I have an EC500-50 forklift that has not been maintained well. I am in the process of rebuilding and repairing it. The problem i am writing about it that the throttle peddle currently does not provide smooth control of the lift. It is quite jerky and hard to feather or vary speed. Especially when trying to move slowly. The peddle has two micro switches, one engaged at full speed and the other at stop plus a rheostat/potentiometer. I do not have any schematics for this lift nor have I been able to find any making it very difficult to perform diagnostics on this drive.
Common sense tells me this thing must have some sort of chopper drive to control the average current to the traction motor but I don't see much in the way of electronics at all. Only electro mechanical items such as large relays and fuses inside the back cover. In my experience one can normally hear the whine of a chopper drive but this lift is quiet except for the hydraulic pump and I am stumped as to where I should start.
The serial number is E355 306 2300 if that helps
Showing items 1 - 7 of 7 results.
Well dang it. Close but not it or my system is older than the PDF I found. The layout is sure not the same. It says General Electric Truc Tronic on it. Clark part number:2318460. Looks like it has one of these on it: IC4484A190
here is a photo link:
http(es):(slash slash)photos(dot)app(dot)goo(dot)gl(slash)rf4QXEhCFAV6Jrbf8
The Clark part number for the pot is 1798161
That's the manual for your controller. Like others have said, the pot wears out or develops opens and is not a smooth sweep causing jerking. The second switch at full throttle activates a contactor that completely bypasses the scr controlling the speed and hooks the battery direct to the motor. Full speed ahead.
OOH! I found this:
http(es):(slash,slash)store(dot)gegridsolutions(dot)com(slash)Manuals(slash)Documents(slash)IC(slash)GEK-28897B(dot)pdf
Thanks! That's something I can check and adjust. I am guessing the first switch (closed on foot off the peddle) engages a brake but the second switch that closes at full throttle,,,,,what does it do?
On the theory of op. SCR huh? Those kind of an all or nothing device. Once turned on they stay on in a DC system. Implies the power is pulsed to the SCR creating perhaps a chopper style drive?
Keshka
This is a SCR controlled truck. By the serial number it is a GE 210 panel. The SCR panel is in one of the lower side panels. I would start with the potentiometer. After the first switch closes, You should see about 4,000 to 5,000 Ohms across the
pot. This should decrease to about 100 Ohms when the second switch closes.
It sounds like the accelerator potentiometer is no good. You can test it with an analog ohmmeter by attaching the leads to the tabs on the pot. When you turn the shaft the the needle should move very smoothly. If it doesn't you need to replace it. There should be a number stamped on the back of the pot.
Forkliftaction.com accepts no responsibility for forum content and requires forum participants to adhere to the rules. Click here for more information.