Hendrickson suspensions
Hendrickson names cover several different jobs: supporting drive axles, steering axles and trailer axles. Air, rubber and monoleaf systems should not be grouped as if they perform the same role. First identify the axle position and full suspension model. Then compare application approval, installed rating, ride height and the complete vehicle. Manufacturer capacity tables do not establish legal road loading or authorize an aftermarket conversion.
Compare the model families
| Model / family | Application | Overview | Model notes |
|---|---|---|---|
| PRIMAAX EX | Vocational rear air suspension | PRIMAAX EX is Hendrickson’s severe-duty vocational rear air suspension. The manufacturer lists single, tandem and tridem configurations. Those configurations have different ratings, so a PRIMAAX EX label alone cannot identify axle count, capacity or the application approved for an individual truck. | In this guide |
| HAULMAAX EX | Vocational rear rubber suspension | HAULMAAX EX is Hendrickson’s rear rubber suspension with a walking-beam layout. Its progressive spring arrangement is intended for vocational work such as dump, mixer and refuse applications. Hendrickson documents production changes within the EX family, making the build date relevant when identifying parts. | In this guide |
| ULTIMAAX | Severe-duty rear rubber suspension | ULTIMAAX is Hendrickson’s severe-duty rear rubber suspension. The manufacturer describes walking-beam technology combined with progressive-rate springs and lists several capacity variants. This is a different suspension type from the PRIMAAX EX rear air system, despite both serving demanding vocational roles. | In this guide |
| AIRTEK NXT | Integrated front air suspension | AIRTEK NXT combines Hendrickson’s STEERTEK NXT front axle with an air-suspension system. The standard product page describes heavy-duty on-highway tractor applications. Hendrickson also publishes separate truck-crane material, which should not be used as the specification for an ordinary highway installation. | In this guide |
| SOFTEK NXT | Integrated front monoleaf suspension | SOFTEK NXT is Hendrickson’s integrated front monoleaf suspension and STEERTEK NXT axle system. Unlike AIRTEK NXT, its spring arrangement is mechanical rather than a front air suspension. The manufacturer describes specific heavy-duty truck applications and ratings, so fitment must be checked against the actual vehicle. | In this guide |
| INTRAAX | Integrated trailer air suspension | INTRAAX is Hendrickson’s integrated trailer suspension, axle and brake system. The manufacturer describes it as a combined package and distinguishes it from the VANTRAAX air-slider assembly. This is trailer running gear, not a truck’s drive-axle or cab suspension. | In this guide |
| VANTRAAX | Trailer air-slider system | VANTRAAX is Hendrickson’s air-slider system for dry-van and refrigerated trailers. The manufacturer describes it as combining INTRAAX running gear with a K2 slider box. It should therefore be evaluated as a complete slider and suspension assembly, rather than simply another name for INTRAAX. | In this guide |
Bring the exact specification.
The family name helps organize your search. The build sheet, serial number and relevant manufacturer documentation identify what is installed. Compare like-for-like applications and request evidence for cost or performance claims.
Manufacturer references support the model facts. Our examples and comparisons are editorial interpretation prepared with AI assistance, not road tests or an expert inspection.
Check the year, market and exact build before applying a specification. This guide does not authorize parts fitment, repairs, modifications or loading.
Hendrickson manufacturer reference ↗Independent editorial resource. Brand names identify equipment; they do not imply a partnership or endorsement.
PRIMAAX EX
Vocational rear air suspension
Source checkpoint:
PRIMAAX EX is Hendrickson’s severe-duty vocational rear air suspension. The manufacturer lists single, tandem and tridem configurations. Those configurations have different ratings, so a PRIMAAX EX label alone cannot identify axle count, capacity or the application approved for an individual truck.
Scope North American model family; equipment and availability vary by model year and configuration.
Which rating belongs to which axle group?
