Derek,
I'm curious to know what exactly happen with your steering - it was not clear from your email if in fact the steering cable broke - have you had a chance to inspect and determine the exact cause?
Steering
Moderator: Jim Walsh
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Derek Matheson
- Posts: 52
- Joined: Sep 21st, '06, 08:07
- Location: 1981 CD28 #282 Gaelic Gal
What broke on the steering wheel
Mark:
We went sailing this weekend and used the tiller, instead of spending a beautiful day trying to fix the wheel. I will take an afternoon off this week and try and find what broke and post the results here. I am curious too, being a mechanical engineer by training and practice.
Derek M.
We went sailing this weekend and used the tiller, instead of spending a beautiful day trying to fix the wheel. I will take an afternoon off this week and try and find what broke and post the results here. I am curious too, being a mechanical engineer by training and practice.
Derek M.
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Derek Matheson
- Posts: 52
- Joined: Sep 21st, '06, 08:07
- Location: 1981 CD28 #282 Gaelic Gal
What broke on the wheel
OK, here's what happened on the wheel.
The wheel shaft has a cast bronze sprocket mounted in the middle of the binnacle. It is pinned thru the shaft. A stainless steel chain wraps over it. The chain is about 12" long and connected at each end to ~3/16" cable that goes to the rudder mechanism via pulleys, etc.
This chain jumped off the sprocket as there is no guard to prevent this. It could, so it did. As the wheel is cranked hard over (about 40 lbs force on the edge of the wheel) the chain rides up and over at the transition to the cable, which is covered in plastic tubing. I recreated the failure a couple of times. This is not a manufacturing or setup problem, but appears to be a design problem, but I will study it further and see if there is a solution.
The wheel shaft has a cast bronze sprocket mounted in the middle of the binnacle. It is pinned thru the shaft. A stainless steel chain wraps over it. The chain is about 12" long and connected at each end to ~3/16" cable that goes to the rudder mechanism via pulleys, etc.
This chain jumped off the sprocket as there is no guard to prevent this. It could, so it did. As the wheel is cranked hard over (about 40 lbs force on the edge of the wheel) the chain rides up and over at the transition to the cable, which is covered in plastic tubing. I recreated the failure a couple of times. This is not a manufacturing or setup problem, but appears to be a design problem, but I will study it further and see if there is a solution.
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
Steering Failure
Hi Derek,
From what I read in your report, my first thought is that the length of the SS chain is too short.
When you turn the wheel hard over and the rudder mechanism reaches it's stops, arbitrarily 45° port and stb'd, there should still be sufficient chain available over the sprocket. I think that the juncture of the chain/cable should never reach the sprocket when hard over.
The chain would have to be lengthened and the cables shortened proportionately. Be aware that if there is any mechanical advantage of the wheel in relation to the rudder swing, an allowance for the new length of the chain must be reckoned with.
Good luck,
O J
From what I read in your report, my first thought is that the length of the SS chain is too short.
When you turn the wheel hard over and the rudder mechanism reaches it's stops, arbitrarily 45° port and stb'd, there should still be sufficient chain available over the sprocket. I think that the juncture of the chain/cable should never reach the sprocket when hard over.
The chain would have to be lengthened and the cables shortened proportionately. Be aware that if there is any mechanical advantage of the wheel in relation to the rudder swing, an allowance for the new length of the chain must be reckoned with.
Good luck,
O J
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Al Levesque
- Posts: 295
- Joined: Feb 6th, '05, 09:00
- Location: Athena CD33 #94 Salem MA
In our boat the rudder reaches the stops in each direction before we run out of chain. Could the cable and chain be off center so that one of the rudder stop points is not reached. Our rudder stop is a short piece of pipe that juts down through the spokes of the wheel sector attached to the rudder post.
Wheel Steered CD28
OJ and Al are correct. Your chain in the binnacle may be too short, and you may be missing a stop pin on the rudder shaft.
The chain may also be off center.
