Mack C150 and C151 Axle Carriers

Quick Facts

Manufacturer: Mack Trucks
Parent Company: Volvo Group
Product Family: Mack C150 and C151 Axle Carriers
Alternative Designations: CRD150 and CRD151
Carrier Type: Top-mounted dual-reduction tandem axle carriers
C150 Position: Forward carrier in the tandem axle group
C151 Position: Rear carrier in the tandem axle group
Published Ratio Range: Approximately 3.11 to 5.66
Primary Applications: Highway, regional, vocational, construction, refuse, and heavy-haul trucks
Compatible Axle Families: Application-dependent Mack tandem axle housings, including selected S440 and S462 configurations
Gear Design: Mack Durapoid bevel gearing with secondary reduction
Power Divider: Mack automatic interaxle power divider in applicable forward carriers
Optional Traction Equipment: Power-divider lockout and interwheel differential systems
Carrier Position: Top-mounted in the axle housing
Product Page Slug: mack-c150-and-c151-axle-carriers

Overview

The Mack C150 and C151 are top-mounted, dual-reduction differential carriers used together in compatible Mack tandem drive axle systems. They are also commonly identified in service and parts information as the CRD150 and CRD151.

The C150 is installed in the forward axle of the tandem and includes the input and through-shaft arrangement needed to transfer power toward the rear axle. The C151 is installed in the rear axle and receives torque through the interaxle driveline.

These carriers retain Mack’s traditional top-mounted and dual-reduction architecture while providing ratios suitable for highway and vocational applications. Published ratios extend from approximately 3.11 to 5.66.

Key Characteristics

The C150 and C151 use two stages of gear reduction. The first stage uses Mack’s Durapoid bevel gearing, while the secondary stage provides additional reduction before torque reaches the wheel differential and axle shafts.

The top-mounted design positions the carriers and driveshafts higher than many conventional axle arrangements. This improves ground clearance and helps protect the driveline during construction, refuse, logging, and other vocational operations.

The C150 forward carrier can incorporate Mack’s automatic interaxle power divider. This system can transfer up to approximately 75 percent of available torque toward the axle with greater traction.

Optional power-divider lockout and interwheel traction systems may be available, depending on the carrier variation and truck specification.

How the Axle or Differential Works

Engine torque travels through the transmission and main driveshaft to the input of the C150 forward carrier.

The first gear stage changes the direction of power flow and begins the reduction process. The secondary reduction further multiplies torque before it reaches the wheel differential and axle shafts.

The C150’s through-shaft arrangement sends power through the interaxle driveshaft to the C151 rear carrier. The C151 then reduces and distributes torque to the rear axle shafts.

Under normal conditions, the wheel differentials allow the left and right wheels to rotate at different speeds. The interaxle power divider allows the forward and rear axles to compensate for speed differences while helping direct torque toward the axle with better traction.

Axle Position and Function

The C150 is installed in the forward axle housing of a Mack tandem drive system. It receives power from the transmission and distributes that power to the forward axle and the rear carrier.

The C151 is installed in the rear axle housing. It receives torque through the short interaxle driveshaft and transfers it to the rear axle shafts and wheels.

Together, the carriers provide final drive reduction, differential action, torque distribution, and traction management for a conventional Mack 6×4 drivetrain.

The carrier itself does not independently establish the axle’s gross axle weight rating. Capacity depends on the carrier, housing, shafts, suspension, brakes, hubs, wheels, tires, and complete vehicle approval.

Common Specifications

Carrier Configuration: Matched forward and rear tandem carriers
Forward Carrier: C150 or CRD150
Rear Carrier: C151 or CRD151
Reduction Design: Dual reduction
First Reduction: Mack Durapoid bevel gearing
Second Reduction: Application-specific secondary gear reduction
Carrier Mounting: Top-mounted
Published Ratio Range: 3.11 to 5.66
Common Published Ratios: 3.11, 3.25, 3.40, 3.56, 3.79, 3.98, 4.19, 4.50, 4.80, 5.04, 5.31, and 5.66
Interaxle Power Divider: Automatic torque-biasing system on applicable C150 carriers
Maximum Automatic Torque Transfer: Up to approximately 75 percent toward the axle with greater traction
Power-Divider Lockout: Optional on applicable configurations
Interwheel Traction Option: Available on certain carrier variants
Related Locking Variants: CRD1501 and CRD1511 configurations may use air-operated interwheel locking differentials

Exact ratios, carrier housings, gearsets, lockout systems, shafts, yokes, bearings, and application ratings must be verified from the carrier identification information.

