Gearchange identification/help please

[heeley]

Hello there,

I've been assisting my mothers partner in sorting out the electrics on his Atlantico cruiser, based in Bristol, and we've come across an issue with the remote gear change. (At this point I'd better make clear that my experience lies more with classic cars and gas boilers than with boats so please excuse any errors in my terminology) .

There is a weird assembly marked ZF situated above the end of the transmission that has several spark plug shaped devices/actuators/solenoids that screw in; upon removing them they appear to have a number of very fine drillings towards their ends so i'm assuming they have some hydraulic function. Each has a single screw terminal which shows electrical continuity with the brass, spring loaded tip of the device . An electrical cable is connected to the terminal that goes on up to the control levers in the wheelhouse.

I have ascertained that selecting forward on the control lever sends 24 volt power to one of these devices, selecting reverse sends power to another. The boat is twin engined and this setup is therefore duplicated.

The problem that we are encountering is that upon selecting forward on the starboard engine the fuse for the remote gearchange immediately blows. Everything is fine on selecting reverse. The port engine/transmission is working flawlessly. The fault does not occur when the forward wire is disconnected at the device (thus ruling out, I guess a wire shorting)

What we can't fathom is that when screwed in, the spring loaded tips of these fellows bear directly on some circular metal components within the transmission which I have confirmed are predictably at ground potential. Because the screw terminal and the these tips show electrical continuity it comes as no surprise that when power is applied the fuse blows.

We've swapped these devices around to no avail, the only thing that our experiments have proved is that the fault would appear to lie not with these plug shaped devices but something maybe internal to the transmission, since the fault only occurs when any of the devices is screwed into the forward gear selector hole.


(I've enclosed a some pictures of the device/s. In the final photograph, the unit can be seen at the bottom, extreme right)




Can anyone identify this type of remote gearchange, or its principle of operation or give any help whatsoever on why its behaving as it is.


Thank you for reading this far and please accept my apologies for the length of this post but we are at our wit's end.


Heeley