Author Topic: Self Steering 'Grunting' (Read 22008 times)

MagicalArmchair · « **on:** October 22 2020, 10:52 »

In the summer, when I returned Mirage from the South coast to the East coast, I noted that the self steering "grunted" when turning to starboard (http://bavariayacht.org/forum/index.php/topic,2930.msg19113.html#msg19113).

I hoped it was due to the boss not being loosened enough on the wheel, however, fully loosened, it still does grunt...

Its very hard to hear, but turn up your speakers and listen at the end of this video. The deck vibrates a little when it squeaks, like the cable is slipping... however, it only grunts when under autopilot NOT when steering normally...

https://youtu.be/44J84MKCnCA

My knowledge of this system is still very scant - I hope fixing this might improve it somewhat as I like to know my way around most bits on board.

So, as I understand it, the wires come down from the binnacle, to this fellow here, that I presume is the motor that drives the steering gear:

The cables then work their way to here:

Where the quadrant moves the rudder stock.

And this guy is the rudder position sensor I'm guessing:

So what's grunting?

Yngmar · « **Reply #1 on:** October 22 2020, 15:54 »

If it's only under autopilot, it can only be the drive unit itself or the chain slipping. Check chain tension first, as that's easiest, although my guess is it's not that but the drive unit. On ours (very similar, but on a 40 Ocean much more accessible) the chain is tensioned by losening the bolts that hold the drive in its bracket and then dropping it down until the chain isn't slack anymore and re-tensioning bolts. You might need some elastic multi-jointed arms for this job by the looks of it!

If that doesn't help, the drive gearbox is probably the problem. For inspecting this, you will have to remove the drive and take it apart. The sound could be a gearwheel with a few teeth missing, or simply lack of grease. Ours made a horrible sound when I forgot to grease one set of the planetary gears after servicing it

Good luck!

MagicalArmchair · « **Reply #2 on:** October 23 2020, 10:27 »

Please excuse my complete lack of knowledge (the last time I fixed an autopilot was somewhat simpler! http://www.albinballad.co.uk/how-tos/fix-a-autohelm-st2000-autopilottillerpilot/), the drive unit is the black doofus? And the gearbox lives inside that guy?

To operate the rudder and wheel, I presume the cable is tensioned around some pulleys inside the drive unit? If that's the case, to remove it so I can service it and inspect it, do you have to detach the steering cable from the rudder stock or can in be released by unscrewing the back plate on the drive unit?

Time for me to find a workshop manual...

Yngmar · « **Reply #3 on:** October 23 2020, 14:08 »

Yes, the black thing is the drive unit. Originally a Whitlock item and now produced by Lewmar. The old Whitlock ones seem to last well, while some here reported trouble with the Lewmar manufactured ones. On the back you can see the pancake motor, in front of that are are few planetary gears and an electromagnetic clutch. All of this drives a sprocket, which drives a chain, which goes up through the binnacle and drives the axle of the steering wheel directly. A separate chain is also attached to the same axle and drives the cables that go back to the quadrant.

Can't find a good drawing of it, the manual I've got is this one: http://mantaowners.org/wp-content/uploads/2014/01/Constellation-Steering-Manual.pdf

But it's not quite right for the Bavaria binnacle, for one it doesn't show the second sprocket driven by the autopilot motor. Once you take a look at things you'll see how it all fits together though. Oh, the way to get a good look at the inside is taking the compass out of the binnacle, as the steering wheel axle with both chains on it is directly underneath. That shouldn't be necessary for this job though. Also the white panel that holds the engine instruments on the binnacle does come out and gives you access to the chain and where the chain attaches to the cables. Also not necessary to access for this job, but having a peek should enlighten you about how it all fits together.

MagicalArmchair · « **Reply #4 on:** October 26 2020, 08:49 »

Ah ha, right, well I've got the VP Control Panel out at the moment (alarm buzzer isn't working, and some bulbs need replacing), and here is what I saw in the 'hole':

I presume its something like one of these?

https://www.mauriprosailing.com/mm5/Lewmar/pdf/Integra-autopilot-manual.pdf

Judging from this: https://forums.ybw.com/index.php?threads/whitlock-motor.215239/ it is likely a DU 145 perhaps?

How easy was it to drop yours off entirely for servicing? I presume you have to take the chain off first?

