Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

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Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Jeff Shanab
I don't think we should be depending on the key at all. If the key
holds, the shear will destroy the shaft as you have discovered,
especially with the compromised shaft (big pilot hole)

For me the key is just there to help assembly and prevent rotation creep
which could become slip.

I used to cringe at hearing conversations on this list on how to cut off
splines or adapt them to keyed shaft. LOL

Are your couplers taper lock?

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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Roland Wiench
Instead of using the standard key in my motor shaft, which I find after 10
years of use, becomes worn and loose.  I had the motor shaft re-key deeper
and use a very hard tool steel stock, that is use for lathe cutting tools.
The edges on this key is so sharp that you can cut your self with it.

This type of key has to be press fit into the motor shaft, not just lay in
by pressing in by hand.  Now because I have a double end shaft motor, I have
to put the whole motor in a horizontal 20 ton press that bridges the motor
and press the motor coupler on that very tight sharp key by pressing on both
end of the motor shaft.

After ten years of this installation, I had to remove the coupler with a
bearing splitter and a impact wrench.  The key is still in perfect shape.

I am going to use a taper lock coupler with the same type of key, and see
what happens.

Roland


----- Original Message -----
From: "Jeff Shanab" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, August 09, 2007 7:48 AM
Subject: [EVDL] Motor coupler issues / was Looking for a Conversion Kit for
a 1929 Ford.


> I don't think we should be depending on the key at all. If the key
> holds, the shear will destroy the shaft as you have discovered,
> especially with the compromised shaft (big pilot hole)
>
> For me the key is just there to help assembly and prevent rotation creep
> which could become slip.
>
> I used to cringe at hearing conversations on this list on how to cut off
> splines or adapt them to keyed shaft. LOL
>
> Are your couplers taper lock?
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Mike Willmon-3
In reply to this post by Jeff Shanab
If you're talking to Mike Willmon, mine are interference fit - heated and pressed on per Jim Husted.
The engineers at Dodge said that 500 ft-lbs was outside the spec for that size Taper-Lock.  The problem being that the small (M6 I think, may be wrong) hardware could not take the torque to provide adequate suck in pressure on the taper lock bushing.

Mike,
Anchorage, Ak.

----- Original Message -----
From: Jeff Shanab
>
> Are your couplers taper lock?

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Couple needed for a L91

Eduardo K.
In reply to this post by Jeff Shanab

Hi,

        I tried this week to buy a coupler for the motor Jim made for me,
but I was turned down (something about needing a dwg file for it)

        Where can I buy a coupler for it? Jim says a coupler for a L91-4003
is the one I need.

thanks

--
Eduardo K.            | Darwin pone las reglas.
http://www.carfun.cl  | Murphy, la oportunidad.
http://ev.nn.cl       |
                      | Yo.

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Re: Couple needed for a L91

Mark Eidson
I bought the coupler for my L91-4003 from McMaster-Carr page 992
http://www.mcmaster.com/
It was a Quick disconnect keyed bushing to belt drive sprocket.  me

On 8/9/07, Eduardo Kaftanski <[hidden email]> wrote:

>
> Hi,
>
>        I tried this week to buy a coupler for the motor Jim made for me,
> but I was turned down (something about needing a dwg file for it)
>
>        Where can I buy a coupler for it? Jim says a coupler for a L91-4003
> is the one I need.
>
> thanks
>
> --
> Eduardo K.            | Darwin pone las reglas.
> http://www.carfun.cl  | Murphy, la oportunidad.
> http://ev.nn.cl       |
>                      |         Yo.
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Re: Couple needed for a L91

Eduardo K.
On Thu, Aug 09, 2007 at 03:08:56PM -0700, Mark Eidson wrote:
> I bought the coupler for my L91-4003 from McMaster-Carr page 992
> http://www.mcmaster.com/
> It was a Quick disconnect keyed bushing to belt drive sprocket.  me

GREAT!

I am impressed on whats avaliable.

Many thanks.


