Discussion:
Load Centre "Rule of Thumb"

Hi just joined up looking for some info about this R.O.T.

Read this today on a forklift training site on the internet.

For every inch the LC extends,reduce the carrying capacity
by 100lbs.

So..... 2000lbs @ 24"LC rated capacity truck with a 4 metre carpet Boom attached ie LC @ 78" ???
  • Posted 28 Mar 2007 03:57
  • Modified 28 Mar 2007 04:17 by poster
  • Discussion started by bobby_b
  • scotland, United Kingdom
Always trying to improve.
Showing items 1 - 15 of 58 results.
Thank you all. It is a interesting discussion. Do we teach what is absolutely accurate knowing most students will never even think about using that information, OR, do we give them a "Rule of Thumb" that is not very accurate but they have a much greater chance of remembering and using?

How often are they put in a position of needing to use that information? In a standard Grocery warehouse in North America, the pallets loads are 40wx48lx48h inches and 2000 lbs average weight evenly distributed. Moving a longer load is very rare. But in a manufacturing plant, or car parts, or lumber yard, etc. the odd sized loads can be 20% of the time. Long loads could be an issue every day.

I am not sure there is a right answer. Perhaps the 3rd option of teaching from our friend in Nova Scotia - have the capacity graph (because its not a straight line formula) on every forklift and teach the student how to read that properly.
  • Posted 24 Dec 2013 01:31
  • Modified 24 Dec 2013 01:33 by poster
  • Reply by DanBeer
  • British Columbia, Canada
"Make it home safe."
We, as trainers and safety professionals, can educate the students until we are blue in the face. Do you think they really listen? Do you believe they do all you have taught them to do?

I teach them to sound the horn and look all around them before reversing, not to hit anyone, and always look in the direction of travel. Do you honestly think they do so once I have left the building?

As I say to them, whatever you do on Monday is your own business. What you do for me today, gets done my way. I will not be here Monday to oversee how you operate the forklift, however, if I am ever pulled into court, with my hand on the bible, I will clearly state that the correct answers were received on the written tests, and they performed their duties safely and properly for me. And the judge will say 'thank you very much, Mr. Maron, you are free to go. End of story.
  • Posted 21 Dec 2013 11:16
  • Reply by dan_m
  • Ontario, Canada
As a trainer wording is a big issue liability wise. It is a slippery slope to climb telling students to use the 100 lbs./inch down rating, another approach may be to talk with the customers health and safety committee and show them the 1/50th calculations then plant the seed to have them draw up a quick reference chart that could be laminated and mounted on the forklift or posted at the receiving doors in large print.
  • Posted 21 Dec 2013 11:09
  • Reply by randal_s
  • Nova Scotia, Canada
Great info and I know what you are saying but my students, as well as most others, will definitely be lost, even with their phones. And in most instances they wouldn't even bother.

We deal in 2 worlds. One is the safe use of a powered industrial lift truck, and the other, real world situations.
  • Posted 21 Dec 2013 10:24
  • Reply by dan_m
  • Ontario, Canada
I suppose what someone needs to do is to develop an APP where the person is told to measure the distance from the drive axle to the fork face; enter the rated load distance and rated load; and then enter the load distance in question.
I've checked Dan's rule for the 25 "5000 lb" forklift models I have data on and it never over-estimates by more than 1%, and is conservative for load distances of 34" or more. On that basis it's fine to use for that size of forklift.
However for 3000 lb forklifts it underestimates capacity by 20% and for 6000 lb forklifts it overestimates capacity by 9% at 36"
A better rule for forklifts up to 7000 lb would be to reduce the load by 1/50th of the rated load per 1" increase in load distance. For 3000 lb forklift 60 lb; for 4000 lb forklift 80 lb; for 6000 lb forklift 120 lb and for 7000 lb forklift 140 lb
  • Posted 21 Dec 2013 09:30
  • Modified 21 Dec 2013 09:32 by poster
  • Reply by John_Lambert
  • Victoria, Australia
Better to strive and experience all life's colours from pain to ecstasy than to exist in a grey life
My teaching are the same but my young students are getting worse. For example, when I give them this example...5000lb forklift, 24" load center, 48" forks, and a truck pulls in with a 60" pallet, how much weight can be on the pallet for you to pick it up safely with your forklift? When they don't get the answer, I ask them what is the load center of the incoming pallet, and they say 30", so what is the load center rating of the forklift, and they say 24", so what do we do then? They say subtract the rated load center of the forklift from the load center incoming pallet...then pause. Out come the smartphones so they calculate 30-24.

