Eaton AutoShift Transmission

Quick Facts

  • Manufacturer: Eaton
  • Brand Family: Eaton Fuller
  • Transmission Type: Automated Manual Transmission
  • Common Generations: Original AutoShift and AutoShift Generation 2
  • Common Configurations: 10-Speed and 18-Speed
  • Representative Models: RTO-10910B-AS2, RTO-12910B-AS2, RTO-14910B-AS2, RTO-16910B-AS2, RTO-18910B-AS2, RTLO-14918A-AS2, RTLO-16918A-AS2, RTLO-18918A-AS2, and other AS2-designated models
  • Forward Speeds: 10 or 18 depending on model
  • Reverse Speeds: Multiple reverse ratios depending on model
  • Maximum Input Torque: Approximately 1,050 to 1,850 lb-ft on many common models; certain specialized configurations may differ
  • Base Design: Eaton Fuller Twin-Countershaft Mechanical Transmission
  • Clutch Operation: Driver-Operated Clutch Pedal for Starting and Stopping
  • Gear Selection: Electronically Controlled and Pneumatically Actuated
  • Driver Controls: Shift Selector, Driver Display, Accelerator, Brake, and Clutch Pedal
  • Operating Modes: Automatic and Manual Gear-Selection Modes
  • Top-Gear Configuration: Direct Drive or Overdrive depending on model
  • PTO Compatibility: Available on compatible transmission models and case configurations
  • Common Applications: Long-Haul Tractors, Regional Trucks, Tankers, Heavy Haul, Vocational Trucks, and Fleet Operations
  • Common Truck Classes: Primarily Class 8
  • Approximate Weight: Commonly around 600 to 750 pounds depending on the base transmission and configuration
  • Diagnostic System: Electronic fault codes and service diagnostics
  • Production Status: Discontinued legacy product; parts, service information, remanufactured units, and used transmissions remain available

Overview

The Eaton AutoShift is an early-generation automated manual transmission developed for North American heavy-duty trucks. It combines an Eaton Fuller mechanical gearbox with electronic controls and pneumatic shift actuators that select and engage the gears.

AutoShift was designed to reduce the amount of manual gear shifting required from the driver while retaining the mechanical efficiency and familiar internal construction of an Eaton Fuller transmission.

Unlike later two-pedal automated manual transmissions, most Eaton AutoShift installations retain a clutch pedal. The driver uses the clutch when starting from a stop and when bringing the vehicle to a complete stop. Once the truck is moving, the transmission’s electronic controls perform the gear changes without requiring the driver to operate the clutch pedal for every shift.

AutoShift was offered in multiple configurations, including 10-speed highway models and 18-speed heavy-duty models. The exact specifications depend on the underlying Eaton Fuller transmission, torque rating, ratio set, electronic generation, and vehicle application.

The AutoShift helped establish automated manual transmissions in the North American trucking market. It was followed by newer Eaton products such as UltraShift, UltraShift PLUS, Fuller Advantage Automated, and the Eaton Cummins Endurant family.

Key Characteristics

The AutoShift is built around a conventional Eaton Fuller mechanical transmission. The internal gears, shafts, bearings, range section, and other major components are similar to those used in related manual transmissions.

Electronic controls determine when a shift should occur. The transmission then uses actuators to move the shift components and select the appropriate gear.

The system communicates with the engine through the truck’s electronic data network. During a shift, the transmission controller requests changes in engine torque and speed so the drivetrain can unload and the next gear can be engaged.

A major distinguishing feature is the clutch pedal. AutoShift automates the gear changes after the truck is moving, but the driver remains responsible for clutch engagement when starting and clutch disengagement when stopping.

The transmission normally provides both automatic and manual operating modes. Automatic mode allows the transmission controller to choose the gears. Manual mode lets the driver request upshifts, downshifts, or a particular operating range when additional control is needed.