Axle Ratios and Gearing

The C150 and C151 carrier family covers ratios from approximately 3.11 to 5.66. Both carriers in the tandem must use the same approved ratio.

Ratios such as 3.11, 3.25, and 3.40 may be used with approved Mack automated transmissions in applications requiring lower engine speed during highway travel.

Ratios such as 3.56, 3.79, 3.98, and 4.19 provide progressively greater torque multiplication for regional, construction, and mixed vocational work.

Ratios such as 4.50, 4.80, 5.04, 5.31, and 5.66 are better suited to applications prioritizing low-speed pulling power, heavy starts, gradeability, and vocational performance.

Not every ratio is compatible with every interwheel power divider, differential lock, engine, transmission, tire size, or gross combination weight rating.

Differential and Traction Options

The standard carrier arrangement includes wheel differentials and the Mack interaxle power divider.

Mack’s automatic interaxle power divider uses cam and wedge components rather than a conventional open gear differential. It can direct up to approximately 75 percent of available torque toward the axle with greater resistance and traction.

An optional interwheel power divider operates between the left and right wheels. It can also redirect up to approximately 75 percent of available torque toward the wheel with greater traction without requiring normal driver intervention.

A driver-controlled power-divider lockout may be used in exceptionally slippery conditions. The air-operated lockout couples the tandem carriers into a more direct positive-drive arrangement.

Brake and Wheel-End Options

The C150 and C151 are differential carrier assemblies and do not independently determine the truck’s brake or wheel-end configuration.

Compatible Mack axle housings may use approved air drum or air disc brakes. Wheel-end options can include conventional hubs, aluminum hubs, dual tires, wide-base tires, and extended-maintenance bearing systems.

Brake and wheel-end compatibility depends on the axle housing, suspension, track width, spindle, hub, wheel, tire, and truck specification.

The complete axle assembly must be identified before ordering brake, hub, bearing, seal, or axle-shaft components.

Common Applications

Highway tractors
Regional-haul tractors
Dump trucks
Concrete mixer trucks
Concrete pump trucks
Refuse trucks
Construction trucks
Municipal vehicles
Snowplows
Logging trucks
Heavy-haul tractors
Transfer trucks
Utility vehicles
Oilfield service trucks
Specialized vocational equipment

Truck, Suspension, and Drivetrain Compatibility

The C150 and C151 are used in compatible Mack tandem axle housings and 6×4 drivetrains. Their application depends on axle capacity, housing construction, suspension, ratio, engine torque, and transmission.

Selected Mack S440 and S462 axle configurations can use 150- and 151-series carriers. Other application-approved Mack axle housings may also support these carriers.

The carriers can be paired with Mack engines and Mack manual or automated transmissions when the complete powertrain is approved for the selected ratio and gross combination weight.

Because these carriers use a top-mounted design, replacement components must preserve the original main and interaxle driveshaft geometry.

Advantages

Mack-designed tandem carrier system
Top-mounted carrier configuration
Dual-reduction gearing
Durapoid bevel gear design
Ratios for highway and vocational operation
Automatic interaxle torque biasing
Transfers up to approximately 75 percent of torque toward the axle with traction
Optional interwheel torque-biasing system
Available power-divider lockout
Improved driveline ground clearance
Favorable driveshaft alignment
Reduced exposure to job-site obstacles
Integration with Mack axles and suspensions
Strong vocational operating history
Mack dealer and aftermarket parts support

Limitations or Considerations

Carriers must be matched as a forward and rear pair
Both carriers must use the same axle ratio
Carrier selection alone does not establish axle capacity
Not every ratio supports every differential option
Dual-reduction carriers contain more gearing than a single-reduction axle
Incorrect setup can produce noise, heat, and rapid gear wear
Top-mounted carriers require compatible axle housings
Replacement yokes and shafts must match the original configuration
Power-divider components require correct inspection and adjustment
Automatic torque biasing cannot overcome a complete lack of resistance in every situation
Power-divider lockout requires correct driver operation
Used carriers may contain internal wear not visible externally
Some parts differ between C150, C151, CRD1501, and CRD1511 variants

Driver and Operator Experience

The automatic interaxle power divider operates without normal driver intervention. When one axle begins to lose traction, the system can redirect additional torque toward the axle with better traction.