Hendrickson publishes the following PRIMAAX EX suspension capacities. These are axle-group configurations, not alternative payload limits for the same truck. The suspension must be paired with appropriately rated axles, and the application must meet Hendrickson specifications and the vehicle manufacturer’s original as-built approval.
| Axle configuration | Suspension capacity (lb) |
|---|---|
| Single | 23,000 |
| Single | 26,000 |
| Tandem | 46,000 |
| Tandem | 52,000 |
| Tridem | 69,000 |
| Tridem | 78,000 |
Compare the complete truck, not the largest number
For example, a listing that says only “PRIMAAX EX” does not establish whether it describes a tandem or a tridem. Put the axle count and suspension capacity beside the seller’s build sheet before comparing asking prices. Record the approved vehicle ratings separately. This avoids treating a larger family rating as spare carrying capacity on a smaller configuration. The manufacturer’s separate site-travel figures are restricted operating ratings; they do not replace the suspension capacity above or establish legal road loading.
What matters in a comparison
For a PRIMAAX EX vehicle, record the exact suspension model and installed axle arrangement. Compare the documented ride height and application with the body and working loads. The manufacturer’s site-travel and vehicle-rating figures describe different conditions; do not treat them as interchangeable payload permissions. Have the as-built configuration checked before considering a change in body or operating duty.
Questions to take to the supplier
- Which model and axle arrangement are installed?
- What ride height and application were approved?
- Does the intended body change require a new assessment?
Sources & limits
HAULMAAX EX
Vocational rear rubber suspension
Source checkpoint:
HAULMAAX EX is Hendrickson’s rear rubber suspension with a walking-beam layout. Its progressive spring arrangement is intended for vocational work such as dump, mixer and refuse applications. Hendrickson documents production changes within the EX family, making the build date relevant when identifying parts.
Scope North American model family; equipment and availability vary by model year and configuration.
The production change behind the same name
Hendrickson’s May 2025 bulletin, SEU-0241 Rev C, documents an enhanced HAULMAAX EX introduced after July 15, 2024. Changes include equalizing-beam saddles, bolster-spring fasteners and frame saddles. The bulletin says vehicle fit and function were unchanged; that does not mean every individual replacement component stayed the same.
A useful way to compare two repair estimates
If two shops quote different hardware for apparently identical HAULMAAX EX trucks, ask each to identify the installed version against the bulletin’s illustrations. Keep the suspension identification and any prior update-kit invoice with that comparison. Registration year alone may not describe the hardware now installed. A quote should make clear whether it covers an individual part, an approved update kit or associated fasteners. This turns “old versus new design” into a documented parts question without assuming that one loose component can be substituted for another.
What matters in a comparison
For HAULMAAX EX, collect the suspension identification and truck build date before comparing service proposals. Ask whether quoted parts correspond to the installed version. Evaluate empty and loaded work separately when discussing ride preferences with the supplier. Capacity, body height and application approval belong in the same assessment; a favourable ride description is not evidence that a different body is approved.
Questions to take to the supplier
- Which production version is installed?
- Do proposed parts match the identification and build date?
- What loaded and empty duty should the assessment cover?
Sources & limits
ULTIMAAX
Severe-duty rear rubber suspension
Source checkpoint:
ULTIMAAX is Hendrickson’s severe-duty rear rubber suspension. The manufacturer describes walking-beam technology combined with progressive-rate springs and lists several capacity variants. This is a different suspension type from the PRIMAAX EX rear air system, despite both serving demanding vocational roles.
Scope North American model family; equipment and availability vary by model year and configuration.
Capacity also changes the spacing choices
The ULTIMAAX table lists axle spacings of 52, 54, 56 and 60 in for the 46,000 and 52,000 lb versions. For the 60,000 and 70,000 lb versions, it lists 56 and 60 in. Hendrickson requires appropriately rated axles and vehicle-manufacturer approval of the original as-built application.
