Autopilot motor drive identification.

S

Steve_N

Well-Known Member
Joined
31 May 2004
Messages
1,104
Location
Fife
Visit site
Can anyone ID this autopilot motor drive please? It's operates with my current ST6000, interfaced with the standard AH course computer, and works a secondary chain on the Whitlock wheel pedestal. I'm sure that it pre-dates the Autohelm and comes from an earlier installation so would be from the early 80s at the latest. I'm just giving it and its wiring a clean up as it works fine but it would be useful to know what it is.

PA090368_zpsdqrg27mr.jpg


A couple more pics here too:
http://s1051.photobucket.com/user/Steve928/media/PA090369_zpsyln8igom.jpg.html
http://s1051.photobucket.com/user/Steve928/media/PA090367_zps2790gsjv.jpg.html
 
I can answer my own question; it seems that it's a Whitlock Marionics Sentinel-N produced c. 1975-85.
The black unit is the drive and the pale blue unit (with the asbestos warning sticker!) is the clutch.

If anyone knows or can guess at what the little red motor(?) and the nylon cogs would have been doing that would be interesting. They are just idling now with the 3 wires to the red motor snipped.
 
Steve_N said:
If anyone knows or can guess at what the little red motor(?) and the nylon cogs would have been doing that would be interesting. They are just idling now with the 3 wires to the red motor snipped.
Click to expand...

I wonder whether it might not be a motor? The gearing would be step-up if it were a motor, and it doesn't look strong enough for that. As an alternative, might it be some sort of rudder position sensor?
 
My guess is a home-made rudder position sensor. It's probably a variable resistor, and all that gear-train is to convert multiple turns of the wheel into a single partial turn of the knob (Raymarine's own rudder sensors are just variable resistors too). It's not really a very good way of doing it, it might not always be an accurate reflection of the rudder position due to slop and backlash in the system. Is your rudder stock particularly hard to get at?

Pete
 
A rudder position sensor is a good thought, thanks. The ST6000's one is mounted on the steering quadrant adjacent to the stock, which is quite easy to get to. This cog arrangement doesn't look home-made however so perhaps that's how it was done back in the day of Whitlock autopilots. I've put the cover back on now but I'll pop it back off tomorrow and see what's written on the little red thing.

I too was thinking along the lines of it being some kind of motor, perhaps to alleviate the drag when the a/p wasn't selected, but that's probably a non-starter.
Either way it looks like I can remove it rather than leave it meshing away to no purpose.
 
I've just had a closer look at the picture and realised that the red thing isn't actually wired in. Perhaps cut off when the Raymarine sensor was added at the rudder. So it and its gears can definitely come off.

Not sure what the larger grey unit is that the gears are on top of. Maybe this was the original Whitlock position sensor, which failed, and the gears and red potentiometer were added as a substitute? I disagree that the "cog arrangement doesn't look home-made" - the soldering on the back of the red pot is amateurish, the axles for the gears are over-long, the mounting arrangements are a bit of a lashup and there's no casing or attempt at waterproofing. That thing was never designed by any competent manufacturer. The gears themselves will be from a model-maker's kit of some kind.

Pete
 
Actually, maybe the grey thing is the clutch, to engage and disengage the motor with the sprocket. Although I'm not quite sure why that would involve having a rotating shaft emerging from the back (the one the small gear is fitted to).

Pete
 
prv said:
I disagree that the "cog arrangement doesn't look home-made" - the soldering on the back of the red pot is amateurish
Pete
Click to expand...

Yes I agree, there are a couple of resistors tacked onto the terminals before the wires.. My thinking is that it was the original Whitlock rudder position sensor and then whoever installed the later Autohelm had tried to get it to work with the AH course computer by fiddling around with resistors etc. and then had given up, snipped the wires and fitted a proper AH position sensor on the quadrant.
 
To tidy this up, it was a variable resistor and is without doubt an original fitment so, yes, a rudder position sensor later 'adapted' to try and interface with the Autohelm.
Now removed and in the boat curiosities box in the loft, leaving just the motor and clutch.
The clutch is from Warner Electrical of Bishop Auckland - the company still produce similar products but now only only in the U.S.
Thanks all for your help.
 

Attachments

  • Capture.JPG
    Capture.JPG
    46.6 KB · Views: 0
Well, very nicely machined at least with brass bushes inset into the alloy bar for each axle but what made my mind up was the fitment on the back of the clutch that drives the first cog - it seemed very unlikely that that just happened to be there waiting to be adapted by some DIYer. Sorry no picture of that and I don't want to take the cover off again to take one so I guess we'll never know.
 
Last edited:
You must log in or register to reply here.

Share this page

Top