Hello everyone. I am on a charter trip from Milwaukee,WI. thru IL. IN. KY. TN. NC. and GA. Left Monday and will return Sunday night. Our bus is a spanken new 2010 MCI J4500(47000 miles) with a CUMMINS engine and ASTRONIC.This handsome monster even has electrical outlets at every seat. We only have 27 people so it is indeed nice to have a seat to myself. Nice coach with the exception of the transmission. Our driver has been doing this for many many many many many many many years and he does not like this transmision. Even our tour director has commented on how jerky this thing could be. But he did admit that it uses slightly less fuel than an ALLISON B500 but the benefits of the B500 outset this. We pulled up to a huge hill and I thought for sure the engine was going to quit. It also didn't go into reverse very smoothly on inclines. I have to wonder if this ASTRONIC fad is peaking and would imagine that many operators will return to ALLISON or replace the ZF with B500's in some buses at some point if they felt it to be worth having a smoother and faster accelerating bus.
I drive a 2005 J4500, Cat C13, and ZF astronic and I love it. I just finished a tour season covering 27000 miles in 41/2 months. This coach gets parked over the winter, and I'm driving a 2007 J4500, Cat C13 and Allison 6 speed and it's disappointing, to say the least. I guess it's a personal thing, like which brand of car you like.....Bill
I rode the Greyhound this spring to go pick up my MC5, on a J 4500 that had the 12 speed ZF AS Tronic. I noticed right away that it shifted lots, both up and down, constantly adjusting to the speed and the load. I went up front and asked the driver about it and he said he liked it, the only thing was it was a little slow climbing hills. I wish I had one.
We just got a new WV Jetta for my wife, and it has a similar transmission: 6 speed shifted by computer. Awesome. It down shift on its own when you take your foot off the throttle.
JC
Been driving them since they were available a couple of years ago now.
Jerky ASTronic needs servicing.
Shifting from forward to backward, coach must be stopped, foot on brake pedal, and driver needs some patience, it is slow to change directions.
Coach should be able to creep smooth as silk, by feathering the throttle, no jerk, otherwise, needs maintenance.
Mashing the throttle to the floor will do the same thing as in an auto or a manual - fling the passengers around.
It is programmed for fuel economy, not performance, so they fade climbing hills, unless the driver intervenes and asks it to shift sooner.
Lots of shifting, first ones had 10 gears, the latest have 12 gears. The computer will skip gears as required, depending on grade and throttle being called for by driver. The driver can also tap the control pad and short shift it like a good trucker for some fuel economy gains over winding it up and skipping gears, and with a little practice, no head bobbing for the customers at all.
A commuter type coach doing city stop and go still needs and Allison, but the rest won't be back.
The tractor trailer crowd are going deep into this as well, with ASTronic, Eaton Ultrashift, & I-Shift.
The economic conditions are masking the retirement of the truck drivers, industry research indicates that the average age of the fleet is way up in the upper 50's and the young ones aren't coming to play, don't want to play, can't play. A driver simply cannot hurt one of these automated transmissions, the computer won't let you, and that's big savings to the owner.
The missing piece? Once the technicians learn how to maintain them properly...
happy coaching!
buswarrior
A little background on the 12spd ZF Astronic. It is a 4 spd main box with a 3 spd planetary gear splitter on the back. It uses its' own electronics (meaning the engines have to be set up to accept the transmission, compared to Allisons or Eatons), and uses its' own 17" single plate organic clutch that is VERY expensive to replace.
Freightliner offered this box for awhile before Eaton came out with the Ultra-shift. But ulimately pulled it from the transmission offerings because of the big cost of the transmission (almost as much as the big Allison). And-even though we have all the specialized tools to repair the transmission, it is so expensive to dip into, we just remove and replace with a factory rebuilt unit and send the faulty transmission back to the factory.
I too have been on buses with the Astronic-it is rough, shifts with clunks, and you're constantly being moved forward and back from the shifts. Personally-would not even come close to dealing with the ZF transmission. Will take an Allison every time-even though the Allison takes about 20hp more to turn.
Eaton has come out with a new transmission-the Ultra Shift 2. On the first Ultra Shift, the clutch was a centrifigul clutch that engaged around 900rpm. The clutch life was limited to 80-100,000 miles-which is too short. The Ultra-Shift 2 uses a conventional clutch that is electonically operated for faster shifts, hill holding capability, and just smoother shifts. Good Luck, TomC
The ALLISON gets the bus up to speed faster and I always thought you want to get up to high gear faster for better fuel economy. Like someone elese said, it's a personal thing. I don't drive bus but am a delivery driver and for me a fully automatic is the only way to go. Besides, 'stick shift" and automated manuals are not even offered on vehicles that I drive for personal and business.
Is the Ultrashift 2 offered from the factory on any buses made today? The only reason I could see for wanting one is if it offers better fuel economy.
Wouldn't a tranny with more gears be able to keep the engine closer to the ideal RPMs thus helping fuel economy?