Rockwell American Axle Operation, Service & Maintenance Guide

Here at Johnson Trailer Parts, we carry a full line of Rockwell American trailer axles — one of the most trusted axle brands in the U.S. trailer industry. We put together this Operation & Service Manual page so our customers have helpful axle maintenance information in one place. Whether you need to adjust your electric brakes, service your hub bearings, grease your Posi-Lube system, or look up suspension torque specifications, we’ve got you covered. Download the PDF below or browse the manual content on this page.

⇓ Download Rockwell American Axle Service Manual PDF

Important: This page is provided as a helpful reference for Rockwell American axle maintenance. Always follow your trailer manufacturer’s instructions and consult a qualified trailer repair technician if you are unsure about any service procedure.

Key Maintenance Takeaways

• Re-torque wheel nuts after the first 50 miles on new trailers.
• Adjust electric brakes after brake components seat and re-check at regular service intervals.
• Use the Posi-Lube system to refresh grease between regular hub and bearing inspections.
• Always verify wheel torque, suspension torque, bearing numbers, and seal sizes before service or replacement.
• Download the full PDF manual for complete warranty terms, service procedures, and manufacturer documentation.

What This Rockwell American Axle Manual Covers

This Rockwell American axle service manual covers electric brake adjustment, trailer brake troubleshooting, hub and drum inspection, wheel bearing maintenance, Posi-Lube lubrication, suspension torque specifications, torsion axle information, wheel torque requirements, replacement parts, and warranty information.

Table of Contents

• Safety Notice & New Axle Setup
• Electric Brakes
• Electric Brake Maintenance & Adjustment
• Brake Troubleshooting Guide
• Electrical — Voltage & Amperage
• Hubs, Drums and Bearings
• Posi-Lube Lubrication Procedure
• Suspension Systems
• Torsion Axles
• Trailer Wheel Torque Specs
• Replacement Parts
• Warranty Information
• Common Rockwell American Axle Service Questions
• Shop Rockwell American Axles & Parts

Safety Notice & New Axle Setup

Providing safe, dependable operation of your Rockwell American axles and related components is essential. This manual provides basic procedures for service and repair using established industry standards.

New Axle Setup Checklist:

• Wheels: Re-torque wheel nuts at 50 miles on new trailers.
• Brakes: Adjust brakes at 3,000 miles.
• Tire Pressure: Inflate to tire manufacturer’s recommendations.
• Brake Controller: Follow brake controller manufacturer’s settings.

Electric Brakes

Rockwell American trailer electric brakes are actuated by an electric magnet triggered by an electrical impulse from the brake controller. When properly installed, the trailer brakes apply smoothly and slightly ahead of the tow vehicle brakes.

Double Check Before Towing:

• Confirm your controller is installed per the manufacturer’s recommendations.
• Make sure brake controller adjustments correctly engage both the tow vehicle and trailer brakes together.
• Seat new brakes by applying them lightly 20–25 times at low speed, under 25 mph, in a safe area.

Below is a view of the 10” and 12” electric brakes used on trailer axles, depending on your trailer and manufacturer’s specifications.

Need replacement brake parts or axle components? Browse our trailer axle parts or contact Johnson Trailer Parts for help matching parts to your axle.

Electric Brake Maintenance & Adjustment

Your trailer brakes should be adjusted between 250–300 miles after all brake components have seated. Re-check brake adjustments at a minimum of every 3,000 miles.

Brake Adjustment Procedure:

1. Make sure the trailer is on a level surface and secured safely.
2. Jack up the trailer and secure with jack stands — tires must be clear of the ground.
3. Locate the adjusting hole cover on the backing plate and remove it.
4. Use a brake adjusting tool to turn the star wheel, expanding the brakes until the tire will not easily rotate.
5. Back off the star wheel in the opposite direction until you feel slight resistance.
6. Replace the hole cover and lower the tire to the ground.
7. Repeat for all wheels — always adjust all brakes at the same time.

Electric Brake Troubleshooting Guide

Dragging Brakes

• Check for defective controller.
• Check for corroded brake assembly.
• Check for weak or broken brake shoe return spring.
• Check for worn or damaged lever arm between magnet and brake shoe.
• Check for improper controller installation.

Noisy Brakes

• Check brake adjustment.
• Check for worn brake shoes.
• Check for contaminated brake linings.
• Check for weak or broken brake shoe return springs.
• Check for bent backing plate.
• Check wheel bearing adjustment.
• Check for worn or damaged wheel bearings.
• Check for worn or damaged magnets.

Inoperative Breakaway System

• Check for dead or weak 12-volt battery on trailer.
• Check all wiring and connections.
• Check breakaway switch.
• If only one brake is operating, check other magnets.

No Brakes

• Check for defective circuit breaker.
• Check for open or shorted circuit.
• Check for properly wired system including a good ground between towing vehicle and trailer.
• Check brake adjustment.
• Check for worn or defective magnet(s).
• Check for a damaged or worn connector between towing vehicle/trailer.
• Check that controller is installed correctly and functioning correctly.

