Why don't any new (newer) trucks run two speed rearends? I know roadrangers have range shifts and probably don't need 'em, but in medium duty trucks that used to be very common and popular, but not now. I run a pete 337 with an eaton 6 speed synchro trans and there are certain shifts that could use to be split out. Do we just have too many drivers that couldn't run a 2 speed the right way so they were taken out? Or are there new 2 speeds out there? I've looked at eaton's site and I can't see where they list them....
2 speeds?
- Thread starter inthedirt
- Start date
The two speeds I remember were problematic, corrosion of the wiring would make them malfunction. I didn't drive a lot of them, but I recall they were temperamental in the timing of the split. The ones I saw were typically on medium duty trucks, larger trucks went with bigger transmissions. I think those problems, combined with the broader torque range of today's diesels, the two speed rear has gone the way of the payphone.
I guess when you are asking about the 2 spds you are referring to the electric shift-actuator types only ??? …..
I have had the 2-spd rears in my WStar since the truck was new in '86 … they are the DT-460's, and both rears have been upgraded to the DT-461 Eaton specs …… You're right about very expensive to repair tho (hence the upgrading into the 461's) …. but as far as practicality goes they are/were awesome to have …. its like a whole different truck when in the bottom side ratio's which geared at 390:1 & 529:1 ……
I remember a job we did about 20yrs ago … we were hauling 8'-6 x 29" high concrete curbs w/super b-trains …. the country we were off loading (1 at a time each being placed onto the road) was about a 12% grade up hill for 3 miles, the crane/picker truck could only reach far enough to place 2 blocks, so we had to lift and move ahead every 2 blocks ….. up to the point when I got hired there were already 2 guys that twisted drivelines off (but then i'm sure the combo of the left and right pedals had nothing to do with it) …… with my truck @ 63,000 Kgs gross and being able to drop the rears in to the 529:1 side you could lift that load at a dead idle of the engine, no slipping the clutch, no twisting the hood off of the hinges, no broken rad mounts, nothing just lift and move ahead.
I have not seen 2 spds in the newer trucks for years …. I would have to guess the extra cost of Eaton having to produce vs the demand to have them was out weighed, plus the the new electronic engines stupidly high torque they now have and the electronics will never let an engine die as you lift, lifting a load softly (without getting carried away with the right foot).
As long as mine hangs in there I'm keeping them…… Cheers
I have had the 2-spd rears in my WStar since the truck was new in '86 … they are the DT-460's, and both rears have been upgraded to the DT-461 Eaton specs …… You're right about very expensive to repair tho (hence the upgrading into the 461's) …. but as far as practicality goes they are/were awesome to have …. its like a whole different truck when in the bottom side ratio's which geared at 390:1 & 529:1 ……
I remember a job we did about 20yrs ago … we were hauling 8'-6 x 29" high concrete curbs w/super b-trains …. the country we were off loading (1 at a time each being placed onto the road) was about a 12% grade up hill for 3 miles, the crane/picker truck could only reach far enough to place 2 blocks, so we had to lift and move ahead every 2 blocks ….. up to the point when I got hired there were already 2 guys that twisted drivelines off (but then i'm sure the combo of the left and right pedals had nothing to do with it) …… with my truck @ 63,000 Kgs gross and being able to drop the rears in to the 529:1 side you could lift that load at a dead idle of the engine, no slipping the clutch, no twisting the hood off of the hinges, no broken rad mounts, nothing just lift and move ahead.
I have not seen 2 spds in the newer trucks for years …. I would have to guess the extra cost of Eaton having to produce vs the demand to have them was out weighed, plus the the new electronic engines stupidly high torque they now have and the electronics will never let an engine die as you lift, lifting a load softly (without getting carried away with the right foot).
As long as mine hangs in there I'm keeping them…… Cheers
Ive seen two speed rears in an 2007 KW lowboy tractor . My old company Has a 92 pete that had 2 speed rears . Sure made it nice in the soft spots and backing into tight places . The 07 KW has a lock to keep you from kicking in the power divider in the low side . 92 Did not .
Ohh wow !!! …. that's really good to see that they didn't scrap the 2 spds in the big tractors but they're probably deff a special order ….