The driver display provides gear-position information and may also display operating status, selected mode, warning indicators, and diagnostic codes.

How the Transmission Works

When the truck is stationary, the driver depresses the clutch pedal and selects drive or the appropriate starting mode through the shift selector.

The AutoShift controller evaluates vehicle weight, road grade, engine speed, throttle position, vehicle speed, and other operating information to select a starting gear.

The driver then releases the clutch pedal manually to move the truck. Once the vehicle is underway, normal upshifts and downshifts are performed automatically.

When a shift is required, the transmission controller communicates with the engine control module. Engine torque is reduced so the drivetrain is unloaded.

The shift actuator moves the transmission out of the current gear. The controller then manages engine speed to help match the selected gear with the vehicle’s road speed.

When the correct speed relationship is reached, the actuator engages the next gear. Engine torque is then restored.

Range and splitter changes are handled through the transmission’s pneumatic system and electronic controls. The exact sequence depends on whether the truck has a 10-speed or 18-speed AutoShift.

When approaching a stop, the transmission downshifts automatically. The driver must depress the clutch pedal before the truck stops completely to prevent the engine from stalling.

The clutch pedal is also used when maneuvering at very low speeds. Because the driver controls clutch engagement, backing into a dock or moving through a tight yard requires clutch and throttle coordination similar to a manually shifted truck.

Common Specifications

Transmission Type

The AutoShift is an automated manual transmission.

It uses a mechanically geared transmission rather than the planetary gearsets and torque converter commonly found in a conventional automatic transmission.

Speed Configurations

Common heavy-duty configurations include:

  • 10-speed AutoShift
  • 18-speed AutoShift

The 10-speed was widely used in highway tractors and fleet applications.

The 18-speed was designed for operations requiring additional ratios, greater low-speed control, or heavier gross combination weights.

Input-Torque Capacity

Torque ratings vary by model.

Common 10-speed AutoShift ratings range from approximately 1,050 to 1,850 lb-ft.

Representative 18-speed AutoShift models include:

  • RTLO-14918A-AS2 — approximately 1,450 lb-ft
  • RTLO-16918A-AS2 — approximately 1,650 lb-ft
  • RTLO-18918A-AS2 — approximately 1,850 lb-ft

The complete transmission model must be checked before pairing the AutoShift with an engine.

Gear Ratios

Gear ratios depend on the underlying transmission family.

Some 10-speed models use direct-drive gearing, while others use an overdrive top ratio.

The 18-speed version provides a wide overall ratio spread with multiple low-range, high-range, and splitter selections.

The exact starting ratio, top ratio, reverse ratio, and overall ratio spread must be confirmed for the individual model.

Clutch System

Most AutoShift installations use a conventional heavy-duty dry clutch controlled by the driver through a clutch pedal.

The clutch is used when starting, stopping, and performing certain low-speed maneuvers.

Once the vehicle is moving, normal gear changes are completed without the driver depressing the clutch pedal.

Electronic Controls

The system commonly includes:

  • Transmission electronic control unit
  • Engine electronic control module communication
  • Gear-position sensors
  • Input-speed sensor
  • Mainshaft or output-speed sensor
  • Range-position sensors
  • Shift actuator
  • Driver display
  • Shift selector
  • Vehicle data-network connections

Exact controls and wiring differ by generation, model, engine, and truck manufacturer.

Shift Actuation

The AutoShift uses electronically commanded actuators to move the shift components.

Compressed air operates range and splitter functions on applicable models.

Correct system air pressure is essential for reliable operation.

Driver Controls

The driver normally has a clutch pedal, accelerator, service brake, shift selector, and gear display.

The selector may provide neutral, drive, reverse, low, and manual gear-selection functions depending on the installation.

Reverse Operation

Reverse must be selected while the vehicle is stopped.

The driver controls initial movement through the clutch pedal and accelerator.

Certain 18-speed configurations provide more than one usable reverse ratio.

