Clunk ... Aaahh! ... Crunch

markpierce said:

Who would thought the universal joints would come apart? Seems the pins all came out. I am presently tied up at home for the next couple of days while a new heater and air conditioner is installed. Won't get back to the boat 'til the end of week.

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I can't visualize what "pins" you are refering to, is it the needle bearings from the cups?
Steve W

RickB said:

If it is made of two or more parts assembled by humans or machines and is subject to movement, vibration, temperature changes, or manipulation - intentional or otherwise - it will come apart sooner or later.

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I would have thought "later" to be the operative word. The other year the U-joints in my 1987 BMW 635 were so worn out that they were allowing the drive shaft to move around enough to contact a heat shield mounted just above it. Obviously continuing to drive it this way would resulted in their complete failure. But I ws amazed at how messed up they coud be and still function. Which is why the failure of Mark's driveline is such a surprise. I assume it's still under warranty?

Marin said:

Seems very odd that at the low rpms we're talking about here that the forces would be great enough to break them or throw them out of their housings.

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My WAG, having only seen the parts in a picture smaller than an avitar, is that it was "infant mortality" and probably related to incorrect or incomplete assembly and has been failing for some time. It should be a warranty issue if there is such a thing on a Chinese boat.

Based on recent experience with another brand new Chinese built 100 foot trawler style boat, I wouldn't touch one with a 100 foot pole unless the importer has a very very good service department and is willing to send techs wherever the boat is at no cost to the owner.

I'll be delighted to tell that story as soon as the lawyers have filed the papers and it becomes public domain.

Steve said:

I can't visualize what "pins" you are refering to, is it the needle bearings from the cups?
Steve W

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Sorry, "pins" was my description of the bearing bearing (doubling intentional) cross piece.

Those units are just like normal universal joints for the most part but some have machined and ground "pins" that fit into the bearing cup that fits tightly in the yoke and holds the bits together.

Others use a bolt through the center of the bearing assembly and fasten to a stubby version of the cross. The outer end of that type of bearing forms a "hat" that seals the bearing and snugs up against the yoke.

Sorry, "pins" was my description of the bearing bearing (doubling intentional) cross piece

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Sometimes referred to as "spider" by the perfomance car and truck folks.

A marine mechanic will visit the Coot Thursday to assess the situation. Builder will provide parts, including a new shaft section, if necessary. One possibility is that the shaft wasn't properly balanced or became unbalanced.

Mark, did those joints have grease fittings or we're they the non-greased type? Curious...

Ray, by the smudges on my hands, I'd say they're greased.

Knowing how the tides can really move their your guardian angel was kind.

MARK - - >

KEEP A CHECK-UP SCHEDULE ON EVERYTHING!

I'm very pleased this mechanical mishap worked out relatively OK for you. Here's to wishing you safe sailing days ahead!

Pictured is a typical automotive/agricultural u-joint. There are two types of retainers shown, the split ring with holes in the end tabs and the split ring without holes.

The bearing cups are removed from the ends of the cross, the cross inserted into the two yokes, and the bearing cups inserted/pressed into the yokes from the outside. Inside the bearing cups are needle roller bearings. After the cups are pressed far enough into the yokes, the split rings are inserted into grooves to hold the bearing cup in place. If a needle falls away from the cups outer wall, it can lodge in the bottom of the cup,preventing the cup from seating. If that happens, the split ring cannot seat in its groove. It is easy for the assembler to knock a needle loose and it cannot be seen. The needles are held in place during assembly by the grease that lubes the bearing.

While assembling these is a simple process, it must be done correctly or the snap ring is thrown out and the bearing cup follows.

psneeld said:

interesting we were just discussing this very same setup in another thread....I'm guessing the same setup that reduces vibration.

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Talking to the mechanic, the set-up reduces the transmission of vibration so one doesn't/hardly notice a vibration issue/problem.

markpierce said:

Talking to the mechanic, the set-up reduces the transmission of vibration so one doesn't/hardly notice a vibration issue/problem.

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Nah...I screwed up..I forgot the Aquadrive system uses CV joints as LarryH pointed out...though I'm sure the have their issues in the marine environment unless inspected regularly also.