Mine has a detroit locker in the F/A and there is no lock-out for the power divider …. I guess its like anything (2 spd or not) you never engage under rotational spinning ….. seen a few of those puppies come right threw the side case of a diff ….. then the hired op saying "what happened ??? " ….duhhhhh !!!
But as you say Tiny, they are sweet to have used properly ….. I found too many pro's vs the cons too list why I wouldn't not have them. ……. cheers
td25c
Well-known member
That sounds like a good setup you have in the western star CRAFT. I like the idea of the front axil using the detroit locker & no lock-out on the power divider.The only tandem truck I was ever around that had 2 speed axils was a early 1980s GMC with an 8.2 detroit in it.It was my buddys truck,he bought it as a cab & chassis & we installed a hoist & grain body on it.Kind of a cool setup as you could have the rears in the low side for crawling out of the field with a load of corn then flip them to the high side when you got to the highway.
Hi Guys (and Gals?).
Just came over from the Heavy Equipment Forum for a look and here I am !
I didn't have anything to do with 2speeds in heavy trucks but I knew they were around.
However I cut my teeth on single drive trucks with Eaton and Rockwell 2speed rear axles.
Electric, vacuum and air shift.
Done properly with say a 5speed main box, you can split every gear, up and down, without a sound from the back end.
I even drove an old "C line" Inter with a 160 Cummins that went 4thlow, 5thlow, 4thhigh, 5thhigh. That thing did 70 MPH but only downhill !
But you are right Steve. They are temperamental and were overtaken a long time ago by the smaller Roadrangers.
In Australia, they were banned in buses and coaches in about the '70's because on a downshift, if the tailshaft is not spun up to the correct RPM for the diff to engage in the lower ratio, they neutralise, and you get no engine braking down hill. This caused many crashes of trucks and buses.
Which leads me to a question as long as you promise not to laugh.
Its only in the last few months that I've got to know the 18speed roadranger.
(No laughing! I'll show you how well I handle twin sticks, 20speed Spicers and lots of others - it's just that I hadn't come across one before).
They are easy and I love 'em.
But during my learning curve, I discovered that unlike the thirteen or 15 speeds, it is possible for the same thing to happen as with the 2speed diff when splitting to LOw ie. if you don't spin the gearbox up to the necessary RPM it will neutralise because it hasn't caught the new lower ratio.
This could lead to a "runaway" downhill if you don't know how to "find another gear", same as the 2speed axles used to do.
Anyone found the same thing ?
Cheers. M.
Just came over from the Heavy Equipment Forum for a look and here I am !
I didn't have anything to do with 2speeds in heavy trucks but I knew they were around.
However I cut my teeth on single drive trucks with Eaton and Rockwell 2speed rear axles.
Electric, vacuum and air shift.
Done properly with say a 5speed main box, you can split every gear, up and down, without a sound from the back end.
I even drove an old "C line" Inter with a 160 Cummins that went 4thlow, 5thlow, 4thhigh, 5thhigh. That thing did 70 MPH but only downhill !
But you are right Steve. They are temperamental and were overtaken a long time ago by the smaller Roadrangers.
In Australia, they were banned in buses and coaches in about the '70's because on a downshift, if the tailshaft is not spun up to the correct RPM for the diff to engage in the lower ratio, they neutralise, and you get no engine braking down hill. This caused many crashes of trucks and buses.
Which leads me to a question as long as you promise not to laugh.
Its only in the last few months that I've got to know the 18speed roadranger.
(No laughing! I'll show you how well I handle twin sticks, 20speed Spicers and lots of others - it's just that I hadn't come across one before).
They are easy and I love 'em.
But during my learning curve, I discovered that unlike the thirteen or 15 speeds, it is possible for the same thing to happen as with the 2speed diff when splitting to LOw ie. if you don't spin the gearbox up to the necessary RPM it will neutralise because it hasn't caught the new lower ratio.
This could lead to a "runaway" downhill if you don't know how to "find another gear", same as the 2speed axles used to do.
Anyone found the same thing ?
Cheers. M.
Yes that can happen. If you are trying to take half gears when downshifting going down a steep hill you better know what you are doing. For the inexperienced, it would probably be better for them to downshift whole gears on steep hills until they figure out how to downshift it properly.
Question. When you upshift a newer 18 speed, do you preselect the split before you shift into the next gear or do you split as you are going through neutral into the next gear.
