Raymarine Linear Drive M81130 Not Releasing

[pbiJim]

Originally Posted by transmitterdan

It's probably a ball screw. An Acme nut is usually hard to turn by pushing on the leadscrew. The Raymarine drives push and pull very easily when the clutch is disengaged.

Some Acme threads are multi-start type, where you have two or more threads running in parallel. Those usually have very steep pitches on the threads & are not that tough to push & pull by hand. They do require a lot of turning torque to spin them though.

I have no idea what is actually inside there. I would be interested to find out. A ball screw certainly is a possibility.

[markmyers]

Well they usually push and pull easily :-)

I will certainly post some photos when I get into it in case it helps someone in the future. I have dismantled it to the point that the photos in the other thread had but now need to go further as the symptoms are still there.

I have gotten it to this point but cant see yet how to get the next part open.

[markmyers]

An update for anybody facing this problem in the future...
I was unable to progress with dismantling the drive for lack of an allen key of correct size (even though I have five sets of keys that are both metric and imperial). Small lug screw through brass plate holding 4 gears.
I found this discussion on another forum which seems to be dealing with the same issue. It would seem that the problem may be with the brass plate with the 4 gears. My plan is to get that off and then test the arm movement before taking the balls out.
Autohelm Linear Drive - jams one way on Standby [Archive] - Yachting and Boating World Forums

An exploded diagram would be really useful but cannot find one on the net. May call Raymarine tomorrow.

[transmitterdan]

Raymarine has good online tech support: http://raymarine.ning.com/

[Jim Cate]

FWIW,

Smaller RM drives (ST4000) do have ball screws, and they are a point of failure. I have one that exhibited similar behavior to what you describe. The 4000 is a simpler device with no clutch and cheesy construction throughout, but I suspect that the basic methodology is similar.

On mine it is possible to disassemble the ball nut for cleaning and/or replacement of defective balls... but it is a daunting task, one that is not described by any RM literature. The info for the 4000 was posted here on CF some years ago, so possibly some clever person has similar info for your unit.

Good luck...

Jim

[pbiJim]

Just a couple of general notes on ball screws -

They are high precision units with very close tolerances in some areas & even tighter tolerances in other areas.

Only disassemble one in an area where you will be able to find the balls that fall out of the reticulation passage. Replacing those balls is often not easy. They are precision ground & sometimes matched to a particular screw. Standard size balls from a bearing house often will not fit.

I usually spread out an old sheet on the workbench & tape down lath strips around the perimeter before attempting to take apart a ball nut.

You might try looking for exploded diagrams of ball screws from screw manufacturers like Rockford or Beaver. Rockford is one of the companies that makes the cheaper rolled ball screws. Beaver is a more high class operation that makes ground screws. Ray had to buy the screw from somebody. If you look around at the different screw manufacturers, you stand a good chance of finding something that matches what you have.

[Jim Cate]

Originally Posted by pbiJim

Just a couple of general notes on ball screws -

They are high precision units with very close tolerances in some areas & even tighter tolerances in other areas.

Only disassemble one in an area where you will be able to find the balls that fall out of the reticulation passage. Replacing those balls is often not easy. They are precision ground & sometimes matched to a particular screw. Standard size balls from a bearing house often will not fit.

I usually spread out an old sheet on the workbench & tape down lath strips around the perimeter before attempting to take apart a ball nut.

You might try looking for exploded diagrams of ball screws from screw manufacturers like Rockford or Beaver. Rockford is one of the companies that makes the cheaper rolled ball screws. Beaver is a more high class operation that makes ground screws. Ray had to buy the screw from somebody. If you look around at the different screw manufacturers, you stand a good chance of finding something that matches what you have.

If anyone pursues this research successfully, please post the source for the bits. I'm sure that there are lots of folks who would benefit from the info... like me!

Thanks in advance

Jim

[markmyers]

Good tip re the sheet. I will be careful. I am resigned to the fact that this will be a bigger job than at first anticipated.

I trolled through Raymarine's online info/docs for this drive but could only find 2D and 3D autocad drawings of the exterior of the drive. I know an exploded diagram exists because I saw a reference to it on another forum (may have to join that to PM the poster if I don't get it from Raymarine).

Off to shore to find another allen key set that hopefully has the right size I need.

[markmyers]

I rang Raymarine and the tech I spoke with said he doesn't think he can send me the exploded diagram as it is proprietary info !!!!! but he will check with his boss. He suggests bringing it in!!!

Anyway, I found this on-line and while it is not a fully exploded diagram it does have some useful info.
http://api.ning.com/files/rRUWEC*XQH...e20Diagram.pdf
In particular the pin I am trying to remove (item 11) is probably not a threaded pin but is a roll pin aka spring pin. Presumably I have to force it out?? Not sure how to best approach that yet.

Also a poster on another forum was experiencing similar problems which for him turned out to be the planet gears (item 14) had been put in the wrong way. See note A. Once he placed them in the right way the jamming was fixed.

The Raymarine tech did say it would most likely be a problem with the planetary gear mechanism.

[pbiJim]

If 11 is a roll pin, then it is usually best removed with a punch & a hammer while supporting the mechanism with a soft block of wood, like pine. If it is an extraction dowel, then it will have female threads inside it that are there for a jack screw to pull it out. It may also be a dog nosed set screw (grub screw). Look for a hollow hex or a slot.

[markmyers]

I have removed the roll pin and the sprocket mount. Not really sure how to get the raceway washer out...maybe a little gentle help with a screwdriver to lift??

I have uploaded photos to document (and will add more as I progress) into an album in my profile (not sure how to link it here) maybe this http://www.cruisersforum.com/forums/...lbums3204.html

[markmyers]

A little pressure pushing the actuator arm in popped out the raceway and bearing washers intact. Fortunately I had the actuator arm in half way position so that the ball didn't go flying everywhere.

It looks a little grungy in there so I thing there may be some crud in the ball screw mechanism. Next step get the balls out and regrease I think.

Photos updated in album

[Matt Johnson]

Nice work! Big thanks for documenting this, but I do hope I wont need it

[markmyers]

before I get to taking the balls out (which I may have to do anyway to make sure there is no crap in there), I think the problem must be with the roller assembly (20) and/or bearing washer (21). With these popped out of the raceway the arm seems to move freely. Surely the spindle should rotate within the roller assembly?? It does not, but maybe I don't understand it fully yet...more think/coffee time.

[markmyers]

I think it is almost definately a problem with the bearing washer/spirol pin. In the photo of the bearing washer you can see that the spirol pin is not sitting flush on one side (on the other side it is recessed) so it has not been centered/inserted correctly. This whole area - raceway, roller assembly, bearing washer etc - no longer had any grease but just had a hardened remanent. I plan to cleanup this area, reset the spirol pin and see if that fixes it.

A couple of questions...
What would be the best thing to clean it with? Kerosine?
What would be the best grease to use on reassembly?

I am assuming the spirol pin is similar to the roll pin (11) and can just be pushed out. Why they call them two different things on the diagram I don't know.