Penn 112h with a shredded SS main gear

[Lane Grant]

Good advice from the reel repair experts here.   I always listen to experience.

My contribution is more from the science side of the house (Caveat:  I am a mechanical engineering fanboy, not trained in this stuff).

In a nutshell, the photo shows damage at an angle along the length of the edge of the teeth on the  the main gear.  This means that the main gear was forced away from the pinion.  The spool shaft supports the pinion on both sides. so if the pinion was angled, the spool shaft would have to been bent, which should have been quite noticeable.

This means that the main gear had to have been angled away.  The main gear  "shaft" is the gear sleeve, which is spins on a post that is press fit into a bridge plate.  The post is only supported on one side.  It can be pushed off-angle angled without significant force.  

1.  Winding force on the handle arm can be one culprit as the handle works like a lever attached to the unsupported end of the gear post (a lever on a lever).  It doesn't take much force to angle a 500/112h main gear post by pulling/pushing the handle knob toward or away from the sideplate.   You will probably be able to see this if you clamp the reel seat in a vice and pull the knob away from the sideplate.  A long handle arm increases the leverage, making this more likely.  

If the damage is limited to a couple teeth, this means that the damage occurred when the main gear was not turning- which means if winding is causing the problem, it is because it is weakening the rigidity of the main gear post, which later causes a failure under drag (see 6)

2.  The gear sleeve post may be loose, or the bridge plate may not be screwed fully tight to the sideplate.   or there may be too much slop between the post and gear sleeve.

3.  You could be using an undergear washer made out of a softer material (like a drag washer) that allows the gear to be angled farther once the gear becomes a bit misaligned.

4.  (most likely IMHO) The gear teeth are too small for the load that you are placing on this particular design Aftermarket high gear ratio sets requires that the pitch diameter (gear diameter at roughly the middle of the tooth) ratio from the main to the pinion increase without changing the center distance.  In order to get a greater ratio for the same center distance, the solution is usually to make the teeth shallower (this is why there are more teeth), which allows for the main gear pitch diameter to increase and the pinion pitch diameter to decrease.  Shallower teeth mean that it takes less misalignment (angled) to cause the load to concentrate on a smaller area on the thinner outside edge of the gear tooth.

5.  Helical cut gears are strong and quiet when they are aligned, but they become vulnerable when the shafts are forced out of alignment.  The tooth path is curved, which causes the load to be further concentrated toward one edge of the tooth in this situation.  I think the wear pattern in the photo illustrates this. If you play with a loose set of gears you can visualize what happens. It is a bit complicated to explain here, but it boils down to the tooth being angled away from the load instead of being at a 90 degree angle.   Helical gears are the only option on these type of reels (for mostly good reasons), so nothing can be done here.

6. (most likely IMHO ) - any slight misalignment combined with excessive load will force the gears farther apart at an angle, concentrating the load on the tip of the gear tooth (what Sal said).

22 lbs of drag off the reel equates to several hundred pounds of force onto the main gear tooth.  This can actually be calculated.  I had to guess on the main gear/filled spool diameters ( 0.9/2.5  in), but with these estimates, the force on the tooth would be 305.56 lbs!

You can give it a try yourself with the correct measurements:https://alantani.com/index.php?topic=14241.msg145318#msg145318

Use formula 3, but substitute the ratchet radius with the pitch circle radius of the main gear (distance from center of hole  to the middle of a tooth)

This is why there is so much force:

A 112h is a fairly tall reel and a 5:1 gear ratio is a  fairly large gear ratio.  The tall spool acts as a lever, which means it takes more torque to produce the same amount of drag.  Gears can be thought of as a set of levers arranged in a circle, so the torque multiplies again by the gear ratio with star drag reels.   With 22 lbs of drag you are actually putting multiples of multiples more force on the gear tooth.