>
> On 8/9/07, Eduardo Kaftanski <[hidden email]> wrote:
> >
> > Hi,
> >
> >        I tried this week to buy a coupler for the motor Jim made for me,
> > but I was turned down (something about needing a dwg file for it)
> >
> >        Where can I buy a coupler for it? Jim says a coupler for a L91-4003
> > is the one I need.
> >
> > thanks
> >
> > --
> > Eduardo K.            | Darwin pone las reglas.
> > http://www.carfun.cl  | Murphy, la oportunidad.
> > http://ev.nn.cl       |
> >                      |         Yo.
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

--
Eduardo K.            | Darwin pone las reglas.
http://www.carfun.cl  | Murphy, la oportunidad.
http://ev.nn.cl       |
                      | Yo.

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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Marty Hewes
In reply to this post by Mike Willmon-3
Actually that's the biggest reason I was thinking a flanged shaft would be
cool.  I'm hearing too many differing opinions about the best way to couple
to the shaft.  Electro Automotive says taper lock is the only way to go,
taper lock says no?  I'll have to look at their specs again, if I recall,
they're all in inch pounds.  Is foot pounds simply inch pounts/12?   On the
other hand, I doubt I'll see 250 foot pounds on the street with a single
motor and batteries I can afford, much less 500.

Another question, if I have a taper lock coupler made that accurately
emulates a Chevy crankshaft, and puts the pilot bushing correctly recessed
into the coupler, not drilled into the motor shaft, it will be long, with
the flywheel mounting surface a ways from the end of the motor output shaft.
Can a taper lock be counted on to hold alignment well enough that this will
not pose alignment, runout and balance issues?

Back to dual motors and monster torque, what kind of coupler is on the
business end of White Zombie?  Has it been a problem?  This looks like a
reason to consider a setup like Otmar's 914 with the two motor's DE's belted
together so the output shaft diameter doesn't end up being on the small side
for the torque of two motors physically in series, although I'm not crazy
about the side loads that may produce.  Makes me want to take a look at the
chain drive setup on the output end of 500 cubes in the 70's Eldorados, or
the gear train used to drive the front drive shaft in a Dana 20 transfer
case.  The Dana 20 has an input gear from the trans, an output gear for the
front drive shaft, and an idler in between.  Might be able to put a motor
where the trans belongs, a motor where the front drive shaft belongs, and
take the output off the idler.

Marty


----- Original Message -----
From: "MIKE WILLMON" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Thursday, August 09, 2007 1:45 PM
Subject: Re: [EVDL] Motor coupler issues / was Looking for a Conversion Kit
for a 1929 Ford.


> If you're talking to Mike Willmon, mine are interference fit - heated and
> pressed on per Jim Husted.
> The engineers at Dodge said that 500 ft-lbs was outside the spec for that
> size Taper-Lock.  The problem being that the small (M6 I think, may be
> wrong) hardware could not take the torque to provide adequate suck in
> pressure on the taper lock bushing.
>
> Mike,
> Anchorage, Ak.
>
> ----- Original Message -----
> From: Jeff Shanab
>>
>> Are your couplers taper lock?
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>


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Re: Couple needed for a L91

Eduardo K.
In reply to this post by Eduardo K.
On Thu, Aug 09, 2007 at 06:46:50PM -0400, Eduardo Kaftanski wrote:

> On Thu, Aug 09, 2007 at 03:08:56PM -0700, Mark Eidson wrote:
> > I bought the coupler for my L91-4003 from McMaster-Carr page 992
> > http://www.mcmaster.com/
> > It was a Quick disconnect keyed bushing to belt drive sprocket.  me
>
> GREAT!
>
> I am impressed on whats avaliable.
>
> Many thanks.
>

ok. I shouted eureka too fast. My order was cancelled because I am
not in the US, although my shipping address is, due to the latest
increase in US export regulations. What harm would a US$20 piece of
metal do to national security it beyond me...

I'll have to get a friend to buy it for me and then send it.

gr.