Intermittent or Surging Brakes

• Check for out-of-round brake drums.
• Check for properly wired system, including a good ground between towing vehicle and trailer.
• Check for defective magnet or wiring.
• Check for loose or worn wheel bearings.

Ineffective or Weak Brakes

• Ensure trailer is not overloaded.
• Check for loose or corroded connections.
• Check for properly wired system.
• Check for a shorted circuit.
• Check for worn or defective magnet.
• Check brake adjustment.
• Check for bent backing plate flange.
• Check for contaminated brake linings.
• Check brake system wiring.
• Check for worn or damaged brake linings.
• Check for weak or broken brake shoe return spring.
• Check for worn brake drums.
• Check that correct controller is installed.
• Check for improper controller installation.

Grabbing or Locking Brakes

• Check for contaminated brake linings.
• Check for weak or broken brake shoe return spring.
• Check for rust on armature plate or brake drum.
• Check for improper controller installation.

Electrical — Voltage & Amperage

Voltage Measurement Procedure: To measure voltage, connect a voltmeter to both electric brake magnet wire leads while the tow vehicle is connected and the engine is running. As the brake controller is slowly increased, voltage should rise from 0 to approximately 12 volts. If the controller does not provide proper voltage control, refer to the brake controller troubleshooting manual. Lower voltage generally provides smoother braking, while higher voltage can create sharper or more aggressive braking.

Amperage Measurement Procedure: Amperage is the electrical current flowing through the trailer brake system when the brake magnets are energized. Make sure your ammeter is properly rated before testing. A common place to check amperage is at the blue brake output wire from the brake controller. Disconnect the wire and place the ammeter in series with the circuit, then compare the reading to the chart below.

Individual magnet amperage can also be checked at each brake magnet by disconnecting one magnet wire lead and placing the ammeter between the two wire ends. Reconnect all wiring securely when testing is complete.

Amperage Chart:

Common Electrical Issues:

• Poor electrical connections.
• Open circuits.
• Broken wires or incorrect wire size.
• Brake controller malfunction.
• Bare wires, defective controllers, or shorts in the magnet coil.

Short Circuit Troubleshooting: To help locate a short circuit, test the brake system in individual sections. If the amperage reading drops to zero after disconnecting the trailer, the short is likely in the trailer. If amperage remains high after all brake magnets are disconnected, the short is likely somewhere in the trailer wiring.

Brake Controller Note: Many electric brake complaints can be traced back to the brake controller, controller adjustment, or wiring connections. Always refer to your brake controller manual to confirm the controller is adjusted correctly and the connections meet the manufacturer’s specifications.

Hubs, Drums and Bearings

Rockwell American axles use industry-standard tapered roller bearings packed with lithium base grease. Bearings are designed to reduce axial end play and extend service life.

Brake Drum Inspection:

• Resurface if wear exceeds .020″ oversized.
• Re-machine if drum is out of round by more than .015″.
• Replace hub and drum assembly if wear or scoring exceeds .090″.
• Armature surface can be resurfaced removing no more than .030″ to a 120 micro inch finish.
• Replace magnets any time drums are turned or armature is resurfaced.

Hub Removal Procedure:

1. Remove wheel.
2. Remove grease cap.
3. Remove cotter pin or bend tang washer on Posi-Lube models.
4. Unscrew spindle nut counter-clockwise.
5. Remove spindle washer.
6. Remove hub from spindle.

Seal Replacement: Always replace seals each time the hub is removed.

Bearing Adjustment — Feel and Drag Method:
Tighten slotted nut until hub drags slightly when rotated. Loosen nut 1/6 turn, or 1 hex flat, to align nut slot with cotter pin hole. Wheel should turn freely. Insert new cotter pin and bend legs to secure.

Bearing Adjustment — Torque Wrench Method:
Tighten nut to an initial torque of 50 ft. lbs. Loosen and finger-tighten. Insert new cotter pin through nut and spindle.

For replacement hubs, drums, bearings, and seals, visit our trailer hubs, spindles, and bearings category.

Posi-Lube Lubrication Procedure

The Rockwell American Posi-Lube system allows grease to be added through a special grease fitting at the spindle end. This provides a convenient way to refresh grease between regular hub and bearing inspections, but it should not replace proper maintenance, inspection, or seal replacement when service is needed.

Lubrication Steps:

1. Remove the rubber cap at the end of the grease cap.
2. Place a standard grease gun tip onto the grease fitting at the end of the spindle.
3. Pump grease into the fitting — you will see old grease pushing out at the cap.
4. When new grease appears, remove the gun, clean off excess, and replace the rubber cap.

Suspension Systems

Rockwell American provides both single and tandem axle suspension systems in double-eye and slipper spring configurations.

• Double Eye Leaf Springs — have eyes at both ends with special bushings. No lubrication needed.
• Slipper Leaf Springs — have an eye at one end only. The trailing end slides against the rear hangers.

