New Light & Medium Duty News

[7Mary3]

Class 2 and 3 GM trucks come with the Allison 1000 series transmissions. Allison makes many transmissions (ever wonder what is in an M1 Abrams?) and the 1000 is the lightest transmission they make. Our fleet has standardized on Allison transmissions in all our class 6 and larger trucks, MT series back in the old days, 3000 series in most our mediums these days. We have found that while the purchase price of the truck with an Allison is higher, overall cost of ownership is quite a bit lower through lower repair rates and higher resale values. We have also seen significatly lower accident rates in Allison equipped trucks. That's not to say every single Allison transmission is perfect, but overall the failure rate is lower for us than any clutch/manual transmisson combination we have ever owned. We do have a very stringent maintenance program, and use Allison sepecified fluids (not all shops do, BTW). We are a 4,500 vehicle fleet that operates throughout Southern California.

 

That having been said, we have a few 6R140's in our fleet and have not have any issues with them yet.

[lfeg]

On fleet preferences, a good friend is head mechanic for a fleet that has some class 6, but is predominately 7 and 8 (in the range of 100 trucks in local and long haul service). They have three approved drivetrains - all Mack, Cummins/Eaton, and Cummins/Allison. All axles are Eaton. They do all maintenance and repair inhouse and these have proven to be the lowest cost drivetrains in their use.

[twintornados]

....They do all maintenance and repair inhouse and these have proven to be the lowest cost drivetrains in their use.

 

For now.....

[lfeg]

Hard to argue with over 20 years of documented experience. In their use. Yours may be different.

[theoldwizard]

So the more forward gear ratios there are in a gearbox, the greater the chance of staying

above the converter's stall speed and avoiding heat build up in the gearbox.

True. I keep wondering if a 2 speed rear axle would be a good idea. High gear would be used when "hauling post holes" !

 

More efficient torque multiplication through additional gear ratios versus oil shearing and heat.

A super low first would be advantageous for low speed up hill climbing with maximum load on board

Ultimately, you don't want to use torque converter multiplication at all, if possible. You want the TC locked up as much as possible, but that would likely require higher line pressure. The "holy grail" has always been a variable displacement pump (all the designs I have seen are constant displacement and pressure is controlled by bleed excess fluid back to the sump), with similar cost and reliability of existing pump designs.

 

A super low gear is always a good idea for vehicles that have to carry a heavy load. See above.

Edited May 14, 2015 by theoldwizard

[Bob Rosadini]

True. I keep wondering if a 2 speed rear axle would be a good idea. High gear would be used when "hauling post holes" !

 

Ultimately, you don't want to use torque converter multiplication at all, if possible. You want the TC locked up as much as possible, but that would likely require higher line pressure. The "holy grail" has always been a variable displacement pump (all the designs I have seen are constant displacement and pressure is controlled by bleed excess fluid back to the sump), with similar cost and reliability of existing pump designs.

 

A super low gear is always a good idea for vehicles that have to carry a heavy load. See above.

For you "auto trans engineers" from an earlier post I made in response to 7M3's surprise at seeing a two speed axle option;

 

7M3-note two speed is restricted to 21,000 lb. I would assume this is a dash mounted switch intended for "loaded/empty" mode? then again, with today's electronics I wonder if we might see it working in conjunction with the Torqshift as iot moves throiugh the six speeds. wild thought.

 

The electric two speed shift control is mounted on the gear shift lever-unless you go back to the 50's and controls were vacuum/mechanical and mounted on the dashboard. In any case, with the "button" on the gear shift lever, a good driver say with a 5 spd, effectively had a truck with 10 forward speeds as you would "split shift the axle up and down. "Non drivers"? it was a "loaded/empty" control or an "on road/off road" control.

 

When Mack came out with the constant torque rise Maxidyne concept in 1965, that changed things a lot. Most diesels were driven in the 1700-2100 rpm band and required multi-speed transmissions or say a 5 spd. with a two speed axle. The Maxidyne rewrote the book as it developed huge torque at 1200 rpm and was built to run in that 1200-2100 rpm band. A lot of old timers had a tough time learning how to drive again as it was instinct to downshift at 1700 to avoid lugging. the Maxidynes were featured with a 5 speed for typical on highway use or a off road version that was a 6 speed two "sticks" but unlike pre Maxidyne engines, the "compound" stick was not meant to split shift providing 10 forward speeds.

