Preventing Induction While Towing

[Baheej]

We have a permanent magnet AC motor on a vehicle. When the vehicle is being towed, the motor might induct current. Is there is a way to prevent this from happening without disengaging the mechanical connection between the wheels and the motor? Thanks.

 

[l3city]

"the motor might induct current"...to where. How about providing a means to disconnect the motor (i.e disconnect switch) while not in use. I guess this is simple, and will prevent the motor to have any influence in other equipment in the car.
Regards

 

[IRstuff]

That's why tow trucks lift one end of the car.

TTFN

 

[Baheej]

l3city: that might be an option. May be I should throw that at the Motor supplier or account for it in our system.
IRstuff: that would be perfect, but we cannot do that on that vehicle. Regards.

 

[sreid]

Put a three pole switch in the motor leads between the motor and the drive. Open the switch when you want to tow. Opening the motor leads keeps the motor BEMF from charging the drive power supply.

 

[Baheej]

Thank you all for responding.

 

[CWMeyer]

I'm coming across this a bit late. I'm in process of designing a special machine for the loading and unloading of disabled passengers from airplanes, and the machine drives at about 3.5 mph, while needs to be towed at 20 mph. I was planning on using hydraulic drive that consists of a motor, brake, and planetary gear. The gear has a lockout feature that allows towing that doesn't turn the motor.

The gears do turn however. I'd like to find a drive motor or planetary gear that allow for some sort of free wheeling that doesn't turn the inner workings. The possibility of using an electric drive is there too, if I can find one that meets my needs.

Anyone using an electric drive or hydraulic drive motor or planetary gear that allow free wheeling without turning internal mechanisms?

 

[waross]

I would look at a planetary drive. Both the Model "T" Ford, and Buicks in the mid 50's used a planetary transmission. The Ford used pedals to apply brakes and bands, and to release clutches. The Buick used hydraulics to accomplish the same task. The arrangement can be arranged to freewheel. Low gear may be engaged by holding a ring gear stationary. This may be acomplished either with a brake or with a mechanical dog. The Ford had a drum which turned with the output. This had the service brake band on it.
The Buick had a similar component which was toothed. A dog engaged the teeth to provide the parking brake function.

respectfully

 

[itsmoked]

CWMeyer; you should've started your own thread.. This is called 'hijacking' and causes some confusion.

You should consider an electric drive for your machine that turns off, (opens a contactor), to the motor when the throttle pedal it lifted. Then the motor is essentially disconnected and you can tow it with no mechanical load except for the fan in the motor. Would be a bunch easier then some mechanical disconnect. Furthermore I can guarantee that you will have a lot of cases of your machine being towed without being mechanically disconnected by some lamoid. I see that occur in all industries, most of which aren't as hectic as aviation. I have seen rail cars dragged miles without their brakes released, cars towed in gear, etc , etc.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com