Inspect suspension components every 6 months or 5,000 miles, whichever comes first.

For springs, U-bolts, hanger kits, and running gear components, browse our trailer axle and suspension parts.

Suspension Torque Specifications:

Shackle Bolt Torque:

• 7/16″ — 45–70 ft. lbs.
• 9/16″ — Snug fit only; lock nut positions parts and allows movement.

Basic Suspension Service Notes

When servicing trailer suspension components, always raise and support the trailer safely before beginning work. Once the trailer is secure, support the axle tube near the area being repaired. On tandem axle trailers, both axle tubes may need to be supported before suspension parts are removed.

Remove the attaching hardware such as U-bolts, nuts, shackle links, eye bolts, and springs as needed for the repair. If spring bushings are worn, replace them before reassembly. Reinstall components in reverse order and torque fasteners to the recommended specifications.

Special Note: The fittings that attach the springs to the chassis mounts are designed to be wear-resistant and should not be lubricated unless the trailer or component manufacturer specifically states otherwise.

Torsion Axles — The Equalizer

The Rockwell American Equalizer Torsion Axle provides independent suspension for each wheel. Each spindle attaches to a trailing arm that rocks during road shock, transferring movement to a steel inner bar. Rubber cords absorb the shock from the twisting inner bar.

Benefits: Independent wheel action provides greater stability and control during towing. Wheel vibration is absorbed by the rubber cords for a smoother, more comfortable ride.

Trailer Wheel Torque Specs

Always use the wheel and tire specifications provided by your trailer manufacturer. Never alter recommended sizes or load capacities.

Lug Nut Tightening Procedure:

1. Start all lug nuts by hand to prevent cross-threading.
2. Snug all nuts before final torquing.
3. Tighten to recommended torque in a star pattern sequence.
4. Re-torque after the first 50 miles, then check periodically.

Required Wheel Torques:

Replacement Parts

Use the following Rockwell American replacement part charts as a reference for common bearing cups, cones, brake shoe kits, magnets, and grease seals. Always verify axle capacity, brake size, hub style, and spindle measurements before ordering replacement parts.

Bearing Replacement Cups & Cones

Brake Shoe Replacement Kits

Magnet Replacement Kits

Seal Replacement

Warranty Information

Rockwell American provides limited warranty coverage on its axle products, including a 2-year limited warranty on tubular axles and a 5-year limited warranty on Equalizer Torsion Axles to the original purchaser against defects in materials and workmanship.

Warranty terms, conditions, exclusions, and claim procedures may vary by axle type and application. For complete warranty details, please view the full warranty information in the Rockwell American axle service manual PDF.

⇓ Download Rockwell American Axle Service Manual PDF

Manufacturer Warranty Support:
Rockwell American
1012 Industrial Drive, Royse City, TX 75189
Phone: (800) 334-6355

Common Rockwell American Axle Service Questions

How often should Rockwell American trailer brakes be adjusted?

New trailer brakes should be adjusted after the brake components seat, and brake adjustment should be re-checked at least every 3,000 miles. The manual also notes brake adjustment as part of the new axle setup process.

How do I grease Rockwell American Posi-Lube axles?

Remove the rubber cap, place a standard grease gun on the grease fitting at the end of the spindle, pump grease until old grease is pushed out, then clean off excess grease and replace the rubber cap. The Posi-Lube system is a convenient way to refresh grease between regular hub and bearing inspections, but it should not replace proper inspection or maintenance.

What torque should trailer lug nuts be tightened to?

Wheel torque depends on wheel size and stud size. The manual provides progressive torque settings and recommends re-torquing after the first 50 miles of use.

When should trailer hub seals be replaced?

Hub seals should be replaced any time the hub is removed. Reusing old seals can lead to grease leaks, bearing contamination, and premature hub or bearing wear.

How do I know which Rockwell American axle parts I need?

Axle parts depend on axle capacity, hub face, spring center, bolt pattern, brake size, bearing numbers, seal size, and spindle type. If you are unsure, Johnson Trailer Parts can help you identify the correct replacement axle, hub, brake, bearing, or suspension part.

Shop Rockwell American Trailer Axles and Replacement Parts

Johnson Trailer Parts carries Rockwell American trailer axles, running gear kits, hubs, drums, bearings, seals, suspension parts, and replacement axle components. If you need help identifying the correct axle, hub, bearing, brake, or suspension part, our team can help match the right components for your trailer.

The Rockwell American axles we sell feature a durable powder-coated finish and the Posi-Lube system for convenient bearing lubrication between regular inspections. Warranty coverage varies by axle type, so please review the full PDF manual for complete warranty details.

Shop Rockwell American Trailer Axles →

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Learn How to Measure a Trailer Axle →

⇓ Download Rockwell American Axle Service Manual PDF

Need help choosing the right axle for your trailer? Give us a call at 602-292-9690 or contact us online. We’re happy to help!

Rockwell American is a trademark of its respective owner. Johnson Trailer Parts is an independent distributor and seller of Rockwell American trailer axles and replacement parts.