 

To counter Mack's success with this engine, Cummins came out with the "Power Torque 270". This was the big "NH" block, (855 cu. in) designed to be driven the same way as the Maxidyne-1200-2100 RPM range. Fuller started building a Roadranger with just 6 speeds (RT-906) for use with this engine. Brockway's approach was to use this engine with a 5 spd. but with a two speed axle with the shift controler on the dash-to avoid the temptation for a driver to "split shift" through the gears-as there was no advantage to doing so and as it would have a very negative effect on fuel economy.

 

So having said all this, how about it JPD80, Olwiz, how difficult to integrate a two speed rear with the 6R140? Shifting an electric two speed requires interupting power to the axle to complete shift, but seems like regardless of how it is done (driver depressing clutch or letting up on accelerator) seems like all the electronics on the 6.7 and the 6R140 could make this possible.

[theoldwizard]

So having said all this, how about it JPD80, Olwiz, how difficult to integrate a two speed rear with the 6R140? ic two speed requires interupting power to the axle to complete shift, but seems like regardless of how it is done (driver depressing clutch or letting up on accelerator) seems like all the electronics on the 6.7 and the 6R140 could make this possible.

Possible yes, likely ? Probably not at Job #1. Ford will likely wait for feedback from the field. If there is demand for the 2 speed year axle, it will happen. (Actually, I was thinking of shifting it when the vehicle was stopped because that is easy to do.)

 

The new 8/9 speed RWD transmission likely won't have the torque capacity for anything more than a 3.5L EcoBoost. I am still hoping there is a replacement for the V10 in the works.

Edited May 15, 2015 by theoldwizard

[sullynd]

The new 8/9 speed RWD transmission likely won't have the torque capacity for anything more than a 3.5L EcoBoost. I am still hoping there is a replacement for the V10 in the works.

Is there an 8/9 speed RWD transmission in the works, or do you mean the new 10 speed unit?

[theoldwizard]

Is there an 8/9 speed RWD transmission in the works, or do you mean the new 10 speed unit?

I probably missed the memo that they added another gear !

[jpd80]

I wonder if you could combine a 2-speed rear end with some sort of load sensing technology

so that the vehicle knows when it full or part loaded or towing. That may make more sense

than a 10 or 12 speeder skipping through gears....or maybe not....:shrugs shoulders

 

I like TOW's idea of a super low first, you could do that with an 8-speeder and probably save a lot of engineering grief..

[Sevensecondsuv]

I wonder if you could combine a 2-speed rear end with some sort of load sensing technology

so that the vehicle knows when it full or part loaded or towing. That may make more sense

than a 10 or 12 speeder skipping through gears....or maybe not....:shrugs shoulders

 

I like TOW's idea of a super low first, you could do that with an 8-speeder and probably save a lot of engineering grief..

A super low first has been "normal" in all HD manual trannies since the beginning of time. Automatics never really needed it due to the torque multiplication through the converter.

 

I guess there's no reason an automatic couldn't have one though. Now that the mediums are switching to autos it kinda makes sense in an effort to save the torque converter from early demise.

.

[lfeg]

Automating a 2 speed axle in concert with an automatic transmission for low speed / heavy load starts should not be that big of a deal. But unless only shifted at a standstill, there is the danger that if a shift is not done just right the axle can make an awful noise and freewheel.

[Bob Rosadini]

Automating a 2 speed axle in concert with an automatic transmission for low speed / heavy load starts should not be that big of a deal. But unless only shifted at a standstill, there is the danger that if a shift is not done just right the axle can make an awful noise and freewheel.

Hah- "been there-done that"! I have to believe as sophisticated as today's electronics are, this should not be the most difficult thing to do. I've never driven one of the new "automated manuals" but they are another example (if I understand them at all) whereby the trans is getting all kinds of inputs with respect to load, speed etc and making shifts accordingly. Again the two speed?-proper clutch or throttle action completes the shift. IMO I would bet we will see this before long.

[theoldwizard]

I've never driven one of the new "automated manuals" ...

Those seem to be popular in EU but I have never heard of them in the US. Not sure why.

[351cid]

I've never driven one of the new "automated manuals" but they are another example (if I understand them at all) whereby the trans is getting all kinds of inputs with respect to load, speed etc and making shifts accordingly.

I've had the misfortune of renting a ProStar with a 460 Cummings and that cussed transmission. Admittedly, I'm old school and feel I can do a better job shifting manually, but there are other reasons I hate driving one of those trucks.

