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Auto-pilot clutch slips under load to portside

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 461 / 470
Forum Description: 461 / 470 Hints and Tips
URL: https://www.myhanse.com/forum_posts.asp?TID=13189
Printed Date: 28 March 2024 at 14:56
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com


Topic: Auto-pilot clutch slips under load to portside
Posted By: psousa
Subject: Auto-pilot clutch slips under load to portside
Date Posted: 31 January 2022 at 17:24
Hi there!
My Jefa autopilot clutch fails when I pull the rudder wheel to port with my hands while the autopilot is engaged. It slips. Before this manual test, I realise this failure few times already when sailing close haul with 15/16 knots winds. The pressure over the rudder increase and the clutch starts failing. The system keeps trying to lock the rudder and eventually do it again when the boat gets into the wind, obviously reducing the pressure over the rudder.
This happens only to one side. To the other one the clutch holds pretty well.

Contacted Jefa and they ask me to do a test: to connect the clutch directly to the battery and try to pull the wheel by hand. Obviously they are trying to exclude the simrad autopilot computer from the equation, but before doing it I would like to ask you guys if you ever had such a problem and what are your thoughts about it. Is it possible to be an autopilot computer issue? Isn't the clutch a on/off only feature?



Replies:
Posted By: JonB
Date Posted: 01 February 2022 at 22:08
Hi,

My old Raymarine auto pilot had Alzheimer's in that it would suddenly let go with 'no drive' warning, I took the motor off to test the clutch, all good and yes its either engaged with pins or its not, so it can't slip. Thinking that it may be an issue between the fluxgate and the compass within the unit I tested the fluxgate. Deciding I didn't really know whether my findings would tell me anything I could understand and having upgraded the E series plotters to Axioms I opted to replace the auto too.  The ACU 200 was fitted and off I went only for it to fishtail the boat until we nearly gybed. I undertook several tests and once again it opted to, under engine (little wind), follow a search pattern without being asked to.

It was a struggle to get Raymarine to accept anything other than a limpware (user) issue, but eventually they sent over an Engineer who came and inspected with the Engineer who fitted it. When the auto pilot was asked to steer +10degrees and the helm was held to simulate weather helm, they were surprised that 15amps was called for by the Jeffa motor, bearing in mind it is protected with a 40amp fuse. They've since changed the unit for an ACU 400 which I assume handles the amperage better and once installed and the boats back in the water we'll be testing again.

Check the rudder sensor, probably by disconnecting it and see if it's the same both sides or cures the problem. You could have a similar issue in that the amperage being asked by the motor exceeds that of the unit fitted.


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Jon B
470e
http://www.norse-king.blogspot.co.uk


Posted By: psousa
Date Posted: 03 February 2022 at 11:14
Interesting... 
Regarding the amp demand for Jefa 12v sprocket drive unit (I guess the one you have), there is a graph which clearly shows it can demand up to 16amps when under weather conditions:  https://www.jefa.com/steering/products/drives/sprocket-150nm.htm" rel="nofollow - https://www.jefa.com/steering/products/drives/sprocket-150nm.htm

My boat is equipped with a simrad ac42 autopilot computer. According to the manual, it can supply:
AC42: ....................30 A continuous, 50 A for 1 sec. peak

More, the issue is happening when pushing the wheel to portside only (doesn't happen when pushing the wheel to SB), so I guess it's not a power delivery issue.

I'll give a closer look ate compass and the rudder feedback when back to the boat.


Posted By: TheWoods
Date Posted: 04 October 2022 at 16:06
psousa - did you find a solution to this question? I had exactly the same symptoms on my 430 this summer and looking to solve the problem as well. Thanks



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Red sky at night....


Posted By: psousa
Date Posted: 14 October 2022 at 15:40
nope! I was in touch with Jeffa and they sent me a PDF with instructions to test the drive unit/clutch. The issues happens even when bypassing the computer unit, so it seems to be a drive issue, we believe. They suggest to send the drive unit back to Jeffa in order to be serviced by them, in Denmark, which I didn't.
I'm living with it. I keep close to the wheel when winds get stronger. But eventually I would need to look at this and fix it.

Please keep us updated with further steps you decide.


Posted By: JonB
Date Posted: 14 October 2022 at 16:49
Did you get a message 'drive stopped'?

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Jon B
470e
http://www.norse-king.blogspot.co.uk


Posted By: psousa
Date Posted: 05 December 2022 at 10:19
No, never got that message but I found the issue: the steering chain/cable has a considerable slack and, under certain tension, the chain slips on the autopilot sprocket wheel. Just gave tension on the steel cable nuts close to the quadrant. On a quick test at the marina, with my hands, couldn't make it slip anymore. I'll check again at the sea (need some rough conditions and winds to test it again).