Yngmar · « **Reply #5 on:** October 26 2020, 09:09 »

Yup, that looks exactly like ours, which is a DU145. What you see there is the two wire ropes going into the terminating pieces of the blue steering cable conduit, and the chain that goes round the autopilot drive. Simply pulling sideways on the chain will tell you if it's tensioned or slack enough to be slipping.

Removal was very easy, although I had much better access! You will need to somehow get to the front of the drive where the sprocket sits. That's where there are two big bolts. When loosened they let you slide the drive up and down in the vertical mounting bracket's slots to adjust tension.

If you remove the bolts entirely, you can move the drive upwards first so the chain goes slack and can simply be taken out of the sprocket teeth. Then the drive just pulls out towards you. Don't forget to disconnect cables first.

Took a picture so you should get an idea of what is on the other side:

MagicalArmchair · « **Reply #6 on:** October 26 2020, 10:32 »

Thank you so much - that photo speaks more than a thousand words - and with the strange little hole I need to squeeze my head in to to get this guy off, it would be nearly impossible for me to get.

Once its off, are there any specialist service parts you need? Or is it a straight (photograph everything as I go so I know which order it goes back in!) strip, clean and grease job? Sounds like a fun winter job for the bat cave!

Ronald · « **Reply #7 on:** October 26 2020, 19:15 »

Hi this may help to understand how the drive stick together.
When I heard grinding noise I got a deja vu as I had the same a few year ago.
What happens is that the 3 Alan bolts at the bottom of the drive worked loose. And we’re killing the gears.

Hope it is someth8ng different. The cause was someone “forgot “ to fit them with loctite as described in the assembly manual.

Regards Ronald.

Yngmar · « **Reply #8 on:** October 26 2020, 21:47 »

In our case it was just a matter of stripping it down, cleaning the old grease off and applying new. Make sure you don't forget to grease one set of planetary gears like I did and then discover this in the middle of a Biscay crossing

Do check if they have all their teeth - the gears are plastic (which is apparently fine). Unless you discover some broken bits, no parts were needed.

Oh, and I had a look at the clutch too. Pretty much just blew the dust from accumulated wear out of it. Seemed to have plenty of life left at the time and hasn't made any trouble in the years since.

MagicalArmchair · « **Reply #9 on:** April 10 2021, 10:28 »

Taking this off and stripping it down is still on my "todo" list. On our shakedown sail, it made its usual grunting noises, and then stopped entirely with the error "Drive Stopped".

We tested it again a few more times, and it did work, however, I fear I can put this job off no longer. Does anyone have any pictures of their stripdown of this unit? Do we think its terminal?

Video of it "grunting" from the sail: https://youtu.be/gBkBfSAoT-0

edit: another similar thread here: http://bavariayacht.org/forum/index.php?topic=1508.0

Yngmar · « **Reply #10 on:** April 10 2021, 11:23 »

Are you sure it's the drive unit? Sounds more like metal on metal friction. When the drive is disengaged, does the steering wheel turn easily by hand? On ours the stainless cover where the wheel axle exits the binnacle was not well centered and rubbing on the wheel axle - could be just that?

When you push -/+10 and it makes large movements the drive sounds completely normal.

If you're sure it's coming from the drive, take it out and take it apart. It's pretty straightforward, just be careful with the cables. Might just need new grease on the gearwheels. Could be the clutch is worn though.

geoff · « **Reply #11 on:** April 10 2021, 12:45 »

If your grunting results in a Drive stop message it is probably motor overload due to excess friction in the clutch area . I suffered from this drive stop for a long time before I stripped the whole unit down to the level of individual componants. I discovered that the clutch had been set with clutch rotor fouling the body. The resulting friction so early in the gear train overloaded the motor. The fix was to relieve the rotor assembly a bit [wet or dry] .No more drive stop ,no more noise. Geoff

MagicalArmchair · « **Reply #12 on:** April 10 2021, 15:01 »

The wheel turns perfectly freely by hand, there is no “grunting” when turning the wheel by hand. Anywhere else there could be friction? In the photos above you can see the chain is up and down - it is a little loose though perhaps?

Geoff, do you have any photos of your strip down and the modification you made to free the clutch motor?

