Hello!
We've had this machine for a while. It finally stopped moving.
I'm not sure if this is relevant BUT In the past, we've had problems with the high speed engaging, especially under load and especially in reverse with a load. We learned to deal with it because none of the forklift 'experts' in our area could figure out the issue.
So, here is what I've done:
I removed the side panel and the top panel to access the controller, contactors, and control wiring/switches.
I found the FWD/REV contactors pull in just fine. I'm not too sure which contactor is the 1A but I am willing to bet that the control of that contactor has something to do with this... but I've learned to not jump to conclusions.
I have a schematic of the EV-1 (oh, yeah, the controller I have is the EV-1) but not everything is clearly defined. I am going to assume that the "TRACTION ARM" motor is the one that drives the truck forward and backward. It looks like the FWD & REV contactors are interlocked in several ways (yay redundancy!). So, the positive feed for the motor goes through A1 contactor, then either the F or R contactor depending on the selection at the stick, and then to the motor. The negative side of the motor goes to a sensor which isn't telling me much but it looks like a shunt in the schematics (no clue where this is on the truck), then it connects to Batt neg.
So, to me, if the F & R contactors can engage and if I can assume just for a minute that the inline "sensor" on the negative side of the motor is okay, the only other thing to get in the way of engaging the motor is the 1A contactor.
1A appears to be quite the security guard in this machine. Load, overheating, acceleration... everything can cause this thing not to engage... but I'm not sure where to begin. I see there are a few experts on here and I am hoping you are still around to give me a hand.
Thanks in advance! I can't wait to poke at this more!
Showing items 16 - 30 of 41 results.
I'll try and post here , don't know if this site will let you post email
That's great news! Thank you! I look forward.
Are you posting the tests here or do you need my email?
Digital meter will work just fine
I will send you some test
That plug on the back was as clean and nicely tight. All wires are clean and seated.
I have a digital multimeter but my VOM took a hike about 20 years ago.
The 1 rec reading is good battery volts on one side half battery volts on other without vom you really can't test much however you can pull the card and test it but you might look at back side of card it has a square plug where recs etc
Plug in make sure they are all plugged in and no loose ones
I had to turn around and head back to work after I read your message about tapping the motor but sadly, nothing.
After throwing the oscilloscope on the motor side of the FWD/REV contactor cables, then confirming the same thing up on the power TB below the EV-1, I'm convinced there is an issue with the card or an input that I just can't see. A good chunk of the the troubleshooting steps shown in the EV-1 manual are not as they say they should be... mind you I don't have VOM. If I had a way to bench test the EV-1, I'd rock it down to the component level but info isn't exactly spewing out.
Key on, I get 36 volts on one side of REC1 and 18 volts on the other. I'm not sure what is normal.
With the oscilloscope and a power analyzer, I tried reading all of the terminals on the power terminal block as well as the cables on the contactors and could not get any pulse-width readings.
Now, the FWD/REV contactors are needing a bit of help from my foot to get pulled in. I think this machine may be just too tired... or maybe I am. I don' know. Do you have any other ideas of what I should try before I call it quits?
You can take a rubber hammer or a regular hammer and tap lightly on the motor then see if it tries to move if do you need motor work
The wires will have continuity , the brush sits against armature that is contact point
As for replacing you pull spring back and rest it on motor unscrew brush and remove it with a pair of needle nose pliers they just slip into guide
Then put new brushes in the back ones you can remove cables and mounting bolts on motor and turn just enough to get them you also need to get two armature stones one course and a finishing to clean armature
Either way you need to replace them or have motor rebuilt
Good to know. Thanks!
I just poked my head in the motor side of things this morning and noticed the brushes are suuuper low. https://i.ibb.co/rQF65XS/Brushes.jpg As much as I want to suspect that those are the cause of my issue (it would make sense), there's still continuity between the wires so I would think I would be seeing some movement, even if it was weak. Please correct me if I'm wrong. Also, I have NO idea how I would change those brushes without pulling the whole motor out and apart.
The two best tools for that would be a multimeter and a handyman a handyman is a tester that test the scrs and diodes for leakage
An oscillator is good for the card but you need a handyman to test scr it turns them on and off and checks for leakage
I think I got you now. The actual speed control is done through the SCRs. The controller card does the checks and is the front side of the 'dimmer,' the rectifiers do the pulse-width depending on the speed control pot setting, and the contactors just let the pulse-width through.
Okay, now the fun begins.
Would an oscilloscope be a handy tool here? I don't know what end is what in regards to the SCR but I'm sure viewing the pulse-width waveform would be handy.
If you go to flight systems industrial products you can view a manual on that system it has test sections for faults just go to ev 1
Yes the panel , the contacts are not part of scr
The scr refers to the three electrical components rec1,2 and 5
The contacts can close but the scr panel is not working after contact closes then when you start to push the handle the potentiometer sends a voltage to card the card turns on scr 1 and 2 imagine an scr like a light switch, if you could turn it off and on super rapidly you can control the brightness and dimness of the bulb
The scr which is short for silicone controlled rectifier is basically an electronic switch
You have scr 1,2and 5 ,sorry the trainer came out in me !
Oh well that changes pretty much everything then. Here I am chasing why the 1A isn't closing. Whoops.
Please pardon me, and this very well could already have been answered but I'm no forklift mechanic/tech, but you say if the contacts close but no scr, what do you mean by 'no scr?' If you mean the panel, isn't it working if the FWD/REV contacts are pulling in?
The 1-A will only close when unit gets to 80%
Speed it is basically your high speed contact
It is referred to as a bypass contact it is to keep your scr panel from getting overheated
When it pulls in at high speed it bypasses the scr panel and goes from battery to motor it will not close until the card or switch on some units bring it in at 80% speed
If your contacts close but no scr you should check your drive motor cables and drive motor
Drive motor brushes , fuses and #1 rec
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