Complete Hendrickson UTKNT40K Suspension Parts List: Components, Specs, and Replacement Guide

The Hendrickson UTKNT40K suspension is a popular air-ride system used on heavy-duty trailers. Understanding its parts list is essential for maintenance, repair, and replacement. This guide provides a comprehensive breakdown of every major component, explains its function, and offers practical advice for sourcing parts.

Overview of the UTKNT40K Suspension

The UTKNT40K is a 40,000-pound capacity air-ride suspension designed for van, reefer, and flatbed trailers. It uses a unique top-mount beam design that reduces weight while maintaining durability. The system consists of a beam assembly, air springs, shock absorbers, axle brackets, torque rods, and hardware. Knowing each part helps when ordering replacements or diagnosing ride issues.

Hendrickson UTKNT40K Suspension Parts List

Below is the complete parts list organized by system function. Part numbers are Hendrickson OEM (original equipment manufacturer) for easy cross-referencing.

1. Beam Assembly

The beam is the core structural component. It attaches to the trailer frame via the hanger and supports the axle.

• Beam Assembly (Part No. 88536-001) – Includes the main beam, pivot bushing, and spring seat. Check for cracks or excessive bushing wear.
• Beam Pivot Bushing (Part No. 100042) – Pressed into the beam end. Replaces every 3–5 years or if you feel looseness.

2. Air Springs (Air Bags)

Air springs support the load and provide ride height adjustment.

• Air Spring Assembly (Part No. 88071-001) – The standard 9-inch high convoluted bag. Used on most UTKNT40K setups.
• Air Spring Adapter Plate (Part No. 20015) – Required when replacing the air spring if the base plate is damaged.

3. Shock Absorbers

Shocks dampen axle movement and prevent oscillations.

• Shock Absorber (Part No. 88303-001) – Twin-tube design, 11-inch stroke. Replace in pairs.
• Shock Bushing Kit (Part No. 100179) – Replaces worn rubber bushings at both ends.

4. Axle Brackets and Hardware

These components connect the beam to the axle.

• Axle Bracket Assembly (Part No. 88261-001) – Welds or bolts to the axle. Includes seat for the air spring.
• U-Bolt Kit (Part No. 88019-001) – Includes four U-bolts and nuts for clamping axle to beam. Torque to 450-500 ft-lbs.

5. Torque Rods

Torque rods control axle alignment and braking forces.

• Forward Torque Rod (Part No. 88178-001) – Connected from the axle to the frame hanger.
• Rear Torque Rod (Part No. 88179-001) – Runs from axle to the opposite side frame bracket.
• Torque Rod Bushing Kit (Part No. 100001) – Replaces worn bushings; can prolong rod life.

6. Frame Hangers and Crossmembers

The hangers attach the suspension to the trailer frame.

• Frame Hanger Assembly (Part No. 88444-001) – Left/right specific; includes mounting plate and bracket.
• Crossmember Support (Part No. 66781) – Reinforces the frame at the hanger location.

7. Height Control Valve and Leveling Components

These maintain proper ride height.

• Height Control Valve (Part No. 64091-001) – Mechanical valve that regulates air pressure.
• Height Control Valve Linkage (Part No. 67097) – Adjustable rod connecting valve to axle.
• Ride Height Sensing Beam (Part No. 88032-001) – Mounts to the frame and actuates the valve.

8. Air System Components

For inflating and exhausting air springs.

• Air Line Kit (Part No. 88033-001) – Polyethylene tubing and fittings.
• Dump Valve (Part No. 64010-001) – Used on trailers with manual dump capability.

9. Wear Items and Fasteners

• Bolt Kit – Suspension Mounting (Part No. 88020-001) – Grade 8 bolts for hanger to frame.
• Washer Kit – Spring Seat (Part No. 88021-001) – Hardened washers for U-bolt assembly.

How to Use This Parts List

When ordering replacements, confirm your suspension model and axle rating. The UTKNT40K is a 40k capacity; verify if your trailer has the standard or heavy-duty variant. Cross-reference your existing part numbers with the list above. Most parts are interchangeable with previous years, but always check the beam serial number.

Replacement Tips and Recommendations

• Inspect air springs every 6 months for cracks or sidewall bulges. Replace in pairs.
• Shocks should be replaced around 200,000 miles or if you notice excessive bounce after bumps.
• Bushings (beam pivot, torque rod) wear over time; replace them when servicing other components to avoid repeat labor.
• U-bolts must be retorqued after the first 500 miles of service and annually.
• Height control valve – If ride height varies, adjust linkage or replace valve.

Where to Buy Hendrickson UTKNT40K Parts

OEM parts are available through Hendrickson authorized dealers. Many heavy-duty truck parts stores carry them. When possible, purchase genuine Hendrickson parts for exact fit. Aftermarket options exist but verify compatibility with your beam design. Avoid unbranded parts for critical components like beams and hangers.

Final Recommendation

For long life and safety, use the Hendrickson parts list above to identify worn components. Replace bushings and air springs proactively rather than waiting for failure. Keep a spare shock absorber and air line kit in your trailer tool box. For major repairs, consult a certified technician. Having this parts list on hand simplifies ordering and ensures you get the right UTKNT40K suspension parts every time.