Evadman
Administrator Emeritus<br>Elite Member
- Feb 18, 2001
- 30,990
- 5
- 81
Nearly all bolt to the ground. However, You have no idea the amount of force a forklift, totally unloaded, even moving at 4 mph provides. A grade 5 bolt has a tensile strength of 120,000 PSI, and a sheer of about 72,000 PSI. Most racks are held in with either one 5/8" diameter lag or three 3/8" diameter lags. So you end up with about .19 square inches of bolt in the best case. So you have a bolt failure at 13,600 pounds worth of side load. To figure out the force applied in an impact, you need to know how long it will take to decelerate from 4 MPH to zero, and that is going to be entirely based on the deformity of the post itself. The fork isn't going to deform in the least. The max you will deform a post is dependent on a lot of factors, but long story short, if it is going to stay attached to the ground and "spring back" to roughly the same position it was in, 1/2 inch would be about the max deformation I could possibly see without the post caving in on itself and causing a failure anyway. At 4 mph, you are moving at 2.92 feet per second, or 35.04 inches per second. so max deformation will require a deceleration from 4mph to 0 in 0.028 of a second.
F = m Dv/Dt
(6000lbs) * ( 4mph) / (0.028 sec) * (.0455)= 39,000 lbs. That last .0455 is a unit conversion since pound-miles per hour per second probably doesn't make much sense to most people.
So a totally unloaded fork hitting a post at 4 mph has about 2.5 times the force required to snap off a bolt or three, holding a post to the floor. Add a normal 4k pallet, and now you are so far over the strength of the moorings it isn't even funny.
You have no frigging idea how much power a fork has until you fvck up. It's all about weight and leverage. Make a very minor mistake on one, and you will kill someone, or yourself.
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