Question. When you upshift a newer 18 speed, do you preselect the split before you shift into the next gear or do you split as you are going through neutral into the next gear.
I was taught and works for me:-
Preselect just before the change and as you are letting torque off the driveline (this saves wear on the air actuated selector forks). One clutch disendagement (maybe only partial) and no double clutching and snappy change into the higher gear.
How snappy depends on if you are pointed up or down at the time.
But be careful because you are changing from hi to lo split, if you are pointed down, you may still miss the "window" and it will neutralise unless you have poured on the power again after the change.
This can happen if you are coming off a hill on the Jake and you want to let it run but only as you work up through the gears, each gear getting you up to 1900rpm or so on the Jake. In this situation maybe a full gear is better but still has the chance of a stuff-up.
So this is UPshifting.
DOWNshifting half gears down the hill is ok because the splitter is going from low to hi but of course you can still get it wrong. The big risk, as you say, is if you try to split the gear you are in from hi to low, you better be sure you got the revs there for it to engage before the roadspeed exceeds what you can spin the gearbox input shaft up to with the engine.
I hope this makes for more talk with you and others but my point is that it brings us back to where we started from where you could loose a truck (or bus) with a 2speed rear axle because you missed the low split.
We have 2 Western Stars with Signatures and 18speeds and an older Star-car with an N14 and a 20 speed Spicer.
I love the gearbox in the old truck but now I have come to terms with the 18,
Preselect just before the change and as you are letting torque off the driveline (this saves wear on the air actuated selector forks). One clutch disendagement (maybe only partial) and no double clutching and snappy change into the higher gear.
How snappy depends on if you are pointed up or down at the time.
But be careful because you are changing from hi to lo split, if you are pointed down, you may still miss the "window" and it will neutralise unless you have poured on the power again after the change.
This can happen if you are coming off a hill on the Jake and you want to let it run but only as you work up through the gears, each gear getting you up to 1900rpm or so on the Jake. In this situation maybe a full gear is better but still has the chance of a stuff-up.
So this is UPshifting.
DOWNshifting half gears down the hill is ok because the splitter is going from low to hi but of course you can still get it wrong. The big risk, as you say, is if you try to split the gear you are in from hi to low, you better be sure you got the revs there for it to engage before the roadspeed exceeds what you can spin the gearbox input shaft up to with the engine.
I hope this makes for more talk with you and others but my point is that it brings us back to where we started from where you could loose a truck (or bus) with a 2speed rear axle because you missed the low split.
We have 2 Western Stars with Signatures and 18speeds and an older Star-car with an N14 and a 20 speed Spicer.
I love the gearbox in the old truck but now I have come to terms with the 18,
I have driven many trucks with two speed rear ends and they have been quite reliable in my experiences with them.The only troubles that I have had were "operator induced" for the most part and any electric device operating in the environment that the two speed hardware found itself in it was a wonder that they operated a good as they did.I do miss the rattle that they made when in operation.The old vacuum operated two speeds used to time out on a long pull so you had to compensate for that eventuality if you had a long pull ahead of you,maybe let up on the gas briefly to replenish the vacuum in the reservoir or be prepared for a runaway engine.Ron G
The first truck of any sort that I drove was in 1974, and it was a 49 Ford with the 2 speed actuator that pulled out of the dash. I hauled grain from the combine to town with it during harvest. I know my learning curve had to be hard on it, but somehow we both survived despite having to remember to pump the brake pedal three or for times before having anything to work with.
I have an 89 Peterbilt 378 now that has 2 speed rears, DT 460's just like Craft except the ratios are 410s and 529s. It also has an 18 speed, and is an ideal tractor for hauling heavy on mountain Forest Service roads. I never shift into the low side of the rears while moving (although it could be done easy enough, I just find the need), but you can shift out of them on the move real smoothly as long as your rolling easy. NEVER shift them with the power divider locked in though.
The thought of downshifting going down hill and ending up free-wheeling is not pleasant, and I am sure that we all have missed a shift once or twice. I learned years ago to place my left foot on the brake pedal and hold the speed for a bit while downshifting going down a steep hill so that I don't have to rush the shift, and then I can match the rpm's and complete the shift in gentle manner. You use just a touch of brake, but the runaway aspect is gone and in my case it is easier on the tranny, and no fear of overspeeding the engine. My old Pete has jakes as well as a retarder so it holds well going downhill. It started life as a logging truck in Oregon and works very well as a lowboy tractor for us, as long as you don't want more than 70 MPH.
