bill c -

Fixed frame would be the standard telehandler configuration where the forklift level position would depend entirely on the tire footing on the terrain.

Frame level is a side-to-side leveling device (usually hydraulic) which can help compensate for extreme axle articulation to improve stability.This is an option on some telehandlers.

As for the hydraulic retraction and the axle sensor questions, I am not familiar with the mechanics of the CAT telehandlers. I would address such questions to CAT or to a telehandler mechanic/technician at a CAT dealership.

You mentioned hired machine. If the machine was a rental, I would definitely question if the operator was trained or certified to operate the telehandler in question.

I agree two different standards of measurement can lead to confusion. I don't foresee any change at this end in the near future (if ever). I'm glad ForklifAction.com added a unit converter calculator to their site. It saves me a lot of time and frustration.

Let us know the results when the final investigative report is completed.

Reply to joseph h
Yes the charts in the hired machine state TH360-B.
The data on HEH2806B is similar but differs more at full height.
Can you explain to me the difference between Fixed Frame and Frame Level
When this machine overturned and remained on it's side for 72 hours could the stabilizers moved? Or would the hydraulic circuit lock them in their last position?
There is an ongoing investigation into this incident by the authorites (equivent to your OSHA) but I am becoming increasing concerned that the stabilizers may not have been used at all
On the rear axle of this machine which is centre point pivoted there is a small electrical sensor/cell fixed to the axle. Is this a level sensor which is linked to the interlocks on the machine which would prohibit the machine being on only 3 wheels?
I repeat I appreciate the help from my USA friends. Having worked in California for 5 years I have great repect for the USAers. But why in 2009 do you all hang on to feet and inches and lbs when Millmeteres and Kilograms are available in the rest of the world. Many thanks once again.

Bill C

bill c:

Do the charts on the telehandler designate they are for the CAT TH360-B? Does the data on the actual telehandler charts approximate the data in the CAT HEHB2806-2 brochure? Hopefully the charts on the telehandler have the same data but in more detail. The brochure is a marketing tool. The actual equipment load charts are the official safety tool. If the telehandler load charts in use are for the CAT TH360-B, I would go by the charts in use and not the brochure.

Not having the official load charts, I can only give an answer based on the brochure data.

Based on the CAT HEHB2806-2 bruchure load chart diagrams, a lift of 11.5 meters with fully extended boom would be at an approximate angle of 55º. The maximum safe weight at this height and angle based on the same load chart diagrams would be:

Stabilizers Up (fixed frame) -1500 kg.

Stabilizers Up (frame level) - 1500 kg. (if this frame level option was in use)

Stabilizers Down - 2500 kg.

The 1600 kg. lift was 100 kg/220 pounds over the safe rated limit if the stabilizers were not in use.

If the stabilizers were elevated 12+ inches above ground level and they were originally in use, it could indicate the operator raised the stabilizers in an attempt to creep the load forward.

Raising/lowering the stabilizers with an elevated load can lead to tip over even with a safe rated load. Creeping forward with a raised load on rough terrain can also lead to tip over even with a safe rated load. An overweight load makes tip over in both situations more likely.

Firstly many thanks for the replies so far. Secondly my regret for the weight error. The load being lifted was 1,600KG's being 3528 lbs. Thirdly the machine was a CAT TH360B.
I now have the Caterpillar machine details for this machine which are interesting.
From our onsite investigations we now know the forks/lifting attachment was at a height of 11.5 Meters and the jib was fully extended. Contrary to what we were told at the time of the incident we now doubt if the stabilizers were down. When the machine was righted they were more that 12 inches (300MM) of the ground.
The ground was not too bad for a construction site but still not level. Around the area of the machine the ground sloped slightly to the left.
I note the load charts on the CAT TH360B document (HEHB2806-2) gives a different load chart than that on the on-board flip charts --Why would this be.
They also state:- Load at Maximum height Stabilizers up 1,500Kgs
Given this am I correct in saying :- Machine overloaded when it tiped leftwards?

Regards Bill C

I concur with much of what Bill said.

