After investigating further it became clear that the drum was not turning freely when the jib was properly tensioned. A hunt around the net suggested that the ball bearings last 4-5 years. This is what the bearings in our drum looked like:
I will describe the parts of the drum and it’s assembly. Disassembly is the reverse and should be simple and low effort. Ours wasn't like that.
Here is an exploded view of the parts of the drum:
I don’t know what the proper names for the parts are so I’ll refer to them as follows:
1. Drum
2. Shackle Pin
3. Standing Part
4. Bush
5. Grub Screw
6. Nut
7. Pin
8. Washer
9. Washer
10. Ball bearings
The first step is to put the bush onto the standing part.
Then the washers can be added
Then the nut can be screwed on until the holes line up and the pin inserted.
Then it’s time to pack the gap between the washers with marine grease. This makes it easy to insert the ball bearings so they stay put.
Pack the inside of the drum with more grease.
Push the standing part, nut first, into the drum and screw the bush in until the hole in the bush for the grub screw lines up with the hole in the drum
Fit the grub screw.
Now fit the shackle pin and we have a fully assembled drum.
Easy. My problems were in the initial dismantling. I tried to follow Moray MacPhail's instructions on the Classic Marine website. I could get the bush to move, but it just jammed against the standing part. If you are servicing a well maintained drum you should have no problems. The bush should just push the standing part out with it. In my case we had to force turn the bush and the standing part around together while holding the drum still with a screwdriver through the shackle ring. It took a lot of force.
My second problem was that the pin was jammed in the nut. I made a punch by filing the threads off a machine screw and forced it out with the punch and a hammer. On my drum and swivel unit the pins are mild steel. Phil Cogdell of Annabel J says his are bronze. If you find steel ones, changing them might be a good idea.
My third problem was that the ball bearings were rusted almost beyond recognition.
My fourth problem was that the washers were both rusty and worst, worn into ridges where the ball bearings had worn the washers.
The washers are not standard. They are thicker than normal washers. The best I can measure them they are 4.5 mm thick. I couldn't find anything to replace them with so I filed them smooth and turned them over so the faces against the bearings were the smoothest ones.
Our gear is size 3. The ball bearings are 7/32”. Finding that out was fun. However, Simply Bearings in Lancashire have an absolutely fantastic web site and delivery service and for the princely sum of £3.59 I had 10 new stainless steel ones within 24 hours. I chose 316 grade stainless as it was advertised as more corrosion resistant than the others and not as hard, which I thought felt right for the application. Having four different types to choose from and all the possible imperial and metric sizes was great.
I also dismantled and serviced the swivel unit. That told me what the experience should be like. It has all the same parts and came apart easily. The bearings were fine – it doesn't get the same exposure to salt as the drum. I re-packed it with grease and reassembled it.
I think the drum should be serviced at least every two years. Possibly every season. The swivel can be left longer, maybe even up to 10 years.
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6 comments:
Hi
Thank you for an interesting article and for the photos of the innards which will help me service my W-M gear.
However, without wanting to be critical, I am not sure about the way that you solved your 4th problem.
"My fourth problem was that the washers were both rusty and worst, worn into ridges where the ball bearings had worn the washers."
These bearings are probably "thrust bearings" (https://en.wikipedia.org/wiki/Thrust_bearing) and the ridges on the "washers" are part of the rings of a thrust bearing which hold the ball bearings in place. These should have been replaced as part of the bearing assembly. I'm not sure that re-using them and indeed reversing them was a good idea as it could create further problems in future with the bearings able to rub against the gear housing.
I understand that the manufacturers of Wykeham-Martin Furling gear, Davey & Co, supply a servicing kit for the W-M gear for between £8 and £12, depending on the size of gear. (http://davey.co.uk/pdf/rigging.pdf) You can also buy thrust bearings elsewhere (eg Simply Bearings) as a complete unit.
Many thanks again
Hi again
I needed to purchase a set of the thrust bearings for myself and I see that Classic Marine does sell them. A bit more expensive than I originally said ... VAT ??
http://www.classicmarine.co.uk/boatstore/product.asp?strParents=0&CAT_ID=0&P_ID=295&strPageHistory=search&numSearchStartRecord=1
Hi, Craig. I knew about the replacement bearings Moray sells and we did plan an expedition to Woodbridge from Lowestoft to get some but it was quite a trek by train and it isn't reasonable to expect the kind of postal turn around from Classic Marine as one gets from places like Simply Bearings.
As you can see from the photo, my bearings were more like grains of coal than ball bearings! What I don't mention in the blog is that to work out what I needed to replace them, I opened up the swivel unit. This was like new. The washers in the swivel unit were smooth with no radial grooves. So I knew filing the grooves off was not wrong. We took the good ball bearings from the swivel along to the local bicycle shops to try and find more. One shop did have some, but they only had 7 in an old box. That is how we knew they were 7/32 and were able to work out what to order.
The photos of the replacement bearings on Moray's site are nothing like what was fitted to my unit. I wouldn't hesitate to use them, I'm sure they are fine.
Thrust bearings like these http://simplybearings.co.uk/shop/advanced_search_result.php?keywords=thrust+ball+bearing are also nothing like what was fitted, but would probably work fine.
I was most concerned to end up with a snug fit with no chance of the shaft wobbling and chafing, leading to more wear. Re-using the old washers with exactly the right size ball bearings seemed the best way to achieve that.
Sorry to drag up a very old post, but I'm refurbishing a W-M #2, and found your blog invaluable.
However, I seem to be having the reverse experience to you.
My drum came apart easily, but the swivel wont budge.
I haven't tried really hard yet, as I cant see any kind of locking screw, as there is on the drum.
Did your swivel have a locking screw, and is there any other wisdom you could share?
Many thanks
David
Hi David, I'm reasonably certain my top swivel has the same grub screw as the bottom but chatting with others I know there is more than one design around so I won't be surprised if yours is different.
It is worth checking though because the grub screw can get hidden under grime so going round with a sharp point might find it.
If you can't find a way in then I'd take it in to an expert. Where are you located?
Another great resource for this kind of thing is the Facebook group 'Gaff Rig Boats Worldwide'. Posting some pictures there is guaranteed to get some great advice.
And just to close this out, my top swivel definitively has no locking screw.
Disassembled it by putting the main body in a collet on a lathe, and putting a couple of hardened pins (drill blanks) into the two holes on the threaded cap.
Cap was pretty tight but eventually came out, revealing the expected knackered bearings.
Once again, many thanks for the original blog post and the prompt reply to my previous message.
David
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