Use spacing to make a listing more informative
When comparing two vocational trucks, add a separate line for axle spacing rather than writing only “ULTIMAAX rubber suspension.” A higher advertised capacity does not establish that the trucks have the same layout or that their suspension parts interchange. Ask for the build specification corresponding to each vehicle and compare it with the installed identification. Keep suspension rating, axle rating and the vehicle’s approved weights in separate columns. That makes an apparent specification upgrade easier to assess without assuming additional usable payload or an approved conversion.
What matters in a comparison
For ULTIMAAX, identify the exact rating and axle spacing before comparing vehicles. Ask whether the body and working conditions match the documented application approval. Distinguish a site-travel rating from the truck’s ordinary road-loading limits. For used equipment, have the suspension and surrounding chassis assessed together; a catalogue capacity does not establish the condition of its springs, beams or connections.
Questions to take to the supplier
- What exact rating and axle spacing are documented?
- Which body and application were approved?
- Is a qualified chassis-condition assessment available?
Sources & limits
AIRTEK NXT
Integrated front air suspension
Source checkpoint:
AIRTEK NXT combines Hendrickson’s STEERTEK NXT front axle with an air-suspension system. The standard product page describes heavy-duty on-highway tractor applications. Hendrickson also publishes separate truck-crane material, which should not be used as the specification for an ordinary highway installation.
Scope North American model family; equipment and availability vary by model year and configuration.
Front air suspension is a specific specification
AIRTEK NXT combines the STEERTEK NXT steer axle with air suspension and an integrated clamp group. Hendrickson lists 12,500 and 13,300 lb capacities for this on-highway tractor system, with drum- or disc-brake compatibility. Those options describe the front system; they do not identify the rear suspension.
Clarify what a seller means by “air ride”
For a used tractor advertised simply as “air ride,” ask the seller to separate the steer-axle system from the drive-axle and cab systems on the specification sheet. If AIRTEK NXT is listed, record its installed capacity and brake type before comparing another truck. For a parts estimate, ask whether the quotation covers the axle, suspension and clamp components or only one of them. This prevents a complete front-system price from being compared with a smaller component-only quote. It is a comparison method, not approval to change brake type or axle capacity.
What matters in a comparison
An AIRTEK NXT comparison concerns the steering-axle system, not the rear drive suspension. Ask for the axle and suspension identification together with the truck build sheet. Compare the complete approved setup and service requirements before evaluating comfort or weight claims. A front-end concern needs diagnosis of the actual vehicle rather than assuming one suspension family explains every ride or steering symptom.
Questions to take to the supplier
- Is this the highway or another application-specific version?
- Which axle and suspension ratings are installed?
- What documentation covers the as-built front-end system?
Sources & limits
SOFTEK NXT
Integrated front monoleaf suspension
Source checkpoint:
SOFTEK NXT is Hendrickson’s integrated front monoleaf suspension and STEERTEK NXT axle system. Unlike AIRTEK NXT, its spring arrangement is mechanical rather than a front air suspension. The manufacturer describes specific heavy-duty truck applications and ratings, so fitment must be checked against the actual vehicle.
Scope North American model family; equipment and availability vary by model year and configuration.
Air disc brakes do not mean air suspension
SOFTEK NXT is a monoleaf front suspension using the STEERTEK NXT axle. Its published capacities are 12,500 and 13,200 lb. The optional Integrated Air Disc Brake knuckles, abbreviated IADB, relate to the brake mounting; their name does not turn the monoleaf system into AIRTEK NXT air suspension.
Read the brake and spring descriptions separately
A specification sheet can correctly say both “SOFTEK NXT” and “air disc brakes.” When comparing two trucks, record the spring system, axle capacity and brake arrangement as separate items. If a replacement estimate includes a knuckle, ask which installed brake-mounting version the supplier identified and which supporting components the quote includes. A similar axle name is not enough to establish identical knuckles or suspension parts. This is especially useful when one advertisement lists a complete front system and another lists only the axle brand.
