack fails is not a smart thing to do.
Jack stands should be inspected before using them to ensure their components are not damaged or cracked. If needed, composite blocks may be used as support devices if they have a load rating.
Wood blocks should not be used since they cannot be rated for a specified load. Never weld any additional supports or make any alterations to a jack or jack stand.
So now that you know the correct equipment to use, how sure are you that you are following the correct procedures when you jack up a vehicle? If you lie awake at night feeling the weight of the sky on your shoulders or fear that a truck might fall on you, here are the steps you should always follow:
Step 1 — Inspect the ground surface where the axle will be lifted. You will need a surface that is fairly flat, hard enough to provide a stable surface and even. You should consider the weight of the vehicle and the type of load it has (shifting or stable).
If it's a bulk/tanker trailer, the load will probably shift on a sloping surface, and if the slope is greater than 5 degrees, the jack's proof load — which is 150 percent of its rated capacity — may not apply.
In some cases, a metal or composite plate can be used under the base of the jack and jack stands to stabilize the load on soft or uneven ground surfaces, but in others the combination of different factors may make it necessary to move the vehicle to a safer location.
Never attempt to lift a vehicle if the weight, type of load, slope or ground surface stability creates a hazardous situation. Move the vehicle instead.
Step 2 — Once you determine the vehicle is in a safe location and before you attempt to lift it, follow lock-out/tag-out procedures that include installation of a lock-out/tag-out device. This notifies drivers that the vehicle is being serviced and cannot be moved. This could save your life.
Step 3 — Chock one set of wheels on both sides of a tire on an axle that will remain on the ground.
Step 4 — Apply the parking brake.
Step 5 — If the jack requires cribbing material for additional height, make sure that composite blocks are used and arranged in a criss-cross pattern.
Additional cribbing should not be used when using an air-over-hydraulic jack that is part of a wheeled carriage or a floor jack. Only use attachments and adapters supplied by the jack or jack stand manufacturer.
Step 6 — Determine the best lift and support points for the axle. Every vehicle is different, so it is best to consult the vehicle manufacturer for the specific lifting and support points it recommends.
However, without this recommendation, the general practice is to place the jack and jack stands directly under the axle.
Below are some guidelines to use when selecting the lift and support points:
- Never lift on the drive-axle housing or any drive-train component if the vehicle is loaded.
- Never lift on any moving component of the suspension system or on the end of the U-bolts.
- Never allow the jack or jack stands to lift or contact the vehicle at an angle.
- Never use one jack stand in the middle to support both ends of an axle.
- Always make sure the jack's saddle is centered on the lift point.
- If using the differential, or "pumpkin" to raise a drive axle, the jack cannot contact the drain plug. You should know that damage may result if you lift a fully loaded vehicle by the differential or in the middle of the axle tube. It is best in these instances to lift and support the axle at both ends.
- On trailers, position the jack near the end of the axle making sure there is enough room for the support stands between the jack and the tire sidewall.
Step 7 — Center the jack saddle under the axle and then use the jack to lift the axle. When lifting both ends of the axle, a jack may be used in the middle of the axle if the vehicle is not fully loaded.
Step 8 — Once the axle is at the proper working height, place a matched pair of support stands set to the proper working height at both ends of the axle, and center their saddles under the axle.
Step 9 — Slowly lower the jack until the stands support the load.
Step 10 — Once the service is complete, raise the axle in the middle to a height where the support stands can be removed.
There are additional guidelines to follow if more than one axle on the vehicle must be lifted.
- Lifting and supporting more than one axle on a loaded vehicle is not recommended.
- Jack stands may not be recommended for supporting both ends of a vehicle at the same time.
- Never lift both axles of a loaded trailer if it is being supported by the landing gear. This is because the landing gear may buckle under the weight of the entire trailer and its load and the front of the trailer will crash to the ground.
When jacks are not in use, they should always be stored with the ram and the extender fully retracted to prevent any rust or corrosion on the threads of the extender or finished surface of the ram. The extender should be oiled periodically to ensure the full lifting height of the jack will be maintained.
Tighten the release valve and store the jack in an upright position where it will not be exposed to water of moisture.
If the jack requires additional oil, use only hydraulic jack oil. Always follow the manufacturer's instructions for replenishing oil in addition to making any other repairs on jacks and jack stands.
Atlas' life would have been much easier if he had had a couple of jack stands with him to support the weight of the sky rather than his shoulders.
But by using jacks and jack stands properly and following the procedures correctly, you too can become the Atlas of modern day, commercial truck tire service.
Peggy can be reached via e-mail at [email protected].
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