Transmissions
An automated manual is not an automatic
It is a manual gearbox with the clutch and the shifting actuated. There is no torque converter, it fails like a manual and it gets repaired like a manual. Conflating the two is the most common mistake in a used listing, and it changes what a worn one costs you.
The transmission is also where most of the last decade’s fuel economy came from. Downspeeding is a gearbox and axle decision, not an engine one: tall top gears and a fast rear ratio let the engine cruise at 1,150 rpm instead of 1,450, which is worth more than almost any aerodynamic device.
Manual
3 boxes
A driver, a clutch and a stick. Cheaper to buy, cheaper to fix, lighter, and increasingly hard to sell: the used market for manuals has thinned as fleets standardised on automated boxes and as fewer drivers can shift one.
| Transmission | Speeds | Torque | Weight | Payload cost |
|---|---|---|---|---|
| Eaton Fuller 10-speed Eaton · 1960s to present | 10 | 1450-1850 | 720 lb | +80 lb |
| Eaton Fuller 13-speed Eaton · 1970s to present | 13 | 1650-2050 | 760 lb | +120 lb |
| Eaton Fuller 18-speed Eaton · 1970s to present | 18 | 1750-2250 | 800 lb | +160 lb |
Automated manual
6 boxes
The same gearbox with the clutch and the shifting actuated. It is NOT an automatic, it has no torque converter, and it fails and gets repaired like a manual. This is now the default in new linehaul, because software shifts more consistently than a person and consistency is fuel.
| Transmission | Speeds | Torque | Weight | Payload cost |
|---|---|---|---|---|
| Eaton Cummins Endurant Eaton · 2017 to present | 12 | 1850-2050 | 640 lb | lightest |
| Eaton UltraShift PLUS Eaton · 2007 to present | 13 | 1650-2050 | 780 lb | +140 lb |
| Detroit DT12 Detroit · 2013 to present | 12 | 1650-2050 | 700 lb | +60 lb |
| Volvo I-Shift Volvo · 2007 to present | 12 | 1650-2320 | 690 lb | +50 lb |
| Mack mDRIVE Mack · 2010 to present | 12 | 1650-2060 | 690 lb | +50 lb |
| PACCAR TX-12 PACCAR · 2017 to present | 12 | 1650-1850 | 680 lb | +40 lb |
Torque converter automatic
2 boxes
A true automatic with a fluid coupling. Smooth, forgiving and heavy, which is why it lives in refuse, mixer and city work where there are hundreds of stops a day and nobody wants a clutch.
| Transmission | Speeds | Torque | Weight | Payload cost |
|---|---|---|---|---|
| Allison 3000 series Allison · 1990s to present | 6 | 1250-1450 | 720 lb | +80 lb |
| Allison 4000 series Allison · 1990s to present | 6 | 1550-1850 | 900 lb | +260 lb |
11 transmissions. Payload cost is weight over the lightest box listed, and on a weight-sensitive lane it is freight you cannot carry. Fuel notes are directional rather than figures, because a gearbox does not have an mpg: it has an effect on one, and the size of that effect depends on the axle ratio it is paired with.