7.  According to the Pro Challenger web site- the 112h 5:1 gear seat uses 304 stainless (cannot be hardened) for the main gear, and 420 (hardened) for the pinion.   This is consistent with the the pinion digging into the main gear as seen in the photo.   The wear marks make me believe that the misalignment is pretty significant, so I am not certain that a harder (and more brittle) material, would have made enough of a difference.

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There could also be some other less likely contributors (pinion hole oversized, etc.).

All of the above could contribute to the failure, but it is hard to tell which one(s) are the most significant without looking at the reel.   IMHO, asking for 22 lbs of drag with higher gear ratio, smaller gear teeth, and a long handle arm is a challenge for this reel, especially for extended runs, from an anchored/drifting boat (bluefin on a party boat).  Maybe you will find a loose gear post, and fixing that puts you back in business, but the physics are not working in your favor.

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Switching back from 5:1 to 4:1 gears takes 20% of the load off the main gear teeth, and allows you to use a 20% shorter handle arm without losing cranking power (and/or be more attentive about how you are levering the gear post when winding).  The greater tooth depth and greater backlash (extra space between teeth) of the 4:1 buys you a bunch more in terms of accommodating misalignment under load as well.   I wouldn't be surprised to see the 4:1 main gear being able to handle 30-50% more drag than the 5:1.  Something else might break, of course.  

I would seriously consider switching back to 4:1,  in addition to finding the most rigid bridgeplate/post combo available  (plus mebbe backing off the drag a bit    ).  


-J

J explains how this is possible. More strain on the gears than the drag washers and line itself. Correct me if I'm wrong.

[Lane Grant]

Also, it was confirmed that the main gear was not heat treated and the pinion was.

[MarkT]

He indicated that he was pulling on the handle which probably put the pressure on the gear sleeve that caused/allowed the gears to get out of alignment and become damaged.  Besides, he landed the fish so I'd call that a win! My best BFT was ~85# and was on 30#... but I used a little 2-speed Accurate DX2-400 backed with 300 yds or so of 50# braid. I've landed 30#ers on 20# and 60#ers on 40# bait and 50# jig (Colt Sniper). A 40#er on 30# is well within expectations.

[MarkT]

Also, it was confirmed that the main gear was not heat treated and the pinion was.

Isn't that why the typical reel has a brass main and a stainless pinion? You want to have a sacrificial element when you get to the failure point.

[jurelometer]

Also, it was confirmed that the main gear was not heat treated and the pinion was.

Isn't that why the typical reel has a brass main and a stainless pinion? You want to have a sacrificial element when you get to the failure point.

I have heard that explanation before as well, and I don't buy it.  Hard to know for sure why somebody makes an undocumented design tradeoff, but I think there are more likely explanations.

Since  the stock gear teeth are deep (and therefore thick), they are strong enough when bearing full load that a hardened material is not necessary.  Hardened teeth are more brittle and are more likely to chip if the load gets concentrated on the edge of the tooth from misalignment.  Hardened stainless  tends to be especially brittle.    A little deformation in soft metal may wear itself back into usable form, but chipped teeth are toast. Having at least one of the gears a softer metal makes the reel feel smoother, as well.

The notch in the pinion on these reels has to mate with the flats on the spool shaft, so this is probably why the pinion has to be hardened.  Flipping a star drag into gear when the drag is set high on a hot tuna is one of the more destructive things you can do to these reels.   It is sort of like shifting a stopped car from neutral to 4th gear at high RPMs without using any clutch.

BTW Lane - if you are live baiting in freespool, it might be wise to back of the drag a bit when drifting the bait, and then ramp up a bit after you have the reel in gear.  I used to paint one of the knobs on the star with nail polish so that I could have a reference that helped me remember where my max drag setting was relative to the handle arm.

Alan C. at Pro Challenger really did you a solid.   I think many other shops would have told you that you pushed the reel beyond it's capacity.

[snip]
It is crushing to learn that a normal human being is stronger than a Penn Senator.  You are a normal human being, right Lane?

