I can see that you remember at least some of your high school or college
physics courses. You are right, in that the wheel that is not turning, is
not getting or dissipating any power. However, if you could magically look
inside the differential while this is happening, you would see that the
stopped side is in fact using some power, by virtue of gears and internal
friction, which I mentioned earlier. In the case where you are stuck, the
torque on both wheels is roughly the same. Torque is similar to pressure or
mechanical force, while power is the energy dissipated by something that is
subject to torque, and moving. You have to be moving, against some
resistance, in order to be dissipating mechanical power.

In the stuck and wheel spinning case, so little energy is being dissipated,
that friction plays a bigger part, as I mentioned earlier. If you could
measure the torque or the power, you would then find that they are not
equal, but pretty darn close. Strictly speaking, you are right, and your
boss is wrong. The wheel that is not turning, has no power applied. It
does have some torque on it, enough to balance the torque on the spinning
wheel. And there is some power being applied on that side, enough to spin
the gears against internal resistance. So maybe you are both right.

Confused yet? I hope so. I certainly don't want to have to format the
equations in ASCII!

Earle

"FrankW" <fworm@mxznorpak.ca> wrote in message
news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
> > They both get equal 'power' Jeff. The spinning wheel just needs very
> > little power to spin, so the stopped wheel also gets the same very
> > little power.
> >
> > It 'acts' like you state though.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Jeff Strickland wrote:
> >
> >>You're both right.
> >>
> >>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
then
> >>it gets all of the power.
> >>
> >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> >>
> >>>Anyone have any links (Bill?) that describe exactly
> >>>how the power is applied to the rear wheels on
> >>>a open differential?
> >>>I'm having a disagreement with one of our
> >>>software engineers. I say the power is applied
> >>>to one wheel only. He says otherwise.
> >>>Maybe we're both wrong.
> >>>Thanks in advance
> >>>Cheers
> >>>Frank
> >>>
>
>

 

I can see that you remember at least some of your high school or college
physics courses. You are right, in that the wheel that is not turning, is
not getting or dissipating any power. However, if you could magically look
inside the differential while this is happening, you would see that the
stopped side is in fact using some power, by virtue of gears and internal
friction, which I mentioned earlier. In the case where you are stuck, the
torque on both wheels is roughly the same. Torque is similar to pressure or
mechanical force, while power is the energy dissipated by something that is
subject to torque, and moving. You have to be moving, against some
resistance, in order to be dissipating mechanical power.

In the stuck and wheel spinning case, so little energy is being dissipated,
that friction plays a bigger part, as I mentioned earlier. If you could
measure the torque or the power, you would then find that they are not
equal, but pretty darn close. Strictly speaking, you are right, and your
boss is wrong. The wheel that is not turning, has no power applied. It
does have some torque on it, enough to balance the torque on the spinning
wheel. And there is some power being applied on that side, enough to spin
the gears against internal resistance. So maybe you are both right.

Confused yet? I hope so. I certainly don't want to have to format the
equations in ASCII!

Earle

"FrankW" <fworm@mxznorpak.ca> wrote in message
news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
> > They both get equal 'power' Jeff. The spinning wheel just needs very
> > little power to spin, so the stopped wheel also gets the same very
> > little power.
> >
> > It 'acts' like you state though.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Jeff Strickland wrote:
> >
> >>You're both right.
> >>
> >>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
then
> >>it gets all of the power.
> >>
> >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> >>
> >>>Anyone have any links (Bill?) that describe exactly
> >>>how the power is applied to the rear wheels on
> >>>a open differential?
> >>>I'm having a disagreement with one of our
> >>>software engineers. I say the power is applied
> >>>to one wheel only. He says otherwise.
> >>>Maybe we're both wrong.
> >>>Thanks in advance
> >>>Cheers
> >>>Frank
> >>>
>
>

 

Figure for easy numbers that a wheel spinning on ice only needs 10 foot
lb of power or torque to break free and spin. You barely have to touch
the gas pedal to send that much power back.

