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[Original50]

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[DEEPNHOCK]

The distributor interrupt part of the circuit is set so that when you actually shift into overdrive the ignition is interrupted
for a very small amount of time to 'unload' the torque applied against the transmission gears allowing the shift to be completed.
While there are several excellent treatises on overdrive operation out there on the web
(including the oft overlooked and under-read http://studebakerdriversclub.com/techtips.asp),
remember that all the electrical circuits on the overdrive are based on a good 'ground'.
The governor is just a path to 'ground', the distributor interrupt switch is just a path to 'ground'.
Most overdrive problems are generally a poor ground issue (even inside the O/D relay box).
It really is a fairly straightforward mechanism, without any black magic going on inside there...
Here is a great picture courtesy of Chuck Collins at

http://www.ncsdc.com/TechnicalPages/Overdrive/Overdrive.htm

Hope the info helps.
Jeff[8D]

quote:Originally posted by Original50


I have a 50 Champion with overdrive, and I have been trying to figure out how the overdrive solenoid works, to see if my solenoid can be tested. There are two terminals on the thing, with one terminal getting the current return path via the overdrive relay fuse which goes though the 20 amp fuse directly to the negative terminal of the battery. The other terminal on the solenoid is connected to the distributor terminal via the overdrive kickdown switch. It seems that somehow the distributor provides something to the solenoid when you punch down on the accellerator pedal. Can anyone give me a hint as to what the distributor has to do with the operation of the overdrive solenoid?

Don Dodson

DEEPNHOCK at Gmail.com
Brooklet, Georgia
'37 Coupe Express (never ending project)
'37 Coupe Express Trailer (project)
'61 Hawk (project)
http://community.webshots.com/user/deepnhock

[Original50]

That's a nice illustration, however it doesn't apply to my 50 Champion. Since my Studebaker is a positive ground car, I will explain what I see like this. Looking at the wiring schematic for my car, there is a terminal on the solenoid labeled #4 which goes to the O.D. Relay fuse, and from the other side of the fuse a wire goes to the negative side of the battery. That arrangement shows that there is a current path from the battery to terminal #4 of the solenoid, and since the solenoid has a connection to the positive side of the battery, the thing is energized ALL THE TIME. That says that there MUST be some controlling factor for the O.D. Solenoid to work. The thing can't be energized all the time, so I am looking at the terminal #6 on the O.D. Solenoid to be the controlling factor. Terminal #6 of the O.D. Solenoid goes to the O.D. Kickdown switch which provides a path to the distributor when the switch is transferred. So my original question is what does the distributor have to do with the operation of the solenoid? Does it provide a negative pulse to the OD solenoid or a postive pulse to the OD solenoid. Once I find out what terminal # 6 of the OD solenoid gets, then maybe I can check out my solenoid to see if the thing is any good. I can of course jimmy up 6 volts to the #4 terminal, but then I have to do something to term #6 to replicate what takes place with that terminal, and then watch the solenoid to see if the plunger does anything. Yes, I am an Electronics technician by trade.

Don Dodson

[Tom Bredehoft]

Difficulty reading, don't have wide screen. Comment on power all the time. Yes, No. 4 terminal is hot all the time, but there is an open pair of contacts right down stream from that terminal. When the governor reaches speed, it shorts to ground, allowing those contacts to close, THEN energizing the solenoid. At this point you let up on the gas and the solenoid pulls out the engagement pawl, allowing the OD to engage. When it engages, it opens the contact again, disconnecting the retraction coil, but leaving enough power in the coil to hold it back. When you slow down, or floor the gas, another set of points operated the solenoid in the opposite direction, driving the pawl in, locking out the OD function. I had to work this out on my '53, by logic, without benefit of Electronic education.

[img=left]http://www.alink.com/personal/tbredehoft/Bothcars.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe
'60 Lark VI
'05 Legacy Ltd Wagon
All three Indiana built OD cars

[Original50]

Thanks Tom! That was what I was looking for.

except for one thing.
That doesn't fit into why the distributor is connected to the second terminal of the OD solenoid. I studied your explanation and copied it so that I could read it by pasting it to an email addressed to my email address.
I'll just figure things out myself when I get the solenoid outta the car. That distributor connection is there for a reason, and from my thinking, the pulse from the distributor fits into the picture by providing a voltage to the solenoid designed on number of pulses required to engage the solenoid based on a average. It appears that the governor gets 6 volts presented to it via the OD Kickdown switch via the O.D relay.

[Tom Bredehoft]

The distributor connection is so that when you floor it, as the solenoid drives the pawl into the locking ring,the distributor is momentarily grounded, the engine quits (takes pressure off the ring) for an instant and allows the pawl to drop into it's pocket. And you're outa there like a scalded cat, full throttle in a lower gear.