On this video you can see the autopilot trying to turn while I was holding the wheel with my hand which results on a slips chain/sprocket wheel: https://mega.nz/file/5xJRURLD#n9VKAVmGdLEbey9Z1Zi8FbwX-bk8DVtXA2DYntjX7Kw" rel="nofollow - https://mega.nz/file/5xJRURLD#n9VKAVmGdLEbey9Z1Zi8FbwX-bk8DVtXA2DYntjX7Kw


Posted By: Wild
Date Posted: 05 December 2022 at 16:58
Originally posted by psousa<div>On this video you can see the autopilot trying to turn while I was holding the wheel with my hand which results on a slips chain/sprocket wheel</div>[/QUOTE psousa
On this video you can see the autopilot trying to turn while I was holding the wheel with my hand which results on a slips chain/sprocket wheel
[/QUOTE wrote:


This looks normal to me.
 moored in the marina with the AP in AUT mode the boat move a bit and the AP will correct this small movements. when you
This looks normal to me.
 moored in the marina with the AP in AUT mode the boat move a bit and the AP will correct this small movements. when you block the wheel by hand this result in the drive unit will turn a bit to left and right and the chain jumps up and down on the sprocket of the drive unit. If you take all the slack of the cables and keep the wheel blocked for a longer period the AP control unit will give first the alarm code NO RUDDER RESPONSE and finally DRIVE OVERLOAD.
When the slack of one of the cables is to big the chain will finally jump of the sprocket our the cable will jump of the rudder quadrant.


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Wild and Wet
Belgium
545e#268


Posted By: psousa
Date Posted: 06 December 2022 at 09:32
Originally posted by Wild Wild wrote:

Originally posted by psousa<div>On this video you can see the autopilot trying to turn while I was holding the wheel with my hand which results on a slips chain/sprocket wheel</div></td></tr></table><div>This looks normal to me.</div><div> moored in the marina with the AP in AUT mode the boat move a bit and the AP will correct this small movements. when you block the wheel by hand this result in the drive unit will turn a bit to left and right and the chain jumps up and down on the sprocket of the drive unit. If you take all the slack of the cables and keep the wheel blocked for a longer period the AP control unit will give first the alarm code NO RUDDER RESPONSE and finally DRIVE OVERLOAD.</div><div>When the slack of one of the cables is to big the chain will finally jump of the sprocket our the cable will jump of the rudder quadrant.</div>[/QUOTE psousa
On this video you can see the autopilot trying to turn while I was holding the wheel with my hand which results on a slips chain/sprocket wheel
This looks normal to me.
 moored in the marina with the AP in AUT mode the boat move a bit and the AP will correct this small movements. when you block the wheel by hand this result in the drive unit will turn a bit to left and right and the chain jumps up and down on the sprocket of the drive unit. If you take all the slack of the cables and keep the wheel blocked for a longer period the AP control unit will give first the alarm code NO RUDDER RESPONSE and finally DRIVE OVERLOAD.
When the slack of one of the cables is to big the chain will finally jump of the sprocket our the cable will jump of the rudder quadrant.
[/QUOTE wrote:


Not to me, Wild. In this video I was holding the wheel with one single finger, pressed 10 degrees starboard button and it fails like this. Also fails if autopilot is on and I steer portside with one single finger. Not normal at all.

This all starts at the beginning of last season, when the autopilot started failing to keep the head when close hauled or reaching over 15knots of wind and light swell. With this conditions I could be sleeping on any of my previous smaller sailing boats. These are quite light conditions for a 47 boat and a strong autopilot unit drive like this and that's why I start talking to Jefa Steering Systems one year ago. They agreed it wasn't normal and even suggest to send the driver unit so they can inspect it. I only identify this issue now, while going through the

Not to me, Wild. In this video I was holding the wheel with one single finger, pressed 10 degrees starboard button and it fails like this. Also fails if autopilot is on and I steer portside with one single finger. Not normal at all.

This all starts at the beginning of last season, when the autopilot started failing to keep the head when close hauled or reaching over 15knots of wind and light swell. With this conditions I could be sleeping on any of my previous smaller sailing boats. These are quite light conditions for a 47 boat and a strong autopilot unit drive like this and that's why I start talking to Jefa Steering Systems one year ago. They agreed it wasn't normal and even suggest to send the driver unit so they can inspect it. I only identify this issue now, while going through the winter maintenance list.