 

First; they shift absurdly hard during acceleration. I did find that easing off the throttle during shift helped, but still would pop a crick in your neck.

 

Second; seems the design is such that when you pull off, the engine is revved and the "clutch" is slipped. This creates a hazard in snow & ice. I was in a city with icy roads and found that pulling off slowly from a red light was not an option. Several times the tractor would sit & spin even with traction control on. Had I had a clutch, drama would have been reduced greatly.

 

Third; backing up to a dock requires a real delicate balance of dragging the brakes (with your left foot) so that you don't try to knock the building down.

[fordmantpw]

Are there any HD trucks with conventional automatic transmissions?

[Sevensecondsuv]

I've had the misfortune of renting a ProStar with a 460 Cummings and that cussed transmission. Admittedly, I'm old school and feel I can do a better job shifting manually, but there are other reasons I hate driving one of those trucks.

 

First; they shift absurdly hard during acceleration. I did find that easing off the throttle during shift helped, but still would pop a crick in your neck.

 

Second; seems the design is such that when you pull off, the engine is revved and the "clutch" is slipped. This creates a hazard in snow & ice. I was in a city with icy roads and found that pulling off slowly from a red light was not an option. Several times the tractor would sit & spin even with traction control on. Had I had a clutch, drama would have been reduced greatly.

 

Third; backing up to a dock requires a real delicate balance of dragging the brakes (with your left foot) so that you don't try to knock the building down.

I know I sound like a broken record, but there is no replacement for a clutch!

[351cid]

I know I sound like a broken record, but there is no replacement for a clutch!

In a class 8 big truck, absolutely. I also lean toward manuals in performance cars as well.

 

My daily driver SuperDuty is an auto and I wouldn't have it any other way.

[Bob Rosadini]

Are there any HD trucks with conventional automatic transmissions?

Sure-Allison- been around forever. I go back to the old days when durability was suspect. Very successful today. In termsw of vocational trucks- note trucks not tractors- I would bet that 50% of vocational trucks dealers have in inventory are Allisons. when it comes to heavy municipal trucks, I would bet 90% are Allisons. fire trucks, 100%.

[fordmantpw]

Sure-Allison- been around forever. I go back to the old days when durability was suspect. Very successful today. In termsw of vocational trucks- note trucks not tractors- I would bet that 50% of vocational trucks dealers have in inventory are Allisons. when it comes to heavy municipal trucks, I would bet 90% are Allisons. fire trucks, 100%.

 

I should have been more specific. I was more referring to OTR type tractors, not so much trucks.

[lfeg]

Back in the day of the Ford Transmatic (an Allison M41 or M42 if I recall correctly) they were quite durable, and Ford pushed them as a lower maintenance option. I see class 7 & 8 snowplow / spreaders with the Allison and they hold up well.

[theoldwizard]

I know I sound like a broken record, but there is no replacement for a clutch!

I was shocked when Ford dropped the manual trans from the F150-F350 !

[fordmantpw]

I was shocked when Ford dropped the manual trans from the F150-F350 !

 

Manuals were such a small percentage of sales, it didn't make sense to offer them. Not to mention, the manuals have to be really beefed up to handle the torque output of the big diesels. Look at Ram, the only one of the big 3 with a manual in their 2500/3500. The torque numbers on the Cummins with the manual behind it are way below that of the automatic. In the 3500, the numbers for the Ram are:

 

Manual: 350 HP/660 ft-lbs

Auto: 370 HP/800 ft-lbs (standard output Cummins)

Auto: 385 HP/865 ft-lbs (HO version)

 

Now, I'm not saying that 350/660 isn't enough, but that's taking a pretty big hit just to get a manual in your truck, when today's autos are far superior in nearly every area.

[Sevensecondsuv]

I wonder how much of the de-rate is due to the clutch rather than the transmission itself. To hold 865 ft-lb you're either going to have excessively heavy pedal or or if you go dual-disc it makes for a very "grabby" clutch.

 

Personally I would upgrade it to dual disc, learn the feel of it, and turn up the engine tune to the auto numbers. I bet it would hold up fine.

[Sevensecondsuv]

 

Now, I'm not saying that 350/660 isn't enough, but that's taking a pretty big hit just to get a manual in your truck, when today's autos are far superior in nearly every area.

They're not superior in one of the most important areas though: absolute control of the truck's movement at all times. Apparently not many buyers care about this anymore given the manual transmission take rate, but it's still true. A clutch gives you a whole 'nother dimension of control over the truck.