RE: (ET) mower motors

["Elie, Larry (L.D.)" <lelie ford com>]

IFF (If and Only If) you have access to a 'junk lathe' (one that people
don't mind you pounding on...)

The bottom 1" of the armature shaft always seems to be the section that 
gets
bent.  The motor shaft is a 
bit wimpy when it comes to hitting a rock, and the bearings hold the rest
pretty well.

You can put the lower end (the part that always gets bent) of the armature
in a good tight collet (no 3 jaw 
chuck please!), unlock the lathe so the motor will not turn the armature,
but will turn by hand, then use a 
dial gauge to find out where the 'high' spot is.  Because of where you are
attached, you are magnifying the 
runnout.  It will look shocking; perhaps 3/8" but remember this is the 
WRONG
END compared to the blade, but 
it lets you see the effects better.  Using a heavy rubber mallet, rap the
armature pretty hard, re-check 
and keep working out the shaft so that the bent section is less than .002"
runnout.  You overshoot a lot, 
but it works.  It helps to know a machinist.

Larry Elie


-----Original Message-----
From: Christopher Meier [mailto:mr23 mn rr com]
Sent: Thursday, May 22, 2003 12:18 AM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) mower motors



Anyone know the procedure for straightening bent motor shafts?
Is the bend always limited to the outside of the motor, because of
the lower bearing, or can the internal part of the shaft/armature
get tweaked?

Thanks,
Chris

----- Original Message ----- 
From: "Elie, Larry (L.D.)" <lelie ford com>
To: "'Humphrey Timothy H Contr AFRL/IFEC'" <Timothy Humphrey rl af mil>;
<elec-trak cosmos phy tufts edu>
Sent: Wednesday, May 21, 2003 10:42 AM
Subject: RE: (ET) mower motors


> I've seen this too, and you should fix it.  It should not do this.
>
> On mine, it was the rivets on the thermal interlock (on top of the motor,
under the cover) were loose.
> The thing wasn't heat sunk well and was going off wrong.  If you have a
spare, it's just two bolts and
> a screw.  If you don't, you could switch with another motor.
>
> A second idea; a motor with a bent shaft WILL run hotter.  You will be
able to feel the difference with
> your hand.  Essentially, a motor with a bent shaft is cutting twice as
much grass.  You can bend a shaft
> hitting one rock, so even a 'new' deck is susceptible.
>
> Tight bearings?  Shouldn't be a problem on a 'new' deck, but do all the
blades spin the same way by hand?
> If one doesn't spin as far with the same hand push, you might have a
problem.  Could there be anything
> like fishing line stuck under the blade?
>
>
> Larry Elie
>
>
> -----Original Message-----
> From: Humphrey Timothy H Contr AFRL/IFEC
> [mailto:Timothy Humphrey rl af mil]
> Sent: Wednesday, May 21, 2003 11:26 AM
> To: elec-trak cosmos phy tufts edu
> Subject: (ET) mower motors
>
>
> Any thoughts on the mower motors overheating.
>
> My rear discharge deck has three motors that were rebuilt by Bill. All
have
> new blades on them, purchased from Bill.
>
> However when I mow the right most motor(view from the seat) seems to
> overheat and cut out a lot more often than the other two. The center 
> motor
> cuts out occasionally. The left motor has never quit. Strangely, the 
> right
> motor also has a new switch/breaker assembly. Does anybody have any 
> ideas.
>
> I have pondered a few thoughts;
>
> The right motor is not broke in yet...not likely.
>
> The switch is not right...not likely, Bill put it on.
>
> The right motor is furthest from the main cord so has the longest
umbilical
> lead. Maybe excessive voltage drop? This seems somewhat likely since the
> center motor has about half the length and runs for a longer period 
> before
> cutting out.
>
> Even after just a few mowings my damn near deaf ears can pick up the
> individual hums of the motors singing their sweet tune in three part
> harmony. I know when one has passed out. The current meter shows it too.
The
> running motor feels no cooler than the stopped motor.
>
> I was thinking though, maybe it would be a neat idea to have a red/green
led
> display for each motor that changes color when the motor drops. My wife's
> hearing is very good but she seems oblivious to the fact that one motor
has
> dropped. When two go she knows it. Last night two dropped and she thought
> the tractor needed recharging, so drove it over to the outdoor plug and
let
> it drink. Not necessarily a bad thing, but not needed either.
>
> It seems to me that the grass I'm cutting shouldn't drop any of the
motors.
> Ambient temp is 70, the grass is moist(internal), not wet(external), and
> about 4-5 inches long. I'm cutting it in half. I'll really be in trouble
> when summer gets here and the ambient is sitting at 85-90. I'm thinking 
> of
> upgrading all of the motor wiring to a heavier gauge. Maybe 8 or 10, I
think
> right now it's 12 at best, maybe even 14. While I'm at it, I'll make all
of
> them equal lengths.
>
> We've got a week of rain forecast, so I'll take this opportunity to 
> switch
> over to the new deck also.
>
> Anybody have any other suggestions?
>
> Stay Charged!
>
> Hump
> I5/NY
>