PTO Compatibility

PTO capability depends on the underlying transmission case, available opening, PTO drive gear, electronic programming, application requirements, and available clearance.

PTO operation may require interlocks, vehicle programming, remote controls, or an elevated engine-idle setting.

Lubrication System

The AutoShift uses heavy-duty manual-transmission lubricant approved for the specific Eaton transmission.

Lubricant requirements and service intervals depend on model, vocation, operating temperature, and production date.

Some models may use an oil pump, filter, or cooler.

Transmission Weight

Weight varies according to the base gearbox and actuator equipment.

A 10-speed AutoShift is generally lighter than an 18-speed configuration.

The clutch, lubricant, PTO, cooler, mounts, and external controls are not always included in published transmission weights.

Installation Requirements

Installation requires compatible:

  • Engine electronic controls
  • Vehicle data network
  • Transmission control module
  • Wiring harnesses
  • Shift selector
  • Driver display
  • Clutch and clutch pedal system
  • Flywheel housing
  • Input shaft
  • Transmission mounts
  • Driveshaft and output yoke
  • Air supply
  • Speed sensors
  • PTO equipment
  • Engine and axle gearing

Replacing an AutoShift with a manual, UltraShift, or newer automated transmission can require substantial electrical, mechanical, and programming changes.

Common Applications

  • Long-haul sleeper tractors
  • Regional highway tractors
  • Day cab tractors
  • Tanker trucks
  • Bulk-hauling trucks
  • Heavy-haul tractors
  • Construction-support vehicles
  • Vocational trucks
  • Fleet-operated Class 8 trucks
  • Dedicated-route tractors
  • Agricultural transport trucks
  • Equipment-hauling tractors
  • Drivers transitioning from manual transmissions
  • Operations seeking reduced shifting workload

Truck and Engine Compatibility

The Eaton AutoShift was installed in numerous North American Class 8 trucks. Availability depended on model year, engine selection, transmission torque rating, vehicle electronics, drivetrain configuration, and truck manufacturer.

Relevant truck platforms with live Truck Equipment Atlas pages include:

Older platforms associated with AutoShift availability also included Freightliner Century Class, Freightliner Columbia, Freightliner FLD, Kenworth T600, Kenworth T660, Peterbilt 379, Peterbilt 385, Peterbilt 386, International 9200, International 9400, and International 9900.

Common compatible engine families with live Truck Equipment Atlas pages include:

The engine must use compatible electronic controls and communication protocols. Peak engine torque must remain within the transmission’s approved rating.

Compatibility must also account for clutch capacity, flywheel housing, input shaft, driveshaft, rear-axle gearing, engine programming, vehicle wiring, transmission software, and intended vocation.

Advantages

  • Automates gear changes after the truck begins moving
  • Reduces driver shifting workload
  • Retains familiar Eaton Fuller mechanical architecture
  • Can reduce driver fatigue on long routes
  • Provides automatic and driver-selectable modes
  • Available in 10-speed and 18-speed configurations
  • 18-speed version offers broad ratio coverage
  • Can improve shift consistency among different drivers
  • Reduces gear grinding caused by poor manual speed matching
  • Allows direct clutch control during starting and low-speed maneuvering
  • Compatible with many heavy-duty diesel engines
  • Electronic diagnostics can help identify system faults
  • Extensive service information remains available
  • Remanufactured transmissions and components remain obtainable
  • Helped fleets transition from manuals to automated transmissions

Limitations or Considerations

  • The clutch pedal is still required for starting and stopping
  • More complicated than a purely manual transmission
  • Older electronic controls may be difficult to diagnose
  • Wiring and connector condition can affect operation
  • Requires compatible engine and transmission programming
  • Shift quality may feel slower than a conventional automatic
  • Power is interrupted during gear changes
  • Low-speed maneuvering requires clutch-pedal control
  • Air-system problems can prevent range or splitter shifts
  • Sensors and actuators add maintenance points
  • Certain electronic parts may be difficult to obtain
  • A replacement transmission may require software configuration
  • Different AutoShift generations may not share the same controls
  • Driver training remains important
  • It lacks many features found in newer automated transmissions
  • Production has ended

Driver and Operator Experience

The Eaton AutoShift reduces the amount of shift-lever work required from the driver, but it does not operate exactly like a conventional automatic transmission.

