Updated 28th July.

If you are unable to login, you probably need to read this change to your username & profile.

 

Welcome, Guest
Username: Password: Remember me

TOPIC:

Re: New Acco only with an Allison 24 Oct 2014 09:25 #149855

  • dieseldog
  • dieseldog's Avatar
  • Offline
  • Posts: 1101
  • Thank you received: 61
I reckon you guys might be over thinking this. Years ago in the ACCO's heyday, their claim to fame was reliability through simplicity. Now that Iveco has them, their goal is just cheap and nasty.

As said earlier, the only users are garbage trucks and agi's- two applications that involve stop start city driving and require good low speed maneuverability, and both of which an auto is better suited.

Think about it- when is the last time you saw an Acco with a trailer, or a tray for that matter. The reason the road ranger isn't offered as an option is cost. If you sell it, you have to provide parts service, service and warranty and if you only sell ten a year, its not really worth it.



Please Log in to join the conversation.

Last edit: by dieseldog.

Re: New Acco only with an Allison 24 Oct 2014 14:21 #149856

  • atkipete
  • atkipete's Avatar
  • Offline
  • Posts: 2653
  • Thank you received: 41
That is news, but I suppose they weren't selling many with Roadrangers and it may simplify things under the cabin.

Please Log in to join the conversation.

Re: New Acco only with an Allison 24 Oct 2014 18:00 #149857

  • d23j
  • d23j's Avatar
  • Offline
  • Posts: 338
  • Thank you received: 25
If the Allison is set up right you get better fuel figures than with a manual and exhaust brake is controlled but the trans and it's cheaper overal!

Please Log in to join the conversation.

Re: New Acco only with an Allison 24 Oct 2014 18:30 #149858

  • dieseldog
  • dieseldog's Avatar
  • Offline
  • Posts: 1101
  • Thank you received: 61

If the Allison is set up right you get better fuel figures than with a manual and exhaust brake is controlled but the trans and it's cheaper overal!


I can't really agree with that mate, because if the transmissions are identical ratio wise, a fluid coupling will always slip to some degree.

However, a Automated Manual Transmission can be more efficient as it will "talk" to the engine and shift at the right times, etc.

The ultimate fuel economy comes with a manual transmission and a good driver- the reason being no power train can predict a load change or see the road conditions.

Please Log in to join the conversation.

Re: New Acco only with an Allison 24 Oct 2014 20:39 #149859

  • mammoth
  • mammoth's Avatar
  • Offline
  • Posts: 2449
  • Thank you received: 146
Err. The future is already here. Volvo's latest flag ship has a transmission which 'remembers' routes and predicts need for down and up changing, so doesn't wait to bog down to prompt a change.

Please Log in to join the conversation.

Re: New Acco only with an Allison 26 Oct 2014 07:01 #149860

  • d23j
  • d23j's Avatar
  • Offline
  • Posts: 338
  • Thank you received: 25
The Allison does better every time because every time the engine fires it is moving the vehicle on when a manual is changing gears the engine goes on but is not moving the load the idle time is much higher, which is wasted fuel, the road relay don't lie!

Please Log in to join the conversation.

Re: New Acco only with an Allison 26 Oct 2014 14:06 #149861

  • dieseldog
  • dieseldog's Avatar
  • Offline
  • Posts: 1101
  • Thank you received: 61

The Allison does better every time because every time the engine fires it is moving the vehicle on when a manual is changing gears the engine goes on but is not moving the load the idle time is much higher, which is wasted fuel, the road relay don't lie!


Not exactly bud. Imagine a very simple manual power train with a clutch, a 1:1 top gear and a 1:1 differential. Every turn the engine makes will result in one turn of the wheel. So if the engine does 1000 rpm, the wheels will turn at 1000 rpm.

