Hi everyone hope everything is well and everyone is staying safe.. Hoping I can get a little help with my AT 40 C Simmons/terex man lift. Everything works on the manlift but the bottom boom valve cylinder was leaking. I rebuilt it with new seals. Check for visual damaged everything checked out okay. Installed the cylinder and open the two bleed screws on it until hydraulic fluid came out. So when I tried to work the boom.. it goes up but not down.. seen like it wants to go down but something in the hydraulics won't let it.. I've tried all the other functions on the machine and they all still work fine. Just the lower boom is the problem.. Maybe a check valve?? Is there another way to bleed the system?? Any help is appreciated. Thanks Russell
You are having a problem with the holding valve. I would safely support the boom and remove the holding valve and inspect for damage or wrong assembly.
Thanks for the reply Today is crappy out but I will get on the machine tomorrow.. I will post results . Thanks again
Slowly remove the holding valve from the cylinder there will be stored energy from the valve not working and the pressure will be high. Be sure that your boom is supported or the energy will be greater and the boom will suddenly drop. I am probably telling you something you already know but I want to make sure that advice that I give doesn't get someone hurt or killed.
So I removed the holding valve and found that it was stuck all the way counterclockwise. I turned it all the way in clockwise.. reinstall it and it all worked well again.. until I raised the top boom and blew a line.. what mess smh.. so away it looks like a 5/16 line .. not sure what psi it should be.. This is a old machine but in good shape other than dry rot disease.. thanks
I think those were fully hydraulic proportional machines. Lots of long hoses. Could get costly. Probably 3000psi hoses.
Is it 4wd? If so could be trouble ahead. The rearends were the weak link on the 4wd. They had bronco running gear and weighed about 15000 lb. too much weight for the axles. I don’t remember if they had an update though
I have a question about the same lift, what model warn manual locking hubs are on these? I have a broken one on mine.
Don’t know for sure but I was always told it was runnin gear from a full sized bronco which was a problem because of the weight.