The driver must depress the clutch pedal before selecting a starting gear. The clutch is then released manually to move the truck.

Once underway, the transmission selects and changes gears automatically. The driver keeps a steady accelerator position while the engine and transmission controllers coordinate the shift.

A temporary reduction in engine power during a shift is normal. The AutoShift must unload the drivetrain before disengaging one gear and selecting another.

When stopping, the driver must depress the clutch pedal before engine speed falls too low. Failing to use the clutch can cause the engine to stall.

Manual mode allows the driver to request gear changes when approaching a grade, descending a hill, entering soft terrain, or controlling vehicle speed with an engine brake.

Drivers should avoid attempting to control the truck on a grade by slipping the clutch. The service brakes should hold the vehicle until the driver is ready to move.

Because AutoShift retains a clutch pedal, drivers familiar with manual transmissions may find its starting and backing behavior more predictable than later two-pedal automated designs.

Maintenance and Ownership Notes

The complete model and serial numbers should be recorded from the transmission identification tag.

Technicians must determine whether the transmission is an original-generation AutoShift, Generation 2 model, AS2 configuration, or another related version before ordering electronic or mechanical components.

Diagnostic fault codes should be recorded before disconnecting batteries or clearing the transmission controller.

Battery voltage and charging-system condition are important. Low voltage can cause actuator faults, communication errors, display problems, and unsuccessful shifts.

Wiring harnesses should be inspected for corrosion, rubbing, loose connectors, water entry, damaged pins, and previous repairs.

The truck’s air system must provide clean, dry air at the proper pressure. Air leaks can prevent the transmission from completing range or splitter changes.

Clutch adjustment, release travel, clutch-brake operation, and linkage condition remain important because the driver operates the clutch during starts and stops.

Lubricant level and condition should be checked according to Eaton requirements. Incorrect lubricant can cause excessive heat, poor shifting, and internal damage.

The shift actuator, speed sensors, transmission controller, engine communication system, mounts, driveshaft, and output yoke should be included in preventive maintenance.

Common Transmission Problems

Transmission Will Not Select a Gear

Possible causes include low air pressure, low battery voltage, an active fault, a failed speed sensor, a defective actuator, clutch drag, a wiring problem, or loss of communication with the engine controller.

Stuck in Neutral

The transmission may remain in neutral when it cannot verify gear position, synchronize shaft speeds, complete an actuator movement, or communicate with the engine.

Harsh or Slow Shifts

Harsh or delayed shifts can result from incorrect engine programming, actuator wear, speed-sensor problems, clutch drag, drivetrain problems, or poor electrical connections.

Clutch Problems

A worn, misadjusted, or dragging clutch can cause difficult starting-gear engagement, harsh launches, gear-selection problems, and fault codes.

Clutch-Brake Wear

A damaged clutch brake can make it difficult to select a starting gear while stopped. It should not be engaged while the truck is moving.

Gear-Position Sensor Faults

The control module must know the transmission’s exact gear position. A failed or inaccurate sensor can prevent shifting or place the system into a fault mode.

Input- or Output-Speed Sensor Faults

The controller uses shaft-speed information to determine when gears can be engaged. Incorrect readings can produce missed shifts, fault codes, or a transmission that remains in neutral.

Shift-Actuator Failure

Worn actuator components, electrical faults, air problems, or mechanical binding can prevent the transmission from moving into the requested gear.

