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  #11  
Old 03-17-2010
Frank W. Frank W. is offline
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I wrote this up a few years ago...was on WOO...you can edit, make a sticky, or whatever. It is long...but the details can be important:

Working safely under your bus…


This is a critical life safety issue. This is “what I do” and I provide it NOT as a guide for YOU but to document my work practices for me. I hope it gives you some “food for thought” and serves as a starting point and overview of working safely under your bus.

So please consider this as “commentary” or “discussion”, not instruction. You are responsible for your safety, you will need to research further and make your own wise choices. I urge you to get proper instruction and seek other sources of information…your life may depend on it.


Part 1 – The facts of life…

We are typically handy sorts with tools who own a classic BB. We do not have a “truck pit” or a lift, but we do have a little spare time and some tools. This combination can be good or bad…compliancy, time limitations, travel plans, and the like can lead us to rush a project and loose sight of potential hazards.

A big mental step for me was realizing the massive weight involved in our buses. Working on a 3 to 4 thousand pound car is nothing like working on an air suspension heavy bus that can range from 25-35+ thousand pounds (depending on your model).

In my prior employment I had several occasions to investigate these types of incidents – these accidents do happen. It is a bad way to die, and most of the ones I saw would never have an open casket funeral. The investigative findings of some representative fatal vehicle lifting accidents are provided at the end of this document (these are not my cases)…remember that every single one of the persons killed in these accidents thought at the end of the day they would be going home….in fact, they ended their day crushed under a vehicle.

Part 2 – The Basic Equipment

Before any special tools and equipment it is your commitment to safety that is the key to working under your bus. Have a plan for safely lifting and then redundantly supporting your bus. Consider what are you going to do…How high are you going to lift? Are you lifting one end of the bus or lifting both ends?

So, let’s get started:

• Have a stable, firm and level working area. Lifting and supporting a bus requires a level surface, an uneven or tilted surface will introduce shear or side loads on your lifting jack and stands. Jacks and stands are designed for straight (up and down) loading.
• You need to both safely lift the bus, then safely support it. Jacks are used to lift. Jack stands and solid wood blocking are used to support.
• Surfaces other than reinforced concrete will need some type of platform to spread weight loading. Typical residential asphalt driveways will often need some type of platform to spread weight over a wider area than a jack stand base. Use suitable 2x10 or 2x12 dimensional lumber, steel plate, or other suitable material in good condition under jacks and jack stands. If the ground allows your lifting jack or supports to “sink”, you are at risk for a bus fall.
• Use 4x4 or 6x6 dimensional wood lumber in sound condition for tire blocks, support blocking and cribbing.
• Use of bricks or cinderblocks is not a safe practice for support.
• Know the actual weight of your bus. Use lifting jacks, jack stands and other blocking devices that are suitable for the job you are doing. Most jack stands are sold in pairs and the capacity of the stands is for both working in tandem. For example, my “12-ton” jack stands are designed to support 12 tons over both jacks, not 12 tons on each jack.
• Use only the main bus frame rails or axles as lifting and support points. Minor frame and auxiliary structures to include the bumpers are not suitable for supporting the bus.
• The HWH leveling jacks are not designed as jack stands for service work under the bus. Remember that hydraulic systems can fail or leak and then the bus comes down; also the jacks do fold back and then…the bus comes down.
• The parking brake is effective only if both rear wheels are solidly on level ground. The parking brake does not have any effect on the front wheels. Block the wheels left on the ground.
• Do not rely on the air bags to hold the bus "up" at any time for any reason for work under the bus. Air systems leak and then the bus comes down.
• If you are working under the bus do not allow persons to move about on the bus.
• When under the bus place your body where clearance is greatest. If at all possible, use an extra jack stand of proper rating as a redundant safety support next to you as a “fail safe”. Alternately, a support column or cribbing of square stacked 4x4 or similar lumber sections could also be used. I bought 4x4 P.T. timbers that I cut into 2 foot sections that work very well for wheel blocks and cribbing.

Part 3 – It does happen…

These reports are from a the California FACE Program, California Department of Health Services, Occupational Health Branch, 1515 Clay St. Suite 1901,Oakland, CA 94612 and are available on the internet.

CASE STUDY #1

INVESTIGATION

On the day of the incident, the decedent was scheduled to perform a rear brake job on a 37,500 pound transit bus. The bus had been backed into one of the bays. The decedent had jacked up the bus and removed the four 24½ inch diameter rear wheels with their tires mounted. Normal procedure thereafter is to set the emergency brake and chock the front wheels. It is unknown if the emergency brake was set. The front wheels were not chocked.