"Give me a place to stand and with a lever I will move the whole world."  - Archimedes.

It seems like the post/gear sleeve design was pretty much the standard for star drags from that era.  I always thought of it as a design screwup, but after thinking about it more- back then ball bearings were expensive, accuracy in manufacturing was very costly,  and line was not very strong.  As long as you had gears with deep teeth and lots of backlash, things would work out just fine.  Once we get to the more modern era, I think of this as more of an error.  The better designed second and third generation star drags (Newell, Pro Gear), oversized the post and gear sleeve, but a bearing in the sideplate would have removed the leverage issue entirely.  I am guessing that the Japanese reels (SLOSH, TLD Star as examples) were among the first to incorporate this very basic engineering principle.

Or, perhaps, the lesson is that you shouldn't screw around with the Penn engineering by making modifications.  Or, perhaps, modifications can be counterproductive if they disregard to overall design.  Or, perhaps, the first modification should be to fortify the bridge and peened gear shaft before monkeying around with the gears.

Pushing something until it breaks is so instructive.
-steve

Agree.

Not a lot of room on these reels to muck with the post design, but a post that  was threaded on the bridge end and passed all the way past the bridge plate so that it could be secured by a flanged nut on the other side, sort of sandwiching the plate?  Might be enough room for that, but would require a custom bridgeplate and post. Maybe possible to reuse the bridgeplate. Should make it a bit stronger, but that post diameter is still pretty tiny.

I have learned a lot from Dave.
Sal

But I have learned a lot more from you, Steve, Rudy and the rest of the reel (real ? ) experts here.  Just trying to contribute where I can...

-J

[Lane Grant]

Just to paint a more accurate picture. I was not fly lining and in free spool with the star drag button down. I was casting a 80 gram colt sniper and it wasn't until the fish was done making his first run that I started to button down the drag and took some line back. I was pumping the rod but I was really aggressive when cranking on the handle. Half way through the fight I noticed a rough grind. I buttoned down the drag even more to prevent the fish from taking more line ( did not want have a bunch of line out if the reel completely broke ). By the time the fish was up and down, I noticed it was physically getting hard to turn the handle and there was an audible clunking sound. I grinded through and was lucky enough to land the fish. Sounds like it shouldn't have happened given the circumstances.

J, is it possible to push the power handle with enough force to cause a misalignment shredding the the main gear in the process?

[Alto Mare]

I have 6 sets of gears In my possession that look just like yours, I did testing prior to production.
Mine were forced passed their limit, in a word, done for a purpose to see how far I could push them.
All failed when I was retrieving weight while turning the handle.
So yes, the sleeve will rock back and forth when under heavy cranking...
Didn't mean to jump in, I just wanted to point out that it has happened to me.
On some I've also bent the arm...we'll see what Dave has to say.
The reason you see damage at the lower part of the gear is because of the helical cut gears.
Those feel as they ride up as they rotate.

From Dave's quote:
The notch in the pinion on these reels has to mate with the flats on the spool shaft, so this is probably why the pinion has to be hardened.

Yup! Also the pinion works much harder than the main gear.
Usually the first number on gear ratio tells you how much harder that pinion is working when copairing it to the main gear.
A 4:1 gear ratio,?the pinion will need to rotate 4x, vs 1x for the main gear.

Sal

[jurelometer]

So of course after posting a long-winded technical drill down, something started gnawing at my brain, and a few days later, I figured it out.  Ol' Juerelometer is not as smart as he thought he was.  Time to eat a  bit of crow.  Mebbe just a drumstick.  Most of what I posted should still stand.

I forgot that the directions of  thrust of helical gear sets reverse when the rotational direction changes, and  a star drag reel gear set rotates in both directions, controlled by whether you or the fish is taking line. This is important because it means that the wear pattern on the shredded gears will tell us if they failed under drag, while winding, or both.