What matters in a comparison
For SOFTEK NXT, compare the complete steer-axle assembly and approved truck configuration. Ask whether the proposed parts match the NXT system rather than another SOFTEK version. A claimed component-weight reduction should be evaluated in the completed vehicle, not treated automatically as additional legal payload. Retain the identification information for future service and replacement decisions.
Questions to take to the supplier
- Is the system confirmed as SOFTEK NXT?
- Which steer-axle and brake configuration are fitted?
- Do service proposals match the exact assembly?
Sources & limits
INTRAAX
Integrated trailer air suspension
Source checkpoint:
INTRAAX is Hendrickson’s integrated trailer suspension, axle and brake system. The manufacturer describes it as a combined package and distinguishes it from the VANTRAAX air-slider assembly. This is trailer running gear, not a truck’s drive-axle or cab suspension.
Scope North American model family; equipment and availability vary by model year and configuration.
AANT 23K is one concrete INTRAAX example
For the top-mount AANT 23K, Hendrickson lists a 23,000 lb suspension-and-axle rating and a 5.75 in large-diameter axle. Brake and wheel-end ratings depend on the selected options. These details identify that published AANT configuration; they are not specifications for every product carrying the INTRAAX name.
Build an identification line that a supplier can use
Instead of requesting “parts for an INTRAAX trailer,” collect the full model designation, suspension identification and trailer build details first. Then separate the axle/suspension description from the brake and wheel-end description on your request. An AANT reference is useful because it narrows the search to a particular arrangement; the family name alone leaves important choices unanswered. Compare supplier quotations at the same scope: a suspension component, an axle assembly and a complete running-gear package are different requests. The rating in a catalogue does not itself establish the trailer’s approved payload.
What matters in a comparison
For an INTRAAX trailer, record the exact model, axle identification and brake configuration. Compare the complete trailer’s work, loading and service history. If a replacement axle or suspension component is proposed, confirm compatibility with the integrated system rather than relying on a similar-looking part. Budget tyre, brake and suspension service separately enough to see what an ownership estimate includes.
Questions to take to the supplier
- Which integrated system and axle model are installed?
- What brake configuration is documented?
- Are alignment and running-gear records available?
Sources & limits
VANTRAAX
Trailer air-slider system
Source checkpoint:
VANTRAAX is Hendrickson’s air-slider system for dry-van and refrigerated trailers. The manufacturer describes it as combining INTRAAX running gear with a K2 slider box. It should therefore be evaluated as a complete slider and suspension assembly, rather than simply another name for INTRAAX.
Scope North American model family; equipment and availability vary by model year and configuration.
What HKANT 40K actually includes
The HKANT 40K example is a tandem slider with 49 in axle spacing. Its 40,000 lb rating covers the slider box, suspensions and axles together; brakes, wheels and tires have separate ratings. Hendrickson lists 42 and 48 in box widths, making the box configuration part of the identification.
Compare a slider quote at the same scope
For a dry-van replacement estimate, ask whether the price includes the slider box or only the suspension and axle assemblies. Put the installed model, box width and axle spacing on the request before comparing suppliers. Two quotations can both mention VANTRAAX while covering different amounts of hardware. Also keep the trailer’s approved weights separate from the suspension-system rating. This gives you a useful purchasing comparison without treating the catalogue’s largest number as cargo capacity or assuming that a complete slider from another trailer will fit.
What matters in a comparison
On a VANTRAAX trailer, identify the slider assembly as well as its axles and brakes. Review maintenance history for the whole running-gear system and ask whether any replacement components changed the original specification. Compare trailer loading needs with the available approved positions and capacities. This profile does not provide slider-operation instructions; use the trailer and suspension manufacturer’s own material.
Questions to take to the supplier
- Which slider and running-gear configuration is fitted?
- Are service and replacement records available?
- What loading requirements must the complete trailer meet?