BlairP Posted June 8, 2021 Report Share Posted June 8, 2021 Hello all, Below are pics of what I assume is a battery cut-off from my '69 PI - in place, and then removed. As you can see, its activating mechanism is not accessible from the engine bay, and there is a hole in the activating handle that seems to imply it was activated from a distance, assumedly by a wire linkage, as a cable would not work. My research has not given me any answers, so to you I turn. Has anyone seen this type before? And if so, do you have any details about how it works? Thanks, as always, in advance. Blair Quote Link to post Share on other sites
RogerH Posted June 8, 2021 Report Share Posted June 8, 2021 Hi Blair, not seen one like that before and no idea of the hole in the handle. I'm sure somebody will be along soon and have all the details. When the handle is turned the pin rides up the cam pushing a spring loaded bus bar onto the two contacts - nice and simple. Just a thought - could the hole in the handle be for a chain etc that can be locked in the 'off' position - Thief proof !! Roger Quote Link to post Share on other sites
Hamish Posted June 8, 2021 Report Share Posted June 8, 2021 Roger my guess would be opposite ie as its most likely an emergency elec off switch with the remote wire function thus the lever turns and moves up the cam ensuring"disconnection" thus the wire pull just needs to rotate enough to get the pin out of the locking grove then the spring does the rest. H Quote Link to post Share on other sites
Les Pettitt Posted June 8, 2021 Report Share Posted June 8, 2021 Hi Blair, There is a vaguely similar cut off switch on page 18 of Vehicle Wiring Products catalogue. Ref 60550 250amps @24 volts They call the arm a key and show a light chain through the hole as though you attach it to a key ring. My guess is the previous owner used to reach under footwell and turn it off as an anti theft device or when working on the car. Regards Les Quote Link to post Share on other sites
john.r.davies Posted June 8, 2021 Report Share Posted June 8, 2021 Never seen one made in that way, but the design is identical to a modern cut off made in plastic. They most usually are connected by a cable to a T-handle on the outside, so that a marshal or other person can switch off the car, if the driver hasn't. "FIA" cut offs have an additional part that shunts the residual output of the alternator to earth, but that would not be needed in a dynamo fitted car. Quote Link to post Share on other sites
Richard71 Posted June 8, 2021 Report Share Posted June 8, 2021 9 hours ago, RogerH said: Just a thought - could the hole in the handle be for a chain etc that can be locked in the 'off' position - Thief proof !! Roger That's exactly what the hole is for, this type of isolator is common fitment on industrial engines (generators etc), simple chain fitted to stop the handle being lost. With this type of isolator the handle can only be removed with the switch in the open circuit (off) position. Richard. Quote Link to post Share on other sites
TRier Posted June 9, 2021 Report Share Posted June 9, 2021 Yep, seen them many times and its exactly that, simple handle to operate the shut off and the hole is for a chain so the key/lever doesn't get lost. You'll notice even with the more modern looking one John showed the image of has a hole in the key. I've put them on our horse lorry or other vehicles a few times and the one thing I would mention wrt the installation you've shown is that they aren't waterproof and can be prone to corrosion problems and heating when they get corroded. I know the sensitive bits of your one are "inside" so should be OK but just something to keep an eye on. Quote Link to post Share on other sites
rwest Posted June 9, 2021 Report Share Posted June 9, 2021 3 hours ago, TRier said: Yep, seen them many times and its exactly that, simple handle to operate the shut off and the hole is for a chain so the key/lever doesn't get lost. You'll notice even with the more modern looking one John showed the image of has a hole in the key. I've put them on our horse lorry or other vehicles a few times and the one thing I would mention wrt the installation you've shown is that they aren't waterproof and can be prone to corrosion problems and heating when they get corroded. I know the sensitive bits of your one are "inside" so should be OK but just something to keep an eye on. +1 about the corrosion. I had a cut-off identical to the OP's photo that caused all kinds of weird problems, mainly petrol pump, when I was driving back from Spain one year. I only happened to notice it because there was the tiniest wisp of smoke coming from the cut-off switch. In the end I bolted the 2 cables together and that got me back to the UK. Quote Link to post Share on other sites
tr6tuga Posted June 12, 2021 Report Share Posted June 12, 2021 I just have the same and it works perfectly. Use it every time I park the tr and take the l shappe key with me. I did clean it during the process of ground earh contact points challenge, it paid of, no more current drains the batery is charging happily. Strongly recomend Quote Link to post Share on other sites
SpitFireSIX Posted June 12, 2021 Report Share Posted June 12, 2021 Replace that corroded thing unless the contact resistance is good. Calculate from volt drop if you cannot measure milliohm's. I do not know why you would need to isolate starter motor current, so 100A should be fine. Cheers, Iain. Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.