Thanks for bumping this thread Ron. I have not been on this forum for quite awhile, but I have a bit of time this time of year and it is enjoyable to catch up on things.
I have an 89 Peterbilt 378 now that has 2 speed rears, DT 460's just like Craft except the ratios are 410s and 529s. It also has an 18 speed, and is an ideal tractor for hauling heavy on mountain Forest Service roads. I never shift into the low side of the rears while moving (although it could be done easy enough, I just find the need), but you can shift out of them on the move real smoothly as long as your rolling easy. NEVER shift them with the power divider locked in though.
The thought of downshifting going down hill and ending up free-wheeling is not pleasant, and I am sure that we all have missed a shift once or twice. I learned years ago to place my left foot on the brake pedal and hold the speed for a bit while downshifting going down a steep hill so that I don't have to rush the shift, and then I can match the rpm's and complete the shift in gentle manner. You use just a touch of brake, but the runaway aspect is gone and in my case it is easier on the tranny, and no fear of overspeeding the engine. My old Pete has jakes as well as a retarder so it holds well going downhill. It started life as a logging truck in Oregon and works very well as a lowboy tractor for us, as long as you don't want more than 70 MPH.
Thanks for bumping this thread Ron. I have not been on this forum for quite awhile, but I have a bit of time this time of year and it is enjoyable to catch up on things.
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I am a little disappointed that there is not more traffic here but of course I have too much time on my hands now and this is my tie to the past and I can't let go of it.I am trying to post as often as I can think of anything intelligent to contribute to maybe catch the attention of fellow members which is easy for me because this all started while I was dying so I have some catching up to do here.The board seems to have all the bases covered and I hope that it catches on like the other board did.Ron G
I expected things to move a little more quickly here as well Ron. HEF took 3 years to see daily posts, we're coming up on 2 here so it's really not out of line yet but I thought heavy trucks being more common that heavy equipment things might happen sooner. I've advertised it a couple times now with limited results and haven't had much luck in getting the HEF members to post here about their truck questions. I still believe at some point the traffic here will exceed HEF. Thanks for your help!!
I sure have a lot of stories to tell but I don't want to come across as ramblin' so I try to restrain myself.lol.I check this every time I log on to HEF.I agree that once it catches on things should get busy here.I must admit that I have seen this reminder every time I logged on but it went right over my head,it was another member here that brought it to my attention by a comment he made in another post about our "sister board". Glad I found it,finally.Ron G
mike in idaho
Member
I saw this early sixties era Freightliner cabover once with a 250 Cummins and a five speed transmission. It had two speed axles with a three-position air shifter control on the shift lever. Apparently the lowest position was both rear ends in low range,"2nd" was one rearend in low and the other one in high. High range had both axles in high. Probably didn't work too bad considering it only had 250 horsepower, you would have 15 forward gears, running a long time in the middle position would probably put some extra miles on the differential gears in the power divider.
mike in idaho
Member
There is a differential coupling in the power divider unit, much like the one in the center of the drive axle. That allows the ring gears to turn at different speeds to compensate for turns, mis-matched tire sizes, etc. That also allows you to spin the wheels on one corner only and be stuck. The differential lock control found in most tandem drive trucks locks out that differential , allows you to get by with one set of chains in the slick stuff instead of two.
I can understand the front rear being a 2 speed if it's done at the input of that rear, the output shaft would then spin to feed the rear rear at the shifted speed, but I'm having trouble understanding how the rear rear could be shifted independently. It seems to me it would push the front rear in your scenario.
Steve,
A bit like if the rear wheels had less traction than the lead ones but still had some traction - the interaxle diff compensates for the difference the same as from side to side when going around a corner.
One diff in high and the other in low would give you a final drive ratio the average of the two different ratios.
Glad to see the board picking up a bit.
Ron, you sure go back further than me because I never thought of loosing the vacuum on a long pull (having only had electric and air shift).
It would be worse if you had vacuum windscreen wipers on !
Cheers. M.
td25c
Well-known member
Well said stondad . Only time I could see a problem is if one axil is in low side and other in high side with the interlock / power divider locked in .