On my wheel steered CD28 if I turn the wheel far over either direction, the quadrant on the rudder shaft hits a stop pin, and the wheel stops turning. The chain in the binnacle should be long enough, and centered on the sprocket, so the cable doesn't have the opportunity to approach the sprocket in the binnacle from either direction.
Have you got a stop pin? Is the chain long enough? Is the chain on center?
Best,
John Ring
CD28 #241 Tantalus
The chain may also be off center.
On my wheel steered CD28 if I turn the wheel far over either direction, the quadrant on the rudder shaft hits a stop pin, and the wheel stops turning. The chain in the binnacle should be long enough, and centered on the sprocket, so the cable doesn't have the opportunity to approach the sprocket in the binnacle from either direction.
Have you got a stop pin? Is the chain long enough? Is the chain on center?
Best,
John Ring
CD28 #241 Tantalus
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Derek Matheson
- Posts: 52
- Joined: Sep 21st, '06, 08:07
- Location: 1981 CD28 #282 Gaelic Gal
Wheel failure
OJ, Al and John:
You all give great advice. Now I will not have to think so hard.
The chain is about 2" off center, which contributed to the failure. I think I have to fix this by adjusting the cable clamps. This is the first step.
On reflection, the chain is probably long enough, as the wheel will swing the rudder 45 degrees one way and 90 degrees the other, until the chain ends. I didn't notice this before.
There is not a positive rudder stop that I noticed. I think this is the real problem. I will now stare long and hard at the quadrant and try to find the stop pin that John describes. If there isn't one, then I will have to make one.
Gentlemen, with your help, I now have a course to follow.
Thank You All,
Derek M.
You all give great advice. Now I will not have to think so hard.
The chain is about 2" off center, which contributed to the failure. I think I have to fix this by adjusting the cable clamps. This is the first step.
On reflection, the chain is probably long enough, as the wheel will swing the rudder 45 degrees one way and 90 degrees the other, until the chain ends. I didn't notice this before.
There is not a positive rudder stop that I noticed. I think this is the real problem. I will now stare long and hard at the quadrant and try to find the stop pin that John describes. If there isn't one, then I will have to make one.
Gentlemen, with your help, I now have a course to follow.
Thank You All,
Derek M.
CD28 Quadrant View
[img]http://i182.photobucket.com/albums/x105 ... istal5.jpg[/img]
As I recall, my stop pin is a steel tube welded onto the red cross brace you see behind the quadrant. The rudder post, is of course directly in the way, so it can't be seen in this photo (best I could do on short notice. And no, the socket set case and scrap vent hose are not stored there when the boat's in the water)
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The stop points straight down into the opening in the quadrant, and limits the quadrant travel. The stop is not attached to anything on the bottom, but does have a rubber coating on it to soften the feel of making contact.
If all is adjusted properly, you should have the same amount of rudder travel in each direction, and hit the stop on each side well before you run out of chain in the pedestal. And of course, the chain should be right on center.
Best,
John Ring
Wheel Steered CD28 Tantalus
As I recall, my stop pin is a steel tube welded onto the red cross brace you see behind the quadrant. The rudder post, is of course directly in the way, so it can't be seen in this photo (best I could do on short notice. And no, the socket set case and scrap vent hose are not stored there when the boat's in the water)
.The stop points straight down into the opening in the quadrant, and limits the quadrant travel. The stop is not attached to anything on the bottom, but does have a rubber coating on it to soften the feel of making contact.
If all is adjusted properly, you should have the same amount of rudder travel in each direction, and hit the stop on each side well before you run out of chain in the pedestal. And of course, the chain should be right on center.
Best,
John Ring
Wheel Steered CD28 Tantalus
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Derek Matheson
- Posts: 52
- Joined: Sep 21st, '06, 08:07
- Location: 1981 CD28 #282 Gaelic Gal
Steering quadrant stop
John:
OK, I get it. The stop is a 'peg' that pokes throught the open section in the bronze quadrant. That makes sense, and should be an easy fix.
Thanks,
Derek M.
OK, I get it. The stop is a 'peg' that pokes throught the open section in the bronze quadrant. That makes sense, and should be an easy fix.
Thanks,
Derek M.