Lull 644B owners- Whats normal - whats not

[Roadoil]

Here

 

[Roadoil]

Here

 

[Roadoil]

After I set my pressures with 2 relief valves my front forks would only go down not up. Took spool apart on valve block for forks cleaned it was fine after.

You prob are losing pressure somewhere in system relief valve etc.

Yours may have the mid inlet system which is different but this gives idea you need to find procedure for your model.

 

[Roadoil]

I basically took out every valve in the valve block checked seals on them etc.

A bad seal could cause problems also.

 

[Andy1845c]

Thanks for posting those. I wonder if those exist for my machine. I believe mine is the mid inlet. I have the spools up front and the manifold in the center near the accumulator.

 

[Roadoil]

Thanks for posting those. I wonder if those exist for my machine. I believe mine is the mid inlet. I have the spools up front and the manifold in the center near the accumulator.


View attachment 304946View attachment 304947

There should be an adjustment test procedure for yours also.

 

[tractormech]

Thats a control manifold system- not a mid inlet

 

[Andy1845c]

I'm working off the service manual JLG has on their website. To me it appears to be what they are calling the mid-inlet. My machine is a 644B-42 serial 1136. It looks like the last control valve unit was 207.

What I am not seeing in the manual is a nice step by step procedure for setting the pressures like roadoil posted for his C series machine.

Are the relief valves I highlighted were the pressure for pump 1 and 2 are set?

 

[Roadoil]

Tractormech Craig was the one that sent me that test procedure I posted.

This shows relief valves you need to inspect.

 

[Roadoil]

That needle inside relief valve was binding on mine I cleaned it up some with fine sandpaper.

Be careful these are very expensive from JLG new $3500 and used from these scrappers like web equipment $1500 so don't lose parts or order when taking apart.

I found and replaced mine with same models Gresen and Husco cheap new from regular parts suppliers old stock. One was for a Cat but same relief just different factory set for pressure.

You gotta adjust them anyway even if a JLG apart because of system wear changes pressures.

 

[Roadoil]

You need to start with a baseline take pressures on all here full
Throttle and record. See what you are dealing with.

 

[tractormech]

I'm working off the service manual JLG has on their website. To me it appears to be what they are calling the mid-inlet. My machine is a 644B-42 serial 1136. It looks like the last control valve unit was 207.

What I am not seeing in the manual is a nice step by step procedure for setting the pressures like roadoil posted for his C series machine.

Are the relief valves I highlighted were the pressure for pump 1 and 2 are set?


View attachment 305023

 

[tractormech]

You're correct- I just looked at it quickly and misidentified it. Sorry for the confusion

 

[tractormech]

Those are the relief valves for pump 1 and 2

 

[tractormech]

Hey all,

I recently purchased a 644B that has been sitting for.... at least 3 years - possibly much longer. I just had the injection pump rebuilt to get it running again and now am working through some other issues and am wondering if anyone has input.

1. When I start it, it takes maybe 30 seconds before the hydraulic functions will actuate. You can hear the engine load a little, like the pump took that long to build pressure. Not sure what to make of this as there are no electronic controls that do anything like this.

2. The steering is "bucky" - seems the worst in crab steer mode. The wheel bounces and fights being turned. Its worse the faster you try and turn it.

3. Fully boomed out at 0 degrees (angle not temp) - I can't raise the boom unless I give it some throttle. Boomed in I can raise it at idle, though slow. Similarly I seem to be fighting the counterbalance valve on the fork curl function - at idle it will move in one direction, but needs some throttle to move the other direction. I did put almost all new hoses on it, and it sat for so long I am sure the system has/had air in it - but I have run it quite a bit now and haven't seen a ton of improvement.

4. I haven't got the transmission to shift. It feels weak. Has trouble getting over minor bumps. I will preface this one by saying I changed the oil and pulled the filter and the filter was awful. The oil was dirty but no water or metal in it. I didn't have a new filter and needed to move it so I cleaned the old one best as I could and put it back in. I have a new one arriving this week. I assume that could cause the issues I am seeing.

5. I am having a bunch of issues with the frame leveling. someone previously disconnected the front cylinder. Fearing it was full of water or something I took it apart. The inside is fine but one counter balance valve was rusty. I have a new one ordered. Twice now i have suddenly had the frame lean all the way to one side while I was playing with the steering - not even touching the frame control. I don't see how these systems are interconnected.


I have never owned a telehandler before and have limited operator experience so hoping some of you can maybe offer some input.

 

[tractormech]

Sent you a pm

 

[Andy1845c]

Progress update.

