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Packard R11 overdrive and Kick down switch question
Just can't stay away
Joined:
2013/6/23 14:44
From Doylestown, Pa. USA
Posts: 63
Could someone please explain how the kick down circuit works? It looks like the kick down switch on the throttle grounds the ignition coil which should kill the ignition altogether.
So by eliminating the ignition, how does this facilitate the drop down from overdrive to the normal drive ratio?
This is done so that you can change from overdrive to a lower gear ratio to allow for higher RPMs for passing or accelerating up hills.

I don't see how grounding out the ignition coil and eliminating the distributor gets the car to downshift out of overdrive.

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jpg  Packard overdrive wiring diagram R11 overdrive.jpg (757.84 KB)
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Posted on: 6/28 18:19:55
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Re: Packard R11 overdrive and Kick down switch question
Forum Ambassador
Joined:
2007/4/20 17:54
From Fresno CA
Posts: 15129
You are correct in that the kickdown action could kill the engine but due to a sequence of operation and close timing between various contacts the ign is only shorted a very brief time.

When the OD completely engages the solenoid plunger extends the pawl into the sun gear and by that action the cutout contacts inside the solenoid close. Ground is then present at one of the terminals on the kickdown switch but that set of contacts in the switch is open so ground goes no farther.

When kickdown is desired and the accelerator is pushed all the way to the floor the kickdown switch does two things. When the plunger in the switch starts to move the first set of contacts near the plunger open to drop out the relay and by that action, the solenoid loses power. With the continued movement of the accelerator and plunger, a brief moment after the relay and solenoid lose power the second set of contacts in the kickdown switch close and the ground passes thru the kickdown switch to the coil terminal and shorts out the distributor pulses.

When the ignition quits, almost instantly the engine loses power. By losing engine power the torque or pressure the sun gear is exerting on the pawl is relaxed and with the solenoid off, the spring inside the solenoid can retract the plunger and pawl. As soon as the plunger moves back into the solenoid the closed cutout contacts open and ground is removed from the kickdown switch and ultimately the coil so engine starts to run again. You are also out of OD because the pawl is no longer holding the sun gear. The entire sequence only takes a few milliseconds to complete so the engine never has a chance to stop rotating and die before the spark is established again.

If there is a mechanical problem and the solenoid takes too long to retract, conceivably the ign would be shorted long enough for the engine to die. As a second protection, if the engine starts to die instinct would have the operator working the accelerator. As soon as the accelerator is relaxed and moves away from the floor the cutout contacts in the kickdown switch would open also removing the ground to the coil and the engine would stay running.

In the kickdown sequence, once the reason for kickdown is over such as needing more power when passing a car, if the car is still moving above the governor cut in speed the OD will also be ready to re-engage when the accelerator is released. If OD is not desired again it will be necessary to lock OD out via the knob on the dash.

Posted on: 6/28 19:18:06
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Re: Packard R11 overdrive and Kick down switch question
Home away from home
Joined:
2008/9/29 7:39
From Cordova, TN
Posts: 936
Here's a short video someone made showing how his overdrive works.

https://www.youtube.com/watch?v=hVFiRkkvask

Wes

Posted on: 6/29 0:59:49
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Re: Packard R11 overdrive and Kick down switch question
Home away from home
Joined:
2014/7/15 11:30
From Terrebonne, OR
Posts: 1154
I had something go wrong with the kick down system on my 1952 Henney-Packard that maintained the coilís short so on the highway when I floored it a bit too long to pass someone, when I released the gas pedal and the coil reactivated, I blew out the seam on the nearly-new muffler from end to end when all the fuel still going into the cylinders ignited! Point is to be careful when testing that it actually is releasing momentarily.

Posted on: 6/29 17:56:14
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Re: Packard R11 overdrive and Kick down switch question
Just can't stay away
Joined:
2013/6/23 14:44
From Doylestown, Pa. USA
Posts: 63
Good explanation! Thank you!

Posted on: 6/29 18:10:18
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