--
Eduardo K.            |
http://www.carfun.cl  | I'm white and nerdy
http://ev.nn.cl       |               Weird Al
                      |

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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Mike Willmon-3
In reply to this post by Marty Hewes
The Dodge R16 Series 'Taper-Lock' Rigid hub is rated for 5050 in-lbs (420 ft-lbs) at 4965 RPM and weighs 8 lbs.  Thats very slightly under the 500 ft-lbs and 5500 RPM I may expect to see.  Although I'm hoping to limit RPM at 5000.

Now the Dodge 1.0 series Rigid Gear Coupler is rated for 7500 in-lbs (625 ft-lbs) at 6000 RPM and weighs 9 lbs.  This is just over my requirements which is a safe place to be.

Now for my daily driver that may never even see 300 ft-lbs and is absolutely limited to 5000 RPM (typically never even sees 4000 RPM)  the Taper-Lock hub adapter is no doubt an acceptable way to go.  Even Dodge would agree.  However when I told them I was doing a dragster and would expect to see 500 hard ft-lbs dropped on the coupler between the motors they steered me away from the Taper-Lock.  They said it would absolutely hold the 300 ft-lbs, but the suck down bolts that pull in the tapered bushing weren't strong enough to put enough pressure to hold 500 ft-lbs.  They said the bushing would probably slip and rely too much on the key to hold.  

The nice thing about the Taper-Lock is that its is easy to remove.

Mike,
Anchorage, Ak.

----- Original Message -----
From: Marty Hewes <[hidden email]>
Date: Friday, August 10, 2007 6:17 am
Subject: Re: [EVDL] Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.
To: Electric Vehicle Discussion List <[hidden email]>

> Actually that's the biggest reason I was thinking a flanged shaft
> would be
> cool.  I'm hearing too many differing opinions about the best way
> to couple
> to the shaft.  Electro Automotive says taper lock is the only way
> to go,
> taper lock says no?  I'll have to look at their specs again, if I
> recall,
> they're all in inch pounds.  Is foot pounds simply inch pounts/12?  
> On the
> other hand, I doubt I'll see 250 foot pounds on the street with a
> single
> motor and batteries I can afford, much less 500.
>
> Another question, if I have a taper lock coupler made that
> accurately
> emulates a Chevy crankshaft, and puts the pilot bushing correctly
> recessed
> into the coupler, not drilled into the motor shaft, it will be
> long, with
> the flywheel mounting surface a ways from the end of the motor
> output shaft.
> Can a taper lock be counted on to hold alignment well enough that
> this will
> not pose alignment, runout and balance issues?
>
> Back to dual motors and monster torque, what kind of coupler is on
> the
> business end of White Zombie?  Has it been a problem?  This looks
> like a
> reason to consider a setup like Otmar's 914 with the two motor's
> DE's belted
> together so the output shaft diameter doesn't end up being on the
> small side
> for the torque of two motors physically in series, although I'm not
> crazy
> about the side loads that may produce.  Makes me want to take a
> look at the
> chain drive setup on the output end of 500 cubes in the 70's
> Eldorados, or
> the gear train used to drive the front drive shaft in a Dana 20
> transfer
> case.  The Dana 20 has an input gear from the trans, an output gear
> for the
> front drive shaft, and an idler in between.  Might be able to put a
> motor
> where the trans belongs, a motor where the front drive shaft
> belongs, and
> take the output off the idler.
>
> Marty
>
>
> ----- Original Message -----
> From: "MIKE WILLMON" <[hidden email]>
> To: "Electric Vehicle Discussion List" <[hidden email]>
> Sent: Thursday, August 09, 2007 1:45 PM
> Subject: Re: [EVDL] Motor coupler issues / was Looking for a
> Conversion Kit
> for a 1929 Ford.
>
>
> > If you're talking to Mike Willmon, mine are interference fit -
> heated and
> > pressed on per Jim Husted.
> > The engineers at Dodge said that 500 ft-lbs was outside the spec
> for that
> > size Taper-Lock.  The problem being that the small (M6 I think,
> may be
> > wrong) hardware could not take the torque to provide adequate
> suck in
> > pressure on the taper lock bushing.
> >
> > Mike,
> > Anchorage, Ak.
> >
> > ----- Original Message -----
> > From: Jeff Shanab
> >>
> >> Are your couplers taper lock?
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
> >
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Tim Humphrey



>
> -----Original Message-----

> Behalf Of MIKE WILLMON
 However when I told them I was doing a dragster and would
> expect to see 500 hard ft-lbs dropped on the coupler between the motors
> they steered me away from the Taper-Lock.  >
> Mike,
> Anchorage, Ak.