Yngmar · « **Reply #13 on:** April 10 2021, 17:04 »

Loose chain would make chain jumping (rattling) sounds, not this grinding noise. I still don't think it sounds like the drive, but hard to tell from a video - can you place the source by ear? Is it coming from the top or the bottom of the binnacle?

It might be a chain sprocket slipping - one is on the drive and one on the steering wheel axle. That could explain this noise and why it only appears under autopilot.

When the autopilot is engaged, is the wheel completely locked? When trying to turn it by hand it should not move (more than a few mm play that is). If that moves and/or makes a noise, my tip would be a slipping sprocket.

geoff · « **Reply #14 on:** April 10 2021, 17:07 »

Sorry no photos, wrong generation!. The clutch is not unlike a car clutch , but is electomagnetic . The problem with mine was the clearance between the body and the non moving plate, there wasnt any. Geoff

MagicalArmchair · « **Reply #15 on:** April 10 2021, 19:36 »

Ha thanks Geoff, I photograph just about everything!!

To be honest, it does sound further up than the drive unit, however, a slipping sprocket wouldn’t explain the “Drive Stopped” overload. It would just grunt and give less resistance, not more you would think?

Can you view the sprocket from above by taking out the compass? And can you operate the autopilot whilst in my berth from extreme to extreme?

geoff · « **Reply #16 on:** April 10 2021, 20:22 »

Yes to both questions I think, but my problem would only occur after at least 5 mins of operating and would then just lock the wheel and message Drive Stop. It would sometimes reengage and do another 5mins. Geoff

MagicalArmchair · « **Reply #17 on:** April 12 2021, 09:23 »

I have the unit off. The three machine screws holding the back on were only finger tight which was surprising. Are these not supposed to have thread locker on them??

How doe I get the back the rest of the way off? Do you need to get the sprocket off? If so, how? I have some awesome pullers...

It looks pretty good.

geoff · « **Reply #18 on:** April 12 2021, 09:48 »

From my wobbly memory there is another hex socket head on the back face . The rear should then free off , sprocket stays on. You then get to a ring of small socket heads . These give access to the second half of the gearbox and the clutch. The motor unit is the pancake front bit held on with philips head screws . with those out you access the primary plastic gears and the clutch driven plate ,where the problem may be. The tricky bit is getting enough slack in the wires to allow easy access . The only puller I needed was to shift one of the clutch plates , but I cant remember which one !. It really sounds complex but is fairly simple. Geoff

Yngmar · « **Reply #19 on:** April 12 2021, 09:55 »

Sprocket comes off easy when you undo the grub screw shown in your photos. Then you just unbolt things and they come apart! I think I have some old photos from when I did the job, but would have to dig in my poorly organized photo archive

MagicalArmchair · « **Reply #20 on:** April 12 2021, 10:43 »

Thank you both! I had a quick peer into the hole in the side of the sprocket where I expected to see a grub screw, and there was nothing to unscrew? I'll take another look when I'm out of meetings - I only grabbed five minutes before the dog walk, so I may well have missed it. Geoff, this is the back, I'll remove this too.

geoff · « **Reply #21 on:** April 12 2021, 11:35 »

The last photo is the motor ,comes off with the 4 screws. The next layer gives access to the clutch driven plate. Geoff

Yngmar · « **Reply #22 on:** April 12 2021, 11:35 »

Missing grub screw may well explain the squeak. It looks like the shaft also has a key slot. Take the sprocket off and see if there's actually a key in there

MagicalArmchair · « **Reply #23 on:** April 12 2021, 12:40 »

Thank you both. So, post meeting, I have it in more pieces. I can confirm there is no grub screw, but the key is definitely still there.

Missing grub screw, note the back and forth movement: https://youtu.be/OOHQHKmXuCM

I've put a puller on it, as it will not just pull off on its own, and its taking quite a bit of force to pull it off. Just keep pulling? It is moving slowly... (the distance by which the key protrudes)

Spinning the sprocket does make a grinding noise:
https://youtu.be/ILYh_29_vcQ

MagicalArmchair · « **Reply #24 on:** April 12 2021, 14:10 »

So in five minutes after lunch, I decided it was time to press on. A bit of a battle later, and out it came:

It'll be interesting getting that back on. I'll need to find a way of lapping that shaft I think. Anyone else struggle getting that sprocket off and on?