Trtxl 1070B Help Needed

[kshansen]

Have a Super liner 1993 with the TRTXL 1070B transmission at work. Diver said he never needed to use the "Low Low" gear till working a paving job on a steep hill last week. Could not get the trans. to shift into "Low Low". It is actuated by a toggle switch type valve on dash. There is air getting to the valve on dash as it vents pressure for a split second when moving from one position to the next.

I don't have any books on this one. Would like to know which air cylinder on shift cover works the "Low Low" shift and which one of the several valves and or regulators on the bracket next to cover work it.

Would be real handy to have a diagram showing all those valves that also said which gear each controls.

I'll have a few hours Monday morning to look at this then I won't see truck again for weeks. Kind of tough trying to fix it when truck is 100 miles away on the road.

My guess is there is a gummed up valve or plugged vent line somewhere. I coould open dash and start tracing from the valve to the trans. but if I knew where the lines hooked on the trans. cover I would save a lot of time I don't have.

Thanks Ken H

PS: Now if this was a good old 18sp. Quadraplex all you would need to do is grab the left lever and click it into Low Low in the Aux section! Guess I'm showing my age with that one!

[kshansen]

Forgot to mention, feel free to email me at kshansen@twcny.rr.com

Have a Super liner 1993 with the TRTXL 1070B transmission at work. Diver said he never needed to use the "Low Low" gear till working a paving job on a steep hill last week.

[buddy]

Have a Super liner 1993 with the TRTXL 1070B transmission at work. Diver said he never needed to use the "Low Low" gear till working a paving job on a steep hill last week. Could not get the trans. to shift into "Low Low". It is actuated by a toggle switch type valve on dash. There is air getting to the valve on dash as it vents pressure for a split second when moving from one position to the next.

I don't have any books on this one. Would like to know which air cylinder on shift cover works the "Low Low" shift and which one of the several valves and or regulators on the bracket next to cover work it.

Would be real handy to have a diagram showing all those valves that also said which gear each controls.

I'll have a few hours Monday morning to look at this then I won't see truck again for weeks. Kind of tough trying to fix it when truck is 100 miles away on the road.

My guess is there is a gummed up valve or plugged vent line somewhere. I coould open dash and start tracing from the valve to the trans. but if I knew where the lines hooked on the trans. cover I would save a lot of time I don't have.

Thanks Ken H

PS: Now if this was a good old 18sp. Quadraplex all you would need to do is grab the left lever and click it into Low Low in the Aux section! Guess I'm showing my age with that one!

The air piston the actuates that low gear is to the drivers side of the shift tower. The low hole will only work in 1st speed as there is a lock out preventing it to engage in any other gear. I had a simular problem so i removed the shift plate on top of tranny wich is the one that the shift tower connects to and low and behold the lock out was broke and the broke piece was probaly chewed up by the tranny. if i can figure out how to post a pic i have a good lock out mechanism and i will post it up. I learned a lot about this tranny in a very short time. Some of the experts on this site guided me through it so you came to the right place. HOOOAH!

[buddy]

this is a broken and a good lock out

[kshansen]

If I was going to guess that would of been the one I'd have went for first.

Does the lock out physically stop the piston from moving or does it prevent air pressure from getting to the piston to activate the low gear? I knew it was blocked somehow as the toggle valve says something about it only being used in 1st gear.

At least knowing the correct air cylinder to be looking at will save lots of time tracing things out.

Thanks for the reply, I'll try to work on it Monday and let you know what I find.

The air piston the actuates that low gear is to the drivers side of the shift tower. The low hole will only work in 1st speed as there is a lock out preventing it to engage in any other gear.

[kshansen]

Okay, they look like the same kind of lock out I remember from the first MaxiTorque transmissions. I'm guessing that the notch in the shaft somehow locks into something when you engage low and prevents you from shifting to another gear. Looks like someone tried to override the lockout.

Had a driver many years have a truck run away on a hill, said he tried to down shift but never got it to go in gear. Funny thing the spiral twist in the drive shaft and the crushed lifters in the engine and exploded clutch tell me he sure did get it to go in to a lower gear!

this is a broken and a good lock out

[buddy]

Okay, they look like the same kind of lock out I remember from the first MaxiTorque transmissions. I'm guessing that the notch in the shaft somehow locks into something when you engage low and prevents you from shifting to another gear. Looks like someone tried to override the lockout.

Had a driver many years have a truck run away on a hill, said he tried to down shift but never got it to go in gear. Funny thing the spiral twist in the drive shaft and the crushed lifters in the engine and exploded clutch tell me he sure did get it to go in to a lower gear!

that notch is where the detent ball sits!!

[kshansen]

Well I did get a little time to work on truck Tuesday. Removed air line from rear of the cylinder that is next to the shift lever and now when toggle valve on dash is put in the "Extended Range" position it snaps in and shift lever is locked into low gear by the lock pictured in above post.

However the line removed from this cylinder is blowing steady air pressure which prevents the air cylinder from moving when it's connected. This at least tells me problem most likely is in on of the air valves on the side of transmission. One is a pressure reducing valve, doubt that would be the problem. Two others are I believe inversion valves, could be the problem area. The big problem now is it could be months before I get to touch the truck again!

I stopped at the local Mack dealer and they could not find any service information that showed an air shift like ours, their books only showed the transmission with a second shift lever to engage the Low Low range. They did copy me some pages out of the parts book on the arrangement we have so that may help some. I'll try to remember to post again when I have more information.

Off on vacation for a week so have fun here without me!

that notch is where the detent ball sits!!

[buddy]

Well I did get a little time to work on truck Tuesday. Removed air line from rear of the cylinder that is next to the shift lever and now when toggle valve on dash is put in the "Extended Range" position it snaps in and shift lever is locked into low gear by the lock pictured in above post.

However the line removed from this cylinder is blowing steady air pressure which prevents the air cylinder from moving when it's connected. This at least tells me problem most likely is in on of the air valves on the side of transmission. One is a pressure reducing valve, doubt that would be the problem. Two others are I believe inversion valves, could be the problem area. The big problem now is it could be months before I get to touch the truck again!

I stopped at the local Mack dealer and they could not find any service information that showed an air shift like ours, their books only showed the transmission with a second shift lever to engage the Low Low range. They did copy me some pages out of the parts book on the arrangement we have so that may help some. I'll try to remember to post again when I have more information.

Off on vacation for a week so have fun here without me!

Ken, the constant air coming from that air line returns the shift fork to the normal position when you flip the air switch on the dash. The trick is the air pressure coming from the air switch has to be greater to engage the low hole shifter. Once you flip the switch to normal position that air pressure returns the the shift fork to direct hence the lock out releases the shifter. if that makes any sense