Nolan, that would be 3500 pound feet of force.
the standard for the US market is available for download from the organization that has taken over responsibility for the B56 standard. currently that is the "Industrial Truck Standard Development Foundation" (ITSDF) and their website is itsdf dot org.
You will have to agree to not sell copies of the standard.

If a load weighing 3500 lbs falls 12' straight down what would the impact force be on the overhead guard?

Not an issue - glad to share what I learned along the way & like all 'free" info - you can accept it or drop it in the recycle bin. I tend not to BS anyone - I might kid you a little but never lie & since 2007 ,when I retired, things (like the effects of Tier IV compliance) may have changed that I am not aware of so it might be dated. That is why I like this site & even Edward T. But I try not to comment on things I'm only semi sure of.

thank you johnr for spelling that out for us

;o)

swoop223,
1. no mentionion of a minimum deflection requirement - it is a maximum amount - meaning it shall not deflect more than X, Y or Y values plus no welds shall break, or if they do add a gussett & retest. I am well aware of these standards - I was working in the lift truck industry in 1969 or 70 for two or three years when the first OSHA standards were published primarily for employer compliance - most lift truck companies that built trucks in the US had been building & testing trucks to comply w/ANSI B56.1 many years and using SAE testing methods as a standard prior to OSHA regulations be coming a Federal Law. Today's OSHA laws have evolved over the years into today's standards & some names have changed and various standards combined to simplify life (sort of) for all.
2. the standards are set by SAE (formally ANSI, ANSI/ASME) by a capacity range - the manufactuers have in put into these standards but a ALL manufactuers in teh USA must comply to these standards. OSHA does not write too many standards the adopt know & well recognized standards - like SAE, ASME, ANSI, etc. etc. Lift truck manufacturer build a family of trucks on a given wheel base to which an OHG of a specific length, width & height will fit - e.g. a 3K,3.5K, 4K lb. capacity units. The manufacturer will test the OHG integrity according to the standards set forth in the SAE standards for teh manufactuerer. Often, manufacturerer call a family of truck, 4K, 5K,6K & 6.5K units but thewheelbase will change and "generally" but not alwayss, the OHG length will change so the 5k unit w OHG will be tested & the 6.5K will be tested against the guidlelines. & so on.

i wouldnt say it is a minimum requirement, it is more of a general requirement though.
Due to the wide variety of capacities of lifts out there they leave it up to the manufacturer to set the impact standards on each class of lift they make and require them to set impact ratings on each OHG based on the capacity of the lift. The mfg's will set a minimum rating based on said capacity based on what OSHA requires them to. They are required by law to label these capacity ratings and apply them to the component in the form of a capacity tag or plate located generally on the OHG usually around the top structure of the OHG.
If you look on the outermost rail on the OHG along the topside either right or left side there should be a dataplate with the capacity and test ratings stamped on it. If this tag is missing someone either removed it or it came off.

Briefly, an OHG design is tested per SAE (used to be ANSI, then ASME/ANSI) standards two different ways. The OHG members must not deflect more than a given an amount in order to pass the tests - Test #1 a 100 lb harwood block cube of a given size is dropped on top of the OHG the cross & /or longitunal members. The block is dropped on the entire top surface. Test 2# Meausred the integrity of the OHG outer members. This test some times referred to as the Oregon Drop Test by people with gray or no hair, bad backs and retired (like me - I have 87% of my original hair) - the state where this test orginated in the 1970's then later adopetd by ANSI/SAE/OSHA. The test involves a bunk of hardwood lumber of a given l x w x h (I believe it to be 4' x 4' x 8') is dropped from a specific height (none are from the nose bleed section) to generate a given impact force which will vary depending on the trucks basic lift capacity. A very distructive test.
Because of the establsihed deflection limits, the operator clearance of 39" (from depressed seat to the under side of the OHG at any possible seat position) was established.