Now imagine the same power train, but instead of a clutch, there is a torque converter. Now bear in mind that the best torque converters are only 95% efficient.
This means that for every turn of the engine, under minimal load, means the wheel will only turn 0.95 of a revolution. At 1000 engine rpm, there is only 950 rpm at the wheels.

A lock up converter will make the ratio a full 1:1 again, but it must be at the correct speed and not "converting". So this counts out most driving conditions except cruising, under minimal load.

A good way to describe it in practice? Imagine a load so heavy, it cannot be pulled up a hill and there is so much traction, the trucks driving wheels cannot turn. A manual transmission will either stall the engine or break something. An auto will allow full engine power to be applied to the wheels, yet you're still not moving.

Try this. Hop into a manual vehicle, start it and look at the revs. Now put it in gear- what happens? Nothing.

Hop into a vehicle with an auto and do the same. What happens? The revs fall by 100 rpm or so? Thats because the convertor is slipping and putting load on the engine. What does load on the engine mean? More fuel consumption.

If your interested, read these...

en.wikipedia.org/wiki/Torque_converter

en.wikipedia.org/wiki/Torque_converter#E...orque_multiplication

I will go onto to say that if your getting better mileage from an auto truck, you have a higher drive train ratio and this is where your getting the advantage.

Please Log in to join the conversation.

Re: New Acco only with an Allison 26 Oct 2014 14:41 #149862

  • d23j
  • d23j's Avatar
  • Offline
  • Posts: 338
  • Thank you received: 25
Sorry total bs Allison locks up at 2nd gear manual still waisting fuel till 18th!

Please Log in to join the conversation.

Re: New Acco only with an Allison 28 Oct 2014 14:11 #149863

  • atkipete
  • atkipete's Avatar
  • Offline
  • Posts: 2653
  • Thank you received: 41
Am I right in thinking a six speed Allison essentially has 7 gears ?
ie first in reduction first locked and then the five higher gears in lockup mode ?

Please Log in to join the conversation.

Re: New Acco only with an Allison 28 Oct 2014 16:03 #149864

  • dieseldog
  • dieseldog's Avatar
  • Offline
  • Posts: 1101
  • Thank you received: 61

Sorry total bs Allison locks up at 2nd gear manual still waisting fuel till 18th!


Your still missing the point, by failing to understand how the lock up device functions. In earlier transmissions it was a centrifugal clutch, these days it is an oil, or wet clutch.

When you get the vehicle moving, the torque converter gets it up to speed. Now the transmission changes to second gear. When the transmission input shaft and flywheel speeds are matched, the oil clutch engages and locks the convertor. You continue to accelerate the vehicle to the point of another gear change- the oil clutch releases and the transmission changes gear while the torque convertor absorbs the speed difference in the engine and transmission speeds. Once the speeds match, the converter locks up again until the next gear change and so on.

A 15 speed RR has 300 rpm or so between gears? An auto transmission has half the gears, so double the rpm difference. How do you think the 600 rpm difference between the engine and transmission is absorbed?

A manual transismmon clutch is either engaged, slipping or released.

An auto lockup clutch is either engaged or released. The slipping comes from the torque convertor.

In very basic terms, both manual and automatic transmissions do the same thing- control power flow and speed, just one does it automatically without driver assistance and in doing this, it sacrifices efficiency.

In terms of the physics behind it, energy between the flywheel and the wheels is lost as heat. That's why manuals are 98% efficient or better. Auto transmissions lose much more heat energy due to the friction of the slipping fluid in the torque converter. This is the reason why auto transmissions have dirty great big oil coolers swinging in the breeze. How often do you see an oil cooler on a manual transmission or cooling fins on a dry friction clutch.


Please Log in to join the conversation.

Time to create page: 0.772 seconds

Historic Commercial Vehicles Club of Australia Inc.  Post: P.O. Box 2020 Bayswater Vic. 3153    Clubrooms: Unit 8 / 4  Macquarie Place Boronia    Club Phone: 0400 025 525    Club Rooms:  03) 9738 1558