Classic cars forum & vehicle restoration.

Mello · Posted: Thu Oct 15, 2009 6:48 pm Post subject: OK Folks, What is This, Please?

I've removed the metal backplate. Is it a 1950's relay or a resistor maybe? And can I get a replacement?? (If so, where?). What's the purpose of the adjusting screw in the middle?

Apologies if this is a dim question, but I've never seen one before! It's off my 1956 103E Pop... mounted on the bulkhead.

Thanks in anticipation...

Pete

47p2 · Joined: 24 Nov 2007 Posts: 2009 Location: Glasgow

It looks like a thermal circuit breaker for a + earth vehicle with the terminal markings
L = live
+ = earth

The adjusting screw is to make small changes to the settings.

The breaker works in a similar way to a fuse, when too much load is applied to the circuit the bi-metalic vane expands and moves away breaking the circuit and when it cools down it makes the connection again.

In some ways handier than a fuse as they don't often go wrong and if it does trip you only have to wait until it cools instead of changing the fuse

They were mostly used on lighting circuits.
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ROVER
One of Britain's Fine Cars

ukdave2002 · Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire

Yep it is a thermal breaker, the centre screw alters the sensitivity.

Mello · Posted: Sun Oct 18, 2009 11:21 am Post subject:

OK - got it! It is a medieval flasher unit. I have a replacement on order as it is not working...

Thanks for the responses gents Smile

47p2 · Joined: 24 Nov 2007 Posts: 2009 Location: Glasgow

I stand corrected, I've never seen a flasher unit like that Shocked

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ROVER
One of Britain's Fine Cars

Mello · Posted: Sun Oct 18, 2009 4:12 pm Post subject:

Thanks 47P2, but I think you are still right... the circuit presumably heats, lights the indicator lamp, then goes out and the process is repeated. Somewhat archaic, but then this was very soon after trafficators, so I gess we are on the cusp of indicator technology here! Laughing

Cheers... Pete

Glenn Crawford · Joined: 06 Dec 2007 Posts: 69 Location: Dorset, SW England

I had one in my first car, a 1949 Ford Anglia, which had been endowed with light-up orange "ears" on the roof early in its life. The medieval flasher unit would flash every two or three seconds - but it needed up to thirty seconds' notice when the headlights were on before it would give its first flash, making local knowledge of road junctions essential!