I have a JLG 45HA that for the most part won't come down. The Swing works good both ways and the Main Telescope works in and out. The Main Lift and the tower telescope will both go up but won't come down and the Tower Lift is about half extended and won't go either way. It just dogs the motor down. Mine looks just like janz that had the brake problem back in August. I will try to get a couple pictures out here as soon as I can my pictures cut down, I can't get them to load as they are too big. Any ideas on what I can check would be greatly appreciated.This message has been edited. Last edited by: JCH,
tower track side
Put all cylinders that can be retracted/bottom then check fluid level. Run the pump until operating temperature then activate to retract. But bleed first. Then post a circuit and hopefully one jlg(Jim) shows up and help.
I can't get the main lift, tower lift or tower telescope cylinders to retract, that's my problem.
In the photo you labeled 'Tower' at the end of the Tower Tube there is a Hydraulic Limit Switch. If this Switch is not fully depressed the Tower Boom will not lower. The Tower Telescope when retracted strikes this hydraulic switch. The striker is adjustable or the plunger on the valve can be pushed in with a little persuasion if needed.
Also, at the pivot end of the Tower Boom near the base of the cylinder there is another Hydraulic Limit Switch. If this switch is not fully depressed the Tower Telescope will not extend.
Check these hydraulic limit switches to ensure they are being activated.
When they rusted they were very difficult to activate.
In your photo labeled 'Hydraulic Valves' the valve bank front and center is the Stepper Valve Manifold. It is the speed selector.
From left to right front row is 1st Stage to 4th Stage. Behind that row is the dump valve for the circuit. On the right side of this manifold is the High Drive Valve.
The valve on the rear wall is the FPS Steer Valve.
The important Valve Bank for us is the Racine Valve Bank on the right.
The top valve is the Swing Valve.
The second from top is the Tower Telescope Valve.
Third from top is the Tower Lift Valve.
The lowest valve is the Drive Forward/Reverse Valve.
You said that Swing functions well. You may want to swap the wires temporarily between the Swing Section and Tower Telescope Section to verify that there is or is not an electrical problem.
At the top of the Upright Assembly is another FPS Valve Bank. This valve bank has the Main Boom Lift Valve, Main Telescope, Platform Rotate and Platform Level Valves in that order from the Inlet Section to the Outlet Section respectively.
There is also a Dual-Pilot Check Valve located bolted to the side of the Upright. This valve is in the Main Boom Telescope Circuit.
It has been known to freeze up from rust or other debris and not permit telescope functions.
Thank you very much for all the great info, I will check these items this afternoon.
Jim, thank you your info was right on the mark. I did find the hydraulic limit switch at the top of the tower cylinder was frozen, sticking out. And you were right they get stuck hard. I put on wd-40 and drove a big screwdriver in between the limit switch button and the cupped bolt adjuster and got it to go in. (it's stuck in now, I will take it off and get it freed up next week) The good news is that fixed my tower tele problem, now TOWER TELE works both in and out great. I misspoke when I first stated my problem, I said the MAIN LIFT and the TOWER TELE would go up but not down. I should have said MAIN LIFT AND TOWER LIFT. I could not find the other hydraulic switch you mentioned. I attached a pic of the switch I found at the top of the tower lift cylinder. Can you tell me where the other switch is relative to this switch? At this point the main lift and tower lift won't come down but we are making great progress. I'm hoping when I locate this other switch it will fix one of these too.
The purpose of the valves are to limit movement for sequencing boom operation.
The switch you worked on is installed to keep the Tower Boom from lowering until the Tower Extend-Retract (Telescope) is completely Retracted.
The lower Limit Switch is installed to prevent the Telescope Cylinder from Extending until the Tower Boom is completely elevated.
They must be working properly to prevent the machine from tipping if the Tower Boom begins lowering before the Telescope Boom is completely retracted.
This is critical.
The valve part numbers are the same and should be available although a bit pricey.
Valve part number: 4640310.
A seal kit is available for a fraction of the cost. Seal Kit part number is 7012649.
Here is a drawing of the valve locations:
Thanks, now that I see the second switch I understand how the 2 switches control the position of the tele tower. What I don't understand is why the tower boom won't come down, the tower tele is all the way retracted and the top limit switch is stuck 'in'. When I toggle the tower lift down it trys to stall the motor.
the light is about ready to come on!
note the position of the Upright Pivot Assembly in your photo and compare it to the one in this drawing.
When the Tower Boom is being raised, the oil is being routed to the Tower Cylinder first and from there the oil travels to the Lower Slave Cylinder's barrel end. This extends the Lower Slave Cylinder keeping the Upright Pivot Assembly perpendicular to the chassis.
When the Tower Lift is being lowered, the oil is fed to the Lower Slave Cylinder's rod end first and from that cylinder to the Tower Lift Cylinder. This will again keep the Upright Pivot Assembly perpendicular to the chassis where it is intended to be.
Your photo shows that the Upright Pivot Assembly Cylinder (Lower Slave Cylinder) on your machine is completely retracted. There is nowhere for the oil to go except over relief.
Find a way to safely swap the two hoses on the Lower Slave Cylinder and then activate Tower Lift down and the Tower should lower. As the Tower is lowering, the Upright Pivot Assembly should start raising in the desired direction. When the Upright Pivot Assembly is perpendicular to the chassis, stop the boom and swap the hoses back to where they were.
If I remember correctly, there is a cover on the face of the Upright Pivot Assembly that will allow access to the Lower Slave Cylinder fittings.
This should get the sections back in alignment.
The Main Boom issue should be a piece of cake. It might just be a connection at the Main Lift Valve.
I had no idea that cylinder even existed but sure enough, it was behind the cover just like you said. I will do the swap in the morning.
I don't know if it's going to end up being why the main lift won't come down, but I forgot to mention I had to disconnect a line on the main lift cylinder and let it leak down enough that I could transport it on the road.
Thanks so much for the help, this will be great if I can get the lift working. I have a big white oak next to my garage that has died and top is starting to come dowm on my roof a limb at a time. It's too tall to drop, because the only way to drop it would be towards the other shed. And I also have another oak that's leaning towards the house and it's way limb heavy on the house side.
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