Is their any hope for these kids who do not know how to subtract 30-24 without the use of a calculator or smartphone?

G-D help us all! lol

I still teach the 1"=100lb rule since there are no other immediate options, and it is the easiest means to collect a very near result.

And since I am not there to babysit them each and everyday, who knows what goes on there when I am not there. As long as I do not get a call from the Ministry of Labour asking me to substantiate why I deemed someone competent, then I have no worries. And fortunately, in the last 15 years, I have never received a call
  • Posted 21 Dec 2013 06:24
  • Modified 21 Dec 2013 06:25 by poster
  • Reply by dan_m
  • Ontario, Canada
Similar question to John. Do you feel the same 5 years later. This was a good debate -
  • Posted 21 Dec 2013 06:08
  • Reply by DanBeer
  • British Columbia, Canada
"Make it home safe."
I read the thread. Most of it was in 2008.

Now, 5 years later, do you, Dan, feel the same way - KISS principle of 1"=100lb is best practice? More important than formulas or charts. or an actual legal engineering statement?
  • Posted 21 Dec 2013 06:05
  • Reply by DanBeer
  • British Columbia, Canada
"Make it home safe."
G'day John

It would help if forklift manufactures would fix the correct load plates to the machine
currently I have had two reach trucks with the incorrect information applied to the machines

total annoyed
  • Posted 16 Oct 2013 07:14
  • Reply by jimj
  • Victoria, Australia
You better believe it!!! So true!!!!

Danny
  • Posted 23 Nov 2008 09:15
  • Reply by dan_m
  • Ontario, Canada
Constantly Lifting The Standard!
Hi Dan

Have no probelm with your scenario - reality is however that in my experience most forklift drivers:
1. Very often have no idea of the weight of the load because the pallet or other item has no weight marked on it;
2. Almost invariably have no weight gauge on their forklift so have no way of determining the load directly;
3. Very often will not check the load distance for the load they are lifting unless it is extreme - that is if the load distance was 30" or 750 mm they would not even check;
4. Often don't even make sure the load is hard up against the forkface; and
5. Virtually never consider the vertical rated distance because they do not know it is an issue.

Basically they try the load and depending on the degree to which the steer tyre flex they decide they can lift the load or not - and usually they are completely unaware that at the point of steer wheel lift off the forklift is normally overloaded by around 40%.

And that is what most managers allow - completely unaware of how much they are exposed to risk.
  • Posted 23 Nov 2008 09:09
  • Reply by John_Lambert
  • Victoria, Australia
Better to strive and experience all life's colours from pain to ecstasy than to exist in a grey life
Okay guys.

I am impressed with all the formulas and explanations and reasonings regarding this forums' topic.

Consider this: Tractor trailer pulls into loading dock. Truckers do not get paid for sitting around but they do get paid handsomely for driving on the highways. The forklift operator who may just have a high school education with mathematics being the poorest subject of all, has to make the determination as to whether he can safely unload the oddball pallets. Honestly, and definitely no offense to John or anyone who has submitted an explanation, of which I understand all, will this character be able to work out this rule of thumb as submitted by John, or any of the other posters? If you explain that 1"=100lbs, can they all tell you what 5"=? Don't laugh. Its true.
So, what has to be determined is, what is the easiest, and safest means to determine this rule of thumb rule? In my opinion, although not necessarily accurate, is the 1"=100lbs. Anything more complex than that is going to mess with most of these operators' minds. And getting fed up with difficult equations will result in these operators NOT working anything out, and just acquiring the pallets any which way they please, which will definitely result in more errors and incidents.