That would mean the other side wheel is still only getting 10 foot lb.,
but it is on dirt so it just stays still. It would need 'say' 100 foot
lb. to break free and spin.

Now if you slam down on the brake pedal and mash the gas to the floor,
it tries to stop the wheel spinning so the power or torque needed to
compensate for the drag of the brake shoe goes up really high under full
throttle. Once the torque on the spinning wheel passes the 100 foot lb.
the stopped wheel needs to break free, away you go with both wheels
spinning and the engine just a roaring.

Come along on one of our winter runs and we can practice it. It works
neat.

Mike

FrankW wrote:
>
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
> > They both get equal 'power' Jeff. The spinning wheel just needs very
> > little power to spin, so the stopped wheel also gets the same very
> > little power.
> >
> > It 'acts' like you state though.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Jeff Strickland wrote:
> >
> >>You're both right.
> >>
> >>Power is applied eaually to both wheels UNTIL one wheel breaks loose, then
> >>it gets all of the power.
> >>
> >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> >>
> >>>Anyone have any links (Bill?) that describe exactly
> >>>how the power is applied to the rear wheels on
> >>>a open differential?
> >>>I'm having a disagreement with one of our
> >>>software engineers. I say the power is applied
> >>>to one wheel only. He says otherwise.
> >>>Maybe we're both wrong.
> >>>Thanks in advance
> >>>Cheers
> >>>Frank
> >>>

 

Figure for easy numbers that a wheel spinning on ice only needs 10 foot
lb of power or torque to break free and spin. You barely have to touch
the gas pedal to send that much power back.

That would mean the other side wheel is still only getting 10 foot lb.,
but it is on dirt so it just stays still. It would need 'say' 100 foot
lb. to break free and spin.

Now if you slam down on the brake pedal and mash the gas to the floor,
it tries to stop the wheel spinning so the power or torque needed to
compensate for the drag of the brake shoe goes up really high under full
throttle. Once the torque on the spinning wheel passes the 100 foot lb.
the stopped wheel needs to break free, away you go with both wheels
spinning and the engine just a roaring.

Come along on one of our winter runs and we can practice it. It works
neat.

Mike

FrankW wrote:
>
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
> > They both get equal 'power' Jeff. The spinning wheel just needs very
> > little power to spin, so the stopped wheel also gets the same very
> > little power.
> >
> > It 'acts' like you state though.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Jeff Strickland wrote:
> >
> >>You're both right.
> >>
> >>Power is applied eaually to both wheels UNTIL one wheel breaks loose, then
> >>it gets all of the power.
> >>
> >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> >>
> >>>Anyone have any links (Bill?) that describe exactly
> >>>how the power is applied to the rear wheels on
> >>>a open differential?
> >>>I'm having a disagreement with one of our
> >>>software engineers. I say the power is applied
> >>>to one wheel only. He says otherwise.
> >>>Maybe we're both wrong.
> >>>Thanks in advance
> >>>Cheers
> >>>Frank
> >>>

 

Figure for easy numbers that a wheel spinning on ice only needs 10 foot
lb of power or torque to break free and spin. You barely have to touch
the gas pedal to send that much power back.

That would mean the other side wheel is still only getting 10 foot lb.,
but it is on dirt so it just stays still. It would need 'say' 100 foot
lb. to break free and spin.

Now if you slam down on the brake pedal and mash the gas to the floor,
it tries to stop the wheel spinning so the power or torque needed to
compensate for the drag of the brake shoe goes up really high under full
throttle. Once the torque on the spinning wheel passes the 100 foot lb.
the stopped wheel needs to break free, away you go with both wheels
spinning and the engine just a roaring.

Come along on one of our winter runs and we can practice it. It works
neat.