I dug up a helical gear set that I drew up and printed earlier to use for an example.  If we ignore the third gear on the left, we have what looks like a main gear and pinion (left hand wind reel - don't ask ) 



First of all, let's talk about how much actual thrust is involved. 

If you look at the side of a helical gear, you will see that the teeth are not at a right angle to the gear face like on a spur gear, but instead are tilted (AKA the helix angle).  The greater the angle, the greater the amount of radial force will be  transferred to thrust, pushing the gears up/down their respective shafts away from each other.  The ratio can be found simply by finding the tangent of the helix angle.

From what I have read, most helical gear sets use something between 5-15 degrees for a helix angle as that is the sweet spot in the tradeoff between getting the benefits of helical gears without too much thrust. 

Eyeballing the 112H gears, I am going to guess toward 5% angle, which would put us around  8.7% of the load on the gear tooth being transferred to thrust. 

Using the previous calculation in this thread with a 112H with a drag set to 22 lbs (ouch!)  the estimated load on a main gear tooth is around 300 lbs  (AKA tangential force), and we get about 26 lbs of thrust.   


Now for the fun part. 

Let's simulate winding under too much load.  The pinion drives the spool toward the far sidepate, and then has nowhere else to go, so the thrust will be directed to push the main gear toward the drag stack.  The load will be on the pinion side of the main gear, so the main  shaft will be forced off alignment, and the main gear will ride up and away from the pinion as they turn:



The opposite will happen when line is being taken under drag.  The main gear will try to drive under the pinion. But it is working against the fixed side of the gear shaft, so it is takes more force to get things out of alignment.

This is also where the yoke can help hold the pinion down against the spool, so that the pinion will not slide away from the thrust.  So Maxed Out was right on the 113H thread, where he stated that a bad or weak yoke could contribute to shredded gears. (I have to eat a bit more crow now



Sooo... by looking at the wear pattern on the main, you should be able to determine if the damage happened under drag, winding, or both.

Of course,  Sal had already explained a bunch of this,  but I am happier understanding the mechanical reasons behind it.

-J

[jurelometer]

BTW,  couldn't shred or slip the printed teeth by hand.   And that is with PLA - weak hobby plastic.   My opinion is that big gear teeth are really your friend when it comes to star drag reels with gear sleeves

-J

[oc1]

Whew.  Okay.  That was good.

For future reference, the main gear in a right-hand reel has a 'S' twist and the pinion has a 'Z' twist.  In a left-hand reel the main gear has a 'Z' twist and the pinion has a 'S' twist.  A 'S' twist has the gear teeth slanting from the top left to the bottom right like the center portion of the letter 'S'.  A 'Z' twist has the gear teeth slanting from top right to bottom left like the center portion of the letter 'Z

The main and pinion must have opposite twist directions so the teeth will mesh.  As the handle is turned, the leading edge of the main gear helix contacts the leading edge of the pinion helix.  I think this indicates that the engineers were more concerned with gear strength when cranking under load, than when pulling drag under load.

In the photo of the stripped main gear on page 1, most of the damage seems to be on the bottom edge (the left side of this gear from a right-hand reel).  Would that indicate that the damage was done while cranking  under too much pressure rather then when drag was being pulled.?
-s

[jurelometer]

Whew.  Okay.  That was good.

For future reference, the main gear in a right-hand reel has a 'S' twist and the pinion has a 'Z' twist.  In a left-hand reel the main gear has a 'Z' twist and the pinion has a 'S' twist.  A 'S' twist has the gear teeth slanting from the top left to the bottom right like the center portion of the letter 'S'.  A 'Z' twist has the gear teeth slanting from top right to bottom left like the center portion of the letter 'Z

The main and pinion must have opposite twist directions so the teeth will mesh.  As the handle is turned, the leading edge of the main gear helix contacts the leading edge of the pinion helix.  I think this indicates that the engineers were more concerned with gear strength when cranking under load, than when pulling drag under load.

Mostly agree.

