HOW Does it Work?

[Robert Janssen]

even though they are stacked on top of each other, it's basically two separate sets of gears with two separate sets of drag washers.  it really is a very clever system. 

Thanks Allen, I get what you're saying, I think...😗 so one gear/washer set slips while the other is fully engaged?

In a nutshell, yes.
The true magic moment lies in the two intermediate idler* gears with the slipping / engaging cam protrusions. Without these, the unit wouldn't work at all.

*they are only idle in high gear. In low gear, the cam protrusions engage with one another, thereby providing drive from the low speed main gear through the now locked intermediate gears to the high speed main gear (which is then slipping, and acting as an idler) to the pinion.

An ingenious gizmo indeed. Curiously, that particular gizmo was in fact not invented by ABU, but was refined and applied by them.

.

[Cor]

Luckily I own only one Abu reel and that one is awkward enough for me.

Great job Gfish, you got it with some help and that is why this site exists.

[mo65]

   Cool reel G! The 2 speed ABUs are fun...once you grasp the concept of how they work. Up to that point they keep you in "mind control"!

[oldmanjoe]

Technically it is a overrunning clutch ..

[Gfish]

Ok, thanks all. Now I'll consider an older Auto 2-speed reel, such as the Abu 10,000 so I can own/use one with better construction and oriented more to saltwater fishin.
Not any affordable on the Bay now. This'n is was relatively inexpensive and came NIB.

[mo65]

   Hey G...you got me to thinkin' about 2 speed reels...and I went back to a thread about my ABU 9000. I've fished that red 9000 a few times, and it performed like a champ. I didn't see you in the comments, so if you missed it, here is a link. 

https://alantani.com/index.php?topic=31116.0   

[jurelometer]

even though they are stacked on top of each other, it's basically two separate sets of gears with two separate sets of drag washers.  it really is a very clever system. 

Thanks Allen, I get what you're saying, I think...😗 so one gear/washer set slips while the other is fully engaged?

In a nutshell, yes.
The true magic moment lies in the two intermediate idler* gears with the slipping / engaging cam protrusions. Without these, the unit wouldn't work at all.

*they are only idle in high gear. In low gear, the cam protrusions engage with one another, thereby providing drive from the low speed main gear through the now locked intermediate gears to the high speed main gear (which is then slipping, and acting as an idler) to the pinion.

An ingenious gizmo indeed. Curiously, that particular gizmo was in fact not invented by ABU, but was refined and applied by them.

.

Thanks to this statement and Greg's photos, I think this make sense to me now.  The top/bottom idler gear combo is the overrunning clutch that Joe mentioned.  Engages in reverse (drag) and slips more or less freely in forward (winding).

This leads to some observations:

1. When the fish is taking line against the drag, the gear shaft or sleeve is locked by the anti-reverse, and the bottom (high speed) main gear and bottom idler are turning against the resistance of the bottom drag stack for at most half a rotation of the bottom idler (probably not noticable)

The rotation causes the bottom (low speed) idler to lock into the top idler.  Bottom main turns bottom idler, which turns top idler, which turns top main.  We get the combined drag from both stacks at this point.

2.  When winding at tension below the bottom drag setting, all four gears are also turning, but since the idler pair is rotating in the detached/ free spinning direction, only the lower main is driving the pinion- high speed retrieve. The top main and idler are not contributing to the drive train, just turning.

3.  In order to get the low gear ratio,  we need the idlers to lock, but that will only happen if the bottom main is rotating slower than the top  main (bottom drag slipping), causing it to move "backwards" relative to the top main and lock the idlers together.  So now, we have the top main turning the locked idler pair as a single unit, and the idler pair turning the bottom main, which turns the pinion.  Four units in the drive train which means that the spool will continue to rotate in in the opposite direction as the handle - even numbers!!  Kinda clever.

4.  So now we get to the drawback of the system.  That resistance that you feel when winding a single speed reel against load when the spool is not turning is happening on the bottom drag stack whenever you are turning the spool with low gear. You may not notice because the spool is still turning, but effort is being wasted on the slippage. You are heating up the bottom drag stack instead of turning the pinion.

If my brain is working properly, the percent of slipping to turning on the bottom main is equivalent to the difference in gear ratios.  If the ratios are 3:1 and 5:1 and turning in low gear, the bottom main is turning 3/5 of the time and slipping 2/5 (or 40%!).

For some situations this tradeoff may be fine.  For example if the bottom (high speed) drag is set very low, just enough to retrieve a lure, the slippage may not be that troublesome - maybe even worthwhile.  But the lost-effort-in-low-gear penalty goes up as the bottom drag setting increases.  Probably one reason why this simple and elegant solution is not seen more frequently.

Did I get all (any) of this right?

-J

[oldmanjoe]

      I think you explained that very well .
  I do not have one to play with , but some how i think that pin and 3 notched hat may have something to do with setting the set points for the shifting /or how much pressure the high speed drags get from the star .

[Gfish]

I was kinda hoping you'ed chime-in Dave. Thanks, that along with comments from Allen, Robert, Mike and Joe, help a great deal. Some stuff I just gotta beat-on mentally 'till I get it, then "I can get by with a little from my friends".
Pretty ingenious, wonder who came-up with it?

These Abu baitcasters never cease to amaze me. They always find a way to "go their own way" when it comes to redesigning typical systems and adding cool little extras to make a better reel. This model prolly has 75 -100 or so parts. Today I worked on my Revo Toro Beast(clean-out and probably replace spool bearings) and it has 130 parts. Shimano"s are prolly the only reels comparable.

[nelz]

I've only come across one reel that I didn't risk taking apart, the Shimano Baitrunner. Heck, I couldn't even get the line roller apart without damaging it. I think I'll add this reel to the "leave it be" list as well! Congats Greg for attempting this. 

[DougK]

Ok, thanks all. Now I'll consider an older Auto 2-speed reel, such as the Abu 10,000 so I can own/use one with better construction and oriented more to saltwater fishin.
Not any affordable on the Bay now. This'n is was relatively inexpensive and came NIB.

interesting reel, thank you for showing us. I didn't realize Abu had made ones other than the 9 and 10000.

I had a 10000 once, bought for I think about $20 used. The two-speed wasn't working right, I stripped it down cleaned and greased and it started working. But I never quite understood it ;-) just did as Alan says, very carefully apart with notes then back the same way.
I was living inland then and looking forward to a sea trip to try it out. Then it got stolen.. grr.

[thorhammer]

I sent Alan my 8000 two speed; it was essentially what led me to this site in 2015. I love you Greg; you're a great dude so don't take it personally when I say that's a whole lotta dang parts just to catch green bass with, lol. Two speeds are for tuna.

[Shellbelly]

I'd throw top dogs in the surf with that.  My old 5000 brings 'em home.  I don't like taking it apart though.

Great tutorial, Gentlemen.  Thank you!