Calling all engineers…I’ve got to pull & replace cutless bearings on a tug this spring. This project will be a first for me & the crew I’m dragging along to help. I’m in the middle of researching online and calling a few trusted cohorts about it & figured that this forum could be a good resource as well. Just looking for procedures & any tips that might make the job easier. We’re going to be working out of a remote location, my goal is to be as prepared as any newbie can be. I’ve replaced split flange and staves before, just not this type.
A few details.
we still need to remove the props & shafts
the bearings are Duramax flanged bearings, both the stern tube and strut. There are no screws to seat the bearings, I believe they are chockfasted in place.
shaft is 4", the bearings are 16" long, OD of 5.25" @ about 35lbs apiece. This tug is triple screw, so I figure by the 6th one, we’ll be experts.
I’m interested in any and all thoughts in regard to procedures, tools…etc for removal, alignment & installation. I’m also looking for a Mate…(towing endorsement a must), but that’s for another day.
As a general rule you get a rosebud, burn out the rubber, then use a long torch to cut a wedge out of the bearing and pull it. Keep the brass for scrap and use it to buy beer for the guy who runs the torch when the project is done.
Clean up the inside of the tube and strut bearing with a flap wheel on a long nose die grinder.
get your machinist to check the dimensions and finish the od of the bearing accordingly.
This installation manual tells you the rest of the steps: http://www.duramaxmarine.com/pdf/FlangedBearingInstallation.pdf
Classed boat or not? Regardless, if you are pulling the props and shaft, you should check the taper fit of the props, as well as the condition of the bearing journals on your tailshafts (are they shrunk fit liners, clad welded, weardown? Looking at the dimensions that you posted, I am guessing that the tug isn’t classed, however the above items should be checked, anyway. If the shafts are solid and without liners/cladding at bearings, it would still be worth your time to have a look at the condition of the journal areas, and maybe even do some NDT (dye penetrant at the minimum) to look for any surface fractures. What kind of seals? If they are stuffing boxes, then also check out the condition of the shaft in way of the stuffing boxes. You should also have a look at the run out of the tailshafts, as well as checking the alignment of the bearings before reinstalling the shafts. Also, don’t make up the coupling flanges until the tug is afloat and make a final check of the alignment at that time. . .
I was given similar advice, being told to cut a wedge. I assumed sawzall for some reason. He didn’t mention a torch. Thanks. I’ll explore this one further, certainly the part about scrapping the brass…should be lots of beer. Thank you for the response.
Cmakin- Tug not classed. We have new shafts on standby, but plan to use the existing ones if the condition warrants. Wheels are good. I need to study up/research the alignment portion of the job…the installed bearings have machined bolt holes, but are not being used. So I’m assuming chockfast was used to secure them. This is the work I’m most concerned about…you know, the part that requires some experience/expertise. Thanks for your response. Much appreciated.