Big Ship Repair Job For Our Shop

[Kracken McGraw]

Do you have galvanized pipe on both sides of the brass cylinder?

No the cylinder(working barrel) is at the bottom of the string of pipe, this is where the water enters.

 

[jackieschmidt]

Tell them the company logo!

 

[linekin]

The coupling end of the shaft has a coupling that fits on a 1 inch in 12 inch taper per foot. We have to “blue fit” the coupling o he shaft just like the prop end.

The coupling has about a 18 inch diameter flange that mates to the reduction gear. The gear manufacturer requires no more than .0015 inch run out on the face of the flange when installed.

her is a picture of the shaft coupling mated to the reduction gear.
View attachment 1341095

.0015 is pretty incredible on that large a coupling. In the recreational boating world on much smaller couplings .003 is the accepted "standard". This is with couplings on shafts 3/4" to 3" with couplings from 4" to 10" or so. At least thats what most shoot for. Getting it that close you will feel no vibration as long as the bearings are in good shape & the wheel is pitched & balanced properly. Tip clearance plays a role too.
Of course these vessels have much less HP (30-600 or so) & much shorter shafts.
.0015 is OUTSTANDING!!!
I realize thats what the gear manufacturer calls for...but gotta wonder what it actually is.

Keith

 

[55fairlane]

Sir, as a machinist & machinery repairman I find this most interesting!
Please post more !

 

[std7mag]

I want one of those hats!
Do you have that on a tee shirt?

Where i work is extremely secretive of their "propreitary proceedures".
We make bulldozer blades & escavator buckets for cripes sakes!

We can take pictures of finished products. But nothing inside the plant. To the point where they monitor our social media. (Yet another reason i'm not unhappy about not having Facebook, Twitter, or Instagram!)

 

[dave@aDave]

Don't forget the one in the water heater of your RV.

There is one in the water heater heater of my house. I replace it about every 3 years

 

[DocCarbon]

I'm getting that now over in the annealing thread . Lol

 

[1lessdog]

Here is the crack in the shaft. We cut it down this far and the fracture was still there.
We can do a repair if the crack is no more than 10% into the core shaft. You can see the thin red die penetrant line still visible.View attachment 1340974

I have die pen and put developer on many strut on Caterpillar mining truck. And seen lots of crack just like you did.

 

[jackieschmidt]

.0015 is pretty incredible on that large a coupling. In the recreational boating world on much smaller couplings .003 is the accepted "standard". This is with couplings on shafts 3/4" to 3" with couplings from 4" to 10" or so. At least thats what most shoot for. Getting it that close you will feel no vibration as long as the bearings are in good shape & the wheel is pitched & balanced properly. Tip clearance plays a role too.
Of course these vessels have much less HP (30-600 or so) & much shorter shafts.
.0015 is OUTSTANDING!!!
I realize thats what the gear manufacturer calls for...but gotta wonder what it actually is.

Keith

The way we insure that the coupling face uncouth is as close to zero as possible is for the final operation on a shaft and coupling assembly we place the shaft back in the lathe and install the coupling on the taper. If there is any runout, we take a very light skin over the coupling face. We then remove it and put it back on and check it. we are shooting for “zero”.

We do this because when the shipyard checks the coupling to gear alignment, they only give you .003 tolerance on the alignment. Insuring that the shaft/coupling assembly left shop dead true is simply removing one more variate ithe equation.

here is a picture of a coupling being checked for the final time in our 38’ American Lathe.

 

[55fairlane]

The way we insure that the coupling face uncouth is as close to zero as possible is for the final operation on a shaft and coupling Assyrian, we place the shaft back in the lathe and install the coupling on the taper. If there is any runout, we take a very light skin over the coupling face. We then remove it and put it back on and check it. we are shooting for “zero”.

We do this because when the shipyard checks the coupling to gear alignment, they only give you .003 tolerance on the alignment. Insuring that the shaft/coupling assembly left shop dead true is simply removing one more variate ithe equation.

here is a picture of a coupling being checked for the final time in our 38’ American Lathe.View attachment 1341725

That is a nice sized lathe...... Lodge & Shipley?

 

[butchlambert]

That is a nice sized lathe...... Lodge & Shipley?

No, American.

 

[jackieschmidt]

No, American.

^^^^^^^
To be exact, a twin carriage American Pacemaker.

We can work 38 feet between centers.

We also have a 32 foot Leehmann, a 28 ft Leblond, and a 28 ft Kingston, plus multitudes of smaller engine lathes.

