Discussion:
Drive Motor Encoder Failure

Okay, this truck has been causing issues for over 4 mechanics now, and has been passed my way. It has been burning out RH drive motor encoders. They might last anywhere from 2 weeks to 2 months. It's currently on it's 7th motor. When testing the encoder outputs, the voltage is around 5.5v on each channel, but when it fails, the voltage drops down to 2-3v and the truck freaks out. However the "input" voltage to the encoder remains a constant 11.2v.

So far, besides motors, the truck also has had a "known good" access3 module installed, and an entirely new wiring harness per NewBremen tech support. Now they want me to install another access3 claiming a bad wiring harness could have damaged the access3 causing the issues. However the LH drive motor has never had an issue, and they both recieve the same "input" voltage but give off different outputs.

Today I installed yet another brand new drive motor assembly, and the output voltage is only putting out 4.6 volts, and should be 5.5v. The LH (good side) motor does put out 5.5v exactly.

So both left and right sides are receiving 11.2v signal but the RH is only giving 4.6 back to the access3 module. Has anyone else in the world had a similar issue. Or anything else that I should check. Tomorrow I plan on switching the input leads between the 2 motors and see if the problems follows, or stays with the same motor.

Any input would be helpful.
  • Posted 14 Feb 2013 09:11
  • By griffman_23
  • joined 5 Aug'09 - 28 messages
  • Michigan, United States
--Just an opinion from some punk ruining the world--
Showing items 1 - 3 of 3 results.
You tried fitting a suppressor across the horn?

Used to have issues with tech's not changing the horn / replacing the suppressor when replacing SKF encoder bearing's on BT Rolatruc equipment.

Tech's found out the hard way as BT would refuse there parts warranty claim when the new encoder bearing failed shortly afterwards if there wasn't also a new horn / suppressor listed on the original job card.
  • Posted 14 Feb 2013 22:05
  • By Forkingabout
  • joined 31 Mar'11 - 862 messages
  • england, United Kingdom
We (the other techs and myself) had gone over Static as a possible cause of the encoder failure. This truck does us Non-Marking tires, and pulls pallets off an automated shrink-wrapper....So you can imagine the possible static buildup. So we've since then made sure the static strap is clean, on top of adding a chain dragging behind, and also running grounding wires between the battery compartment, seat, hood, power unit, and main frame of truck. We even went through and did Ohm testing, and had good continuity to the grounding chain.

Currently, the truck is down, and they're using a loaner of the exact same model, with no issues and no static problems. So I think that kind of eliminates the environment as a possible cause of failure.

But at this point, I'm open to any ideas. Lol
  • Posted 14 Feb 2013 12:17
  • By griffman_23
  • joined 5 Aug'09 - 28 messages
  • Michigan, United States
--Just an opinion from some punk ruining the world--
I had a Jungheinrich EFGDFAC20 w hitch had a similar problem in that it went through about 6 encoder bearings, some lasted 2 days others 2-3 weeks, genuine SKF bearings and no one including Jungheinrich had a lue why! The only thing I came up with out of desperation was that something was spiking them and knocking them out, I fitted a chain on the bottom of the chassis which dragged on the floor to discharge static and since then not a problem!
We have lots of these that don't have a static chain and have never had an encoder go for some unknown reason, it was just this particular truck. I have heard of static problems when trucks are fitted with non marking tyres but this one was fitted with standard blacks. Just a thought!
  • Posted 14 Feb 2013 10:41
  • By danny_k
  • joined 3 Mar'05 - 310 messages
  • Buckinghamshire, United Kingdom

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