- Got my test coupler Friday. Ordered one off Amazon. The damn thing is so far out of tolerance it wouldn't even work until I took it apart and ground some off the front of the sliding collar. It wasn't coming forward far enough to hold the locking ball bearings down and the thing would just pop right off. Now it sort of works, pops off and sprays oil on my boot half the time. Pretty disappointed. Lesson learned to buy something better next time around.

-Pulled the relief valve for the carriage tilt/frame leveling circuit apart. There is a seal in the end of it that is damaged. I am going to have to explore my options on this one. Looks like there was a seal kit available once upon a time but not seeing that part number come up online. I see similar HUSCO valves for sale in different pressures. I have a couple resources I can reach out to for ideas on this. I think this makes sense why I can't get the frame leveling and carriage tilt to work well. I can only get about 1200 PSI before this valve opens.

- Screwed around with the steering some today. What I found is I am only getting about 1000 PSI on the steering. I jacked the back axle up and with no weight on the rear wheels it steers fine in all modes. The way they have the cylinders in series when its in either of the 4 wheel steer modes makes me think with the low pressure I am just not getting enough to operate all the cylinders.
Whats kicking my ass a little though is where is the steering pressure set? The manual says 2200 PSI is the proper reading - but doesn't say what to check if its low. It appears there is another relief valve in the control block - but this is set to 2450 and the manual specs 2200 max for the steering.
It looks to me like the steering is coming off pump 1. Pump 1 test pressure is around 2500 PSI.
I am leaning toward there being something going on in the control block.

-Brakes and accumulator I was getting 0 PSI. Confused about that one but leaving that be for now. The brakes do sort of work on the machine, but not what I would call well.

Have some work and travel plans now so it will be a bit before I can dive back into this.

Thanks for all the help so far!

 

[Roadoil]

Progress update.

- Got my test coupler Friday. Ordered one off Amazon. The damn thing is so far out of tolerance it wouldn't even work until I took it apart and ground some off the front of the sliding collar. It wasn't coming forward far enough to hold the locking ball bearings down and the thing would just pop right off. Now it sort of works, pops off and sprays oil on my boot half the time. Pretty disappointed. Lesson learned to buy something better next time around.

-Pulled the relief valve for the carriage tilt/frame leveling circuit apart. There is a seal in the end of it that is damaged. I am going to have to explore my options on this one. Looks like there was a seal kit available once upon a time but not seeing that part number come up online. I see similar HUSCO valves for sale in different pressures. I have a couple resources I can reach out to for ideas on this. I think this makes sense why I can't get the frame leveling and carriage tilt to work well. I can only get about 1200 PSI before this valve opens.

- Screwed around with the steering some today. What I found is I am only getting about 1000 PSI on the steering. I jacked the back axle up and with no weight on the rear wheels it steers fine in all modes. The way they have the cylinders in series when its in either of the 4 wheel steer modes makes me think with the low pressure I am just not getting enough to operate all the cylinders.
Whats kicking my ass a little though is where is the steering pressure set? The manual says 2200 PSI is the proper reading - but doesn't say what to check if its low. It appears there is another relief valve in the control block - but this is set to 2450 and the manual specs 2200 max for the steering.
It looks to me like the steering is coming off pump 1. Pump 1 test pressure is around 2500 PSI.
I am leaning toward there being something going on in the control block.

-Brakes and accumulator I was getting 0 PSI. Confused about that one but leaving that be for now. The brakes do sort of work on the machine, but not what I would call well.

Have some work and travel plans now so it will be a bit before I can dive back into this.

Thanks for all the help so far!

As long as it's a Husco 4545B it's the same but factory set pressures different for various applications

Loosen locknut set pressure with hex key.

Your pressures too low with relief valves.

Bad O ring on valve can cause issue go to hydraulic seal supply or measure go to Hercules or rocket seals or O rings and more order new.

 

[Andy1845c]

Bad O ring on valve can cause issue go to hydraulic seal supply or measure go to Hercules or rocket seals or O rings and more order new.

We have a hydraulic sales rep at the plant I work in. I shot him an email this morning asking for some advice. He also suggested Hercules and pointed me to a few seals I can try. I need to measure it and see what they have that might work. I'll report back in case it helps someone else. He also thought I can likely buy a $60 1800 PSI valve and put my spring in it. Like I told him, often there is some off the shelf solution for these old/obsolete/over priced parts - but sometimes its hard to get there without specific knowledge and experience.

 

[Andy1845c]

Someone on a hydraulic cylinder repair facebook group I am in sent me this - which I found helpful.

The 51790 part number lead me to this place -

51790 from HUSCO - SEAL KIT

www.ironwingsales.com

They have the seal kit for 16 dollars. Hopefully its correct. I ordered it, but will be out of town for a bit.

Will report back if it is the right kit.