Jack stands are used to support the bus while work is being performed. Usual parts of the undercarriage where jack stands would be placed are the frame rails and the axle housing. In this instance the decedent placed the jack stands under a moveable part of the suspension called trailing arms. The trailing arms were 4 7/8 inches wide at the point of placement.

The jack stands the decedent used were shop-made by a local welding company. According to the district manager, they were brought on site by a mechanic that no longer works for the bus company. In addition, he stated that they were apparently made to the specifications of another bus company. The jack stands used were 13½ inches high. They were constructed by welding a 7½ inch square piece of ¼-inch plate steel to the top of a piece of square tubing. The square tubing served as the support post. A 12-inch by 11-inch piece of ¼-inch plate steel had been welded to the bottom of the square tubing. The top plate was completely flat, having no lip unlike commercial jack stands that always do.

The decedent's job was to remove the 19-inch diameter brake drum assembly. At the time of the incident he was using hand tools to perform this task. As he was under the bus, the jack stands tipped and the bus suddenly shifted sideways to the right. It fell off the jack stands and the rear axle pinned the decedent between itself and the concrete floor.

CAUSE OF DEATH
The certificate of death stated the cause of death to be blunt abdominal and pelvic injuries.

RECOMMENDATIONS/DISCUSSION

Recommendation #1: Employers should ensure employees use only tools and equipment that have been tested, certified and rated.
Discussion: The jack stands used in this instance had not been tested or certified as to their rated capacity. They were not permanently marked with a rated capacity. Their construction was not in accordance with commercial jack stand construction. Lips are employed on jack stands to cradle the area being supported. The missing lips meant that the jack stand's center of support could not be determined because the part of the vehicle being supported could not be cradled. When the part being supported is cradled equally between the lips of a jack stand, it is placed so the weight has been placed over the center of the jack stand. This makes it very difficult for the jack stand to tip. In addition, using a flat plate on the bottom of a jack stand, as in this case, does not allow for the possibility of an uneven surface. Commercially made jack stands have legs, normally constructed in a tripod fashion. Tripod jack stands are able to compensate for small surface imperfections or make larger surface imperfections readily apparent. Their legs make an uneven surface apparent by one, or two, legs not touching the surface. If the decedent had used the commercial jack stands available in the shop, placed them correctly, or if the employer had removed the shop-made jack stands from service, this incident may not have happened.
Recommendation #2: Employers should ensure employees chock the wheels of vehicles that remain in contact with the working surface.
Discussion: The decedent failed to follow shop policy and chock the wheels of the bus prior to beginning the brake job. Chocks keep vehicles from moving while parked. In this case, chocks placed under the front wheels may have prevented the front wheels from shifting when the jack stands shifted slightly. Enough movement may have been prevented to keep the bus from falling off the jack stands.
Recommendation #3: Employers should ensure employees do not place jack stands on portions of a vehicle that are not fixed in place.
Discussion: In this fatality, the decedent placed the jack stands under the trailing arms of the rear suspension. Although trailing arms are meant to move up and down, the do have some sideways movement. Jack stands are normally placed under the frame rail, axle housing, or another fixed area capable of supporting the weight of a vehicle. Both the frame rail, 3½ inches wide, and the axle housing were available for jack stand placement in this instance. To do this, the decedent would have had to use the available commercial jack stands since the shop-made stands would not work. If the decedent had placed the proper jack stands under fixed parts of the undercarriage, this incident may not have happened.
CASE STUDY #2

INVESTIGATION

The site of the incident was a small auto repair shop that specialized in import vehicles. The shop yard was cluttered with disabled vehicles and miscellaneous debris. On the day of the incident, the owner of the auto repair shop retrieved a forklift that had a leaking hose from a customer. The owner told the customer that an estimate for repairs would be available after a mechanic evaluated the problem. Later that afternoon, the victim lifted the forklift with a large bottle-type hydraulic jack and blocked only one tire of the forklift with a piece of wood. The forklift was in the shop area where the ground was at a slight incline.

While the victim was lying on a creeper reaching under the forklift to remove the leaking hose, the forklift slipped off the jack and struck him in the head. A witness to the incident stated he ran to find the owner who subsequently called 911. The paramedics administered CPR and transported the victim to the hospital, where he died shortly thereafter.

CAUSE OF DEATH
The cause of death, according to the death certificate, was blunt head trauma.