Here's an area I know nothing about....

Will there really be 500ftlbs on the coupler BETWEEEN the motors?

If one arm is producing 500 ft-lbs AND the other arm is producing 500 ft-lbs, the coupler will see ZERO won't it?


--
Stay Charged!
Hump
I-5, Blossvale NY

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Re: Motor coupler issues

Hi-Torque Electric

--- Tim Humphrey <[hidden email]> wrote:

> Here's an area I know nothing about....
>
> Will there really be 500ftlbs on the coupler
> BETWEEEN the motors?
>
> If one arm is producing 500 ft-lbs AND the other arm
> is producing 500 ft-lbs, the coupler will see ZERO
> won't it?

Hey Tim

Here's my take on it 8^)

Let's say you and I are on a tug of war team (I'm in
front and your in back (just shut up and get behind
me)(no back lip) LMAO.  The gun goes off and we both
start pulling. What you're saying is that the rope has
"X" amount of pull but none between us!

Well unless you've slipped off to a lawn chair to
watch me get pulled through the mud, there is half the
load in the rope between us 8^)

Now that I think about it, you take front 8^o hehehe.

Hope this sheds some light.

Cya
Jim Husted
Hi-Torque Electric




       
____________________________________________________________________________________
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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Mike Willmon-3
In reply to this post by Marty Hewes
White Zombie has a single solid shaft running through both armatures.  No keys or couplers to shear or slip, or welded flanges to worry about when removing it;  just one big long a$$ shaft.  The business end has a hardened (I think) involute splined shaft that a slip yoke attaches directly to the drive shaft.  Again no flanges, adapters, keys or such.  All business and (depending on who's driving) no BS.

I'll let Jim elaborate more if need be on any problems, like wagging the motors, which is a technical term I think Jim coined for motors who's tail ends are allowed to wander around in circles ;-P  (I think it was compared to the actions that make a dogs nose brown ;-)

;-)

Mike W.

Marty Hewes
> Back to dual motors and monster torque, what kind of coupler is on
> the
> business end of White Zombie?  Has it been a problem?  

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Re: Motor coupler issues / was Looking for a Conversion Kit for a 1929 Ford.

Hi-Torque Electric

--- MIKE WILLMON <[hidden email]> wrote:

> White Zombie has a single solid shaft running
> through both armatures.  No keys or couplers to
> shear or slip, or welded flanges to worry about when
> removing it;  just one big long a$$ shaft.  The
> business end has a hardened (I think)
 
Hey Mike, all

Probably should make a new thread here if it continues
lol.  Poor 1929 guy got hijacked 8^o

I really don't know what Keith used for materials to
be honest (trade secret probably, lol)  You ask him
and he'll tell you it's "starchy"  I call it having
boing 8^)
I have heard the term "magnetic stainless" though I
can't remember from who or if such a stainless exists
so no laughing 8^P  What ever it is it isn't hardened.
In fact if it were I probably wouldn't have the
rubbing but it would have stood a higher chance of
snapping.  Nice catch 22 huh 8^)

John could stand to have something like the TransWarp
tranny bushing to externally help hold the shaft nice
and true.  Even Tim was saying last race when we
talked about it that the slip yoke isn't to tight a
fit and there is that little bit of slop, which it
needs.  In my minds eye this aspect could be improved
and could at least contribute to a vibration problem.