Mike

FrankW wrote:
>
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
> > They both get equal 'power' Jeff. The spinning wheel just needs very
> > little power to spin, so the stopped wheel also gets the same very
> > little power.
> >
> > It 'acts' like you state though.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Jeff Strickland wrote:
> >
> >>You're both right.
> >>
> >>Power is applied eaually to both wheels UNTIL one wheel breaks loose, then
> >>it gets all of the power.
> >>
> >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> >>
> >>>Anyone have any links (Bill?) that describe exactly
> >>>how the power is applied to the rear wheels on
> >>>a open differential?
> >>>I'm having a disagreement with one of our
> >>>software engineers. I say the power is applied
> >>>to one wheel only. He says otherwise.
> >>>Maybe we're both wrong.
> >>>Thanks in advance
> >>>Cheers
> >>>Frank
> >>>

 

Because if it only takes 15 foot pounds of torque to spin a tire, then
that's all that gets delivered. The tire that has traction needs 20 foot
pounds of torque to move the vehicle, but the tire that is spinning can spin
with 15 foot pounds, so 20 foot pounds is never delivered to the tire that
has traction.

So, both tires get the same amount of power -- expressed as torque -- but
when one tire starts spinning uselessly then it get what is effectively all
of the torque, and the other tire gets nothing. Mike was saying that the
other tire doesn't really get nothing, but it dopesn't get what it needs to
move the vehicle, so it may as well get nothing.

Now, there is a strategy that the driver can employ that involves tapping
the brakes to change the power distribution and get the vehicle moving, but
the open diff left to its own devices will effectively deliver all of the
engine torque to both tires equally when both have traction, but to the tire
with the least traction if traction is compromised.




"FrankW" <fworm@mxznorpak.ca> wrote in message
news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
>> They both get equal 'power' Jeff. The spinning wheel just needs very
>> little power to spin, so the stopped wheel also gets the same very
>> little power.
>>
>> It 'acts' like you state though.
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>>
>> Jeff Strickland wrote:
>>
>>>You're both right.
>>>
>>>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
>>>then
>>>it gets all of the power.
>>>
>>>"FrankW" <fworm@mxznorpak.ca> wrote in message
>>>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
>>>
>>>>Anyone have any links (Bill?) that describe exactly
>>>>how the power is applied to the rear wheels on
>>>>a open differential?
>>>>I'm having a disagreement with one of our
>>>>software engineers. I say the power is applied
>>>>to one wheel only. He says otherwise.
>>>>Maybe we're both wrong.
>>>>Thanks in advance
>>>>Cheers
>>>>Frank
>>>>
>

 

Because if it only takes 15 foot pounds of torque to spin a tire, then
that's all that gets delivered. The tire that has traction needs 20 foot
pounds of torque to move the vehicle, but the tire that is spinning can spin
with 15 foot pounds, so 20 foot pounds is never delivered to the tire that
has traction.

So, both tires get the same amount of power -- expressed as torque -- but
when one tire starts spinning uselessly then it get what is effectively all
of the torque, and the other tire gets nothing. Mike was saying that the
other tire doesn't really get nothing, but it dopesn't get what it needs to
move the vehicle, so it may as well get nothing.

Now, there is a strategy that the driver can employ that involves tapping
the brakes to change the power distribution and get the vehicle moving, but
the open diff left to its own devices will effectively deliver all of the
engine torque to both tires equally when both have traction, but to the tire
with the least traction if traction is compromised.




"FrankW" <fworm@mxznorpak.ca> wrote in message
news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
>> They both get equal 'power' Jeff. The spinning wheel just needs very
>> little power to spin, so the stopped wheel also gets the same very
>> little power.
>>
>> It 'acts' like you state though.
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>>
>> Jeff Strickland wrote:
>>
>>>You're both right.
>>>
>>>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
>>>then
>>>it gets all of the power.
>>>
>>>"FrankW" <fworm@mxznorpak.ca> wrote in message
>>>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
>>>
>>>>Anyone have any links (Bill?) that describe exactly
>>>>how the power is applied to the rear wheels on
>>>>a open differential?
>>>>I'm having a disagreement with one of our
>>>>software engineers. I say the power is applied
>>>>to one wheel only. He says otherwise.
>>>>Maybe we're both wrong.
>>>>Thanks in advance
>>>>Cheers
>>>>Frank
>>>>
>

 

Because if it only takes 15 foot pounds of torque to spin a tire, then
that's all that gets delivered. The tire that has traction needs 20 foot
pounds of torque to move the vehicle, but the tire that is spinning can spin
with 15 foot pounds, so 20 foot pounds is never delivered to the tire that
has traction.