Data-Network Communication Problems

Damaged wiring, incorrect terminating resistance, poor grounds, failed controllers, or incompatible engine programming can interrupt communication between the engine and transmission.

Oil Leaks

Leaks can develop at the input seal, output seal, case joints, PTO openings, shift housing, or auxiliary section.

Range or Splitter Problems

Low air pressure, leaking seals, damaged valves, restricted air lines, or internal auxiliary-section wear can prevent proper range or splitter shifts.

Buying Considerations

  • Confirm that the transmission is an Eaton AutoShift rather than an UltraShift.
  • Locate the complete model and serial numbers.
  • Identify the AutoShift generation.
  • Confirm whether it is a 10-speed or 18-speed.
  • Verify the input-torque rating.
  • Confirm direct-drive or overdrive gearing.
  • Check the engine and transmission communication compatibility.
  • Verify that the transmission controller is included.
  • Confirm that the correct shift selector and driver display are included.
  • Inspect the wiring harnesses and connectors.
  • Check the gear-position and speed sensors.
  • Inspect the shift actuator.
  • Verify clutch-pedal and clutch-system compatibility.
  • Check PTO availability and controls.
  • Inspect the transmission case for cracks or repairs.
  • Check the lubricant for contamination.
  • Scan the transmission controller for active and inactive faults.
  • Road-test every operating mode.
  • Verify automatic and manual shifting.
  • Confirm proper reverse operation.
  • Check parts and diagnostic support in the operating area.
  • Calculate the cost of programming, wiring, clutch work, and installation.

Variants and Configurations

  • AutoShift 10-Speed
  • AutoShift 18-Speed
  • AutoShift Generation 1
  • AutoShift Generation 2
  • AS2 Models
  • Direct-Drive Configurations
  • Overdrive Configurations
  • Line-Haul Configurations
  • Heavy-Haul Configurations
  • Vocational Configurations
  • PTO-Equipped Configurations
  • Oil-Pump and Cooler Configurations
  • Multiple Input-Torque Ratings
  • Remanufactured AutoShift Transmissions

Comparison to Similar Equipment

Compared with an Eaton Fuller manual transmission, the AutoShift selects and changes gears electronically after the vehicle begins moving. The driver still controls the clutch when starting and stopping.

Compared with the Eaton UltraShift, the AutoShift retains a driver-operated clutch pedal. UltraShift uses an automated centrifugal clutch and normally provides two-pedal operation.

Compared with the Eaton UltraShift PLUS, the AutoShift uses older electronic controls and lacks many later features such as improved low-speed maneuvering, hill-start assistance, creep functions, and more advanced shift strategies.

Compared with the Eaton Cummins Endurant HD, the AutoShift is heavier, uses an older transmission architecture, and requires a clutch pedal. Endurant HD is a newer integrated automated manual transmission with 12 forward speeds and two-pedal operation.

Compared with an Allison automatic transmission, the AutoShift uses a mechanical clutch and conventional geartrain rather than a torque converter and planetary transmission. The Allison generally provides smoother power delivery at low speed, while the AutoShift retains the operating characteristics of a mechanically geared transmission.

Best Fit For

  • Fleets operating older AutoShift-equipped trucks
  • Long-haul highway operations
  • Regional trucking fleets
  • Drivers transitioning from manual transmissions
  • Operations wanting automatic shifting with manual clutch control
  • Fleet maintenance departments familiar with Eaton electronics
  • Heavy-duty trucks requiring 10-speed ratio coverage
  • Heavy-haul operations using compatible 18-speed models
  • Owners with access to AutoShift diagnostic support
  • Buyers restoring or maintaining older Class 8 trucks

Related Truck Types

Related Truck Models

Related Engines

Related Transmission Types

Related Equipment Systems

Related Guides

Understand the operating principles in How Commercial Truck Transmissions Work, compare drivetrain designs in Manual vs Automated Manual vs Automatic Transmissions, and evaluate gearing, application, and compatibility in How to Choose a Commercial Truck Transmission.