Here are some pictures. Three clips and bearing caps fell apart, and three more were working their way out. The shaft and the universal joints will be sent to a shaft shop for repair. One of the yokes on the rear universal is slightly bent, and the forward universal needs to be removed from the transmission for closer inspection.

Holy Cow. Glad it came out "okay" (relatively) and your builder is stepping up and making things right.

The builder is sending a replacement shaft assembly.

Mark

I was under the impression old style multi piece and needing lubrication interval Universal Joints (very similar to the pictures...of which I’ve had many on trucks and cars of yester year) were pretty much replaced by sealed unit fully lubricated Constant Velocity Joints. Any chance your boat builder can supply you with improved drive line joint mechanisms? Just a thought!?!?

Art said:

Mark

Any chance your boat builder can supply you with improved drive line joint mechanisms? Just a thought!?!?

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No. Upgrades are my responsibility.

Was backing into my slip with curret and wind fighting me a few years ago with my Amberjack when i felt it was the right moment i did hard aft then shifting to forward shot the fuel to it again only to learn the shift cable had broken, so i slammed the dock with the swim platform at a pretty good speed , crunch and slam the floating docks were shaking and everyone staying on their boat for the week end was outside trying to see what happend, we all ducked below and turned off the lights for 20 mins then went sneaking out after pushing what was left of the the swim rack out from under the floating dock, It happens.

On my Drag cars we had drive shaft loops that were nothing more that stainless steel hoops that were a inch or so from the shaft so in the event it became unleashed it keept it inside those. they were bolted and removeable for service.

The replacement shaft has arrived in the USA, in New York City! Another week to get here (Martinez, CA)?

Good Lord! That's a month since your crunch. You could have smelted the steel and built one in less time.

bobofthenorth said:

Good Lord! That's a month since your crunch. You could have smelted the steel and built one in less time.

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or just driven over to Kevin's Prop Shop and Driveline in Antioch with the old parts.

RickB said:

or just driven over to Kevin's Prop Shop and Driveline in Antioch with the old parts.

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That would be what they call "local knowledge". Lecuyer Welding in Nipawin could do it too but the freight might be prohibitive.

Meanwhile, the Coot is my "cabin." Perla and I are meeting tomorrow for lunch on the Coot, and among the goodies is home-made peach ice cream (peaches grown in Perla's yard).

But thanks for the sympathy!

RickB said:

or just driven over to Kevin's Prop Shop and Driveline in Antioch with the old parts.

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That's a thought! Then I'll have a spare.

Universal joints MUST be installed "in phase".

The yokes must be in a proper relationship to each other in order to survive.

Look at an auto site to see the proper relationship.

In addition the drive and driven parts must be parallel to each other .

Perhaps the normal install requirements were unknown or ignored , causing the early failure?

FF

FF said:

In addition the drive and driven parts must be parallel to each other .

Perhaps the normal install requirements were unknown or ignored , causing the early failure?

FF

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They don't have to be in parallel. If they have an angular misalignment the centerline of the shafts must intersect at the longitudinal center of the Cardan assembly.

You are probably correct in that no one knew, no one inspected, and no one really much cared.

I just looked at a Chinese built boat where the overhead lighting was installed by using a large diameter hole-saw to drill through the overhead paneling ... all the way to and through the deck beams above.

It is a real gamble buying a Chinese boat without having knowledgeable oversight at every stage, on site, with the power to enforce standards. The boat described was built under Class supervision but the damage was done when no one was looking. Even a Class surveyor will not remove light fixtures unless he or she suspects something is hidden by them. Caveat emptor.

This post won't apply to this particular type of coupling, but might be helpfull anyway. If the coupling uses "aircraft locknuts", the kind with nylon inside, you should keep an eye on them. The transmission/shaft coupling on my other boat has these and I noticed they come loose eventually due to the engine vibration. It appears these are single or limited use items and should be changed out when they start vibrating loose. Because of this I have installed new ones and now include inspection of this area in my regular maintennance schedule.

Good point, Avalon. To take it a step further, the best would be safety wired bolt and nut to physically restrict both components from rotating loose.

While this image is not an example of an aviation quality safety wire job, it illustrates the concept.



Here's how an aviation spec'd job looks. Notice the wrap density and no snag ends exposed.