So, both tires get the same amount of power -- expressed as torque -- but
when one tire starts spinning uselessly then it get what is effectively all
of the torque, and the other tire gets nothing. Mike was saying that the
other tire doesn't really get nothing, but it dopesn't get what it needs to
move the vehicle, so it may as well get nothing.

Now, there is a strategy that the driver can employ that involves tapping
the brakes to change the power distribution and get the vehicle moving, but
the open diff left to its own devices will effectively deliver all of the
engine torque to both tires equally when both have traction, but to the tire
with the least traction if traction is compromised.




"FrankW" <fworm@mxznorpak.ca> wrote in message
news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> That's the part that gets confusing.
> How can one wheel have power if it's not turning at all
> while the other wheel is spinning?
>
> Mike Romain wrote:
>> They both get equal 'power' Jeff. The spinning wheel just needs very
>> little power to spin, so the stopped wheel also gets the same very
>> little power.
>>
>> It 'acts' like you state though.
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>>
>> Jeff Strickland wrote:
>>
>>>You're both right.
>>>
>>>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
>>>then
>>>it gets all of the power.
>>>
>>>"FrankW" <fworm@mxznorpak.ca> wrote in message
>>>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
>>>
>>>>Anyone have any links (Bill?) that describe exactly
>>>>how the power is applied to the rear wheels on
>>>>a open differential?
>>>>I'm having a disagreement with one of our
>>>>software engineers. I say the power is applied
>>>>to one wheel only. He says otherwise.
>>>>Maybe we're both wrong.
>>>>Thanks in advance
>>>>Cheers
>>>>Frank
>>>>
>

 

Hi Earle,
You may remember the old rear wheel drive cars, just spun the right
rear, that's because the engine torque twisted the left rear against the
ground like a lever, then lifted the right rear to lose traction. The
two to one differential action means about a quarter of the power goes
to the slipping tire, but then it doesn't have any traction, so it can't
even hold that, so we brake it.
If you want both tires to turn make a Lincoln locker:
http://----------.com/differential.htm
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Earle Horton wrote:
>
> I can see that you remember at least some of your high school or college
> physics courses. You are right, in that the wheel that is not turning, is
> not getting or dissipating any power. However, if you could magically look
> inside the differential while this is happening, you would see that the
> stopped side is in fact using some power, by virtue of gears and internal
> friction, which I mentioned earlier. In the case where you are stuck, the
> torque on both wheels is roughly the same. Torque is similar to pressure or
> mechanical force, while power is the energy dissipated by something that is
> subject to torque, and moving. You have to be moving, against some
> resistance, in order to be dissipating mechanical power.
>
> In the stuck and wheel spinning case, so little energy is being dissipated,
> that friction plays a bigger part, as I mentioned earlier. If you could
> measure the torque or the power, you would then find that they are not
> equal, but pretty darn close. Strictly speaking, you are right, and your
> boss is wrong. The wheel that is not turning, has no power applied. It
> does have some torque on it, enough to balance the torque on the spinning
> wheel. And there is some power being applied on that side, enough to spin
> the gears against internal resistance. So maybe you are both right.
>
> Confused yet? I hope so. I certainly don't want to have to format the
> equations in ASCII!
>
> Earle
>
> "FrankW" <fworm@mxznorpak.ca> wrote in message
> news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> > That's the part that gets confusing.
> > How can one wheel have power if it's not turning at all
> > while the other wheel is spinning?
> >
> > Mike Romain wrote:
> > > They both get equal 'power' Jeff. The spinning wheel just needs very
> > > little power to spin, so the stopped wheel also gets the same very
> > > little power.
> > >
> > > It 'acts' like you state though.
> > >
> > > Mike
> > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > > 88 Cherokee 235 BFG AT's
> > >
> > > Jeff Strickland wrote:
> > >
> > >>You're both right.
> > >>
> > >>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
> then
> > >>it gets all of the power.
> > >>
> > >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> > >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> > >>
> > >>>Anyone have any links (Bill?) that describe exactly
> > >>>how the power is applied to the rear wheels on
> > >>>a open differential?
> > >>>I'm having a disagreement with one of our
> > >>>software engineers. I say the power is applied
> > >>>to one wheel only. He says otherwise.
> > >>>Maybe we're both wrong.
> > >>>Thanks in advance
> > >>>Cheers
> > >>>Frank
> > >>>
> >
> >