Regulatory and Compliance Notes

The AutoShift must be installed with compatible engine controls, wiring, clutch components, driveshaft equipment, mounts, air systems, and vehicle programming.

Changes to the transmission, rear-axle ratio, tire diameter, speed sensors, engine software, or control modules can affect speedometer accuracy, cruise control, engine braking, and emissions-system operation.

Electronic faults should be diagnosed using appropriate Eaton service information and compatible diagnostic equipment.

A replacement control module may require programming or configuration for the truck’s engine, axle ratio, tire size, transmission model, and operating features.

PTO installations must include the correct controls, interlocks, guarding, and programming.

The truck must remain within its gross vehicle weight, axle-weight, gross combination weight, and transmission input-torque ratings.

Real World Operating Notes

The Eaton AutoShift feels different from both a conventional manual and a modern two-pedal automated transmission.

The driver manually controls the clutch when moving from a stop, backing, docking, and stopping. Once the truck is moving, the transmission performs normal gear changes automatically.

Drivers should allow the engine and transmission controllers to complete each shift. Rapid throttle changes during a shift can reduce smoothness.

AutoShift gear changes include a noticeable interruption in power because the drivetrain must unload before the next gear is engaged.

On grades, manual mode can help the driver hold a desired gear and avoid unnecessary shifting.

The driver should depress the clutch before coming to a complete stop. Forgetting the clutch can stall the engine.

A well-maintained AutoShift can provide dependable service, but technicians must understand both its mechanical Eaton Fuller gearbox and its electronic control system.

Frequently Asked Questions

What is an Eaton AutoShift?

It is an automated manual transmission that uses electronic controls and actuators to shift an Eaton Fuller mechanical gearbox.

Does the Eaton AutoShift have a clutch pedal?

Most AutoShift installations retain a clutch pedal. The driver uses it when starting, stopping, and maneuvering at low speeds.

Is AutoShift the same as UltraShift?

No. AutoShift normally uses a driver-operated clutch pedal. UltraShift uses an automated centrifugal clutch and normally operates without a clutch pedal.

Was AutoShift available as a 10-speed?

Yes. The 10-speed AutoShift was widely used in highway Class 8 trucks.

Was an 18-speed AutoShift available?

Yes. Eaton offered 18-speed AutoShift models for applications requiring broader ratio coverage and greater heavy-duty capability.

Does the AutoShift shift automatically after the truck starts moving?

Yes. Once the clutch has been released and the truck is moving, the system normally performs upshifts and downshifts automatically.

Can the driver select gears manually?

Most AutoShift systems include a manual mode that allows the driver to request upshifts and downshifts.

Why does an AutoShift become stuck in neutral?

Possible causes include low air pressure, low voltage, sensor failure, actuator problems, clutch drag, wiring faults, or lost communication between the engine and transmission controllers.

Can an AutoShift use a PTO?

Compatible AutoShift models can support PTO equipment. The transmission opening, drive gear, PTO ratio, electronic programming, and application must be verified.

Is the Eaton AutoShift still produced?

No. AutoShift is a legacy product. Used and remanufactured transmissions, service parts, and technical information remain available.

Availability and Where to Find

Eaton AutoShift transmissions are available through heavy-duty transmission remanufacturers, Eaton parts distributors, commercial truck dealers, salvage yards, used-parts suppliers, and commercial-truck marketplaces.

Buyers should confirm that a replacement includes or supports the correct transmission controller, shift actuator, wiring, sensors, shift selector, and driver display.

The complete AutoShift model and serial numbers should be matched before purchasing a replacement. Similar-looking transmissions may have different torque ratings, ratios, control generations, input shafts, output arrangements, and electronic requirements.

Eaton provides legacy AutoShift driver instructions, installation information, parts publications, diagnostic resources, and training materials through its commercial-vehicle transmission resources and transmission-identification guide.

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