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Old 02-19-2018, 09:40 AM   #1
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Shear pin keeps shearing

I just replaced the motor on my maxwell 1200, 12v electric windlass. In one week I have shaeared the shear pin twice. The first time I was pulling the anchor and just as it cleared the bow roller the pin broke. Half a day later, because of bad access, I was able to replace the shear pin. The pin broke the second time while I was setting the anchor. As I have done on every boat I owned, I dropped the anchor and then backed down on it to make sure it was set. The anchor was set and I would forward to put on a snubber line. When I try to put slack in the chain, I found the shear pin again broken.

The shear pin goes through the motor shaft and aligns in a slotted shaft in the gear housing.

I had anchored with this windlass many times before the motor required replacement. For two years I never had a problem, and then now. The shear pin is a split, spring pin that is hollow and compresses as it is driven into the hole. I am thinking of replacing the spring pin with a solid pin.

Has anyone experienced similar issues?

I am in Marsh Harbour the Bahamas and getting parts here is difficult. I was able to find similar shear pins in an auto parts store, but it broke like the first on.

Other info: using 3/8ths bbb chain and 60 pound Manson Supreme anchor. I always drive up on the anchor, never pulling the boat with the windlass. Backing down on the anchor with my 50k pound boat obviously broke the pin. However, I have used this procedure for two years with this boat, and for more than 20 years with previous boats, to include charters, with no issue. And backing down a n the anchor does not explain the first breakage.

Anyone have sage advice?

Gordon
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Old 02-19-2018, 09:55 AM   #2
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I just replaced the motor on my maxwell 1200, 12v electric windlass. In one week I have shaeared the shear pin twice. The first time I was pulling the anchor and just as it cleared the bow roller the pin broke. Half a day later, because of bad access, I was able to replace the shear pin. The pin broke the second time while I was setting the anchor. As I have done on every boat I owned, I dropped the anchor and then backed down on it to make sure it was set. The anchor was set and I would forward to put on a snubber line. When I try to put slack in the chain, I found the shear pin again broken.

The shear pin goes through the motor shaft and aligns in a slotted shaft in the gear housing.

I had anchored with this windlass many times before the motor required replacement. For two years I never had a problem, and then now. The shear pin is a split, spring pin that is hollow and compresses as it is driven into the hole. I am thinking of replacing the spring pin with a solid pin.

Has anyone experienced similar issues?

I am in Marsh Harbour the Bahamas and getting parts here is difficult. I was able to find similar shear pins in an auto parts store, but it broke like the first on.

Other info: using 3/8ths bbb chain and 60 pound Manson Supreme anchor. I always drive up on the anchor, never pulling the boat with the windlass. Backing down on the anchor with my 50k pound boat obviously broke the pin. However, I have used this procedure for two years with this boat, and for more than 20 years with previous boats, to include charters, with no issue. And backing down a n the anchor does not explain the first breakage.

Anyone have sage advice?

Gordon
I think you might do better asking the windlass manufacturer directly.

The shear pin is designed to protect the windlass. A solid pin disables that protection and if there's a problem, something more expensive will break.

Also, the shear pin you find in an auto parts store may not be the same as the original. Replacing the pin with the manufacturer's part may solve your problem. Again, contact them.
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Old 02-19-2018, 10:07 AM   #3
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A roll pin as they are called are generally not used as a shear pin as you have a clutch for the purpose of overload. My guess is you have something binding in your gearbox causing the roll pin to break. Try separating the motor and gearbox and no chain on sprocket and see if gearbox turns easily.
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Old 02-19-2018, 10:32 AM   #4
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I should have said that I did contact the manufacturer. The US representative had no great ideas. He suggested that I look for binding in the gear housing. Because the anchor pays out so easily, he thought that was probably a low percentage issue. Also, I never had this problem with the old motor. I swapped the motor because it begin dragging. After removing and troubleshooting we learned that there was some internal shorts in the motor that were unrepairable here in the Bahamas.

I suspect that perhaps that Maxwell Might have received substandard pins. I wish I had saved the old motor and I could have remove that pin and re-used it.
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Old 02-19-2018, 12:14 PM   #5
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If this began after replacement of the motor, then I would look there. Perhaps the fit of the motor is different such that when you bolt down the motor it is crushing or partly sheering the sheer pin? I would be looking for some sort of interference in the motor fit.