 

Hi Earle,
You may remember the old rear wheel drive cars, just spun the right
rear, that's because the engine torque twisted the left rear against the
ground like a lever, then lifted the right rear to lose traction. The
two to one differential action means about a quarter of the power goes
to the slipping tire, but then it doesn't have any traction, so it can't
even hold that, so we brake it.
If you want both tires to turn make a Lincoln locker:
http://----------.com/differential.htm
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

Earle Horton wrote:
>
> I can see that you remember at least some of your high school or college
> physics courses. You are right, in that the wheel that is not turning, is
> not getting or dissipating any power. However, if you could magically look
> inside the differential while this is happening, you would see that the
> stopped side is in fact using some power, by virtue of gears and internal
> friction, which I mentioned earlier. In the case where you are stuck, the
> torque on both wheels is roughly the same. Torque is similar to pressure or
> mechanical force, while power is the energy dissipated by something that is
> subject to torque, and moving. You have to be moving, against some
> resistance, in order to be dissipating mechanical power.
>
> In the stuck and wheel spinning case, so little energy is being dissipated,
> that friction plays a bigger part, as I mentioned earlier. If you could
> measure the torque or the power, you would then find that they are not
> equal, but pretty darn close. Strictly speaking, you are right, and your
> boss is wrong. The wheel that is not turning, has no power applied. It
> does have some torque on it, enough to balance the torque on the spinning
> wheel. And there is some power being applied on that side, enough to spin
> the gears against internal resistance. So maybe you are both right.
>
> Confused yet? I hope so. I certainly don't want to have to format the
> equations in ASCII!
>
> Earle
>
> "FrankW" <fworm@mxznorpak.ca> wrote in message
> news:ev-dnfzRMMZ-vNnenZ2dnUVZ_s-dnZ2d@magma.ca...
> > That's the part that gets confusing.
> > How can one wheel have power if it's not turning at all
> > while the other wheel is spinning?
> >
> > Mike Romain wrote:
> > > They both get equal 'power' Jeff. The spinning wheel just needs very
> > > little power to spin, so the stopped wheel also gets the same very
> > > little power.
> > >
> > > It 'acts' like you state though.
> > >
> > > Mike
> > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > > 88 Cherokee 235 BFG AT's
> > >
> > > Jeff Strickland wrote:
> > >
> > >>You're both right.
> > >>
> > >>Power is applied eaually to both wheels UNTIL one wheel breaks loose,
> then
> > >>it gets all of the power.
> > >>
> > >>"FrankW" <fworm@mxznorpak.ca> wrote in message
> > >>news:Raydnbe9F_r_Yt7eRVn-pw@magma.ca...
> > >>
> > >>>Anyone have any links (Bill?) that describe exactly
> > >>>how the power is applied to the rear wheels on
> > >>>a open differential?
> > >>>I'm having a disagreement with one of our
> > >>>software engineers. I say the power is applied
> > >>>to one wheel only. He says otherwise.
> > >>>Maybe we're both wrong.
> > >>>Thanks in advance
> > >>>Cheers
> > >>>Frank
> > >>>
> >
> >