FEH vehicle recovery
#11
04-12-2009, 03:22 AM
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Join Date: Mar 2005
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Re: FEH vehicle recovery
Please also see this thread:
https://www.greenhybrid.com/discuss/...trailer-21463/
Which is another illustration that shows the correctness of Bill's posts, and the error with GaryG's.
( The FEH is not good for pulling out "stuck" vehicles, and is unlike any other regular vehicle. )
https://www.greenhybrid.com/discuss/...trailer-21463/
Which is another illustration that shows the correctness of Bill's posts, and the error with GaryG's.
( The FEH is not good for pulling out "stuck" vehicles, and is unlike any other regular vehicle. )
#12
04-12-2009, 09:39 AM
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Join Date: Sep 2006
Location: Beautiful Pacific NW
Posts: 1,678
Re: Synchronous Machines
Just realized that there is another issue with the FEH & getting someone out of snow & ice.
The two machines in the transaxle are synchronous machines with a powerful permanent magnet type rotating element. If the stators rotating field gets ahead of the rotor and the torque angle exceeds a large enough angle the output of the motor goes to zero.
Once this slip has begun you cannot recover it unless the rotor also has induction windings built in. Don't know if Ford put these in.
My thoughts are that Ford designed the controller that creates the rotating field for the stator so that it would shut down if slip is approached or detected since what happens then is very large currents are drawn by the motor. Since the power source is a battery these currents could get very large, very quickly.
The inherent characteristics of these motors call for some motion in order to begin pulling hard. The torque speed curve for a synchronous machine (without induction windings) shows virtually zero starting torque. Once things are moving it is capable of very large torque.
The two machines in the transaxle are synchronous machines with a powerful permanent magnet type rotating element. If the stators rotating field gets ahead of the rotor and the torque angle exceeds a large enough angle the output of the motor goes to zero.
Once this slip has begun you cannot recover it unless the rotor also has induction windings built in. Don't know if Ford put these in.
My thoughts are that Ford designed the controller that creates the rotating field for the stator so that it would shut down if slip is approached or detected since what happens then is very large currents are drawn by the motor. Since the power source is a battery these currents could get very large, very quickly.
The inherent characteristics of these motors call for some motion in order to begin pulling hard. The torque speed curve for a synchronous machine (without induction windings) shows virtually zero starting torque. Once things are moving it is capable of very large torque.
No, the rotor weight/inertia is kept to an absolute minimum. The low startup torque comes almost purely from electromagnetic forces.
And yes, these are permanent magnet rotor multi-phase AC synchronous motors. But I would bet a goodly amount that they have an integral position feedback so the "rotating" AC field does not rotate from phase to phase unless the rotor is following.
#13
04-12-2009, 09:49 AM
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Join Date: Sep 2006
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Re: FEH vehicle recovery
Folks out in Wyoming (where I spend some winter time) usually do not try to pull someone stuck in the snow starting with a taut line, they always allow some, but not too much, slack to start the stuck guy with a bit of a jerk to get it out of any ruts it might have dug into.
So in pulling someone out with a hybrid, you could use that to get the electric motors going and avoid the stall/torque problem of the computer controller.
With regard to the Ford Roll Stability Control (RSC) in the 09:
My 01 Mustang has Traction Control (TC) with an on/off switch. I found by experience that I had to turn it off when stuck in ice & snow or I'd never get out.
What I believe is going on is that with TC on, the system prevents the locking rear axle from kicking into the lock mode. Thus one wheel can spin (against the brake as TC applies brake pressure to reduce its spin) and the wheel with more traction doesn't ever get power because the difference in spin is not large enough to lock the axle.
Traction Control is not the same as RSC but with regard to wheel spin there may be a parallel. When I turn it off, the locking feature is so good as to get going on anything so long as the snow is not deep enough to seriously interfere with the undercarriage.
So in pulling someone out with a hybrid, you could use that to get the electric motors going and avoid the stall/torque problem of the computer controller.
With regard to the Ford Roll Stability Control (RSC) in the 09:
My 01 Mustang has Traction Control (TC) with an on/off switch. I found by experience that I had to turn it off when stuck in ice & snow or I'd never get out.
What I believe is going on is that with TC on, the system prevents the locking rear axle from kicking into the lock mode. Thus one wheel can spin (against the brake as TC applies brake pressure to reduce its spin) and the wheel with more traction doesn't ever get power because the difference in spin is not large enough to lock the axle.
Traction Control is not the same as RSC but with regard to wheel spin there may be a parallel. When I turn it off, the locking feature is so good as to get going on anything so long as the snow is not deep enough to seriously interfere with the undercarriage.
With FWD or F/awd TC has become a rather serious safety feature. Loss of "drive" traction on the front/driven wheels also means loss of directional control. So recovery from this condition must be as instantaneous as can be possible.
The sole, ONLY, use for TC "off" functionality is to be able to use wheelspin in order to "rock" the vehicle back and forth to get unstuck.
#14
04-12-2009, 09:14 PM
Re: FEH vehicle recovery
Please also see this thread:
https://www.greenhybrid.com/discuss/...trailer-21463/
Which is another illustration that shows the correctness of Bill's posts, and the error with GaryG's.
