TRL-107 gear ratios?

[Freightrain]

Google is lost, can't find anything listing the actual ratios of this box.  It brought me back here but it lists everything but the old 5 spd.

This is all research for my 300+ project this winter.  I'm also curious why this is just a twin countershaft and not a Triple?  Granted it was a reman and wonder if they removed one?

 

Thanks.

[Geoff Weeks]

1 hour ago, Freightrain said:

  I'm also curious why this is just a twin countershaft and not a Triple?  Granted it was a reman and wonder if they removed one?

 

Thanks.

Multiple counter shafts are arranged so all the forces on the main shaft are equal, so a twin would be 180 deg apart on the countershafts. I can't see a triple with one shaft removed even working, it would continually be trying to push the main out of alignment?

[Joey Mack]

Freightrain, didnt you have a TRD 72 transmission? 

As far as the 107 ratios, what transmission model are you wanting info on. I have books...

[Joey Mack]

Sorry, i just realized you posted TRL 107.. dumb me.....

[Joey Mack]

https://photos.app.goo.gl/q2UgQ9Gp2nbRzSMY7  https://photos.app.goo.gl/Xiwp6VutU7NZqJ8M6

 

This is right out of the book. hope this is what you need..  Jojo

[Geoff Weeks]

This thread seams to confirm 2 counter shafts, I wonder why/how that works? Learn something new every day.

[Joey Mack]

Eaton and Meritor have 2 counter shafts...  i guess its what year range is the subject. 

[Geoff Weeks]

Yes, but the countershafts are 180 deg apart on the fuller and spicer, the Mack case has two on top and one under, each force plays against the other two.

[Joey Mack]

and??  I may have missed something here..  sorry GW..  even though I was a tranny builder for Mack years ago, I have lost some memory.  So I say its best that I drop out..  

[Geoff Weeks]

Well, Mack's 3 counter shaft design is strong, because all three shaft push against the main shaft and all forces counter act each other, Kind of like a 3 planet, planetary gearset.  

Fuller, Spicer and Meritor two countershaft design the counter shafts are 180 deg apart, so the forces counter act eachother.

With three counter shafts 120 deg apart the forces counter act eachother, but when you remove one, the mainshaft is side loaded toward the missing shaft.

Having the forces counter-act allow the gears on the main shaft "float" without bushing or bearing supporting the gears on the main shaft.

You could use bushing and remove one countershaft but that make the transmission much weaker than a 3 countershaft or a two countershaft that are 180 deg apart. 

It would still be stronger than a single countershaft design of the same shaft sizes, as that one suffers from no counteracting forces on the shafts at all, they are always trying to push each other apart.

The counter shafts always are being pushed out from the main shaft but with a 2 or three countershaft transmission those forces are divided equally between all the countershafts, so each would carry 1/2 or 1/3 of the force. When a three counter shaft case has one removed, the main shaft must counteract the forces normally carried by the (missing) 3rd shaft.

[Mark T]

4 hours ago, Freightrain said:

Google is lost, can't find anything listing the actual ratios of this box.  It brought me back here but it lists everything but the old 5 spd.

This is all research for my 300+ project this winter.  I'm also curious why this is just a twin countershaft and not a Triple?  Granted it was a reman and wonder if they removed one?

 

Thanks.

There's an old thread hear from back in '09 about a fire truck with one and a 300 (285)  nothing about ratios. If I had to guess likely not an overdrive, so the ratio set in JoJo's response seems plausible. Guy points out they're easy to shift.

[Geoff Weeks]

A main shaft on a 2 or 3 countershaft transmission only sees rotational forces, the two or three counter shafts share the  lateral forces pushing them away from the main shaft.

[Freightrain]

3 hours ago, Joey Mack said:

https://photos.app.goo.gl/q2UgQ9Gp2nbRzSMY7  https://photos.app.goo.gl/Xiwp6VutU7NZqJ8M6

 

This is right out of the book. hope this is what you need..  Jojo

Those are 1076, 1078 which can't be right.  Mine is just a 107. They must have lo split because you would never start out with only a 5.xx ratio first??

 

Geoff, I don't think physical placement is that critical, as the countershafts are being pushed away, so I don't think there is uneven forces on anything.  As long as the countershafts don't deflect, it all accepts a load.

In a single countershaft, they both try to deflect, which is the cause of a failure.  Putting the main shaft in the center of all three would keep it centered and as typical if the CS's don't deflect they will fine.  Macks are in a Y shape, but the two on the side are level with main shaft as it would make the case even larger if not.

Eaton or such likely just makes them 180* for ease of assembly or just physical transmission shape?

[Mark T]

I went back and looked at that link again.  That's an overdrive.  Probably matched with like a 7.5 axle (or lower)  that old post says they're the same as a triple countershaft . Probably the same as any direct in that series.  Seems 1st wouldn't be much below 8 to one if that even.