Two points:
1) until 1967 or thereabouts there was no reverse lamp circuit;
2) the transmission switch for the reverse lamps is the exact same switch as
the OD lockout -- check out the part numbers. So there isn't any improvement
in reliability -- you'd just be trading one identical input for another.
What's the point?
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
on 6/1/06 1:03 PM, Hans Duinhoven at h.duinhoven@planet.nl wrote:
> Do we all fear the Prince of Darkness!
> I do not have an OD, but would immediately arrange an extra interlock
> activated by the reverse light circuit.
> Being an electric engineer, I dare to challenge the Prince.
> Faultfinding on a circuit I have ever worked on, is not difficult 4 me.
>
> Cheers,
>
> Hans
>
> ----- Original Message -----
> From: "Paul Hunt" <paul.hunt1@blueyonder.co.uk>
> To: "Hans Duinhoven" <h.duinhoven@planet.nl>
> Cc: <mgs@autox.team.net>
> Sent: Monday, May 29, 2006 10:40 AM
> Subject: Re: LH Overdrive help needed
>
>
>> Hi Hans,
>>
>> Yes, it could, but I have never known an interlock switch fail closed, so
>> there is no real need to provide a *second* interlock circuit, which still
>> needs the reverse light switch (same design as the OD switch) and wiring
>> to
>> be working. The more components there are in a circuit the more the
>> chance
>> of failure, and if you had two interlock circuits you wouldn't know the
>> 1st
>> one had failed until the 2nd one did as well, unless you monitored both in
>> some way, which is even more components! Such a relay would depend on
>> several other components like the green circuit fuse, and its various
>> bullet
>> connectors, also working correctly. In this case the bypassing of the
>> interlock was deliberate, so presumably the bypassing of a 2nd interlock
>> would also have been done. You could use the relay off the reverse light
>> system *instead* of the original interlock switch (with all the provisos
>> about green circuit fuse, wiring, connectors etc.) to allow you to have OD
>> in all four forward gears, but the reason it was limited to 3rd and 4th
>> (4th
>> only on V8s) is that it isn't strong enough to take the torque reversals
>> in
>> the lower gears. I believe some of the TRs had a stronger unit and so had
>> OD in 2nd as well.
>>
>> Cheers,
>> Paul.
>>
>> ----- Original Message -----
>>> Just curious how the OD works: can't the OD circuit be interlocked with a
>>> relay, which is activated by the reverse light voltage?
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