Drivers may therefore experience improved mobility without manually locking the tandem during every minor traction event.

The optional power-divider lockout is intended for more difficult conditions. Drivers must follow Mack instructions when engaging or disengaging the lockout.

New gear whine, clunking, vibration, delayed lock engagement, or unusual tire scrub can indicate a problem with the carriers, power divider, driveline, tires, or lubricant.

Maintenance and Ownership Notes

Routine maintenance includes checking carrier lubricant, inspecting axle breathers, examining pinion and housing seals, and monitoring the main and interaxle driveshafts.

The C150 forward carrier contains additional components for the input, through-shaft, and power-divider systems. These parts should receive particular attention when diagnosing vibration, noise, or traction problems.

The correct Mack-approved lubricant must be used. Lubricant requirements and change intervals depend on the axle, application, duty cycle, and operating temperature.

Carrier replacement or rebuilding requires accurate bearing preload, gear backlash, gear contact, shaft adjustment, and seal installation.

Common Axle or Differential Problems

Input pinion seal leakage
Carrier bowl lubricant leaks
Low or contaminated lubricant
Restricted axle breathers
Ring-and-pinion gear wear
Secondary reduction gear wear
Pinion-bearing wear
Differential-bearing wear
Excessive gear backlash
Incorrect gear contact pattern
Power-divider cam or wedge wear
Power-divider lockout problems
Interwheel power-divider problems
Air-operated differential-lock problems
Through-shaft bearing wear
Interaxle driveshaft vibration
Yoke or universal-joint wear
Clunking during acceleration or deceleration
Whining or humming under load
Overheating caused by low lubricant or incorrect setup

Identification Information

Manufacturer: Mack Trucks
Forward Carrier Designation: C150 or CRD150
Rear Carrier Designation: C151 or CRD151
Related Locking Variants: CRD1501 and CRD1511
Primary Identification Source: Carrier tag, stamped part number, or casting information
Important Carrier Information: Model, part number, serial number, ratio, and differential configuration
Important Forward Carrier Information: Input design, through-shaft, power divider, and lockout configuration
Important Rear Carrier Information: Gearset, differential type, and axle-shaft compatibility
Vehicle Information: Mack model, year, VIN, and original build sheet
Axle Information: Axle housing model, capacity, suspension, brakes, hubs, and track width

Both carriers should be identified before ordering gears, bearings, shafts, seals, differential components, power-divider parts, or replacement assemblies.

Buying Considerations

C150 or C151 carrier position
CRD150, CRD151, CRD1501, or CRD1511 designation
Exact carrier part number
Original axle ratio
Forward and rear carrier ratio match
Axle housing model
Tandem axle rating
Engine torque
Transmission model
Tire size
Gross combination weight
Power-divider design
Power-divider lockout availability
Interwheel traction system
Input yoke dimensions
Through-shaft arrangement
Axle-shaft spline compatibility
Condition of gears, bearings, shafts, and differential components
Evidence of overheating, lubricant contamination, or gear damage
Availability of rebuild parts and qualified service

Variants and Configurations

Mack C150 forward carrier
Mack C151 rear carrier
Mack CRD150 forward carrier
Mack CRD151 rear carrier
Mack CRD1501 locking forward carrier
Mack CRD1511 locking rear carrier
Standard interaxle power divider
Power divider with driver-controlled lockout
Standard wheel differential
Interwheel power-divider configuration
Air-operated interwheel differential lock
Highway-oriented ratios
Regional-haul ratios
Vocational ratios
Matched carrier sets
Remanufactured carrier assemblies
Individual replacement carriers

Comparison to Similar Equipment

The C150 and C151 replaced or supplemented earlier Mack carrier families with updated gearing, lighter construction, and ratios for modern highway and vocational powertrains.

They are used within selected Mack S440 and S462 Axles and related Mack tandem configurations.

