This thing seems to constantly turning it's self on and off alot while trying to travel. It almost does it all the time. It acts just like if you take your finger and lift one of the moveable contacts off it's connection on the f&r contactor and set it back down. On and off, every5-10 feet of travel. If have checked the contactors, new pot, all wiring in the handle, and emergency rev. switches, everything is fine. Jacking the wheel off the floor and it seem to run smooth and fine. If I make it creep very slow, on the floor, sometimes motor will turn 1/2 turn, stop, start, stop, start while holding the pot steady. Sometimes it will throttle up to speed and then act up. I'm thinking there is a cracked field coil in the motor that is causing it to turn on and off like this. Any ideas?
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I figured it out. When I said I checked all the wiring in the handle I meant continuity and that the switches and pot worked ok. I didn't check for any grounds. One of the wires to the emergency switch had a ground. I don't think it was reaching the chassis of the machine because of the wear in the handle pivot pin and bushings until the machine started to move and the handle giggled a bit then it would make the machine stop and go.
Luckily I had another machine there so I checked the Curtis controler and that was fine. Then I took the handle off the bad jack and just plugged it to the good jack to check it. It worked fine but I didn't have it grounded to the good jack, it was laying on the painted battery cover so I thought everything was ok with the handle. Then I hooked it back up to the bad jack and had it laying on the battery cover, loosened the brake up, and tried creeping a bit. Everything seemed fine. That's when it dawned on me there must be a ground in the handle.
It sure acted strange. If I held the throttle steady to creep it would creep a inch, stop, go, stop, and sit there and pulsate. Sometimes would not go at all, sometimes throttle up ok then pulsate but kept traveling.
6 hours of labor and now my head hurts a little bit. **** thing. Live and learn. :-)
What do the brushes look like , or is it a perm. mag ? also you may want to check your cables from the controller to the motor , look for any signifigant amp draw , voltage drop , or corrosion , bypass if need be with a different set of cables
make sure the voltage isnt droppin out while drive power is ramping up
check the battery while traveling and the voltage to the contactor while traveling
also check for voltage drops on the negative side while traveling
i had an old raymond order picker do something similar with a bad battery
you would travel and it would reset every 3 seconds as the voltage dropped out
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