I believe John is having vibration issues but they've
changed and went away and come back (correct me if I'm
wrong here John).  The change to Siamese happened
right after John did the 12.99 run (again correct if
wrong) and now with a 11.47 at 115 MPH I didn't see
Tim freaking out about vibation, actually it was about
stuck throttles 8^o, well actually Tim doesn't freak
out about anything 8^)  Wayland was the one freaking
out 8^o  It may have been excitment that they had
broke something though, hard to tell 8^P

>From what little I've heard it's not a completely
bottled genie.  As far as drivelines and angles go I'm
sure that Tim and John are aware of this as both are
top end mechanics and race freaks 8^)  Tim isn't just
the driver!

Anyway the motor's pretty well documented and can all
be seen at John's site.  It ain't perfect but I'm
thinking it beat his old keyed shaft 8^)
 
http://photos.plasmaboyracing.com/buildsequence


> I'll let Jim elaborate more if need be on any
> problems, like wagging the motors, which is a
> technical term I think Jim coined for motors who's
> tail ends are allowed to wander around in circles
> ;-P  (I think it was compared to the actions that
> make a dogs nose brown ;-)


Okay here's my take on this.  I've seen motors that
are mounted by just the drive end and just let the
rest of the motor hang off, no problem really as
that's the torque end.  Now picture mounting the motor
via just the comm plate and going direct drive from
there.  I just think you could ask more from the DE
mounted one.  

Another thought is I didn't design it to be hung, as
there are just 8 little itty bitty 1/4" X 20 bolts
that hold that side to the other side, plus the two
7/16th bolts that the flang is bolted to which mount
and help hold the halves together.  Now call me
paranoid but that freaks me out a little bit!  

Hey Mike let's test this, how bout you leave those
last two bolts out of those holes I put in and see
where it gets ya, LMAO!

Anyway for those who want to know about the Siamese 8
it's all there at Johns site.

Cya
Jim Husted
Hi-Torque Electric



      ____________________________________________________________________________________
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Re: Motor coupler issues

Jeff Shanab
In reply to this post by Hi-Torque Electric
Please keep in mind that launching a 4000lb beast at 1/2G (paltry) is
the same amount of torque at the motor as launching a 2000lb dragster at
1G(slow dragster, but you get the point)

F=MA: 4000lb*16ft/sec  = 2000lb*32ft/sec

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Re: Motor coupler issues

Eduardo K.
In reply to this post by Hi-Torque Electric
--- Tim Humphrey <[hidden email]> wrote:

> Here's an area I know nothing about....
>
> Will there really be 500ftlbs on the coupler
> BETWEEEN the motors?
>
> If one arm is producing 500 ft-lbs AND the other arm
> is producing 500 ft-lbs, the coupler will see ZERO
> won't it?


If both motors are identical, wired exactly the same and connected
in series:

The coupler between the transmission and the first motor will see 1000ft/l
The coupler between the motors will see 500ft/l



--
Eduardo K.            |
http://www.carfun.cl  | Freedom's just another word
http://ev.nn.cl       | for nothing left to lose.
                      |    

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Re: Motor coupler issues

Marty Hewes
In reply to this post by Jeff Shanab
Do you suppose motor coupler failures are more common on cars without a
trans?  With an overall gear reduction of 10 to 1 in first gear (trans and
axle), the motor will only see 10% of the torque the axles see (compared to
roughly 33% of it with only an axle).  I won't attempt to figure out what
the maximum torque would be at the axle before the tire spins, but only 10%
of it would get back to the coupler in this case.  I suppose once you hit 1
to 1 in the trans, you'd be back to the roughly 33% number, but how many of
us will be producing full motor current and torque once the motor RPMs are
coming up?  Sounds like if you are running a trans, attempting to pass a
truck on the freeway in top gear is where the coupler is heavily loaded, not
during a tire smoking launch in first.  Am I on track here?

