Bucket truck rotation gear

[squisher]

Ok.

Many of you have probably read of my bucket truck trouble the last week and a half or so here. My rotation pinion gear (the small one that drives the rotation of the booms at the house) broke two gears off under no severe abuse or anything. It's been cold here but nothing ridiculous I was rotating not even with full juice and it jammed up I came right down and it had already broke the two gears off.

So I replaced the entire gear box because it wasn't that much more than just replacing the gear/shaft and I was somewhat suspect of the internals of the old gearbox thinking they could have had something to do with the failure if a bearing or something had worn to much and developed play. Also I hadn't been maintaining the gear lube properly, after careful study of the manual I had been lubing the rotation bearing but not the rotation gear, that I'm thinking was the main culprit in this failure. An expensive lesson to learn in fully understanding all the maintenance that is nescessary on a piece of equipment.

Anywho I got the new gearbox and have it installed. Somehow in the sending of a $3800(by the time it arrived on my door) gearbox no one thought to include any of the special plasti-gage shims that I can't seem to source anywhere around here locally. I have been using plasti-gage for measuring mainbearing journals to help me in my adjustment/set-up of this new gear.

My question is does anyone here have any experience with setting up the 'gear lash' on a rotation pinion for a boom? Any suggestions, tricks, or comments?

I have it set-up to where I finger is the proper tolerances but I've never done this before and can't find/don't know anyone at all local who has any experience with this. My worse nightmare is to have this thing go crunch again. Obviously I'll be monitoring it like crazy the 1st while and on a regular basis afterwards but just thought I'd check with the House to see if anyone has any info.

Thanks,

Justin

 

[lumberjack]

You need plastigage?

You can also use grease (preferably a bright color, they make grease just for this) to check the contact pattern of the teeth.

 

[sotc]

Prussian blue if it is all clean but on something that slow I wouldn't worry about getting that dialed in. Tacky lube in aerosol form is great for that gear set. Good reminder, been awhile

 

[squisher]

I've been using grease, just normal grease to check contact so far.

My boom(versalift vo255) calls for a .002 piece of plastic 2"x5" to be able to pass through the gears without being broken apart while rotating across it with the boom full extended horizontally(upper flipped over 180 and straight out). The piece of plastic they refer to is a 'part' that I could order from them, would've seemed logical to me to have included with the gearbox when it was sent from the factory but heh that's just me. I'm probably overthinking this, but I'm not often accused of that. Lol.

I've been told by what I consider a somewhat unreliable source that paper is .004? Seems to me that it would depend on the paper?

 

[squisher]

Prussian blue if it is all clean but on something that slow I wouldn't worry about getting that dialed in. Tacky lube in aerosol form is great for that gear set. Good reminder, been awhile

In my manual it's quite a procedure to set-up. There is a 'high tooth gear' on the house bull gear, one gear that is slightly higher than the rest and the initial set-up is done off of this. It's supposed to be checked every six months. Apparently all booms have a high tooth gear for this very reason, a hydro guy told me this the other day. In the manual it sites improper adjustment as a cause of premature gear failure or wear.

 

[Reddog]

So it needs to be setup with .003-.004 backlash it sounds like. Do they give a backlash spec in the setup manual?
Use a dial indicator and have someone wiggle the boom back and forth. Adjust in until you only have .003 play.
That was how we adjust large bull gears on stamping presses.

 

[Reddog]

The high tooth should be marked with a stamped symbol or punch mark on the side.

 

[squisher]

Yah I've got the high tooth gear(center punched three times, faint from a decade of being run over but six cans of brake fluid later it was the 2nd to last tooth I cleaned) and I've done my procedure from the manual to get the gearbox set-up. 1st time it seems dead on to me. Also I've run this boom alot so I know the 'feel' of the side to side play while rotating/stopping. It's slightly tighter than it was but it isn't tight in any area all the way around.

Forgive me for being dense but I can't immediately envision the dial indicator set-up as your referring to it? I've never set-up gears like this before. Where or how is the dial indicator set/inserted?

 

[squisher]

So it needs to be setup with .003-.004 backlash it sounds like. Do they give a backlash spec in the setup manual?

It doesn't give a backlash spec, just that the .002 piece of plastic needs to travel through without being cut to pieces so I think you are correct that I'm looking for as close as possible so .003 or .004 like you said.

 

[Reddog]

Most likely would use a magnetic base for it then find a place on the house to check how much play was in the gears(backlash) to the deck. If the house doesn't have anything flat to put the indicator against then just use another mag base to let it hit.

