Clark TW40:
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
  • Discussion started by specequip
  • Michigan, United States
Showing items 76 - 90 of 94 results.
Describe in complete detail what it is doing, everything from turning the key on, to how much you as pressing the petal, sound of contactors clicking in or off, to how often it does it, when it does it, and exactly how it is reacting to what you are doing.
  • Posted 17 Aug 2012 04:47
  • Reply by mrfixit
  • New York, United States
It is an ev1 system. So you are saying this is maybe not whats wrong?
  • Posted 17 Aug 2012 04:39
  • Reply by specequip
  • Michigan, United States
He said it's a EV1 system which, I think, would trip right off if there ws something wrong with the SCRs as soon as the forward contactor closes, and it doesn't do that.
  • Posted 17 Aug 2012 04:15
  • Reply by mrfixit
  • New York, United States
In my notes for parts for a Clark TM15 With the ev100 system I have the part numbers: numbe r2 rec:910576
Number 5 rec: 910575......not sure if these are what you need for your truck or not??
  • Posted 17 Aug 2012 04:06
  • Reply by kevin_t
  • Pennsylvania, United States
Do you happen to know the part # of the #5 rectifier? #2 is 998517.
  • Posted 17 Aug 2012 04:02
  • Reply by specequip
  • Michigan, United States
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
  • Reply by kevin_t
  • 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
  • Reply by specequip
  • 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
  • Reply by specequip
  • 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
  • Reply by edward_t
  • 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
  • Reply by specequip
  • 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
  • Reply by kevin_t
  • 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
  • Reply by MEngr
  • 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
  • Reply by specequip
  • 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
  • Reply by specequip
  • 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
  • Reply by mrfixit
  • New York, United States

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