I was working under two raised dump bodies today ...
Both Peterbilts (triaxle and a single axle). Both have positive locks (bars like Jerry described) that raise up and engage the bed so it cannot come back down. We also put wood blocks in closer to the hinges wedged in on top of the frame rails. All of our dump bodies (mostly "East" manufactured and one is a shop built) lower under gravity. Which can be a PITA if, for any number of reasons (most bad), the load does not completely dump and the bed is stuck raised ... but mostly works fine. We have a small truck (IH 4900 single axle dump -- our "sport truck") that has a power down so you have to remember to put the lever back in the neutral position when it is down. It will NOT power down if, say..., an inattentive driver forgets to unlock the gate before raising the bed and the load wedges the gate shut (locks won't release under pressure) ... It wasn't me, but I was part of the shoveling crew to correct it ... at night ... in a blizzard ...
Never EVER prop up a loaded bed, let alone work under it. Dump it in place if you need to lighten the load. Cleaning up a mess is preferable to getting someone hurt or the truck seriously damaged.
2ManyTrucks -- while they might not have put a bypass in the system originally, I would highly recommend putting one in now. That hammer effect is brutal on the pump and the hoses and it is not that complicated to install a bypass. Installing a bypass -- easy. Bursting a line (and having a loaded bed slam down) or blowing up an expensive hydraulic pump truly makes for a bad day ... just sayin'
The experts will know for sure, but I'm guess on the older trucks, a power down ability was used more on the "platform dumps" (dumping flatbeds) than the true dump trucks because the rear axle was set more forward on the frame (and probably so was the hinge point for the bed), so even when empty, there might be more of a tendency for the bed to remain in the raised position, not having enough weight forward of the fulcrum point to let the bed come back down ... ?? Maybe??
We had a friend (who will remain anonymous
for obvious reasons) who had that power down feature on his Stovebolt Big Bolt and he bent his bed because a chain remained attached and unnoticed during the power down. So care is needed!
John
