Middle axle only use in rear

[tobyS]

Has anyone looked at what it would take to disable that power divider. I know if I want to make a locked pig (differential) to put a spot of weld at four key points on two gears and she is locked, forever. Can you just permanently lock it by a couple strategic weld spots?

 

[coachgeo]

Has anyone looked at what it would take to disable that power divider. I know if I want to make a locked pig (differential) to put a spot of weld at four key points on two gears and she is locked, forever. Can you just permanently lock it by a couple strategic weld spots?

Not sure a weld up/lincoln locker arrangement would work..inside a differential that has an air locker installed already. Im sure something could be welded to lock it..... just might be a different place is all.

Yet, instead of exploring new uncharted territory... rather just send air to it and use as close to OEM as I can in this hybrid of a set up.

 

[coachgeo]

On your 1078 there will be a single solenoid. On the 1088 I parted there was a paired solenoid. If I can find it in the garage I'll snap a picture.

was this pair and single both in a dry or wet line?

 

[tobyS]

Reading another site about the power divider they talked about it locking out the two high gears. If 50/50 is locked in in your system, will you still have 6 & 7?

 

[tennmogger]

Reading another site about the power divider they talked about it locking out the two high gears. If 50/50 is locked in in your system, will you still have 6 & 7?

No. Overdrives are not available.

 

[tobyS]

No. Overdrives are not available.

I don't have one to go look at, nor have I driven one. I'm trying to educate myself on their operation and how the power divider works. I have an M929 and have an M35A3 4x4 project, but no FMTV.

On the other site they described the tranny as a 6 speed and that there is a granny gear that is part of the transfer case. I think 6th is less than 1/1, like .78/1 (would need to research that).

Anyway, they said that when the 50/50 was engaged, locking the front and rear at 1/1, that it electrically kept the transmission from going into the top two gears (5th and 6th of the Allison).

Thus my question was, if he engages the lock (50/50), will having it locked in all the time prevent it from going into those top two gears?

Or did I misunderstand and it operates differently?

 

[tennmogger]

I don't have one to go look at, nor have I driven one. I'm trying to educate myself on their operation and how the power divider works. I have an M929 and have an M35A3 4x4 project, but no FMTV.

On the other site they described the tranny as a 6 speed and that there is a granny gear that is part of the transfer case. I think 6th is less than 1/1, like .78/1 (would need to research that).

Anyway, they said that when the 50/50 was engaged, locking the front and rear at 1/1, that it electrically kept the transmission from going into the top two gears (5th and 6th of the Allison).

Thus my question was, if he engages the lock (50/50), will having it locked in all the time prevent it from going into those top two gears?

Or did I misunderstand and it operates differently?

Ok, I should have elaborated. It's the numbering scheme that is confusing. The transmission is 6 speed but with an additional lower gear (called 1st) in the drop box (aka, transfer case). The transmission knows to NOT shift into 5th and 6th in the transmission if MODE (locks the 'middle differential') is engaged, but that is 6th and 7th on the controller readout that the driver sees. Both 6th and 7th are over drives. 5th is the top straight-through gear, as numbered on the display.

I put 'middle differential' because that's how it behaves, like a geared, lockable, differential, but done with clutches.

Make sense now?

 

[coachgeo]

Tenmogger describes well on how tranny works and also when mode kicks the locker in the Power Divider (middle differential) on a 6x6 as well. You are right that the last two available ratios are electronically (programmed) out of play when in Mode. You are also right that in previous trucks the middle diff. was activated manually where in the MTV it happens automatically.

But.... my truck is NOT a 6x6... thusly it's computer is not programed for it and will act on the rear axle as if it is the OEM single axle. Therefore in Mode it will NOT turn on the Power Dividers Locker since it does not know it is there. I have to do it myself and "as described earlier"... it will have to be on all the time or the truck will not move at all.

So now just need to find out if the MTV's; like the other trucks Floridison describes, uses dry air or wet air for that lockers activation.

 

[Awesomeness]

But.... my truck is NOT a 6x6... thusly it's computer is not programed for it and will act on the rear axle as if it is the OEM single axle. Therefore in Mode it will NOT turn on the Power Dividers Locker since it does not know it is there. I have to do it myself and "as described earlier"... it will have to be on all the time or the truck will not move at all.

Are the computers actually programmed differently, or is there possibly just an extra pin/wire/line that doesn't get connected on an LMTV? They could be more similar than you assume.

 

[coachgeo]

Are the computers actually programmed differently, or is there possibly just an extra pin/wire/line that doesn't get connected on an LMTV? They could be more similar than you assume.

Your probably right.... Might be better say "in my case; won't have a connection between tcu and the axle; thus expect TCU will take act upon it as it would OEM LMTV axle".

 

[Smike740]

Tenmogger describes well on how tranny works and also when mode kicks the locker in the Power Divider (middle differential) on a 6x6 as well. You are right that the last two available ratios are electronically (programmed) out of play when in Mode. You are also right that in previous trucks the middle diff. was activated manually where in the MTV it happens automatically.

But.... my truck is NOT a 6x6... thusly it's computer is not programed for it and will act on the rear axle as if it is the OEM single axle. Therefore in Mode it will NOT turn on the Power Dividers Locker since it does not know it is there. I have to do it myself and "as described earlier"... it will have to be on all the time or the truck will not move at all.

So now just need to find out if the MTV's; like the other trucks Floridison describes, uses dry air or wet air for that lockers activation.

Per the air system schematic the RR diff solenoid is supplied air from the same source as the fan which is via the pressure protection valve on the wet tank.

 

[Floridianson]

Correct but all the tanks are after the air dryer ( if working correct) so it will be dry air so not to worry about water if that's the case.

