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15069Re: Click of death.........RM Gear-case failure

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  • Bill
    Jul 1, 2008
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      < Yeah I know you're gonna complain>
      --------------------------
      Has my reputation preceed me? ;-)
      ============================
      > Swapping the gear case is relatively easy- pull the wheels,>
      ---------------------------------------
      Not ~THAT~ easy because I have 'dualy-wheels', two knobby wheels
      bolted together which eliminated the stuck-on-stupid behavior in my
      sandy soil.
      First the wheels must be unbolted before I can get to the snap ring.

      Maybe I wasn't clear, but my RL-800 now has the gear-case robbed from
      my low-hours RL-500.
      The only original RL800 parts are one drive-motor shroud with the
      thermistor attaced.

      Now...........
      about the new gear-case.....
      I just want to get it clear in my mind.....
      the new gear-case has replaced the white plastic bearings with
      ball bearings?
      If not ball bearings, then what is it?
      I understand the plastic composition has changed for the frame,
      pinion/motor assy and the gears, but I need a clear explanation of
      what has replaced the white 'bearings' before I plunk my money down on
      a frame/new gear-case/ drive-motor assy.

      BTW, I'm an engineer and this stuff interests me...........
      especially now that I have a NEED. :-)

      TIA

      WB




      --- In RoboMower@yahoogroups.com, <dannym@...> wrote:
      >
      > Ah yes, the click of death.
      >
      > Those plastic bushings were recognized as a problem and fixed in
      later designs. They changed out the plastic bushings with proper
      bearings, changed the plastic the whole case is made of so the motors
      don't soften it and sag, and changed the type of plastic the motor
      pinion is made out of.
      >
      > You'd think you could just get the plastic gear frame and side gears
      cheap, but really the other problem was motor pinion wear and heat
      tolerance. Unfortunately the motor pinions are not removable; you
      need new motors there. So it comes down to just swapping the whole
      thing out, otherwise the old worn pinions will eat into your brand new
      gears anyways.
      >
      > Yeah I know you're gonna complain about how much the mower cost
      initially, this is a sort of defect, how somebody should fix it for
      free, blah blah. I *do* feel your pain. But the mower was a
      completely innovative design when it came out (actually there's a LOT
      in here which is innovative), so it's not surprising that it's not
      going to be a completely maintenance-free deal in the first 5 yrs.
      Gas mowers break too and taking one back to the dealer to get fixed
      would probably run you more than this gear case will cost. The good
      news is the new gear case WILL be a long term fix. There's enough
      benefit there to justify the $ to buy a new drive train (gear case).
      It's not a cheap fix but not monumentally expensive either and it's
      really good.
      >
      > Swapping the gear case is relatively easy- pull the wheels, take off
      the tach board, unplug the motor wires, IIRC move some wires going to
      the rear out of the way, pull the gear case out, reverse steps with
      new one. Test to see if you have the motors hooked up the right way
      before putting the top back on (hook up controller and drive forward,
      if it reverses or turns them obviously you need to fix that).
      >
      > I don't think lubing the plastic is gonna help. In fact it may
      attract dirt which acts as an abrasive and accelerates the problem.
      But really the problems are inevitable no matter what you do. Getting
      the improved gear case is essential.
      >
      > Danny
      >
      > ---- Bill <wild_bill_howell@...> wrote:
      > > Well, it finally happened.....
      > > part of the gear-case failed after 328 hrs on my RL-800.
      > >
      > > It did NOT fail at the drive-motor pinion, although it shows some
      > > wear, there was still plenty of teeth engagement to work.
      > >
      > > The failure occured in the gears which are 'supported' by two white
      > > 'bushings'/bearings'.........
      > > two 'bearings' on each wheel or a total of four on the same shaft.
      > > what a junky POS, crappy-assed design.....
      > > designed as though it was INTENDED to fail!!!
      > >
      > > The 'clicking' came from only one side where the part of the gear that
      > > receives the 'bearing' had worn so badly that it formed a cone-shaped
      > > hole so the gear wobled on the shaft...
      > > the other side was on the verge of failing in the same manner.
      > >
      > > So...
      > > I cannabalized my $200 Woot RL-500 and swapped out the gearcase.
      > > I, of course had to remove the drive-motor shroud with the thermistor
      > > pop-rivited to it from the original 800 and put it on the replacement
      > > gear-case and resolder the thermistor leads.
      > >
      > > Just for drill, I lubed up those white bearings with "Break-Free" oil
      > > and put it all back together.
      > >
      > > While I was already into the job, I decided to make an additional
      > > heat-sink "shade" for the two motors with two pieces of 1/6" alum
      > > angle.
      > > I cut them so that they will also serve as a 'spreader' to prevent the
      > > drive motors from ever sagging inward from over-heating.
      > > One angle required cut corners to provide relief for the part of the
      > > plastic frame which have molded gussets.
      > > I also put TWO layers of heat-shrink tubing over both thermistor leads
      > > to keep them from shorting out...
      > > In addition, as a further precaution, I glued some 'fish-paper'
      > > (phenolic impregnated fiver paper) on the 'shade' in the area that
      > > might come in contact with the thermistor as an additional electrical
      > > insulation precaution.
      > >
      > > I oriented the drive-motor shroud containing the thermistor in the
      > > 'valley' of the alum angle, then clamped each end of the angles to
      > > the ends of the two drive motors with hose clamps.
      > >
      > > Here is my question....
      > > Why did Friendly use those two crappy-assed white 'bearings' instead
      > > of something more substantial?
      > > I swear, it looks to me like it was designed to fail in order to
      > > generate after-sales repair income.
      > >
      > > What is REALLY new with the new generation RMs to eliminate this
      > > failure mode?
      > > If the answer is 'a better plastic formulation', then it's still not
      > > very satisfactory.
      > >
      > > Those white plastic 'bearings' are gonna require periodic PM lube to
      > > keep them from failing....
      > > and considering what must be done to just get to them for that
      purpose ...
      > > really is an unnecessary time-waster and it pisses me off that I'll
      > > have to disassemble the mower just to keep an eye on it.
      > >
      > > Grrrrr.
      > >
      > > WB
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > > ------------------------------------
      > >
      > > Yahoo! Groups Links
      > >
      > >
      > >
      >
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