Genie Z45/22 DC - Help!

[ccundiff12]

I just picked up a Genie Z45/22 DC Boom Lift from a neighbor. It's 2WD and runs on 2 large battery banks. I've run into an issue where it seems like I'm not getting all of the power to the drive wheels. The manual says it'll traverse a 30% grade with the boom stowed in low range. Right now at about a 3% grade it slows to a complete crawl, groans a bit, then stops. On a completely flat surface it operates normally/ but seems to be stuck in slow/turtle mode. Anyone have any thoughts here?

 

[OFF]

I just picked up a Genie Z45/22 DC Boom Lift from a neighbor. It's 2WD and runs on 2 large battery banks. I've run into an issue where it seems like I'm not getting all of the power to the drive wheels. The manual says it'll traverse a 30% grade with the boom stowed in low range. Right now at about a 3% grade it slows to a complete crawl, groans a bit, then stops. On a completely flat surface it operates normally/ but seems to be stuck in slow/turtle mode. Anyone have any thoughts here?

Well, my first thought was wondering about the condition of your batteries. They don't last forever. Any indication of their age? Are you able to load test them or have them load tested?

 

[ccundiff12]

Well, my first thought was wondering about the condition of your batteries. They don't last forever. Any indication of their age? Are you able to load test them or have them load tested?

Yes. The batteries were changed 3 years ago. There are 8 6v and i've used an automotive load tester all of which read close to their original rating. They've also been recently topped off with distilled H20. I did let it charge this afternoon for about 4 hours and noticed that it seems to happen after one of the drive wheels has appeared to slip? I managed to get the thing stuck now with my endevour. Only one of my drive wheels appears to be spinning where i am stuck, the other is not trying to move at all. The low/high range switch does nothing.

 

[willie59]

Welcome to HEF ccundiff12. :drinkup

An automotive type load tester won't phase those type of batteries, the amp/hr capacity is just too great, have to use a big carbon pile type load tester to get any accurate assessment. Aside from that, it's critical for operation for the batteries to be fully charged. As the batteries become discharged from use, at a certain point of discharge the motor controller begins to shut down the drive motors to protect them from high amperage damage. Boom and steer functions will still work, but it will drive slow or won't drive at all.

 

[ccundiff12]

It was not an expensive tester so i can't be 100% sure about the batteries... but my sense is that it they are likely in a usable state. After getting this thing unstuck; Had to think in 3D... Used the Boom to push off a tree!... I got it under the barn. Further investigation reveals that one of the drive wheels is in fact not working at all. There are two "drive" motors, one powers the boom hydraulics and the other directs to a manifold that powers the drive wheels. The wheel drive motor appears to have been replaced at some point. The drive wheels hydraulics come out of what looks like a large manifold. both sides are actuated by 6 solenoids and are wired in parallel.

Here's what i'm assuming & please correct me if i'm wrong:
1) its not a safety device issue as 1 wheel will drive the machine on a level paved surface without issue.
2) the hydraulic drive motor works in some capacity - the wheel that spins never switches sides and again pushes the thing around ok.
3) the solenoids are wired in parallel so when power is called for both wheels should spin.
4) i'm assuming that the 6 solenoids are for: forward/reverse, low range, & high range - don't know which is which.
5) the maintenance manual only has flowcharts for both wheels failing not just one.
6) I can't get it into "rabbit" high range, but I've noticed the limit switches on the boom are broken & it won't work in high range unless it thinks the boom is parked.

Few questions:

1) is it safe to assume the drive motor is OK since one wheel works as it should?
2) My next thought was to remove & switch the solenoids to the opposite side of the manifold to see if the other wheel now spins?
3) there is a "tow" pin built into each drive wheel... basically its a plate that when reversed presses in and disengages the hydraulic pump to be used when it's towed. Could this be somehow stuck? I read that its supposed to pop back out under pressure.

 

[willie59]

Ok, I've looked over the diagrams for the Z-45/22DC. Just for clarity, it's an electric machine that operates the controls on 24V and the electric motors on 36V. That puppy has some batteries, that would be an expensive sum-b-i-itch to replace those batteries.

It has two electric motors, one operates the boom function hyd pump, the other electric motor operates the drive/steer pump. The drive electric motor/pump sends oil to the drive control manifold. The manifold has the control valves for steering, fwd/rev drive, high/low drive speed and other valves required to operate drive. Oil leaves the drive manifold and goes to the left and right drive hydraulic motors as directed by the manifold.

its not a safety device issue as 1 wheel will drive the machine on a level paved surface without issue.

It would be a safety issue if, in fact, one of the drive planetary hubs (torque hub) were inoperable as you would then only have one brake holding and braking the machine.

the solenoids are wired in parallel so when power is called for both wheels should spin.

The solenoid valves at the drive manifold are not wired in series, you're looking at the common ground wire at the solenoids. Each solenoid has it's own power input.

I can't get it into "rabbit" high range, but I've noticed the limit switches on the boom are broken & it won't work in high range unless it thinks the boom is parked.

