Discussion:
Forklift jumps then dies?

We have a TW40 3 wheel forklift and it devloped an issue where it jumps and then nothing. It will basically move 2 feet on the motor jump then its dead. If you try to creap it in does nothing until you are far enough in to engage the motor which dies instantly. You can still shift if forward and reverse the reverse beeper comes on. TO get it to jump another few feet you have to put it in nuetral and cycle the key on and off. We are guess it is the throttle but I am not sure what to test or check 1st. Any suggestions would be greatly appreciated.
  • Posted 16 Aug 2012 06:19
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
Showing items 81 - 94 of 94 results.
It is ALWAYS recommended to change out the #5 REC along with the #2 REC.....just a word of advice.
  • Posted 17 Aug 2012 04:00
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
I had a local company come check everything out. He found #2 rectifier or SCR #2 open. He feels that is the issue. Of course they don't have it in stock and 3 days out from clark. JOY
  • Posted 17 Aug 2012 03:57
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
1st off thanks for the replys!! I am not sure what to do next? Call a tech would be great but $200 to come out plug $125 an hour is alot for us to bear. I am very good with tracing circuits but I do not follow MEngr is saying. How do I check the capacitor charge up? and where do I find T2 or the wiring diagram. We have a service manual but it seems to proceed the truck by a few years.
  • Posted 16 Aug 2012 22:31
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
don't let computers or other solid state electronics get wet, and do recognize that the controllers in an electric forklift are 'solid state logic circuits'.
while a good few days air dry may have been able to bring this machine back from getting wet, at this stage I would guess that you are going to bite the bullet and get someone in that can check the SCRs for opens or shorts, the symptom you describe we call a "PMT" (Pulse Monitor Trip), which is caused by a SCR not turning off correctly.
  • Posted 16 Aug 2012 20:03
  • By edward_t
  • joined 5 Mar'08 - 2,334 messages
  • South Carolina, United States
"it's not rocket surgery"
It is never used in the rain. Just left outside during a storm. Truck has about 3600 hours on it. No leaks.
  • Posted 16 Aug 2012 10:40
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
is it a regular used outside and gets wet alot? this is not good for an electric truck and yes it is relevant,wont last long being an older truck and possibly in poor condition?
  • Posted 16 Aug 2012 10:16
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
specequip;
The forktruck is a 36 Volt, 4000 lb lift capacity Clark that was produced in Apr 1985 with GE EV100 oscillating speed controller and 24 Volt traction control power relays. It also had a Sevcon accelerator speed controller. The wiring diagram is IN-24012. The first item to check would be your truck's battery along with the electrical cleanliness of the truck's chassis. If these items check out to be alright, then check your truck's speed controller capacitor's charge up rate and in addition see what the voltage split T2 to Positive is.
  • Posted 16 Aug 2012 09:53
  • By MEngr
  • joined 15 Jan'11 - 247 messages
  • Missouri, United States
The battery is old. It holds a charge ok but a few months ago it got left in the rain and the gage is always on red. I think the gage is bad but it may be a short somewhere. After the forklift gets wet it is unresponsive. It has to dry and then it works. Maybe relevant?
  • Posted 16 Aug 2012 09:43
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
Yes that is exactly what it does. So I need a new pedal assembly? Is it possible to just the wires to test this. There are 5 sets of wires comeing out of the pedal assembly. OTherwise it appears to be a sealed unit.
  • Posted 16 Aug 2012 09:41
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
If you put it in forward and press the petal a little can you hear the contactors click in but it goes no where? Then if you floor it, it will jump 2 feet and shut down? If so, it sounds like the speed control pot or accellerator control has problems, located down by the throttle petal.
  • Posted 16 Aug 2012 09:10
  • By mrfixit
  • joined 11 Dec'08 - 1,434 messages
  • New York, United States
What condition is the battery in? water in the cells? corroded or bad cables/connections? charged good??
  • Posted 16 Aug 2012 08:32
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States
Well just for an update. We have a clark ev1 system. I jacked up the front wheels and both are turning in low and high gear. The problem is it seems to pop a thermal reset when you let off the pedal or switch from forward to reverse. I can see the contacts drop for low and high gear in forward and reverse. Sometime high gear will not engage. also it seems to happen more in reverse then in forward. My forklift is stuck in our parking lot so if anyone has any suggestions let me know ASAP.
Thanks,
Jason
  • Posted 16 Aug 2012 08:30
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
I can only read stamped numbers on the tag:
TW40
TW235-0108-5745FA 4 85
IS56-1350 S/S
3250 24 188 24
6350
8850
2470 1728
720-6 E
36
  • Posted 16 Aug 2012 06:52
  • By specequip
  • joined 16 Aug'12 - 53 messages
  • Michigan, United States
Two things you will need to post for this machine are the full model and serial number and second,what control system does it have EV1 or EV100,could be a few things but unless you know how to test components or have access to a GE handset(to get any trouble codes to post) if it an EV100 system, everyone will be only guessing.
  • Posted 16 Aug 2012 06:26
  • By kevin_t
  • joined 2 Dec'10 - 1,301 messages
  • Pennsylvania, United States

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