Eaton Fuller Roadranger Transmission Model Breakdown

Roadrangers include applications from:

• Freightliner Cascadia
• Kenworth W900 / T800
• Peterbilt 379 / 389
• International HX / PayStar

Roadrangers are known for:

• Twin countershaft design
• High torque capacity (up to ~2,250+ lb-ft in later models)
• Modular ratio configurations (9, 10, 13, 15, 18 speeds)
• Exceptional durability in vocational and linehaul applications

Breakdown:

Prefix (RTLO)

• R = Roadranger
• T = Twin Countershaft
• L = Low inertia design
• O = Overdrive

Numeric Model (18918)

• 18 = Approx. torque rating → (18 × 100) + 50 ≈ 1,850 lb-ft
• 9 = Design level (seal system / gearing generation)
• 18 = Forward speeds

Suffix (B)

• Revision level / engineering update

RT = Roadranger Twin Countershaft (Direct Drive)

Key Features:

• Direct drive (1:1 top gear)
• No overdrive
• Extremely durable for vocational use

Common Models:

• RT-8608LL
• RT-8908LL
• RT-9509

Applications:

• Dump trucks
• Logging trucks
• Heavy vocational fleets

Era: 1960s–1990s (still found in legacy fleets)

RT models are the baseline architecture for all modern Roadranger transmissions.

RTO = RT + Overdrive

Key Features:

• Overdrive top gear (typically 0.73–0.86 ratio)
• Improved fuel economy
• Ideal for highway speeds

Common Models:

• RTO-14910B
• RTO-16910C
• RTO-18910B

Applications:

• Long-haul tractors
• Fleet spec highway trucks

Era: 1970s–present

One of the most popular heavy-duty transmission families ever produced.

RTLO = RT + Low Inertia + Overdrive

Key Features:

• Reduced rotating mass for smoother shifting
• Better fuel efficiency vs RTO
• Common in high-performance fleets

Common Models:

• RTLO-16913A (13-speed)
• RTLO-18918B (18-speed)
• RTLO-20918B

Applications:

• Owner-operator trucks
• Performance diesel builds
• Heavy haul

Era: 1980s–present

These are among the most recognizable Eaton transmissions in the field today.

FRO = Fuller Roadranger Overdrive

Key Features:

• Medium-duty variant
• Lower torque capacity than RT/RTO
• Overdrive gearing

Common Models:

• FRO-12210C
• FRO-16210C
• FRO-18210C

Applications:

• Box trucks
• Regional delivery
• Utility trucks

Designed for Class 6–7 vehicles, not heavy linehaul.

FR = Fuller Roadranger (Twin Countershaft)

Key Features:

• Predecessor / alternative to FRO
• Available with or without overdrive

Variants:

• FR = Direct drive
• FRO = Overdrive
• FRF / FROF = Forward shift bar housing

Often seen in earlier or medium-duty configurations.

RTX = Overdrive + Direct Shift Pattern

Key Features:

• Alternate shift pattern design
• Specialized vocational or export use

Examples:

• RTXF-14615
• RTXF-14710B

Less common in North America but important for interchange mapping.

FA = Fuller Advantage

Key Features:

• Reduced weight (~75–100 lbs lighter)
• Improved efficiency
• Optimized for modern emissions engines

Variants:

• FAO = Overdrive
• FAM = Multi-torque
• FAOM = Overdrive + Multi-torque

Represents Eaton’s latest manual transmission platform.

Key Suffixes and Modifiers

These suffixes dramatically change interchange and fitment:

• F = Forward shift bar housing
• LL = Double low (deep reduction gears)
• L = Single low gear
• C / B / A = Design revision
• T2 = Automated top gears (AutoShift variants)

Example:

• RTO-14908LL = 10-speed with deep reduction gears
• RTLO-18918B-T2 = 18-speed with automated top gears

Torque Ratings & Capacity

Torque rating formula:

(First two digits × 100) + 50 = lb-ft rating

Examples:

• RTLO-18918 → ~1,850 lb-ft
• RTO-16910 → ~1,650 lb-ft

This system allows quick identification of application suitability.

Most Common Models in the Field

• RTO-14910B → Fleet standard 10-speed
• RTLO-18918B → Most common 18-speed
• RTLO-16913A → Popular 13-speed

Engine Pairings

• Cummins N14 / ISX / X15
• Detroit Diesel Series 60
• Caterpillar C15 / C16

Why Fleets Choose Roadranger

• Simplicity vs AMTs
• Lower repair costs
• Driver control (especially 13/18-speed)