what is this call?

it didnt. it rolled off the dock and hit my trailer

 

The main feature of Surelok is to prevent dock walk. That happens when the springs compress under the forklift. The swing of the axle coming up pushes the trailer chassis, against the set brakes, away from the dock an inch or less. When it rebounds, now you're not tucked up against the dock any more. After several trips of the forklift, the gap can get dangerous. Envision how an inchworm moves. That's what's going on when the trailer walks away from the dock. The Surelok arms take the swing out of the suspension for loading, preventing that.



The newer docks with hooks that grab the bumper serve the same purpose, not just to keep a mad driver from taking off.

My first trailer was a crappy old Trailmobile that would walk a couple inches, even with the trailer chocked and truck brakes set. Sliding the tandems all the way back tends to reduce this, by taking leverage away from the forklift by shortening the distance from the axles to the rear of the trailer.

 

They did. Here is the product info.

Hendrickson - Trailer Surelok

 

It is called surelok ride height lock mechanism

https://www.hendrickson-intl.com/getattachment/a2f84d46-1526-48e9-8178-409db46a76a1/L622.pdf

 

fork lift was un manned and rolled off the dock between my trailer