FAT-30 Auxiliary Transmission for American Truck Simulator
Eaton UltraShift PLUS 11- and 18-speeds paired with the FAT-30 auxiliary: up to 54 gears for heavy haul, mining and oversize loads on 200+ trucks. ATS 1.58.
Download FAT-30 Auxiliary Transmission
More screenshots on Steam Workshop ↗
What this mod does
FAT-30 Auxiliary Transmission, by Crabby with help from Abby J, adds heavy-haul transmissions: it pairs the Eaton UltraShift PLUS VMS (11-speed) and VXP (18-speed) with the Cummins-Meritor FAT-30 auxiliary transmission, originally developed by Fabco. It’s designed for mining, logging and oversize loads.
How the FAT-30 works
It’s a three-speed auxiliary mounted behind the main transmission: underdrive (2.50:1), direct (1.00:1) and overdrive (0.86:1), rated for 30,000 lb-ft of torque.
Combinations
- VMS + FAT-30: 33 forward gears, 9 reverse and a retarder.
- VXP + FAT-30: 54 forward gears, 12 reverse and a retarder.
- Differentials from 3.42 (about 130 km/h) to 4.30 (about 95 km/h) for the heaviest loads on grades.
Control setup
With so many gears, the author recommends sequential mode: in automatic, choose “Simple Automatic” and enable “Smart Sequential Shifting”; with a controller or keyboard, choose “Sequential” and the same option. For H-shifters, the tips are on his Discord.
Compatibility
Version 1.1 (February 2026) is made for ATS 1.58 and supports more than 200 trucks. It works with the Heavy Cargo Pack DLC and has high priority so it overrides other files. Unofficial mod, not affiliated with Eaton, Cummins, Meritor or SCS.
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User rating
Highlights and things to keep in mind
- Huge gear reduction for extreme loads
- More than 200 compatible trucks
- Detailed explanation of differentials and controls
- Marked for ATS 1.58
- Too many gears for an H-shifter without setup
- Some of the help is only on Discord
Requirements
- American Truck Simulator 1.58 (according to the author)
- Steam account
- Optional: Heavy Cargo Pack DLC for heavy loads
How to install it
- Open the “FAT-30 Auxiliary Transmission” page on Steam Workshop and click “Subscribe”.
- Launch American Truck Simulator and wait for Steam to finish downloading the mod.
- In your profile's Mod Manager, enable “FAT-30 Auxiliary Transmission”.
- Give it high priority (near the top) in the mod list.
- In Options, choose “Simple Automatic” or “Sequential” and enable “Smart Sequential Shifting”.
- Go to a service shop and fit a VMS or VXP transmission with the FAT-30 and the differential you need.
Version history
-
1.124 Feb 2026Current
200+ trucks; tweaks to gear names and compatibility; H-shifter tips moved to Discord
-
1.08 Oct 2025
Release
Common problems
How many gears does it have?
Up to 54 forward and 12 reverse with the 18-speed VXP plus the FAT-30.
Can I use it with an H-shifter?
Yes, but the setup tips are on the author's Discord.
Do I need the Heavy Cargo Pack DLC?
It's not required; the author says it's compatible with it.
Does it work on the Volvo VNL 2025?
A user asked for it in May 2026; the description doesn't confirm it.
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