The boom switches do in fact prevent high drive when boom is above horizontal. In order for high drive to operate you would have to repair/replace boom switches.

there is a "tow" pin built into each drive wheel... basically its a plate that when reversed presses in and disengages the hydraulic pump to be used when it's towed.

That's the torque hub disconnect. It doesn't disconnect torque hub from the hyd pump, it disconnects the hyd drive motor shaft from the torque hub. You need to determine if that torque hub has a problem before we can suspect other things. If that torque hub were inoperable it would cause the problems you're having.

 

[ccundiff12]

Ok... After a full charge, and some further testing...

I still think only one wheel is getting power... But I observed some more.
I read that low range with full torque is only archived when boom is stowed. - something about powering the wheels in parallel instead of series. I zip tied the switch to the "stowed" position for testing purposes.

In low range high torque mode - when I try and go up a very slight slope the machine "bogs down". I observed this several times with no wheel slip. I'm talking no more than a slight 3% grade of a gravel drive way. With the drive lever all the way forward it will groan, rapidly click, then the drive stops responding until its let go back to center. It feels like there is still a strain on the batteries because all other functions slow until its put back to center. It does the same sometimes with a full turn, but never actually stops. It just feels like there is not enough pressure at the wheels / or even at the wheel that spins.

I did also do some further testing of the batteries. I charged both banks individually through a complete cycle, topped off with distilled water, left on charger overnight, and checked the specific gravity. The left side average was spot on, the right side was slightly less, but still in between tolerances.

By solenoids in parallel... I meant that it appeared if the left wheel was engaged the right "should" be doing exactly the same thing. I think this is incorrect after my reading, but it does not explain why the machine will bog down with no wheel slipping. Any thoughts on where to start?

 

[willie59]

I'm not a Genie expert, but I still contend you need to verify that both wheel drives are proper. If you suspect one is dead in the water, you need to verify. In low range, if one drive wheel was inoperable, either by failed torque hub, failed hub disconnect, or broken drive motor shaft, that drive motor would have no load on the hyd system. This would cause the transmission valve to shift the spool to direct oil to the opposite motor, but that motor wouldn't be totally efficient in that mode. You really need to verify both drive wheels are in proper working order before you can progress further.

 

[ccundiff12]

OK I have verified that both drive wheels are functional. However what is happening is that if one wheel slips, the other isn't trying to push the machine forward. once either side lets go that wheel will simply continue to spin. It happens to either side exactly the same.

 

[willie59]

Going back to your first post, you stated it wouldn't pull much of a grade, certainly not what was stated by Genie. And then there's the issue of the wheel spinning. I think you have two issues here.

First, the wheel spin when it looses traction. To some degree this is normal on this machine. Even though it's sort of a full size machine, it's still designed very much like a slab machine, a machine that works on a flat slab. Its rigid frame and non oscillating steer axle makes it real easy to lift a drive wheel off the ground on uneven terrain, it's simply not designed for that. The way the hyd circuit for drive is designed they didn't provide a mechanism to engage the wheel still on the ground when in low drive, drive motors in parallel. However, if you get your boom limit switches sorted out proper, if you get in a spot with a drive wheel spinning, you can momentarily bump it into high drive (motors in series) and it should power the wheel still on the ground.

Second, the low grading power. This could be the drive pump has excessive wear, or the relief valves in the drive manifold faulty or not right. The first thing I'd do is pull the steering relief valve (item 16 on parts diagram), and the main relief valve (item 28). Clean the valve cartridges with brake cleaner and inspect the o-rings. If they're flat or look bad, replace them. Keep in mind there's back up rings on those cartridges, don't mistake them for o-rings. Then you need to connect a 4,000 to 5,000 PSI test gauge to the test port on the drive manifold. Operate the steer (either direction) until the steer cylinder deads out, your gauge should be reading around 750 PSI. Remove the allen head cap on the end of the steering relief valve and turn the adjusting screw inside a couple of turns CW. Operate steer and check gauge. You want to keep adjusting steer relief until you see 3500 PSI, that's the setting of the main relief.

If you adjust the steer valve until it bottoms out, and still don't have 3500, remove the cap on the main relief and adjust it CW, see if you can obtain the required 3500 PSI. If you do get it, back off steer relief and operate steer until you get 750 PSI.

After you've done all of this, touch the drive pump and see how warm it is. If it's just warm to the touch, no worries, if it's hot enough to burn your fingers/hand, the pump may be getting excessively worn.

 

[ccundiff12]

OK... it's been a few years, and i'm about to finally tackle this. Since my last post, it turns out that the batteries were bad. I have replaced all 12. The behavior is the same. I can pretty much get everywhere i need to go except up the hill back into the barn. I've been using the boom extend to help "push" the machine up the grade.

When the last poster mentioned to test the drive pump to see how warm it is, is he talking about the physical hydro pump, or the electric drive motor pushing the pump?