[img=left]http://www.alink.com/personal/tbredehoft/Bothcars.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe
'60 Lark VI
'05 Legacy Ltd Wagon
All three Indiana built OD cars

[gordr]

Man! This thread is hard to read. Something set the page much wider than my browser window.

Don: the distributor sends NO pulses to the overdrive solenoid. When the overdrive is engaged, the solenoid receives power from the relay, which has been switched on by virtue of its coil having received a path to ground from the overdrive governor. The wiring diagram Jeff posted sorta shows this, but a schematic diagram is much better to explain the functionality of the parts. I think Randy Rundle's website has a pretty good explanation up.

Continuing, when the OD solenoid is engaged, the terminal that connects to the kickdown switch (#12) is grounded by a pair of contact points inside the solenoid. This does absolutely nothing unless the accelerator is depressed to the floor, in which case one pair of contacts in the KD switch closes the circuit between that grounded terminal on the solenoid and the ignition points. The other pair of contacts on the kickdown switch OPENS, and breaks the circuit between the OD relay and the governor. These actions happen simultaneously. The first action kills the engine's ignition; the cylinders don't fire, and that relieves torque on the driveline. The second de-energizes the solenoid, and the spring inside it pulls the OD pawl out of the blocker ring, effectively downshifting the unit from OD to direct drive. As the solenoid retracts to its rest position, it opens the grounding contacts to the kickdown switch, and the engine resumes operation, even if the pedal is still on the mat. The whole operation takes place in a fraction of a second.

The whole electrical system can be thought of as a set of binary logic units, some having manual inputs, and some having automated inputs, and this logic network performs actions that are hardwired into it. It is, in every sense of the word, a very rudimentary computer.

For what it's worth, the overdrive will operate without the kickdown circuit being connected; it'll come on when you reach the cut-in speed, and it will shut off when you drop below cut-out speed AND slack off the throttle. You could "kick it down" by momentarily switching off the ignition. A bare-bones overdrive circuit is simply the solenoid plus a toggle switch connected to the battery. Problem is, if you throw the swithc at the wrong time, parts could get damaged. All the additional circuitry is there to automate the process so that the overdrive shifts at the appropriate time.

If you are not sufficiently confused now, let me know, and I'll try harder next time.

By the way, you didn't say if your overdrive is working OK. If it is not working, the first place to look is the governor; frequently the contact points within it get oil-coated and don't pass current. It is easy to remove, disassemble, and clean.

Gord Richmond, within Weasel range of the Alberta Badlands

[Original50]

Thanks Gord ! Between you and Tom, I am beginning to see how this thing works. There are a lot of hidden things going on that the schematic doesn't show such as the electrical issues inside the relay, and the governor, and the solenoid.
I guess I'm just a person who delves into the unknown before I get there. The car is at my mechanics abode waiting for him to get started on her. He is an execellent mechanic, but I am trying to insure he has what he needs to do his part of the resto. He counts on me to get involved with the electrical in's and out's, and I enjoy a challenge. Being retired doesn't mean that I can sit down in the rocking chair. Gotta keep the shnoozel going.
Thanks agin, Yaw!

Don Dodson

[DEEPNHOCK]

The reason the page is so wide is the width of the picture...
Since it was just linked to off of Chuck Collin's web page, that is the default size.
Sorry...
I'll re-size the picture...
Jeff[8D]

quote:Originally posted by gordr

Man! This thread is hard to read. Something set the page much wider than my browser window.

[gordr]

Don't delete the picture, Jeff. It is certainly of some help. Looks like an early 12 volt overdrive; in later years they went to a 3-terminal solenoid and did away with the relay.

The '50 Stude OD will also have a reverse lockout switch mounted on the left side of the OD housing behind the OD lockout linkage. It is a simple 2-terminal switch connected between the governor and the rest of the circuitry. Other than provide a place to leak oil, it really has no function, and Studebaker eventually did away with it when they determined that nobody drove 27 mph in reverse anyway.

BTW, Don, the picture Jeff posted is called a "wiring diagram", not a schematic. A wiring diagram contains drawings of the actual components and the wiring harnesses used in an application, although the harnesses may be truncated for simplicity's sake. But every terminal point is clearly called out in a wiring diagram, and they can be used if someone hands you a box full of wires and parts and tells you to hook 'em up. In short, a wiring diagram depicts the actual physical connections of the wires, and has little to say about their function.

A schematic diagram, on the other hand, is a diagram of the circuit using conventional symbols for the components, and simple lines to indicate the wiring that links them. Tie points and plugs are usually not depicted, unless needed to clarify the function. Components on a schematic diagram are usually laid in such a way as to clarify the function of the circuit, and not necessarily as they are found in the vehicle. The purpose of the schematic diagram is to help you understand the function of each component in a circuit, and to trace the path of current flow. In the case of electrical problems, the schematic diagram can give you a clue as to what component may be at fault, and the wiring diagram then can be used to enable you to locate that component and its related connections on the car.

