Electronic engines and ten speed manual transmissions

[TomC]

The only true air shifter I have known in a truck was a Spicer 14 speed.  It had a 5 spd shifter with a 4 speed air controlled splitter.  In gears 1,2,3, you only used 1st and 2nd of the splitter.  In 4th and 5th of the gear shifter you used all 4 positions of the air splitter.  Also, there was a 4x4, 5x4, 6x4 where the 4 spd splitter box was competely air shifted.  Today, there are the 9, 10, 11, 15 spd Roadranger transmissions that have an air range selector for low range and high range.  On the 13, and 18, there is the addition of the overdrive splitter, so the gear shift knob will have two air splitter valves.  Personally believe a truly air shifted transmission would be difficult to drive.  Good Luck, TomC

[Sojourner]

Tom C...I was thinking you when they ask more about air shift transmission. Thanks for your reports.
My question is about the air shift trans, does it needs to communicates to engine via electronically?

If not, then how do we know when to shift without feeling movement of mechanical shift lever? Does it have a light indicator when it time to release the clutch?

Thanks.
Sojourn for Christ, Gerald

[TomC]

If you all will notice, there is NOT a single vehicle made today with an air shifter-and for good reason.  The Army had a 16 spd semi automatic that was air shifted that was a maintenance nightmare trying to keep the air lines clean, and training the drivers to shift it only one way and the very important timing to the shifter.  They replaced them with Allisons. 

On any other air shifter, it would be just plainly difficult to get a smooth shift, since our Roadranger transmissions are still of the dinosaur like crash box.  If on the other hand, we had the more sophisticated manual transmissions that are in the European trucks that are synchronized, or computer assisted in shifting, electronic with air assist would be possible.

The two ways that come to mind to do the shifting mechanism on the  Roadranger transmission, is to have a single long rod like that is done on most trucks and buses.  The other was previously mentioned using heavy duty shifting cables (two are needed).  I have that on my cabover truck and have been very easy to shift.

As with all systems on your bus, I highly recommend you stay with the tried and true and not try to reinvent the wheel.  Remember you'll be traveling in areas that are not littered with truck supply houses or Home Depots.  Having a shifting system like an air shifter go out because of a simple O ring or such can really ruin your day. 

Whether you use the tried and true HT740 or HT754 Allison or the newer World Transmission Allison, the ease and performance of the Allisons is second to none.  If driven properly, the Allison will get very close to the manual in fuel mileage (this has been proven with driver training in large truck fleets). The remaining fuel mileage difference will be offset by the convenience factor of not having to play truck driver when you're out on vacation (unless that's what you want) and anyone will be able to drive your bus in a pinch. Good Luck, TomC