This is a 150nm sprocket drive, so it should be able to handle forces which are quite demanding for humans to keep. The whole system should be able to handle these conditions as well. You can see the graphics here:  https://www.jefa.com/steering/products/drives/sprocket-150nm.htm" rel="nofollow - https://www.jefa.com/steering/products/drives/sprocket-150nm.htm

I emailed again to Jefa with this update as I just want to understand if the culprit may be the sprocket failing. I don't know if this is something we should replace time to time.



Posted By: Wild
Date Posted: 06 December 2022 at 10:50
Sorry 
In your previous posts you write “holding the wheel with my hand” 💪
You didn’t mention “with one finger”☝️
I my 12 year experience with the same Jefa steering system (545= same as 470) when the wheel can’t move freely in AP mode I have that issue.


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Wild and Wet
Belgium
545e#268


Posted By: moli
Date Posted: 21 March 2024 at 20:34
Hello,
I carefully read the previous posts, I also had the same problem with the jefffa autopilot, it slides in one direction and holds in the other direction and my chain is tight, it doesn't jump over the sprocket.... Hmm new ideas? THX


Posted By: Dogscout
Date Posted: 22 March 2024 at 12:42
Hello all. I am experiencing a problem with my 430 that I believe is the same as postd here. I believe that mine is the clutch disengaging when pressure (force) against the rudder is to great and causes an over current protection thus the computer releases the clutch. This makes a banging sound. I have inspected the sprocket and chain and there is no abnormal wear so I do not believe that the chain is alipping. Tension seem correct. What I have noticed is that the wiring from the AP (NAC 30) is original 2008 and has turned green and black at the connections in the rear lazarette. The red and black wires coming from the motor are this way and too short to cut back to clean copper without opening the motor. I found this because the red wire broke at the fuse holder. I replaced the fuse holder and tried to solder a new one in but the condition of the wire made that difficult.  

I will eventually replace all of the wire from the AP computer back to the motor, but not able to for a few months.









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Adventure awaits


Posted By: JonB
Date Posted: 22 March 2024 at 14:45
What amps is the fuse next to the motor rated at, my 470 was at 40amp yet according to Raymarine's appointed Engineer, the Autopilot could only handle 15amp and so it was realised that the model installed that replaced like for like, almost, with the old one was too small.

The way we tested it was we put the autopilot on to hold course and then pushed the wheel over to represent weather helm and the electrician measured the amps.  This took it easily to 15amps quite quickly.  However, if it is 'slipping' in only one direction then are there teeth missing on the cogs, an easy spot.


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Jon B
470e
http://www.norse-king.blogspot.co.uk


Posted By: Dogscout
Date Posted: 22 March 2024 at 17:18
My fuse at the motor is 15 Amp. B&G say that the NAC 30 will give 30 Amp to the motor. The previous original AP computer was a SIMRAD I do not recall the model. I want to put clean new tinned wire in and will likely choose a heavier wire. I think that the existing wire is 6 mm2 so I'll put 8 mm2 when I replace it. I do not think that I have a mechanical problem. I think it's all electrical. But hey I could be wrong. 

There is no noise or problem when hand steering in heavy weather.  


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Adventure awaits


Posted By: JonB
Date Posted: 22 March 2024 at 18:02
Could this be another problem in that if the Autopilot is holding you steady in bad weather and the NAC 30 compensates for a wave slap or gust and increases the amperage you'll pop the fuse and well, we all know when these occasions occur!

Check the steering limiter sensor as if working ok in one direction but not the other it could be this that is faulty.

If your boats out of the water then set a course with the Autopilot, lash the wheel/tiler down and move the rudder, or get someone to hold the rudder steady and move the wheel and see if it 'lets go'.

We found we'd just were blown where ever the wind wanted to take us but luckily we were usually on deck and saw NK changing course, because ours fuse could more than handle the output from the Autopilot, the Autopilot would 'let go' and so it happened quite early in reasonable winds, it didn't need to be in bad weather


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Jon B
470e
http://www.norse-king.blogspot.co.uk


Posted By: Dogscout
Date Posted: 22 March 2024 at 22:40
The fuse has never blown. Is it unreasonable to consider that the motor requires more current but the wire cannot carry it? I'm no Electrical Engineer, I'm Industrial. I have replaced the cables because one was severely frayed and I set the cable and chain tension as Jefa requires in the service sheet. I have looked at the chain and sprocket and there is no wear. Years of motorcycles have shown me what that looks like.  

I would like to put a meter on it to show the current when the fault happens but again I am not a sparkey and not really sure how to do that.  


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Adventure awaits



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