Gord Richmond, within Weasel range of the Alberta Badlands

[Original50]

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[gordr]

Sorry Don,

I saw the following in one of your posts: "Thanks Gord ! Between you and Tom, I am beginning to see how this thing works. There are a lot of hidden things going on that the schematic doesn't show such as the electrical issues inside the relay, and the governor, and the solenoid."

I guess what you typed wasn't quite what you meant, there. No problem, my computer does that, too.

Gord Richmond, within Weasel range of the Alberta Badlands

[Original50]

Well, I found out what the OD Kickdown switch does, or how it works. I went over to my mechanic today armed with a ohm meter and checked the OD kickdown switch. I even tore into the thing to see how it was made. It is a slider switch with a plunger on one end. With the car just sitting there, with nothing going on, the switch has normally closed points and normally open points. The NC points connects the distributor to pin 6 of the solenoid. The other pin on the solenoid has 6 volts on it all the time, so the solenoid looks at the distributor pulses all the time. From my experience with such matters, the solenoid will energize or do it's thing when enough pulses are felt by pin 6 to energize the solenoid. I know that distributor has pulses on it 'cause on my Charger, the tach is fed by
such an arrangement. They are negative pulses on the Charger, but I suppose they are positive on a postive ground car. I'll scope the thing when I get a chance, to see if they are 6 volt pulses or hotter ones. Anyway, those pulses are what tells the solenoid that the car can shift into the overdrive gear when the plunger works it's magic, once the voltage rises high enough to provide the controlling factor. The connection of the other terminal on the OD solenoid is simply a gate.
When you punch down on the accellerator, the OD Kickdown switch will transfer the slider to the other side of the switch, and that will provide 6 volts from the governor through the Transmission lockout switch , along wire labeled K, through the OD kickdown switch to the OD relay, and the relay will energize or transfer. Now I need to tear into a OD relay to see how that thing is made. And I also need to check the Transmission lock-out switch to see what is going on there. I tried to remove the Trannie lockout switch today, and when I got here loose, oil started running outta the transmission, so I put the switch back in real fast to keep from making a bigger mess.
Electro-Mechanical devices? Yep one needs a schematic to unnerstand the goings on of a circuit with such things. Too many hidden factors. I guess that is one of the reasons that IBM had schools for all of their machines, soz we could understand the workings of the mechanics in relation to the electrical. I'll get her figured out, yaw can count on that.

Don Dodson

[Dick Steinkamp]

quote:Originally posted by Original50
Gord, I don't think that was necessary.

Don,
I'm sure you well know the difference between a schematic and a wiring diagram and just made a simple mistake in your post.

I didn't know the difference, and Gord's explanation was very helpful to me. I'm glad he pointed out the difference. I learned something. Sorry you took it negatively.

[gordr]

quote:Originally posted by Original50

Well, I found out what the OD Kickdown switch does, or how it works. I went over to my mechanic today armed with a ohm meter and checked the OD kickdown switch. I even tore into the thing to see how it was made. It is a slider switch with a plunger on one end. With the car just sitting there, with nothing going on, the switch has normally closed points and normally open points. The NC points connects the distributor to pin 6 of the solenoid. The other pin on the solenoid has 6 volts on it all the time, so the solenoid looks at the distributor pulses all the time. From my experience with such matters, the solenoid will energize or do it's thing when enough pulses are felt by pin 6 to energize the solenoid. I know that distributor has pulses on it 'cause on my Charger, the tach is fed by
such an arrangement. They are negative pulses on the Charger, but I suppose they are positive on a postive ground car. I'll scope the thing when I get a chance, to see if they are 6 volt pulses or hotter ones. Anyway, those pulses are what tells the solenoid that the car can shift into the overdrive gear when the plunger works it's magic, once the voltage rises high enough to provide the controlling factor. The connection of the other terminal on the OD solenoid is simply a gate.
When you punch down on the accellerator, the OD Kickdown switch will transfer the slider to the other side of the switch, and that will provide 6 volts from the governor through the Transmission lockout switch , along wire labeled K, through the OD kickdown switch to the OD relay, and the relay will energize or transfer. Now I need to tear into a OD relay to see how that thing is made. And I also need to check the Transmission lock-out switch to see what is going on there. I tried to remove the Trannie lockout switch today, and when I got here loose, oil started running outta the transmission, so I put the switch back in real fast to keep from making a bigger mess.
Electro-Mechanical devices? Yep one needs a schematic to unnerstand the goings on of a circuit with such things. Too many hidden factors. I guess that is one of the reasons that IBM had schools for all of their machines, soz we could understand the workings of the mechanics in relation to the electrical. I'll get her figured out, yaw can count on that.

Don Dodson

Whatever. I think I have a spare transmission on hand if yours blows up.[}]

Gord Richmond, within Weasel range of the Alberta Badlands