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    Guest Message by DevFuse
     

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    Twin Stick Transmission Shift Patterns



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    45 replies to this topic

    #41 OFFLINE   jaysm35a2

    jaysm35a2

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    Posted 02 May 2010 - 04:19 PM

    Yes it has the orginal engine. Am I shifting too low at 1200 RPM? I was told that was what it shifted at. I havent drivin it much. Im going to learn the correct way to shift it before I do much more. I know you go : 1 low 1 high 2 low 2 high and so on from what I read. Seems like everyone has there own way of driving. I read that stay in high and shift like a 5 speed when empty and dont lug under 1500 PRM while driving your ok also. Thanks for talking with me on this. -

    #42 OFFLINE   HK Trucking

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    Posted 02 May 2010 - 04:37 PM

    If you're using the tach to upshift the main, then yes, if you run the engine up to 2100 you'll catch the next gear on the main at about 1200. If the engine will accelerate from 1200 with no problem then that's not considered lugging. Lugging is when the engine is working with full throttle under 1500 RPM and will not increase RPM. Use the compound as necessary to prevent the engine from lugging.
    "If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

    #43 OFFLINE   b6133994

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    Posted 15 May 2010 - 09:48 AM

    Hi,
    I have two trucks with duplex transmissions, one is a trd720, the other is a trd72. I will start with the trd720, this is simple, 5 speed box with low and direct rear box, this trans has 5 progressive ratios, with no overdrive, so it is shifted 1st, low then high, 2nd low then high, and so on, 10 gears... the other trans screws things up some, the front box has 5 progressive ratios BUT 4 th is direct and 5th is overdrive( also known as overgear) and has the some low and direct two speed box on the rear. This will give yo 10 gears right? well yes and no, 4th gear in direct is 1.0 to 1.0 ratio, ( input shaft turns 1 turn output 1 turn). now if you shift into 5th low the main box is in over drive( 0.69 to 1) but the low gear in the 2 speed box lowers the ratio, this will give you a ratio of 1.04 to 1 , almost the same a 4th direct, so you have no need to use this gear sence it is the same a 4th high and uses two gear reductions to get the same ratio as conecting the input shaft to the output shaft. So the the proper shift for the 9 speed overgear trans is the same as the 10 speed other than you omit the 5th low because it is a duplcate ratio. If thats not enough for you you can get into your trdx72 and trdx720 trans, these trans. have a very low gear in 1st. for heavy work, this realy misses up things, this trans you have to shift very differently than the other two. All 4 of these transmissions are duplex transmissions. So I would say that all of you are correct. I believe that is why all of these trucks have those little tags up by the sun visor, there are so many variations, it just comes down to what your truck was designed to do, and if the guy that ordered the truck knew what he was doing. Fred

    p.s. the triplex and the quadraplex have some duplicate ratios also because of the overgear 5 speed front box and overdrive in the rear box. :SMOKIE-LFT:


    You are exactly right, a quad is not a quad. Not all quads used the same sequence hence 14spd, 18spd, 20spd. You have to know your ratio list before you can figure out what you can use and what you can't. I bought a '60 B613 witha 20spd when I was 18 yrs old and had it down in no time. Once you get the feel it sure is a lot of fun!

    #44 OFFLINE   HK Trucking

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    Posted 15 May 2010 - 10:56 AM

    You are exactly right, a quad is not a quad. Not all quads used the same sequence hence 14spd, 18spd, 20spd. You have to know your ratio list before you can figure out what you can use and what you can't. I bought a '60 B613 witha 20spd when I was 18 yrs old and had it down in no time. Once you get the feel it sure is a lot of fun!


    The "20 speed" would be thr TRQ720, those had more overdrive on 5th, so you could actually use all 3 splits in 5th if you wanted to.

    I've seen the TRQ7210 referred to as the 14 speed quad box, but I owned one of those in a 1962 B613T, and drove one in a B61SX, and they shift the exact same way as the TRQ7220, which is known as the 18 speed quad box.

    The TRQ7210 and the TRQ7220 have some miniscule differences in various ratios, but I could never tell the difference when shifting one or the other.

    .
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    #45 OFFLINE   other dog

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    Posted 15 May 2010 - 11:42 AM

    If you're using the tach to upshift the main, then yes, if you run the engine up to 2100 you'll catch the next gear on the main at about 1200. If the engine will accelerate from 1200 with no problem then that's not considered lugging. Lugging is when the engine is working with full throttle under 1500 RPM and will not increase RPM. Use the compound as necessary to prevent the engine from lugging.

    I started reading this and thought "gee,this sounds familiar"...didn't realize the original post was that old. But I would imagine that if you're not used to older equipment it's hard to imagine nowadays. The newer engines are so different. Lugging the engine was just something you never did, you had to keep 'em "wound up"-now they're all about like a maxidyne, you can pull down to 11-1200 rpms and it won't hurt them. That's what they say anyway, I still downshift at about 14-1500. And it used to be if you let the temp. get much over 200 too much, you'd cooked an engine. Now the fan doesn't even come on until it gets to 205 degrees.
    "I'm off like a herd of turtles"- Old Bill

    #46 OFFLINE   fundadtn

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    Posted 18 June 2011 - 01:53 AM

    I have never had the oppertunity to drive a twin stick mack transmission and I was wondering how they are setup. For example I have herd that the basic setup is a 5 or 6 speed main and a hi-lo-reverse secondary. Is the hi-lo ment to split the gears? Also is there any online info on the different mack twin sticks and diagrams/pictures/instruction on the shift patterns? How does one shift progressivly through the gears?
    I saw one mack on ebay that had a real weird shift pattern that loked like an incomplete H shift pattern like this :

    gear - gear - gear
    xxxx- gear - xxxx

    (it was one of the two shift patterns and you could not really see the other pattern for the second stick)

    Thanks!


    There were several types of "TWO STICK" transmissions. After the Maxidyne engine came out, with the 5 speed transmission, Mack also made what was known as an extended range transmission, that did have 2 gear shifts, but is not anywhere near the same as the old original 2 stick transmissions. The Duplex was essentially a 10 speed tranny with a 5 speed main box, and a 2 speed auxilliary. For each gear on the main box, you split it with the auxilliary transmission. So each MB, gear was divided into 2 steps. The triplex had a 3 speed auxilliary, and a quadraplex had a 4 speed auxilliary. With the Quadraplex, when you upshifted the main, you brought the aux immediately back to 2nd, if you brought it back to low/1st then your speed ratio was the same as the previous MB gear in high on the aux. THIS CAME IN HANDY WHEN YOU WERE PULLING A HEAVY LOAD UP A HILL FROM A START AT THE BOTTOM.

    For the "most part" unless you were really havily loaded, you started off in 2nd on the MB, and 1st on the Aux. You progressed through the aux to 4th, and then the next shift, you shifted to 3rd on the MB, and then brought the aux immediately back to 2nd. Then you upshifted to 3rd aux, and then 4th aux, and then the MB to 4th, and the aux back to 2nd. Down shifting was the opposite. If you were really havily loaded or in soft dirt, you started off in 1st MB, and 1st in the aux. (being really easy on the clutch to keep from throwing a U=joint, or wrinkling the drive line.) There are some videos on youtube if you want to see how the 2 stick was progressively shifted. I also created a visual video demonstrating how to shift a quadraplex. these types of transmission were primarily designed for the old gasoline and early thermodyne engines, with low torque factors. If you try to use one behind a maxidyne or later variant engines, it will take out the bearings in the trans... pretty quickly, and I have heard it will break the gears, so I wouldn't recommend using one with the high torque engines. I hope this helps you.

    Dan.




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