Cage leveling on aerial lift

[BeezFun]

Mystery solved. Its all starting to make sense now.

Yeah, I feel confident trying to solve the other problems now that I'm sure how it works.

Return oil usually results in a leak and not a point in which you get air in the system. Rather a suction line from the tank to pump (if its not a submerged pump) is a source for air. But that would also cause air and jerkeyness in the other hydraulic functions.

It has two pumps, one is electric driven and it's inside the tank. But the gas engine driven pump is external and has about 3-4' of suction hoses and the filter/housing. Maybe this winter I'll pull those suction hoses and replace them to see if that helps. I only get jerkiness in the leveling cylinder. The problem that started this thread was that the basket would move out of level when I wasn't even moving. At first I thought the seals must be leaking in the cylinder, but the cylinder was moving in the retracted direction so it couldn't be the seals. So I decided it was probably air in the cylinder and as I moved around in the basket I was compressing the air and it went out of level. So I'm hoping that air is the root of the problem.

I agree that the simplest method is to operate the basket cylinder fully both directions a couple of times and see if it starts acting better. This would best be done from the ground controls if you have a ground control for the basket

After I go through the bleed process it's smooth for a day or two, then starts jerking again. I think I'll make this a winter project so I can take my time and fiddle with it. The manufacturer used to have a really sharp guy that answered the technical line and he could almost walk me through any repair, but he's been replaced with the generic help line people who read from a script they've been given. There is a local dealer and they're really sharp, if I can't figure it out I might take it in for some help.

 

[BeezFun]

Do you also have a leak? You could dye the fluid.. StackPath

Obviously, many different brands and can be bought just about anywhere.

I might try that. Some of the hoses are 50' long, and besides being expensive it will be a bugger to thread a new hose through the boom arms with the fittings crimped on. I replace hoses when I notice a puddle forming on the floor, so far I've only had to replace the outrigger hoses and they were pretty easy to get at. It lives indoors so there's no UV damage, hopefully hoses will outlive me.