Quadraplex Question

[rewdoxiepup]

Good Morning All,

Can anyone tell me why on my R-400 there's a dash tag that says " Do not use 1st or 2nd underdrive in the aux. trans. when in 5th in the main trans". It is a quadraplex 18 spd.. Is the jump from 4th direct to 5th direct possible without taking a nap waiting to get into 5th gear ?. Just a question from a Roadranger person, never owned a married Mack type transmission. The only trans. iv'e had that even comes close is a 5X4 in a 1974 Paystar Tri Axle log truck with a 400 Cummins. Thanx E.S.D.

[Freightrain]

Repetitive ratio's

Using 4th in lo, direct and Hi, then going to 5th lo, direct would be a repeat in gears since 5th is actually OD and using lo and direct would repeat 4th direct and over. Maybe not exactly, but close enough that Mack just tells you not to.

Hope this was clear enough.

[blegh]

Good Morning All,

Can anyone tell me why on my R-400 there's a dash tag that says " Do not use 1st or 2nd underdrive in the aux. trans. when in 5th in the main trans". It is a quadraplex 18 spd.. Is the jump from 4th direct to 5th direct possible without taking a nap waiting to get into 5th gear ?. Just a question from a Roadranger person, never owned a married Mack type transmission. The only trans. iv'e had that even comes close is a 5X4 in a 1974 Paystar Tri Axle log truck with a 400 Cummins. Thanx E.S.D.

The usual shifting sequence was to go 4th direct - 4th over - 5th over. That works best with the ratios. If you hit a rise, you can drop down one on the aux.; less of a drop than going back to 4th over. have fun - that is the sweetest trans I have ever driven without using a clutch.

cheers

[HK Trucking]

The reason Mack tells you not to use 5th lo split & direct is that 5th lo is a downshift (1.01 ratio, compared to 4th hi ratio of .84.) 5th direct is an exact duplicate ratio of 4th hi (.84) There's not much RPM drop from 4th to 5th on the main anyway. The drop from 4th hi to 5th hi is the same as from 4th direct to 4th hi, don't wait long for the RPM's to drop or you'll miss it.

This info applies to the large TRQ 7220 quad box, not the small TRQ 770 quad box that was used with the scania motors & gas engines.

[mudslut28]

Ok guys these were a little ahead of my time but did you really have to shift both sticks at the same time or am I just confusing myself?

[Freightrain]

You don't actually move both at the same time. You move one, then the other. Now, granted someone will say you can, but usually you end up with double nothing(neutral). At least that's what happens with my Triplex.....as I've tried it a few times to see. I end up doing some fancy handwork and playing to get one back in gear so that you can get the other in gear.

I made a little video showing two hand shifting.

http://fords.kilonet.org/freightrain/bride1.wmv

This gives ya a look see on how I do it.