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