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TR2/3/3A Overdrive Switch question. TR3A, Problem Solved!

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Tinkerman

Tinkerman

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I have a new overdrive switch and I was going to put it in my just now installed dash. I remember something on the forum from awhile back about the positioning of the switch. Checked it out in my file on BCF Tips and found that down is the on position. When I tried to check it for continuity I had none. This is bad right? I should have continuity in the on position between the two bullet connectors. I would have thought. This is a new unit I don't really know where I bought it. Might have been on eBay but more likely from TRF on one of their weekend specials.
Nother question, is it a bear to take apart? Any thoughts on all of this would be deeply appreciated.

Thanks, Tinkerman
 
Re: Overdrive Switch question. TR3A, A type O/D

Her's part of the answer for an original switch:

OD switch is tear drop shape. When mounted in the dash with the side marked 'overdrive' facing the steering wheel, lever pointed up is OFF, down is ON.

Haven't taken one apart but looks like 5 or so screws total to split the cover. After that, you're on your own.

Good Luck.
 
Re: Overdrive Switch question. TR3A, A type O/D

Easy to take apart; easy to change which way it works. TS39781LO had it wired the opposite way (up for on) when it came to me, and I've perpetuated the error so now TS13571L works 'backwards' too.
 
Re: Overdrive Switch question. TR3A, A type O/D

I bought an original switch from someone on eBay and was alarmed to find no continuity when I checked it with my meter. I then tried checking it using a battery and bulb and the switch was fine! Don't know the reason for it, but maybe worth a try!
 
Re: Overdrive Switch question. TR3A, A type O/D

As Randall stated, the "sense" of the switch is easily changed and it was designed this way. The switch face reads, "overdrive", and this face should be turned towards the driver. Of course, in order to maintain the same "convention", the switch would need to be flipped 180 degrees from home market to a "left-hand-drive" market. The following photo shows an OD switch mounted properly in a "left-hand-drive" car. The switch is shown in the "ON" position.
OD.jpg

I realize that this sounds silly and trivial to many people, but this sort of thing has always been of interest to me. When I lived in England in the early nineties, I was renting a house near Swindon, Wilts. I noticed that all of the light switches on the walls in the house were mounted upsidedown (as compared to the USA). What I mean, in the USA to turn a wall switch to the "ON" position(per National Electrical Code)the switch should be "UP" and the "OFF" position should be "DOWN". Everything I have seen in the UK is opposite. I once asked about this practice, years ago, during a seminar I was attending. The seminar pertained to the new NEC Code after some significant changes had been made. The instructor said that this was "convention" in the USA and was related to the way a switch could accidentally be turned "ON". Something to do with gravity and the early switch designs of the 1930's. :crazyeyes:

So, yes, down is "ON" and the lettering should face the driver.
 
Re: Overdrive Switch question. TR3A, A type O/D

In my grandfather's house here in Canada he had the house wired about 1910 or there-abouts. The wall switches at that time had two circular push bottons. You had to push hard for it to get pushed in to turn on the light because this also pushed out the other round button and I suppose the lever or toggle connection action between the upper and lower push buttons was by means of mechanical internal levers.

I seem to remember that pushing inwards on the top button turned on the light and pushing inwards on the lower round button turned off the light.

In my opinion, I believe that gravity would have had very little contribution to accidentally turning on (or off) these switches.

BTW, I have always liked my overdrive switch since I re-set it so that flipping up on the lever switch turned on the overdrive like all switches in Canada and the USA. No TRA or VTR judge ever docked me points for this. It's my TR3A and that's the way I like my overdrive switch to operate.
 

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Re: Overdrive Switch question. TR3A, A type O/D

Don, have you ever taken one of these switches apart? I'm about to try the light bulb test suggested by Nick. Doesn't make any sense but there are a bunch of things I've seen in the world of electricity that are "eccentric". So I'm going to try what he suggests and then if that doesn't prove out, its, take apart time.
Thanks for the picture, Dick
 
Re: Overdrive Switch question. TR3A, A type O/D

Don Elliott said:
In my opinion, I believe that gravity would have had very little contribution to accidentally turning on (or off) these switches.
Click to expand...

Don, the story I heard (I think it was on the History Channel) was that a knife switch was turned off in the up position while an electrician was working on the system. I think it was high-voltage stadium lighting. The knife was pulled down by gravity and closed the circuit, electrocuting the electrician.

As they say, regulations are often written in blood.
 
Re: Overdrive Switch question. TR3A, A type O/D

Dick - Yes I have taken mine apart. Once to flip the switching action and once to spray it with black aerosol spray paint. They are too simple to explain. With the wires disconnected, pull the whole assembly out the dashboard in one piece to do the innards on your dining room table. Remove the screws and carefully separate the two halves. Make sketches of what you see. Clean and lightly file the tips where the electrical contact is made. Watch out the small spring (or springs) don't fly all over. Then re-assemble it as per your sketch. It should work.
 
Re: Overdrive Switch question. TR3A, A type O/D

I agree with you Nick it was worth the try. Now it's take it apart time. The battery/bulb test also showed no continuity.
Thanks to Don I have some "yes its easy if your careful" encouragement. So I'm off to the bench.
I believe you are quite correct Two Sheds. I used to work in electrical industry selling industrial motor control and those big knife switches were easy not to get them fully home so I can see where that would happen.

Thanks all of you for your input.

Tinkerman
 
Re: Overdrive Switch question. TR3A, A type O/D

So I undid the three screws eased it apart, a simple switch. Worked it a little, it was a little stiff, a shot of contact cleaner and FIXED!

Again thanks for all your input.

Tinkerman
 
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