Ellis Kinney
Well-known Member
How do you actually look at a gear and tell if it is worn?? Ellis
- Thread starter Ellis Kinney
- Start date
timcasbolt
Well-known Member
On ring and pinion sets I measure the backlash.
Also, on gears that have been sitting for a long time, look for rust pitting. That breaks through the hardened part and into the soft core.
Another sure sign is when the gears come to a point.
flying belgian
Well-known Member
I never really thought about that. I guess as long as there is not a tooth broke out it doesn't matter if they are worn.
Mike(NEOhio)
Well-known Member
- Location
- Newbury, Ohio
If you can, look at some unworn gears and get used to what the curvature of the tooth should be. Most are an involute curve with either 14-1/2 or 20 degree pressure angle. The 20 degree makes a slightly thicker and stronger tooth but the backlash increases more with wear. I look at the central area of the tooth face and compare it to the tips and roots of the tooth. With a little practice you can usually see the wear pattern there. If one gear is narrower than the other you can see the original tooth form on the wider one.
You can draw an involute with a pencil and string. Tie the string to the pencil and wrap it around a can or something similar. With the pencil against the can, unwrap the string and it will draw a spiral. The first little bit of the spiral is the tooth form.
You can draw an involute with a pencil and string. Tie the string to the pencil and wrap it around a can or something similar. With the pencil against the can, unwrap the string and it will draw a spiral. The first little bit of the spiral is the tooth form.
Eagle Beagle
Member
I was in a Cat dealership week long tech training class for this very thing. Many things come into play when considering reuse and reliability when dealing with toothed gears and planetary gear sets. Of course, pitting and flaking will disqualify a component for reuse, but other telltale signs like contamination and bruising by foreign particles come into play.
A frank discussion with the owner, taking note of his expectations, of longevity of the powertrain is always warranted.
Our Cat dealership started a non-destructive testing of transmission components and found almost one third did not meet reusability guidelines due to hidden fractures revealed only under ultraviolet and magnaflux examination.
Beagle
A frank discussion with the owner, taking note of his expectations, of longevity of the powertrain is always warranted.
Our Cat dealership started a non-destructive testing of transmission components and found almost one third did not meet reusability guidelines due to hidden fractures revealed only under ultraviolet and magnaflux examination.
Beagle
Eagle Beagle
Member
The center of the tooth contact is a good indicator of wear and the presence of spalling and contamination, but the very bottom of the tooth is where small pitting ( hard line contact wear ) and chipping of the outer edge comes into guesstimating the number of hours of operation are left in a gearset.
My good friend had a job for more than thirty years estimating the life expectancy of gearbox's and open tooth gear trains on the 100 yard and bigger draglines in southern open pit coal mines. Most electric producers knew almost to within a week when to expect a failure.
Beagle
My good friend had a job for more than thirty years estimating the life expectancy of gearbox's and open tooth gear trains on the 100 yard and bigger draglines in southern open pit coal mines. Most electric producers knew almost to within a week when to expect a failure.
Beagle
mikewood869
Well-known Member
Usually if the teeth are worn or missing a lot of teeth (I call the gear dead), The teeth on the first reduction gear are worn in some spots to were the starter won't catch the gear.
Steve@Advance
Well-known Member
Really need more information...
Is it a transmission, ring&pinion, working tractor or trailer queen?
Bevel gear in a mower?
Big, open gears are very forgiving, precise gears are not. Speed and load also a major factor.
Is it a transmission, ring&pinion, working tractor or trailer queen?
Bevel gear in a mower?
Big, open gears are very forgiving, precise gears are not. Speed and load also a major factor.
OP
OP
Ellis Kinney
Well-known Member
I have been trying to get the wobble out of the front end of an M tricycle. I have rebuilt the column from bolster up. I turned the sector gear 180 degrees and bought a new/used steering shaft/worm gear from Bates. The gears all look good to me. Someone on YT suggested putting a washer under the sector gear. I thought I would make a thin washer out of sheet metal with hole saws on the drill press. I can understand how this would make the gears mesh in a different location. I also have a new steering shaft bracket I am going to install when I take the sheet metal off to paint. Thoughts on the washer idea??? Ellis
OP
OP
Ellis Kinney
Well-known Member
Working tractor, M Farmall, See above. Ellis
Janicholson
Well-known Member
Turning the sector, and replacing the worm gives you all the reduction in backlash you can expect. Putting in a shim will probably only make the taper and key not work correctly. If it is together, and has slop yet, look at the deep groove bearing on the end of the worm. it must be of minimal slop. If the worm can move in and out it will wobble. A finest quality highest ball count deep groove bearing is one answer. Jim
Jason the Red
Member
Not sure if this is feasible, but what about moving the steering wheel mount at the driver's seat to the right to push the worm gear into the sector gear? Never worked on the steering so this might not be achievable.
Jason the Red
Member
On second thought not at the steering wheel, but move the carrier bearing at the steering u-joint.
RedRoundhead
Member
There is a span over x number of teeth measurement for any gear - span measurements are the way to go for gear segments. An entire gear usually has an over-wire measurement.
Not sure where you would find the spec. Would need that and a good caliper or disc micrometer. Just need to rest them on the pitchline.
The worm will have an over pin spec as well.
As was stated, make sure the worm bearings are not sloppy.
Also, the center distance of the two shafts/bores is important.
Not sure how that could be off, but if either was ever bushed for repair, that would do it.
Not sure where you would find the spec. Would need that and a good caliper or disc micrometer. Just need to rest them on the pitchline.
The worm will have an over pin spec as well.
As was stated, make sure the worm bearings are not sloppy.
Also, the center distance of the two shafts/bores is important.
Not sure how that could be off, but if either was ever bushed for repair, that would do it.
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