The lighter Mack S38 and S40 Axles may use different carrier and housing combinations according to the truck’s capacity and application.

Unlike a complete tandem axle, the C150 and C151 are removable carrier assemblies. The axle housings, shafts, brakes, hubs, suspension, and wheel ends remain separate components.

Best Fit For

Compatible Mack tandem axle systems
Mack S440 axle applications
Selected Mack S462 axle applications
Highway trucks requiring ratios near 3.11 to 3.40
Regional trucks requiring balanced gearing
Vocational trucks requiring higher numerical ratios
Construction and dump trucks
Concrete mixer trucks
Refuse vehicles
Logging and heavy-haul trucks
Fleets needing automatic interaxle torque biasing
Applications requiring a power-divider lockout
Owners restoring or repairing compatible Mack axles

Related Truck Types

Related Truck Models

Related Axle and Differential Types

Related Equipment Systems

Transmission Systems
Suspension Systems
Driveshaft Systems
Brake Systems
Tires and Wheels
Traction Control Systems

Related Guides

Regulatory and Compliance Notes

The C150 and C151 carrier ratings and ratios must be approved for the engine torque, transmission, axle housing, suspension, tires, wheels, brakes, and complete vehicle application.

Installing a different carrier or ratio can affect engine speed, road speed, gradeability, emissions-system operation, speedometer calibration, transmission programming, and driveline torque.

Both tandem carriers must use matching ratios. Operating mismatched carriers can cause severe driveline binding and component failure.

Power-divider and differential-lock systems must be operated and repaired according to Mack procedures.

Real World Operating Notes

The C150 and C151 provide the greatest benefit when used as a correctly matched pair within their approved Mack axle housings.

The automatic power divider can improve traction without requiring the driver to operate a switch during every minor traction event. The optional lockout remains useful in exceptionally slippery conditions.

Higher numerical ratios provide stronger pulling performance but increase engine speed and reduce maximum road speed. Ratio selection should reflect the truck’s actual duty cycle.

Frequently Asked Questions

What is the difference between the Mack C150 and C151?

The C150 is the forward tandem carrier. It includes the input, through-shaft, and power-divider arrangements. The C151 is the rear carrier and receives power through the interaxle driveshaft.

Are C150 and CRD150 the same type of carrier?

C150 is commonly used as a shortened product designation, while CRD150 appears in Mack service and parts information. The complete part number should still be verified.

Are these single- or dual-reduction carriers?

They are top-mounted dual-reduction tandem carriers.

What axle ratios are available?

Published ratios extend from approximately 3.11 to 5.66. Exact availability depends on carrier variation and application.

What is the Mack interaxle power divider?

It is an automatic torque-biasing system that can redirect up to approximately 75 percent of available torque toward the axle with greater traction.

Does the power divider require driver operation?

The standard torque-biasing function operates automatically. An optional lockout can be controlled by the driver for exceptionally slippery conditions.

What is an interwheel power divider?

It is an optional system that biases torque between the left and right wheels. It can be combined with the interaxle power divider for improved traction.

Can a C150 be installed in the rear axle position?

No. The C150 is designed for the forward position because it contains the input and through-shaft arrangement. The C151 is designed for the rear position.

Can different ratios be used in the two carriers?

No. The forward and rear carriers must use matching approved ratios.

Which Mack axles use these carriers?

Selected S440, S462, and other application-approved Mack tandem axle housings can use 150- and 151-series carriers.

What commonly causes carrier noise?

Common causes include low lubricant, bearing wear, gear damage, incorrect backlash, improper gear contact, driveline vibration, or previous incorrect assembly.

How should a replacement carrier be identified?

Use the carrier tag, stamped part number, ratio, differential configuration, axle housing model, and Mack vehicle build sheet.

Availability and Where to Find

Mack C150 and C151 axle carriers may be available as new service components, remanufactured exchange units, or used assemblies.

Authorized Mack dealers can use the truck’s VIN and carrier identification to locate compatible replacements. Independent differential rebuilders and heavy-truck parts suppliers may also offer complete carriers and internal components.

Before purchasing, verify the carrier position, complete model, part number, ratio, power-divider configuration, differential options, yokes, axle housing, and original vehicle application.

Current information about Mack carrier technology is available through the Mack Axles and Carriers page.

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