Also, if it was a CAT TL642, it does not have a rear stability cylinder. For that matter many 3 ton machines do not have a rear stability cylinder to lock the rear axle when the boom is raised. Most telehandler accidents in the US (not sure about EU countries) are lateral tip-overs as you describe. Front outriggers only slightly reduce the lateral tip-over risk.

See graphic at constructionequipment.com/articles/images/CEX/20060201/cex0602_herobL.jpg

As you raise the boom the CG moves up and back, making the machine easier to tip. The rear cylinder turns the "triangle of stability" into a "box of stability" which greatly reduces the chance of tipping. My guess is the operator used a jib attachment pointed almost vertical, with the rear of the machine downhill.
ISZ

bill c:

The 1600 kg/33,000 pound load on a 3 ton/6500 pound telehandler readily caught my attention. The ForkliftAction Unit Converter quickly confirmed that the 33,000 was most likely a keystroke error. A 6500 pound rated telehandler is not going to lift a 33000 pound load; let alone lift it to 45 feet.

The ground terrain may have played a part in the tip over. It is more likely that the telehandler in question was handling a load beyond the rated capacity as shown on the load chart. You did not mention the model number of the CAT telehandler. The CAT TL642 is a 65000 pound rated telehandler with front stabilizers that has a 42 foot reach. Your telehandler may be the same or similar.

The TLB42 manufacturer's load chart decreases the load rate from a high of 6500 pounds to 6000 pounds to 4000 pounds to 3000 pounds to 1700 pounds based on boom angle and boom extension with stabilizers in use and the load being lifted using the standard fork attachment. This load chart must be readily visible on the telehandler. It is completely useless prior to an accident if the operator has not been trained in its use or does not understand how to properly interpret the load chart. Did the operator know how to interpret the load chart?

If the load was being lifted by the use of a mast boom attachment, the telehandler load ratings would decrease even more. The rating for the mast boom attachment would require a revised load chart from the forklift manufacturer or a qualified engineer and must also be readily visible on the telehandler.

If you did not record the boom angle and boom extension at the time of the tip over, you could get a rough idea from photographs of the incident.

Did the operator perform a trial lift (without load) to determine the boom angles and boom extensions that would be impacting the lift to determine the safe load limit?

I would also determine how the truss was attached. Was it balanced on the forks? Was it secured to the forks to prevent slippage? Was it freely suspended by a sling which would allow the load to swing? Small load movements can have a big impact on tip over during telehandler lifts. Load shifting may have been a contributory factor.

Moving the stabilizers or activating the frame level with the load elevated can also contribute to tip over. Did the operator manipulate the stabilizer or the frame level controls while the load was elevated? Such actions have caused many telehandler tip over accidents in the past.

What was the training and experience of the operator making the lift? How much actual experience did the operator have using the telehandler in question? Was the operator familiar with the telehandler manufacturer's safety warnings and operating procedures? Was the operator familiar with the mast boom attachment manufacturer's safety warnings and operating procedures (if used)?

What were the wind conditions at the time of the lift?

What were the soil conditions at the time of the lift (wet, dry, loose soil, etc)?

Were the tires in good condition and properly inflated?

The cause of your telehandler incident is most likely a combination of all of the above and more. There is little margin for error on many telehandler lifts.

The following article is a good overview of telehandler stability. Google: Telehandler Popularity Increases Concerns of Safe Operation

The following requirements for freely suspended loads used in Australia and New Zealand may also be of interest. Google: Construction Bulletin No. 30, March 2006, Telehandlers Used as Mobile Cranes.

The United States National Institute for Occupational Safety and Health (NIOSH) through its Fatality Assessment and Control Evaluation (FACE) Program documents some telehandler fatality accident investigations. These reports can be reviewed on-line. Google: cdc/gov/niosh/face/inhouse.html.

what kid of cat are we talking about here

first, you can get a job working fo NASA, doing the math for the Mars missions, with that conversion from 1600k, (one too many zeros?)
second, you don't tell us which model or series of "cat" tele-handler you were using, and there is a real possibility their may have been some "down-rating" where you can only lift a weight only so high and so far out before you have to "de-rate" the capacity of the machine, and lastly, you are correct, it is possible to be on such an unstable surface as to make lifting a less than capacity load unsafe