Clear as mud right?

http://www1.mscdirect.com/eCommerce...064&005=6309049992&006=10349786104&007=Search

 

[squisher]

Much clearer than it was, espescially with the link. Thanks for taking the time I will inquire about such gauges at my industrial supplier tomorrow.

So the side to side movement within the gear will be the backlash? Sorry if that question seems obvious, just wrapping my head around this.

 

[Reddog]

Yes like grabbing the boom all the way horizontal and trying to push it back and forth on the house rotation. That play you feel is the back lash.
But you may also get some play from the hydro rotation motor and other gears in the setup. So you need to study it out and make sure your measurements are just the back lash of the gears your setting.

 

[lumberjack]

20 lb copy paper is about 4 thou thick, FWIW.

 

[squisher]

Excellent. With this info and maybe a new gizmo tomorrow as well as hours of endless rotating in all boom positions I think I'll feel confident in the repair!

Thanks Wally!

And thanks for the paper clarification too Carl.

 

[Reddog]

No problem.
Shot you a PM also.

 

[squisher]

Yes like grabbing the boom all the way horizontal and trying to push it back and forth on the house rotation. That play you feel is the back lash.
But you may also get some play from the hydro rotation motor and other gears in the setup. So you need to study it out and make sure your measurements are just the back lash of the gears your setting.

I see what you're saying, I'll have a good look at it in the morning.

 

[sotc]

Wally, wouldn't he be looking for closer to .006 if measuring on the pedestal with a dial? Both sides of the gear?
Why did it break to begin with? Did something get lodged between the gear teeth?

 

[squisher]

So I replaced the entire gear box because it wasn't that much more than just replacing the gear/shaft and I was somewhat suspect of the internals of the old gearbox thinking they could have had something to do with the failure if a bearing or something had worn to much and developed play. Also I hadn't been maintaining the gear lube properly, after careful study of the manual I had been lubing the rotation bearing but not the rotation gear, that I'm thinking was the main culprit in this failure. An expensive lesson to learn in fully understanding all the maintenance that is nescessary on a piece of equipment.

No trauma happened to the boom to cause failure. I believe a lack of maintenance/adjustment to be the cause although maybe something in the old gearbox?

 

[Al Smith]

I'm no expert on it but here's what I've seen .The pinion gear can waller out the keyway on the gear causing a lot of slop .That slop will cause the bearing in the top portion or the one next to the pinion to get sloppy which could play havoc with the internal gears of the hydra motor .Just the bearings and a shaft costs a kings ransom for one of those things .The big bearing on the bull gear is really a pricey item if that one fails .

Tom had one rotater that broke the tabs off of the casting .I made a half assed clamp deal to get him going on that one .We just used grease to set it back up .

 

[SkwerI]

I can't offer much since I know little about what you're dealing with, but if I were in a similar position I would be calling my Altec guy Rich. He's very knowledgeable on all kinds of aerial lift stuff and I'm sure he's replaced or repaired many rotation gears. I'll PM his phone number to you if you would like to give him a call and get some advice.

 

[Reddog]

Wally, wouldn't he be looking for closer to .006 if measuring on the pedestal with a dial? Both sides of the gear?

Yes that is correct, but it will depend on how the teeth are shaped and engage each other.

And after thinking about this more, it may be more like .010-.020 total.
I have never worked with a plastic gage setup like is being described. In order for a .002 piece of plastic to flow through it may need to be more open than just .004. Hence why I had asked if they referenced a backlash number in the manual.

 

[Al Smith]

If I recall correctly on one of Toms booms the bull gear had collected probabley what was fine dust mixed with grease which clung to the gear .Even though that gear is some what encased that damned dust can filter in .Perhaps that subject is covered in the maintainance manual of PM's .

 

[sawinredneck]

I've got everything you need to test it sitting in the garage, Justin, but I can't say I'd get it shipped to you in a timely manner or not?
The backlash on these gears shouldn't be that much of an issue, it's more about how they mesh together, they should be somewhat of a rounded cut gear, meaning a high spot in the center of the gear. You want the high spots to hit each other, they are cut this way to clearance each other, the closer you can get it set to hit the "lobes" of the round spots on each gear, the better.
You will also have to check and adjust this, say in two or three months, then again in a year as they wear in together.

 

[stehansen]

I'm with Skwerl on calling the Altec guy.

 

[squisher]

I called Lonnie at ITE(Iron Technics Enterprises) who I bought the truck from. Going over things with him on the phone made me feel confident that I have it set-up properly. Thanks for the number Brian of your tech guy and thanks everyone else too for their input and advice. I've run it now a couple of days and it's smooth as silk with no sign of any wear. I'll be watching it closely from now on.

I was pruning street trees with it today where I'd reach a couple from each setting so lots of rotating and it worked flawlessly.