ST4000 Auto Helm Keeps Stripping Belt

[jonathanteller]

I have a raytheon st 4000+ autohelm wheel pilot, it has stripped the belt of it's grooves in one area on the belt. I have replaced the belt and it did the same thing again 200 hours later. I do not have the rudder position sensor(optional) for this auto helm. Would this solve the problem? I believe it happens when the boat swings violently off course (say 100 degrees or so if I loose the sail trim) and the auto pilot kicks in ,the rudder swings into full deflection to right the course, but the course is not recovered quick enough, meanwhile the auto pilor motor is still cranking away trying to turn the rudder pasr the point it can go. off couse the rudder wins the battle and my drive belt gets stripped in that one location on the belt !!!!

If I install the rudder position sensor will this tell the autohelm to stop turning ?

[senormechanico]

Not a fix, but belts are a lot cheaper on ebay than trying to get them thru Raytheon dealers.
This is just one example.

BELT Raymarine D169 Autohelm ST4000 AutoPilot Raytheon: eBay Motors (item 120550472578 end time Oct-26-10 05:52:38 PDT)

[cal40john]

I've never used the wheel pilot, I have the 4000 tiller version. The controller drives the motor until it reaches the limit of travel and the motor stalls out. After a few seconds I can hear the motor turn off. I assume the controller has a sensing resistor in the path and when the motor draws enough current in the locked rotor condition, the controller shuts down. IIRC it periodically tests by turning on the motor again for a short period. I believe it does this for the times when there is too much helm and it stalls out not at the end of travel but before, so if the helm load decreases it tries again later to try to put the helm farther over.

I believe that the control heads are the same, so I would have to guess that the motor should stall out before tearing anything up. Could it be that your belt isn't tensioned enough so it jumps cogs which tears up the belt?

John

[jonathanteller]

I see. In that case I'll just have to be more attentive not to broach the boat. I'm not going to spend money on a rudder sensor if it won't solve the prob. besides she sails great on auto pilot without a rudder sensor

[Chief Engineer]

If you refer to the manual...I believe there is an adhustment that can be made.

If you are allowing the vessel to fall off 90 degrees....you are expecting too much from this unit

[CalypsoP35]

Hi all, I know this is an old thread but, but I also have a belt issue with the ST4000 and thought I would revive the thread. My problem is that when the autopilot is disengaged (both the latch is in the off position and the auto pilot is in the standby position) the belt continues to catch and makes it difficult to turn the wheel and when the whee does turn it often makes a rattling sound as if the the belt is being dragged over the gear.

I've tried installing a new belt and cleaning the inside wall of the autopilot wheel. The next thing I'm going to try is to sand the inside wall of wheel on which the belt touches with fine sandpaper. I don't want to lube it because of course this where the belt gets traction when it is engaged. Has anyone else had this issue?

Obviously it's an old piece of equipment and the plastic is worn and the fit of the wheels that track the inner plastic wheel with the outer casing that is attached to the wheel are worn. But when I put it back together without the belt the inner plastic turn very freely within the outer casing.

Any thoughts, experience or ideas would be appreciated.

[Capn Dan]

Some brands of belts are just too stiff and they will cause the problem that you are describing. They have a problem making the tight bend around the drive gear and the two adjacent rollers. The result is that they catch on the drive gear.

You can also loosen the belt cam and that might help. Make sure that both rollers next to the drive gear are free and rotate easily.

[henryv]

I have had the same issue but I simply spray the drive with a little silicone lube and it goes away. The belt has contact over such a large surface that the lube does not appear to prevent it from doing it's job when engaged.

[CalypsoP35]

I didn't think the belt moved within the gear and roller mechanism, even when not engaged. I just assumed it was not sliding properly over the plastic housing.

You did give me something else to consider. The belt I had in there originally is the same as the belt I tried replacing it with. The old belt worked well when I bought it a couple of years ago at which time I bought a back up belt. So I suppose both belts could be hardening with age at the same rate and becoming equally less plyable.

I'll see if I can adjust the mechanism, and if that doesn't work I'll try ordering a fresh belt. I may also try flexing the new belt to see if I can make it more plyable.

Thanks for the input Capn Dan.

[CalypsoP35]

Originally Posted by henryv

I have had the same issue but I simply spray the drive with a little silicone lube and it goes away. The belt has contact over such a large surface that the lube does not appear to prevent it from doing it's job when engaged.

OK, I guess that settles it, I need to focus on getting the belt to move within the drive mechanism and not worry about the plastic wheel housing. Thanks HenryV

[Capn Dan]

You are correct that the belt should not move when the wheel is disengaged. The "catching" you described is probably the belt moving when it shouldn't and bumping across the gear teeth.

I have replaced new belts in drives that had this "catching" and have solved the problem. The silicone trick may work as well and costs less!

[senormechanico]

I had the same problem with catching a couple of years ago.
It was a combination of a new belt which had been folded in its bag when purchased.
It was solved after a few applications of silicone spray on the wheel drive surface.

[wstu]

When you say wheel drive do you mean the gear that is on the end of the motor that extends into the wheel housing. Also, I need a belt for a 1992 year unit and have no idea whether to get the D169 or the 36014 belt. Any help would be appreciated

[Therapy]

I would start with cleaning and then go to the cam adjusment.

Solved it for me.