Hi folks on the forum
I have a old truck
Lansing foer9 2.0
sn 78052472
72V
TP
4005831-2
sn 78061670
The truck has started to stall when fwd or rev pedal is pushed.
The relay that drops out is the main DC one under the rhs cover next to the driver. DC is 72 falling to 68 when mast is moving.
There is no sound from the traction motor when the pedal is pushed which is odd, then the truck will jump and stall.
We pulled off the front panel and can see the turret turns and the micros operate the main fwd and rev contactors.
If I had a cct diag I could maybe tell you more, I think this is now a permanent fault, it has happened before and the with persistant resetting it has cleared, but now the truck is stuck and will not move. Any help /feedback would be welcome, we are electrical engineers and have all the test equipment to provide any more data you may require to assist.
Thanks
Laurence
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Hi Laurence
Your problem is a built in safety device. The system is :FAILING TO SAFE; The reason for this is varid, but to start with it is most probable one of the comutating devices, which consist of the following, DIODES, THYRISTORS,CAPACITOR BANK. OR MOTOR GROUND FAULT. As you are in the biz these can be checked with a multimeter. Be aware though that as the SCR's thyristors are high on the list a small battery and bulb will clear them to clear working order, when gated. Not sure if I still have drawings as I am half packed to move house in a few weeks. If you are still stuck let me know and you can contact me and I will talk you through. Also make sure you isolate the pigtails. Another problem could be the overcurrent relay located under the right hand floor plate, and if the battery is low as you say the volt drops on lifting this could also be a factor. This hytronic system relies on pull-in and drop-out voltage of the operating contactors, so any volt drop will affect it. There are a few more obscure faults that will cause this fault but these are the most common. Good luck
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