Self leveling crane pallet fork

[Lsos]

I’ve been looking at this “Self leveling pallet fork” which is supposed to, as the name suggests, keep itself perfectly level regardless of the load applied.

I guess I can see how it would adjust itself depending on the weight, but I just can’t wrap my head around how it can possibly adjust itself depending on the center of gravity for the weight.

I other words, if the tool picks up a pallet with me on it, I don’t understand how it can possibly keep itself level if I was to walk around on the pallet. If I was standing perfectly still in the center, fine. If I was moving around…I don’t get it. Can anyone help me understand it? Does it maybe work with the assumption that the pallet is perfectly evenly loaded?

[PLAIN]http://www.heidenco.com/images/Pal_Fork.jpg [Broken]

http://www.youtube.com/watch?feature=player_embedded&v=IEnoJavoFX8

 

[turbo]

That arm on the top appears to be spring-loaded (and possibly hydraulically-damped as well) so that the connection-point can move to the center of gravity of the load. Nothing is perfect, and you will notice that in the video, the pallets are quite evenly loaded and they are hoisted only after the tines are fully inserted into the pallets. Put a very heavy load out near the ends of the tines, and things might not be as pretty.

 

[Lsos]

That arm on the top appears to be spring-loaded (and possibly hydraulically-damped as well) so that the connection-point can move to the center of gravity of the load. Nothing is perfect, and you will notice that in the video, the pallets are quite evenly loaded and they are hoisted only after the tines are fully inserted into the pallets. Put a very heavy load out near the ends of the tines, and things might not be as pretty.

Since it's spring loaded, I would expect the connection point to move as a function of weight on the fork. Only.

I just don't see how moving the center of gravity around could possibly cause the spring to stretch and cause the connection point to move.

 

[AlephZero]

They are not meant to handle uneven loading over the area of the pallet. The adjustment compensates for the CG position of the weight of the load plus the weight of the fork itself. Like any pallet lift, they are not meant to lift weights using just the tips of the tines either.

As turbo said it is basically a spring loaded hinge, often with a gas spring which also provides some damping.

They usually have a minimum weight of about 20% of the SWL before the auto-levelling kicks in. Below that, the ends of the tines tend to point up, which at least stops light loads from sliding off.

There are simpler and cheaper crane forks with manual adjustment of the lift position, but the automatic ones save time and operator errors handling "mixed" loads.

 

[Lsos]

I see...so basically they work with the assumption that the pallet is evenly loaded. That explains why it didn't make sense to me!