It looks to me like the factory setup requires more force to lever the gear sleeve out of alignment from the drag (not winding), as noted in my previous post.  This is because the angular force is closer to the base of the gear sleeve post which is fixed to the bridge plate.

We will always wind under less load than the drag, usually a lot less.  So it would make sense for Penn to choose the twist direction that favors the drag.

With a short stock handle arm, small torpedo knob, and a stock gear sleeve that rounds off at the handle under load over about 10 lbs, gear shredding under wind was not so much a concern.  Winding force was generally not enough to cause a problem.  At least until we started upgrading the reels.  Fix the weakest link, and you get to find out what is next in line.

Also: under drag, the pinion is being pushed up against the yoke.  So maybe if the gear teeth twist was reversed, there would be more rapid wear on the yoke (much more winding revolutions than drag revolutions over the life of a reel).   So at least two potential benefits that I could come up with.
------

But you are definitely asking  the $64,000 question.   If it did not make any  difference, Penn wouldn't have bothered to make left hand gear sets.  The thrust is the same, only the direction changes based on which way the teeth twist.   The leading edges will always engage first.  It will just be on one side of the gears or the other, depending on the rotational direction. Top (toward sideplate) when winding, and bottom when spinning from drag. 

I am curious if anybody out there has dropped in a gear sets from an opposite hand reel.    If the failure in upgraded reels is more likely to occur while winding, would swapping in left hand gears actually make the reel less likely to fail when cranking on bigger tuna, or will we just grind up the yoke, or bust something else more quickly?

In the photo of the stripped main gear on page 1, most of the damage seems to be on the bottom edge (the left side of this gear from a right-hand reel).  Would that indicate that the damage was done while cranking  under too much pressure rather then when drag was being pulled.?
-s

I think so.

-J

[Rancanfish]

I think so too,  since that is when the OP said it occurred.   

Thanks J for the thought provoking analysis.  I especially appreciated the 'fix the weak link, and you get to find out what is next in line.

All this only applies to the guys that fish for larger fish.  I never catch anything over 20lbs so I have no worries.

[alantani]

way past my pay grade......   

[jurelometer]

J, is it possible to push the power handle with enough force to cause a misalignment shredding the the main gear in the process?

Sorry Lane,

I was so happily drilling down, I drilled right by this question.

Yes.  The longer arm gives you more leverage, and the bigger knob gives you a better grip, and smaller gear teeth means less misalignment before failure.   Based on your description of events, and the wear pattern,  and Sal's destruction tests, it seems like we are getting fairly confident that the failure occurred due to winding under load. 

Usually when we are winding under heavy load, we are pulling and pushing the knob up and down, and relying on the rigidity of the bridge post to end up with a (mostly) radial motion.

Ergonomically, it is pretty much impossible to apply strictly  radial force with any amount of strength. You have to stick your elbow out to the side and spin like you are speed winding an iron. 

So your choices are to take more  time to land the fish with a more delicate pump and wind, or rail the sucker and wind away to improve your odds of landing the bluefin.   I would trade a set of gears for a decent bluefin any day.

Stick the rod in a vice, tie the line to something solid,  and turn the handle.  Set the drag a little higher, rinse and repeat.  You should be able to see at what amount of force the gear sleeves starts to tilt a lot.  Pay attention to the the lifting part of the wind,  that is where you have the most power.

If you wanted to get all "engineery",  with a bit of duct tape, a rubber band, and a cheap digital caliper, you could actually measure the travel which would allow us to calculate the angle of the gear sleeve under a given winding load.   Combined with a measurement of tooth depth and pitch circle for the main gear, we could determine how much force the reel could be wound at without getting into the danger zone, where only the endges of the teeth are engaged.

The measuring part is probably overkill for those of us who do not geek out on the engineering side of things.
 
"When in doubt, choose the one with strong teeth"  is a useful axiom for all sorts of situations in life 

-J

[nelz]

So what does this all say about the new "micro gear" tech that's out there now, with "smaller teeth and more of them"?