K.I.S.S.
  • Posted 23 Nov 2008 08:42
  • Reply by dan_m
  • Ontario, Canada
Constantly Lifting The Standard!
Hi again

I do not have information about other countries, but in Australia the most common "base" forklift has an international rating of 2500 kg at 500 mm with the smallest mast. Typically these forklifts are rated at around 2200 kg at 600 mm (4850 lb at 24 inches) with the masts and/or sideshifts commonly fitted.

Increasing the load centre by an inch reduces capacity by nearly 200 lb if you consider the forks only.

Alternately at my recommended maximum increase in load centre of 50% before referring to the manufacturer, the following apply:
1. If you consider stresses at the base of the forks, at 900 mm or 36" the reduced capacity of these forklifts is around 3230 lb or 1470 kg.
2. If you consider the forklift safety margin based on the see-saw calculation about the drive axle, the reduced capacity of these forklifts would be around 3780 lb or 1720 kg
3. If you apply the 100 lb per inch rule, the reduction is 1200 lb giving a rating of 3650 lb or 1660 kg.

You might assert 3650 lb is near enough. As I know of cases of forks failing, and know how serious the consequences could be, I would not agree as I would suggest that you should not go above 3230 lb. However THIS ASSUMES THE FORKS THEMSELVES ARE RATED AT AROUND 3000 KG AT 500 MM (20% safety margin for off centre loads) - if the forks fitted had a higher rating then a higher forklift rating at 36 " may be fine.

Alternately if as I have observed with some China based forklifts the forks were rated at 2500 kg at 500 mm, then I would suggest that firstly the rating should be reduced to 2090 kg or 4600 lb at 500 mm to give a 20% safety margin, and then adjusting to a 36" or 900 mm load centre the rating would give 1160 kg or 2560 lb. This is 1090 lb less than the 100 lb per inch rule would give you.

AS I'VE SAID BEFORE, IF YOU'RE REALLY CONCERNED ABOUT SAFETY YOU CAN'T AFFORD TO COMPROMISE WITH FORKLIFTS
  • Posted 23 Nov 2008 07:05
  • Reply by John_Lambert
  • Victoria, Australia
Better to strive and experience all life's colours from pain to ecstasy than to exist in a grey life
bobby b

Yes was well aware of that. ROT is only a rough guide but somtimes the ROT calculations come pretty close to ones that are worked out by the formula given. but for standard forks only.
  • Posted 22 Nov 2008 17:58
  • Reply by gazb
  • BUCKINGHAMSHIRE, United Kingdom
gazb
HI again to you all

I won't repeat any of my previous comments, but emphasis that forklifts are inherently dangerous (can have a low "safety factor" when fully loaded and the load is raised to maximum height) so there is a strong need to ensure safety is maintained.

I emphasise that the rated distance is both a horizontal and vertical measure - a load with a COG height greater than the rated distance (24" in USA, 600 mm in Australia and 500 mm in many other countries for small forklifts) destabilises the forklift in respect of both tipover and rollover. So unless loads are all low in height the formulas above are misleading.

The 100 lb per inch formula is an approximation for 1500 - 1800 kg or 3000 - 4000 lb forklifts only WHEN carrying low loads - that is it's application is very limited.

And you need to be aware of other limitations. At the rated distance the forks themselves are quite rigid so there is limited tendency for the load to rock back and forwards on flexing forks. However because of the fork taper, as you move the load distance out, the forks flex increases quickly so that laods may start moving back and forth significantly. This is why standards limit fork extensions (slippers) to 150% of the fork length. And it could be argued that a prudent forklift manager should get advice from the manufacturer WHENEVER the rated distance exceeds 150% of the rated distance - in the case of small forklifts where it is greater than 36 inches/ 900 mm or 750 mm depending on the standard distance in their country.
  • Posted 22 Nov 2008 17:37
  • Reply by John_Lambert
  • Victoria, Australia
Better to strive and experience all life's colours from pain to ecstasy than to exist in a grey life

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