( The FEH is not good for pulling out "stuck" vehicles, and is unlike any other regular vehicle. )
https://www.greenhybrid.com/discuss/...trailer-21463/
Which is another illustration that shows the correctness of Bill's posts, and the error with GaryG's.
( The FEH is not good for pulling out "stuck" vehicles, and is unlike any other regular vehicle. )
Well, just to be truthful, I never thought anything you posted to be true!
GaryG
#15
04-13-2009, 12:08 AM
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Join Date: Mar 2005
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Re: FEH vehicle recovery
Take everything GaryG says with a grain of salt, no, several.
Everyone who's been here more than a few days does.
He has very poor technical skills, and is notorious for posting false and misleading information. It's best to just ignore him!
Everyone who's been here more than a few days does.
He has very poor technical skills, and is notorious for posting false and misleading information. It's best to just ignore him!
#16
04-13-2009, 03:03 AM
Re: FEH vehicle recovery
Where I spend some serious winter time, in Wyoming, the snow gets to 5 to 6 feet. Roads get plowed and the plows do well... but getting stuck is simply a fact of life.
Most people get seriously stuck at least once or twice a season. I've been on the receiving end of a pull several times and learned by observation which techniques get someone out the fastest.
I have given a pull to people with my Suburban but just haven't had the opportunity to pull someone out with the FEH.
My long term plan is to mount a 2 or 3,000 lb winch on the front of the FEH. Pulling with a winch is always more powerful than trying to pull with wheels.
As for GaryG's remarks... he's approaching being #2 on my ignore list... right next to wwest.
Most people get seriously stuck at least once or twice a season. I've been on the receiving end of a pull several times and learned by observation which techniques get someone out the fastest.
I have given a pull to people with my Suburban but just haven't had the opportunity to pull someone out with the FEH.
My long term plan is to mount a 2 or 3,000 lb winch on the front of the FEH. Pulling with a winch is always more powerful than trying to pull with wheels.
As for GaryG's remarks... he's approaching being #2 on my ignore list... right next to wwest.
#17
04-13-2009, 03:19 AM
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Join Date: Mar 2005
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Re: FEH vehicle recovery
A winch is probably the safest way to go.
You can use it to free yourself, and others.
Gary has not tried half the things he posts about....
In Sunny, Flat, Florida.
You can use it to free yourself, and others.
Gary has not tried half the things he posts about....
In Sunny, Flat, Florida.
#18
04-13-2009, 03:27 AM
Re: FEH vehicle recovery
gpsman1:
Saw your line about sunny, flat, Florida.
You haven't seen glorious, wonderful sunlight until you see a clear, winter day, with the mountains covered with (5-10 feet) snow in Wyoming. Glorious, just glorious.
Of course, days like that typically get up to -20ºF on a good day!
Saw your line about sunny, flat, Florida.
You haven't seen glorious, wonderful sunlight until you see a clear, winter day, with the mountains covered with (5-10 feet) snow in Wyoming. Glorious, just glorious.
Of course, days like that typically get up to -20ºF on a good day!
#19
04-13-2009, 03:35 AM
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Join Date: Mar 2005
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Re: FEH vehicle recovery
Are you aware I live on the CO/WY border?
I know exactly what you mean, and I also know how the FEH behaves in some of the harshest and most demanding conditions.
I think the lowest temp. I've had to run her in was -19'F.
The hottest was 114'F in Las Vegas in July.
I've run the car at well over 12,000 feet elevation.
I've gone up some of the steepest trails CO has to offer, both on and off road. I've only towed over major roads and Interstates.
I know exactly what you mean, and I also know how the FEH behaves in some of the harshest and most demanding conditions.
I think the lowest temp. I've had to run her in was -19'F.
The hottest was 114'F in Las Vegas in July.
I've run the car at well over 12,000 feet elevation.
I've gone up some of the steepest trails CO has to offer, both on and off road. I've only towed over major roads and Interstates.
#20
04-13-2009, 05:24 AM
Re: FEH vehicle recovery
Where I spend some serious winter time, in Wyoming, the snow gets to 5 to 6 feet. Roads get plowed and the plows do well... but getting stuck is simply a fact of life.
Most people get seriously stuck at least once or twice a season. I've been on the receiving end of a pull several times and learned by observation which techniques get someone out the fastest.
I have given a pull to people with my Suburban but just haven't had the opportunity to pull someone out with the FEH.
My long term plan is to mount a 2 or 3,000 lb winch on the front of the FEH. Pulling with a winch is always more powerful than trying to pull with wheels.
As for GaryG's remarks... he's approaching being #2 on my ignore list... right next to wwest.
Most people get seriously stuck at least once or twice a season. I've been on the receiving end of a pull several times and learned by observation which techniques get someone out the fastest.
I have given a pull to people with my Suburban but just haven't had the opportunity to pull someone out with the FEH.
My long term plan is to mount a 2 or 3,000 lb winch on the front of the FEH. Pulling with a winch is always more powerful than trying to pull with wheels.
As for GaryG's remarks... he's approaching being #2 on my ignore list... right next to wwest.
GaryG