I have seen similar decals on the OHG on some Toyota forklifts over the years. My sentiments exactly to the previous poster, and that is how I explain it to my students. Therefore, the overhead guard will not support a falling capacity load, but will deflect small items should they fall. I guess the theory is...do not drop your loads!

Our Komatsu trucks (4,000Lb & 5,000Lb cap) have a decal on the overhead guard stating that the FOPS has been tested to withstand an "impact of 16,000 foot pounds".
In interpreting that statement, the simple explanation is something like "a 16,000 pound object dropped from a height of one foot".
The extrapolations from that point are infinite and my own examples are certainly not going to be mathematically accurate, but will serve to show how a "16,000 foot pound impact" can be generated with less than 16,000 pounds of mass.
16,000 Lb dropped from height of 1 foot = 16,000 foot pound
8,000 Lb dropped from height of 2 feet = 16,000 foot pound
4,000 LB dropped from height of 4 feet = 16,000 foot pound
2,000 Lb dropped from height of 8 feet = 16,000 foot pound
1,000 Lb dropped from height of 16 feet = 16,000 foot pound

What's the maximum rated lifting capacity on the truck data plate of your Toyota 7 series please?

BT / Toyota has several different test weight standards for the overhead guard depending on the machines rated capacity.

Also I do know there are certain differences between American & European spec machines, I've no idea if the overhead guard spec would be different for a US spec machine.

Keep in mind, OEMs have to view the standard as a minimum requirement. If Toyota goes beyond the standard in their construction there is nothing wrong about that. I emplore you to look at that section in the B56.1 standard... it details the tests and the minimum expected impact protection guidelines.

It is a Toyota 7 series cushion tire. I did not see anything on the toyota site that says what the overhead guard is rated for so if you have that information that would be great. I am still trying to understand the osha standard that says the overhead guard will not protect the driver when a large load hits them but Toyota says it will seems like they would be violating the standard

I have BT / Toyota technical data for there own overhead guard load test.

If I could have the rated capacity of this forklift in question I could post what test values BT / Toyota would use if it was one of there own machines & you could compare the standards.

Also if anyone has a link to the European standards id be grateful for a link.

Having twice seen the aftermath of a 1.1 ton pallets of stock land on top of a Reflex reach truck cab from nearly 11 meters up & a racking collapse that took several days to dig the truck out all I can say is both times the overhead guard saved the operators life.

Well, the requirements are spelled out in the B56.1 standards, but in general the overhead guard will protect you from falling objects. I feel like most impacts tend to be partial loads (like a few items from the top of the pallet stack) and the guard should handle that type of impact. A worthy (common sense) disclaimer is that if the objects are small they can fall between the grating.

The overall point I believe they are making is that the guard is not designed for very heavy, very hard, full load capacity hits from elevation. They want you to know the limitations of the guard and therefore take precautions to keep the loads from falling. If your top pallet is stretch wrapped or tightly packaged, so it will fall as a complete 3,000 lb. 4x4x4' cube the lift's guard may not handle that *complete* load's impact, depending on your lifts basic chassis capacity and the height of the fall. You see I have to specify the size of the load, the weight, the capacity of your trucks, etc. just to put this in context... that is why I believe they are not more specific, because there is so much to consider in each scenario and they do not want the liability of putting approximated impact protection... they defer you to the ANSI B56.1 standards which requires a little legwork and your truck data to figure the expected fall protection.

In your case, if you are looking to limit your liability and improve the safe handling of these loads I would suggest extending the backrest to comply with the 1910.178 standards and head off the likelihood of a fall altogether.

This is the scenario that I am asking about. The pallets weight around 3,000 lbs each (approx 4ft high) and are stacked 4 high. The forklift must grab the top two together due to mast limit. The top pallet iwould only have 6 inches of back support to stop it from rolling rearward. The pallets cannot rest against the backrest because of tight stacking and forks are longer than pallet. Is it correct to say that even if the load falls rearward onto the forklift the overhead guard will protect you. I am not clear on the standards meaning because it says the overhead guard will not protect you 'period'. My question is this just a minimum requirement for a forklift to only protect from small packages