The only other explanation would be that there actually is an internal gear box issue that caused the old motor to just slowed down, where the new one is pushing past the resistance to the point of breaking the sheer pin. I'm not sure how to test for such binding other that rigging up some sort of hand crank in place of the motor, and cranking by hand.
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Old 02-19-2018, 12:27 PM   #6
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Is it correct to assume you replaced the motor in kind with matching OEM?
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Old 02-19-2018, 02:25 PM   #7
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What you describe does not sound like a shear pin but a spring or roll pin used to hold a gear in place on a shaft.
The designers would not have expected there to be enough load to shear the pin so you need to find the source of that load.
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Old 02-19-2018, 04:10 PM   #8
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Yes

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Is it correct to assume you replaced the motor in kind with matching OEM?
I replaced it with a Maxwell replacement motor
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Old 02-19-2018, 04:33 PM   #9
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One standard rule of troubleshooting is that if something was working OK and then you worked on it and now there's a problem, the first place to look is at the work you did.

SO - If the windlass was working until the motor failed and never broke the pin but since you replaced the motor it's been shearing pins, I would be checking the installation of the new motor. Alignment, binding, etc.
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Old 02-19-2018, 05:00 PM   #10
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I can’t see a roll pin as being substantial enough to pull a 60# anchor with unknown weight of chain, or to back down on to set anchor. Roll pins typically just hold gears or parts in place.
Maybe you could get a spec on the torque value that it should shear at?
I’d pull the whole thing apart , inspect, clean and grease, and then put it back together making sure everything meets specs (no parts worn out).
Maybe the new motor is stronger than the old one, I see that on some replacement starter motors.
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Old 02-19-2018, 06:31 PM   #11
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Could you post a picture ?
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Old 02-19-2018, 09:09 PM   #12
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All ok

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Originally Posted by aboatman View Post
One standard rule of troubleshooting is that if something was working OK and then you worked on it and now there's a problem, the first place to look is at the work you did.

SO - If the windlass was working until the motor failed and never broke the pin but since you replaced the motor it's been shearing pins, I would be checking the installation of the new motor. Alignment, binding, etc.
Motor alignment is impossible to screw up...literally. Two bolts hold it on. The shear pin on the shaft either,fits into the end of the worm drive shaft, or it doesnít.

Hordon
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Old 02-19-2018, 11:36 PM   #13
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I'm having a bit of a problem visualizing the connection between the motor shaft and the gear, but if its like I'm thinking, if the slot that the gear end gets worn, it can try and kick the pin out. Since that pin is inserted in the shaft, it can get in a bind. I have a smilar issue on a slide for a motorhome and once that connection starts getting worn, it can go through pins pretty quickly.

good luck

toni
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Old 02-20-2018, 12:29 AM   #14
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Somehow, the motor is the greatest suspect. It worked before the new motor. I don't see how it could be anything else.

While there may be no obvious alignment, there could be enough play in the bolts to allow a bind on the motor or gear box if the bolts aren't taken up together.
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Old 02-20-2018, 05:56 AM   #15
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"As I have done on every boat I owned, I dropped the anchor and then backed down on it to make sure it was set."

Almost every windlass mfg sez to never anchor the boat to the windlass , just use it to lift the gear , After it is broken out.

Perhaps a bit too much reverse to "set" the anchor ?
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Old 02-20-2018, 06:49 AM   #16
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Perhaps a bit too much reverse to "set" the anchor ?
Or at least set the cog wheel lock AND the bridle before applying strain, whether backing down or allowing from Mother Nature.

But I'm ignorant on purpose and design for Maxwell's shear pin. Thanks for post Gordon, I didn't know one even existed. Does on deck anchor load shear it or something else?
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Old 02-20-2018, 08:28 AM   #17
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................ Almost every windlass mfg sez to never anchor the boat to the windlass , just use it to lift the gear , After it is broken out.
Yea, I posted that in another thread and people gave me grief over it.

You're right though, the windlass is designed just to lower and raise the ground tackle, not for holding the boat or backing down.
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Old 02-20-2018, 09:22 AM   #18
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Gordon,
Long shot: not all roll pins are created equal.
Most are single wall construction, but I have also spec'd 3-wall "coiled" pins that have a lot more shear strength than the single wall pins (back when I was a machine designer.)

Given where you are, I am wondering if you could DHL-in a bag of pins from McMasterCarr or some place like that.
https://www.mcmaster.com/#roll-pins/=1bnifcy
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Old 02-20-2018, 09:33 AM   #19
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I'm with Gone Farrell on this one, maybe the pins you're using are too soft ..? Failing that, perhaps there is a wobble of sorts that eats into the pin ....... FB
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Old 02-20-2018, 11:11 AM   #20
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Actually

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Yea, I posted that in another thread and people gave me grief over it.

You're right though, the windlass is designed just to lower and raise the ground tackle, not for holding the boat or backing down.
I saw a YouTube video from the windlass manufacturer in which they also used the windlass when backing down. They only secured the windlass to a cleat after they knew the anchor was set.

I am in a marina in the Bahamas with about 50 other long-term trawler owners. I asked several of them how they set the anchor. They All back down on the anchor before attaching the bridal. Into years of owning this boat I never had an issue until I swapped the motor. It is the right motor. It is for sure installed correctly.
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