 

[tobyS]

As Smike and Floridianson have said, it is dry air. Notice that is a 3 port, 2 position valve that exhausts air in the non-energized position and that it is spring return to that position.

Does someone have an electrical schematic that shows where that valves electrical supply comes from?

 

[Jbulach]

Does this power divider have an actuator cylinder that you can pull the cap off of and just put a puck in instead of messing with air?

 

[tobyS]

Does this power divider have an actuator cylinder that you can pull the cap off of and just put a puck in instead of messing with air?

That (similar mechanical method) is what I was asking. Or just replace the electrical signal to the OEM valve.

 

[coachgeo]

That (similar mechanical method) is what I was asking. Or just replace the electrical signal to the MTV OEM valve.

being that is an LMTV suppose it won't have the 3 way OEM valve but will look.

Have looked at the parts breakdown, it looks like one could put a puck in there. Was concerned about going that route cause the piston in the actuator might allow for a little stress relief . Don't know if that is something Meritor took into account as an advantage or disadvantage? Thus this unknown made me lean toward keeping it air actuated as designed.

 

[coachgeo]

As Smike and Floridianson have said, it is dry air. Notice that is a 3 port, 2 position valve that exhausts air in the non-energized position and that it is spring return to that position. ....

that is perfect info was looking for. Mucho thanks.

Per the air system schematic ...

thanks was having hard time finding the schematic.

Honestly am confused though.... Like Tenmogger and others point out..... plumbing apparently comes from the wet tank ...... while others are correct..... it does go thru air dryer "prior" to wet tank.... Looks like everything including brake tank air goes thru wet tank. so what makes a tank wet and dry?

UPDATE- answered my own question in next post

 

[coachgeo]

according to http://beamalarm.com/Documents/stopping-with-air-brakes.html

seems the air used for fan and axle solenoid is "wet-ish" air. It's source is after dryer but comes from the tank with highest probability of "some wet" still being in the air AKA the Wet Tank. Maybe they should call it the Wet-ish tank. Till saw the diagram and video was assuming "wet tank" did not get sent dry air to it, but only wet air... The ol' saying fits.... "you know how assume is spelled right?"

So everyone thus far (besides myself) has been correct. Will at some point take Bob's / Tenmoggers suggestion and grab from just after pressure protection valve off of wet (wet-ish) tank cause that will be more convenient. Thanks Bob. Will also put a valve there that will allow for exhausting as TobyS shows is the oem arrangement. We have temporary idea to hold the solenoid mechanically if their is not a diaphram in the way.

 

[coachgeo]

Update......

had conversation with mechanic am working with this tonight (Chris Jones) as we worked on other things... he had an idea on how to mechanically lock the air solenoid very easily. He'd been holding out on me lol.. apparently this was an idea rolling around in his head for a while. Then by shear accident; tonight ran into Neal Harrison online. He is owner of Western Canadian Rockwell and does ton of Meritor stuff. Good guy. He liked the mechanical idea and said it should work fine.

So here it is.....
. take an NPT air fitting and drill it out and tap it for straight thread.
. Put fitting into the air port at end of cup on the air solenoid. It happens to sit straight inline with the piston.
. Insert and screw in a bolt to push the piston home to hold locker activated permanent.
. Use a locknut to hold it extra secure.

Neal is going to send me an extra cup that is the outer cap on the solenoid eventually so I can revert back to an air system if want in future. Having ability to shut off air locker opens up a unique.. but probably not wise way, to run a PTO off the rear output of the Power Divider.

We also talked about heat..... he supported my thoughts that it probably won't get any hotter than that axle does in the Tandem unlocked environment cause all the gears turning are same ones always turning anyway. Except the few additional gears that are part of the locker. This addition should not cause any additional undue stress thusly all should operate rather normally in this arrangement was the concensses. Will watch temps over time and compare with folk whom have 6x6 though.

 

[Jbulach]

Does this power divider have an actuator cylinder that you can pull the cap off of and just put a puck in instead of messing with air?

Without knowing the spring pressure, shape and durability of the piston and cap to resist point loading and wear from contact with a small steel bolt, it might be wiser to just have a simple wooden puck turned to fit nicely in the cylinder, maybe with some circles cut out of inner tube to go on each end, but it’s your truck...

Update......

had conversation with mechanic am working with this tonight (Chris Jones) as we worked on other things... he had an idea on how to mechanically lock the air solenoid very easily. He'd been holding out on me lol.. apparently this was an idea rolling around in his head for a while. Then by shear accident; tonight ran into Neal Harrison online. He is owner of Western Canadian Rockwell and does ton of Meritor stuff. Good guy. He liked the mechanical idea and said it should work fine.

So here it is.....
. take an NPT air fitting and drill it out and tap it for straight thread.
. Put fitting into the air port at end of cup on the air solenoid. It happens to sit straight inline with the piston.
. Insert and screw in a bolt to push the piston home to hold locker activated permanent.
. Use a locknut to hold it extra secure.

Neal is going to send me an extra cup that is the outer cap on the solenoid eventually so I can revert back to an air system if want in future. Having ability to shut off air locker opens up a unique.. but probably not wise way, to run a PTO off the rear output of the Power Divider.

We also talked about heat..... he supported my thoughts that it probably won't get any hotter than that axle does in the Tandem unlocked environment cause all the gears turning are same ones always turning anyway. Except the few additional gears that are part of the locker. This addition should not cause any additional undue stress thusly all should operate rather normally in this arrangement was the concensses. Will watch temps over time and compare with folk whom have 6x6 though.

There will actually be less parts that can possibly turn than with the power divider unlocked, so extra heat should be a non issue.