Marty

----- Original Message -----
From: "Jeff Shanab" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, August 11, 2007 10:11 AM
Subject: Re: [EVDL] Motor coupler issues


> Please keep in mind that launching a 4000lb beast at 1/2G (paltry) is
> the same amount of torque at the motor as launching a 2000lb dragster at
> 1G(slow dragster, but you get the point)
>
> F=MA: 4000lb*16ft/sec  = 2000lb*32ft/sec
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>


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Re: Motor coupler issues

George Swartz
The motor armature and associated drivetrain constitute a second order
ocillatory mechanical system.  The armature has a high moment of inertia and
is coupled via a "spring" which is the drive train.  Any step applications
of torque will cause torque overshoot, up to a doubling of the intended
torque.  This factor has always caused high stresses in electric motor
propulsion and has led to surprise failures of couplings, drive shafts,
motor mounts, etc, when this is overlooked.  

You may say that step torque applications don't occur in well designed
electric propulsion, but spinning tires on a crosswalk stipe, and then
hitting good pavement is an example.  

Also, drive train components do not necessarily break right away, but can
fatigue slowly and weaken, eventually breaking.








On Sat, 11 Aug 2007 11:02:17 -0500, Marty Hewes wrote

> Do you suppose motor coupler failures are more common on cars
> without a trans?  With an overall gear reduction of 10 to 1 in first
> gear (trans and axle), the motor will only see 10% of the torque the
> axles see (compared to roughly 33% of it with only an axle).  I
> won't attempt to figure out what the maximum torque would be at the
> axle before the tire spins, but only 10% of it would get back to the
> coupler in this case.  I suppose once you hit 1 to 1 in the trans,
> you'd be back to the roughly 33% number, but how many of us will be
> producing full motor current and torque once the motor RPMs are
> coming up?  Sounds like if you are running a trans, attempting to
> pass a truck on the freeway in top gear is where the coupler is
> heavily loaded, not during a tire smoking launch in first.  Am I on
> track here?
>
> Marty
>
> ----- Original Message -----
> From: "Jeff Shanab" <[hidden email]>
> To: <[hidden email]>
> Sent: Saturday, August 11, 2007 10:11 AM
> Subject: Re: [EVDL] Motor coupler issues
>
> > Please keep in mind that launching a 4000lb beast at 1/2G (paltry) is
> > the same amount of torque at the motor as launching a 2000lb dragster at
> > 1G(slow dragster, but you get the point)
> >
> > F=MA: 4000lb*16ft/sec  = 2000lb*32ft/sec
> >
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> >
> >
>
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Re: Motor coupler issues

Marty Hewes
Interesting.  So what you're saying is that due to elasticity in the drive
system, the drivetrain can wind up, resulting in maybe twice the normal
torque load if, for example, the tires slip, then stick?  Seems to make
sense logically.  How does this impact the idea of using a rubber donut in
the driveshaft, or a spring equipped clutch hub, or even higher profile
tires to absorb shocks?  Sounds like it may actually make the torque peaks
higher by maybe reducing resonant frequency and allowing more wind-up
amplitude, or does it just change the frequency of oscillation?  Would
increasing frequency or stiffness push the shock energy back to the contact
patch and battery instead of storing and releasing it, or does the shock
wave do a fixed end reflection when it hits the momentum of the armature and
oscillate until something dampens it out anyway?  What is the implication to
the drivetrain design?  I suppose the answer is complex.

Marty
----- Original Message -----
From: "George Swartz" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Sent: Saturday, August 11, 2007 11:29 AM
Subject: Re: [EVDL] Motor coupler issues


> The motor armature and associated drivetrain constitute a second order
> ocillatory mechanical system.  The armature has a high moment of inertia
> and
> is coupled via a "spring" which is the drive train.  Any step applications
> of torque will cause torque overshoot, up to a doubling of the intended
> torque.  This factor has always caused high stresses in electric motor
> propulsion and has led to surprise failures of couplings, drive shafts,
> motor mounts, etc, when this is overlooked.
>
> You may say that step torque applications don't occur in well designed
> electric propulsion, but spinning tires on a crosswalk stipe, and then
> hitting good pavement is an example.
>
> Also, drive train components do not necessarily break right away, but can
> fatigue slowly and weaken, eventually breaking.


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