RECOMMENDATIONS/DISCUSSION
Recommendation #1: Ensure all jacked loads are properly supported before beginning work.
Discussion: Most jacks are designed to lift heavy objects, not support them. Proper use of a jack involves knowing the weight limit and proper placement of the jack. Once a jack lifts a heavy object, the object must then be supported by either a jack stand or cribbing. Cribbing is the process whereby blocks of wood are placed under the object to support it in an elevated position. Supporting elevated objects with jack stands or cribbing ensures stability of the object especially when work has to be performed under the object. Had the decedent used proper jack stands or cribbing to support the load before placing his body underneath it to do work, this incident might have been prevented.

Recommendation #2: Ensure all vehicles are on level floors before elevating them.
Discussion: Most jacks are designed to lift a load straight up. This is why it is essential to assure that the surface the load is on is level. An elevated load is unstable to begin with and an un-level surface will allow the center of gravity of the load to shift more rapidly to the down side. Any movement caused by work being performed on the load could also cause the load to slip off the jack, especially if it is not properly cribbed or blocked. Had the victim used a jack on a level surface, this incident might have been prevented.

END DOCUMENT

Frank W.
85FC33
Woodbridge, VA.
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  #12  
Old 03-17-2010
Pepperell Pepperell is offline
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I don't think you would want to use 4 jack stands of lesser rating on one end. Getting all 4 to share an equal load would be difficult (teetering 4 leg chair syndrome). So if the load is 24,000# and you use 4 X 6,000# jack stands 2 per side, it's likely that one stand will be overloaded. If it fails, 12,000# will fall on the remaining jack which then fails. Not good.

Note that if you attempt to put jack stands under each corner by jacking the corner up you could also exceed the jack stand load limit. Jacking from the middle (if possible) would be best.

Note: I have never jacked a coach up!!! I'm not an expert, YMMV, I'm not a lawyer nor do I play one on tv.
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  #13  
Old 03-17-2010
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I don't trust those jackstands that say they are rated for 6 tons or 3 tons or whatever. I'm talking about the type with the teeth cast on to the part that raises. It looks to me if you overloaded one of these stands with the load being supported by a tooth on the upper portion, the tooth will shear off and so will the next until it bottoms out.

These make me nervous under a car or pickup! For the bus, I jack the frame, then crib it up with wood and let the stack of wood support the weight. See the gentlemans earlier post about how to go about cribbing up the frame.
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  #14  
Old 03-17-2010
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Randy Dupree Randy Dupree is offline
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Speaking for all of us here on WOG,please be careful working under your coach.
Cheap jack stands,or placing them on asphalt or dirt is not good,level ground is a must.

We have all heard the stories of cars.trucks and coachs falling on people,very few survive.
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  #15  
Old 03-17-2010
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Mike Hohnstein Mike Hohnstein is offline
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I have seen several posts where fellows have talked about WOOD supports. Very scary.
Anything less than tagged commercial stands, level CEMENT work surface is irresponsible.
I'm a little puzzled by Harvies comment regarding axle support as I place my stands there, using a floor jack to elevate the coach @ the rear axle banjo housing and center of front axle. Rear up first then front, roll floor jack in from rear under mud flap, haven't had any scary moments raising or lowering. Use 4 20ton stands.
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  #16  
Old 03-17-2010
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Mike Hohnstein Mike Hohnstein is offline
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http://http://www.menintools.com/hydraulic/otc5009.html

Floor jack specs are the OTC 20 ton model
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  #17  
Old 03-17-2010
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Mike Hohnstein Mike Hohnstein is offline
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Quote:
Originally Posted by Mike Hohnstein View Post
http://http://www.menintools.com/hydraulic/otc5009.html

Floor jack specs are the OTC 20 ton model
Nice link, ***, google 20 ton floor jack and check out what is needed to elevate a bus.
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  #18  
Old 03-17-2010
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Blocking the tires must also be an exact science with the proper blocking tools or material.

Although pretty scary to us cowards, It seems that MH is safer with four stands, rather than two stands.
Less chance of the bus rolling or shifting.
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  #19  
Old 03-17-2010
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Quote:
Originally Posted by Mike Hohnstein View Post
I have seen several posts where fellows have talked about WOOD supports. Very scary.
You're right Mike. Wood support can be scary. It has to be done correctly but when it is, it provides excellent support. The key is knowing how to do it. Many shipyards keel support dry docked vessels using dimensional lumber but again they know what they're doing.
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  #20  
Old 03-17-2010
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Here in our heavy truck and equipment shop, on a level and rated concrete floor, we use axle stands that are rated for 12 ton each, that is 48,000 lbs per pair. We always place them under the axle, never under the frame and only lift one end of the vehicle at a time whenever possible. This follows accepted Ontario Labour Safety Standards practice and has been our procedure here for many years without incident.
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