 

[55fairlane]

^^^^^^^
To be exact, a twin carriage American Pacemaker.

We can work 38 feet between centers.

We also have a 32 foot Leehmann, a 28 ft Leblond, and a 28 ft Kingston, plus multitudes of smaller engine lathes.

I ran a 48 (swing) 15ft between centers LeBlond ....plus a 72 walderich & a 40 inch Hercules....gap bed machines .....I love seeing what your doing...please keep posting

 

[Clous]

I’m fascinated by this!
My first job was rough turning huge freshly forged cranks on an old LeBlond.

 

[jackieschmidt]

I’m fascinated by this!
My first job was rough turning huge freshly forged cranks on an old LeBlond.

We used an old 56” swing by 32’ NR LeBlond for years, but needed more length.
I found the 38’American Pacemaker up in Chicago. We worked out a deal.

here is a picture of them moving the old Leblond out of our big shop, and moving the American in.

 

[linekin]

The way we insure that the coupling face uncouth is as close to zero as possible is for the final operation on a shaft and coupling assembly we place the shaft back in the lathe and install the coupling on the taper. If there is any runout, we take a very light skin over the coupling face. We then remove it and put it back on and check it. we are shooting for “zero”.

We do this because when the shipyard checks the coupling to gear alignment, they only give you .003 tolerance on the alignment. Insuring that the shaft/coupling assembly left shop dead true is simply removing one more variate ithe equation.

here is a picture of a coupling being checked for the final time in our 38’ American Lathe.View attachment 1341725

Last Friday I had a 1" shaft out of a sailboat for cutlass bearing & the o-rings on the dripless shaft seal replacement. I always check the shaft runs true & reface the coupling whenever one is out of the boat. Just SOP.
Most of these smaller vessels engines are not rigid mounted. They sit on flexible engine mounts & have a Drivesaver installed between the couplings. You can get away with a little misalignment with these configurations. As I mentioned, .003 is the acceptable standard & you could probably get away with as much as .010 without any significant vibration. All that in a wood vessel & the owner is in 7th heaven as wood absorbs alot
I'm sure thats not the case in the steel tug/pushboats you're dealing with.
Just out of curiosity whats the reduction on the gears if any?

 

[jackieschmidt]

Last Friday I had a 1" shaft out of a sailboat for cutlass bearing & the o-rings on the dripless shaft seal replacement. I always check the shaft runs true & reface the coupling whenever one is out of the boat. Just SOP.
Most of these smaller vessels engines are not rigid mounted. They sit on flexible engine mounts & have a Drivesaver installed between the couplings. You can get away with a little misalignment with these configurations. As I mentioned, .003 is the acceptable standard & you could probably get away with as much as .010 without any significant vibration. All that in a wood vessel & the owner is in 7th heaven as wood absorbs alot
I'm sure thats not the case in the steel tug/pushboats you're dealing with.
Just out of curiosity whats the reduction on the gears if any?

Reduction gears will have an overall reduction from 4 to 1 to 7 to 1, depending on the input RPM, torque, and ideal prop speed.

A typical 2000 HP twin screw pushboat, that being 1000 on each side, will have a typical engine RPM of 1800 with around a 6 to 1 reduction into a 74 inch diameter x 56 inch pitch prop.

Many of the new vessels we are involved with a this time are from 2400 hp to 3600 hp. surprisingly, many are using the same reduction gear, the Twin Disc 5600 series, as it covers a wide power range.

Twin Disc | Products

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larger vessels with higher torque lower speed diesels will typically use a 4 to1 reduction with a input rpm of around 900 rpm. Of course, you are then swinging a prop of 100+ inches.

Here is a installation we were involved with, the realignment of large Lufkin Gears in a 5000 hp harbor tug. After the shipyard does the alignment, we come in and drill and ream the foundations for body fit bolts, in this case, the bolts being 1 3/4 inches. We make the bolts out of B-7 blanks.

 

[55fairlane]

Holy fright....900 rpm thru a 4-1 gives me 225RPM...and a 100 inch prop turning 225 RPM gives me aprox 6500SFM.....I'm surprised the prop tips don't shear off!!

On those 1¾ bolts....do you roll the threads or just screw cut em?

Aaron

 

[STORM2]

Fascinating! I could spend a week watching.

 

[Sandstorm]

Jackie..looks like you have one fascinating job, and it appeals to the Engineer in all of us.
You could do a Youtube chanel and have a slew of people watching it all day every day.
Thanks for the look at shipyard work.