problem with hydraulics on bucket truck

[WBODDE]

Repair Altec AA500 bucket truch

I do not know much about hydrolics on bucket trucks.
I have a problem with the boom on 1986 Chevy c60 bucket truck. The outiggers work but the boom will not raise. The hydrolic is making a thumping noise when it tries to build up with pressure.
The outriggers down and working. Loosen the bottom line on boom cylinder and does not leak oil when tring to raise.
System has been sitting a long, long time not being used.
The coil on switch over valve was bad and put new one on [ sounds like valve is working and is full of oil in tank ]
There only seems to be only one safty valve with coil for outrigger to boom use.

Bill

 

[greg storms]

hydraulics.. gotta study them

1st, I'd call and see if a maintenance manual is available. My truck is a 2000 model & they got me a manual : service and operators' for about 250$ & it took a couple of weeks. Call Ed...but it'd be wise to learn your truck's hydraulics' systems 1st. I knew very little about hydraulics also, but work at a chemical plant & know how to trace lines. Find the supply & return lines & see where they go. If 1 spool valve has a collapsed o ring, the flow will stop there. So, if your outriggers work, but the boom doesn't, there is a restriction...possibly. In my case, the bumper mounted 20000# (hydraulic) winch worked in 1 direction only. Upon disassembly of the spool valve for the directional control of the winch, I found a loose/swelled oring. Fixed that, then found a few leaks. Fixed that & all works fine. It's just like plumbing in a house....determine what goes where & see what's stopping it. Now, BEWARE of 3000PSI hydraulic lines with pressure on them. I borrowed gaGES from a hydraulic repairmen & ended up removing 3 trees in trade for his assistance. Also, there is pilot pressure (300psi on my truck) & true hydraulic pressure (300psi on mine). There are places to test the pressure, but you need gages...& they are expensive. It would have been cheaper for me to repair a serviceman (maybe 1000$), but i wouldn't have learned the truck as I did. If it breaks down in the middle of a job, I want to understand it in order to safely operate/repair. I was out of work with an illness (paid leave for 5.25 mos) so had nothing better to do. You might be better off paying a serviceman...or barter.

 

[WBODDE]

hydraulics.. gotta study them

Greg
Thanks for reply.
I was playing around with controls last night and found out when I would purge top and hold lever then try to move boom it works great on boom controls, Except bottom boom did work but not now it tries to lift top is ok.
I did ordered a maintence and parts book but on a older 1985 system not veary much info in it.
They did not keep good records on them back then they said. The l;ines on purge system look correct, in the beginning when I purged it it had oil flow in upper and bottom controls. It had air in lines from sitting so long and almost no oil from being worked on, but it did clear up.
Might have to rebuild purge valve because it has a leak when purging bottom controls. Upper controls OK no leaking.

Bill

 

[WBODDE]

Aa500

Grey

Got system up and running now had a missing o-ring in purge valve and rebuilt outriggers.
Works great except Altec boom tag said 54 ft work height but it only measured 37 ft height when all the way up from top of bucket to ground.

Bill

 

[greg storms]

got it going!

hey, great that you got it going! Now, you've gotta run it & test it. If it says 54' somewhere, but you measured 37', there must be something amiss. are both booms relatively straight up & you only show 37'? I still haven't stayed in my bucket while booming mine around. I'm repainting the boom & all the parts that secure the bucket to the boom before I run it with my 210# in the bucket. If yours sat for quite a while without fluid flowing & cylinders working, you might want to keep purging it & booming it around from the ground to give the cylinders working time. There may be seals that are somewhat out-of-round from sitting for extended periods. The manual says that can be the case from EXTENDED storage. Also, if your tank/oil reservoir has a bottom drain, drain a gallon or five out & check for contaminates (water would settle to bottom of tank & should be drained)...drain 1st quart or more in something you can see through...to see a interface between water & oil. The hydraulic oil should be yellowish, not milky white (water contaminated). gOOD lUCK! bE CAREFUL!

 

[WBODDE]

Testing

Greg

The boom tag said 54' [bottom of platform] and when I called Altec when they first read sales records on it they said 54' but that unit only came out with 44' bottom of platform max. I think they sold it to state as 54' and scam them out of money.
I have put the unit to running test but not the 800# boom hold test yet. all works good but think I need to lower the max psi down to 1750 it is now 2000 [ 2100 is max psi ]
Had it at 2000 to get outriggers to work before rebuild. It did have milky white oil but it cleared up after getting oil warm.
Have already cut limbs with it but no lifting until I get weight test done. Will need to make me a jib for it [ missing ].
If you need any new Altec pins for it let me know and will look to see if have a print on it.

Bill

 

[shawn watson]

Have ford 800 bucket truck bucket goes up an to the right as it should but left an down not so good have to pump it up then maybe go left then pump to go down whats the problem any help

 

[Johnkawi]

My bucket truck won't go side to side or up and down on the bottom boom from pistol grip control in the bucket all lower controls work fine but I can only go up and down with top boom from the bucket I have checked fluid level and bled the system off to check for air and still nothing any one have any idea what is going on