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RRS_Dave

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Reply with quote  #1 
Has anyone ever balanced crane brake wheels in situ? If so, what weights did you use and where do you palce them? Inside the drum with stickum?

D
ivibr8

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Reply with quote  #2 
RRS_Dave
Well that's an interesting question.

One of my "side jobs" before I retired was as the L&H engineer and I never even thought that a crane brake wheel would need balancing. The ones I worked on never got up to any speed that would even require balancing.

 Can you elaborate why you have the concern?

Jim P
RRS_Dave

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Reply with quote  #3 
I had a customer call and wanted to know if I could balance the brake wheels on one of their high cranes. I asked if they were sure it was the crane wheel and not the motor, and he said, no, it was the brake wheel that needed balancing. I'm not sure how they determined that.[confused]

I'm not sure what I'm getting into, as sometimes this customer is squirrely, but I told him that if it rotated and balance was the problem, then I could do it.
Then I got to thinking about what I was going to use for weight (been a long time since I've had any need for dyno weight) and how I was going to attach it.
Not sure, but the job was supposed to be next week, and he called today saying the furnace went down yesterday, and they wanted the crane work done tomorrow.
I guess I'll see what it is I've gotten myself into. I told him he had to have a young stud there if I had to climb any ladders carrying anything. I've lost interest in that[biggrin]

D
Walt Strong

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Reply with quote  #4 
Dave,
I have not balanced a brake drum, but I have balanced air clutch drums on a tugboat. If there is an inside surface to work with, then I would probably use stick-on wheel weight strips. I would be concerned with the brake generating heat that could deteriorate any adhesive. You might consider a high temperature epoxy or use welded steel weights for the permanent fix after using temporary weights. I think the hard part of the job will be to climb up to the crane and to keep from looking down!

Walt
RRS_Dave

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Reply with quote  #5 
Well, I went and saw what they had. High lift crane, 200 ton with 60 ton aux. They had changed out all brake wheels, shoes, actuators, electrics, etc. Refurbished the brake system. But whoever bought the parts, did not have the wheels balanced (said they saved money. I told them wait till they get my bill, then do the calculations) so they wanted them balanced in place. First wheel they turned on (Auxiliary hoist) was obviously not turning concentrically about the center. Put a dial indicator on it and read 0.035" radially TIR and 0.040" axially TIR on the face. Told them wheel was cocked on the shaft, they said couldn't be, tapered shaft and they put it on with a 1-1/2" torque wrench. Three people, one holding the socket on, one holding the handle (a 4' piece of pipe) and one running the trigger, it can't be cocked. Well, whatever, I can't balance it. Balance only cures unbalance.
On to next one, main hoist. This one has the motor driving a gear box off both sides, with brakes between the motor and gearbox. I can see we're not going to go anywhere with this, but I hook up with a two plane balance, and we run it up on third point, 1200 RPM. Twice. I get 0.200 mils @ 1212 RPM and 0.411 mils @ 1215 RPM. The supervisor says he can live with that. I'm glad, cause I don't think I had a chunk of steel that would fit inside that wheel that would have made a big change across those two gearboxes[biggrin]
During this time I convinced them to take the aux. brake wheel off and take it to machine shop to have bores checked. They agreed, and that's when I learned that the wheels had come with a pilot hole in them, and their machine shop had bored the tapers. I know their machinists, and they are pretty picky, so I was scratching my head trying to figure out what the problem could be, because I just didn't think they could be that far out, but who knows.
As I'm packing up, one of the machinists crawls up on the girders and told the guys who were going to try and bust that 2-1/2" nut loose with a breaker bar "I told XX that the keyway on the inside was not deep enough. He didn't have that bore plumb when he cut that key way. I'll bet that's what it is.
I kinda bet the same thing now.......I shook hands, wished them luck, charged them a day and came home.

D
RustyCas

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Reply with quote  #6 
I've had a few of those over the years.... "You want to do what? Why?" Usually there is a way to either do it, or as you did Dave, prove it didn't need to be done.

Dial indicators are wonderful tools. Too bad few folks know how to use them. I only have one or two customers who even have a machinist anymore, so just having measurement tools gets me quite a bit of work. Another really handy tool is a smaller mag base drill with annular cutters to recut holes in the base when a motor is bolt-bound. I've never seen one besides mine on a job. Seen the big ones, with just a drill bit, but they're useless when you need 1/2 a hole more (and I will not let them use a torch - I just say No!).

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RRS_Dave

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Reply with quote  #7 
I have a larger Milwaukee mag drill with all sizes of annular cutters. I modify a lot of bases for two customers. They are slowly both getting rid of older Reliance motors, and buying new for replacements. Most of the new motors have a different footprint. Hard to find a 700 HP motor in a small frame size like they used to do.
Only problem with mine is it is heavy. I need one of the smaller slugger's for carrying around. They beat a drill bit all to heck. I'm not even sure how you would drill a 2" hole in a 1" plate in the field without one.

D
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