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markmyers · 01-08-2013, 16:07

I have an issue with my Raymarine Linear Drive that I am hoping someone can provide some guidance on.

The drive works fine when on autopilot (well the last time I used it anyway) but if I put the autopilot into standby (or turn it off completely) then I am unable to manually steer the boat. The problem is that the ram will not compress/retract but will expand meaning that I can steer to starboard but not to port as the drive resists. Presently the only way I can steer is to use the adjustment buttons when in autopilot mode. (I hope I have explained that well).

I am wondering if it is a clutch issue (don't think so), or a hydraulic/lubrication issue??

Matt Johnson · 01-08-2013, 16:29

Does it still prevent you turning the wheel with the autopilot breaker flipped off? It cant be hydraulic as it uses a threaded rod not oil to move the shaft. Try disconnecting the two small wires for the clutch and see what that does.

sabray · 01-08-2013, 17:13

I think raymarine linear drives are mechanical not hydraulic. That is the way the describe them. Is it correct that you have electromechanical drive? Or is it hydraulic with a ram.?
If its linear drive it should travel free. Something is probably gummed up in drive. These are not hard to take apart and replace parts.

goboatingnow · 01-08-2013, 17:27

Its has a clutch , ( a two core red and blue wire) , check connections , it then could be clutch failure , or issues with the drive circuit in the course computer. Given that it doesn't release when you turn it off, I'd say its a mechanical issue in the clutch

Dave

markmyers · 01-08-2013, 18:40

Thanks for the replies. I have checked through manuals and specs and you are right it is not hydraulic. It is... "a high tensile belt drive and epicyclic gearbox controlled by an electromagnetic fail-safe clutch".

Yes, it prevents me turning the wheel even when the autopilot breaker is switched off and autopilot course computer is completely off.

I will try disconnecting the clutch this weekend and try again but I suspect that it may be a mechanical issue but will try a few things.

As maintenance should I spray lubricant onto the push rod? I am thinking it wouldn't hurt?? One thought I have had is that the linear drive motor is providing much more force than I am with the wheel so may be overcoming a physically stuck rod???

Will try isolating the clutch though.

Matt Johnson · 01-08-2013, 20:56

Sounds like a stuck clutch...without power, it should disengage. Remove the two small wires for the clutch and then try running the autopilot. If the drive still turns the wheel, the clutch is stuck.

markmyers · 02-08-2013, 15:08

Thanks for the suggestion re clutch. I have removed the clutch fuse and the linear drive no longer turns the wheel so the clutch is not stuck. I will test for some other ideas.

BTW, a correction to my previous post, with autopilot disengaged I am able to steer to retract the drive but not to extend it, ie it will contract but not extend manually.

pbiJim · 02-08-2013, 16:14

I don't know if it's going to help you or not, but I found this PDF of a manual - http://www.sv-zanshin.com/manuals/ra...rivemanual.pdf

You might want to physically disconnect the linear actuator from the steering system & see if the steering system then moves freely.

If the rest of the system moves freely & it's possible for you to open up the gear box case, you might want to take a look inside.

markmyers · 02-08-2013, 17:59

Yes thanks I have that manual. Not much in there. I have disconnected the actuator from the steering system and now the wheel moves freely. Unfortunately it is in a VERY hard to get to place so I will try to use the autopilot to hard steer it to max and try some lubrication and see if that helps (doubtful). Just trying to avoid having to uninstall it just to be able to work on it but may come to that.

pbiJim · 02-08-2013, 19:47

I'm guessing that it's either the clutch as others have said, or else maybe a worm gear or a bearing inside the gearbox that has gone bad on you. I don't know where in the driveline the clutch is located in that particular unit, so I don't have a good feel for what all the possibilities are.

Matt Johnson · 02-08-2013, 20:13

click here for a photo series showing inside of drive

markmyers · 03-08-2013, 01:53

Hey thanks for the link. The pics are good.
I spent the day pulling the drive unit out and opening it up. The clutch looks good as does the motor. With it all disassembled I can spin the disc at the end of the actuator arm and it moves the arm in and out (both directions) with ease and I can push it in (mimicking manual steering) but cannot pull it out. One of the photos on that link gives me an idea so I will try tomorrow. It must be a mechanical jamming which only happens when pulling out as opposed to being pushed out by the mechanism.

pbiJim · 03-08-2013, 07:17

After seeing those pictures, I'm guessing that it's a thrust bearing problem or else a problem with the screw. It sounds like you are on the right track.

Try spinning the disk at the end of the actuator arm while pushing on it & also while pulling on it. See if that makes any difference in how free it spins.

I'm curious if they use a ball screw or an Amce screw in that actuator. I think that in a salt water environment, I would opt for an Acme screw with a nylon nut. Ball screws are wonderfully efficient, but they are also horribly sensitive to contamination & grit. Clearances in some parts of a ball screw are normally less than a thousandth of an inch. It wouldn't take much salt on the screw face or in the reticulation passage to bugger them up.

transmitterdan · 03-08-2013, 08:16

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. The OP will probably have to get to the nut on the leadscrew to find the problem.