Haldex-Type Automatic Slack Adjusters: 400 Series Specs & 9 Cross Numbers

Ask any parts counter how they identify a slack adjuster and you will usually hear a number rather than a description, and that number is the most useful thing a buyer can carry into a quotation. Cross numbers matter for four unglamorous but expensive reasons: they identify the part at the counter when the customer has no box in front of them, they are the reference a warranty claim is written against, they are how a returned or rebuilt unit is matched back to its origin, and they are where one supplier’s catalogue stops and another’s begins. Get them wrong and the cost is not a returned parcel; it is a truck in a yard with an inboard brake out of adjustment.

Everything here is drawn from our own published pages: the 400-Haldex automatic slack adjuster cross reference, the Haldex series automatic slack adjuster product page with its published specification and cross-number list, and the company information behind them.

Nine numbers, one adjuster

The cross list published on our Haldex series product page runs to more than a thousand entries, because the number of OE and replacement numbers that describe one automatic slack adjuster type is genuinely that large. Quoting all of it would be a list, not a guide, so here are nine of them, taken from that published list, that illustrate the three things that actually vary inside it: the base number, the same base number with a suffix, and the ranges that appear with a suffix on some entries and without on others.

The full published list continues well past these nine, in blocks that run from the 10xxx numbers through 12xxx, 70xxx and 72xxx. Two rules follow from looking at it. Because a suffix is part of the identifier and not decoration, so a number quoted without its suffix may denote a different part revision, so the safest habit is to treat every cross number as an exact string, letter included, and to confirm the suffix against the physical part rather than assume it is interchangeable. And because a long cross list is a sign of how widely a part type is used, the more numbers a catalogue carries for one adjuster, the more likely the market treats it as a standard item rather than a speciality.

What a cross number actually does at the counter

Four jobs, and each one fails differently.

Identification. A fleet manager whose adjuster has failed often has no part in front of them. The number that came off the housing, the number on the invoice and the number in the catalogue are the same conversation. If the housing number is worn or overpainted, the physical features of the part matter more, and that is where the specification below earns its place.

Warranty evidence. A claim is only as good as the reference it is written against. A cross number that matches the part actually fitted, plus the purchase document, is what turns a conversation into a claim. A supplier who cannot tell you which numbers their part answers to is a supplier whose warranty you will argue about later.

Returned and rebuilt units. The trade buys, rebuilds and returns adjuster assemblies, and a unit that comes back without a traceable number cannot go back on a shelf. Cross numbers identify the original part after stripping, which is why the suffix matters here more than anywhere else.

Finding the interchangeability boundary. Two numbers that both appear on one cross list are, in the supplier’s words, numbers this part answers to. Two numbers on two different cross lists are not evidence of anything, and neither is a similarity in the digits. Because the list describes what one part answers to rather than what fits any vehicle, so the fitting question is answered by the thread, the caging position and the brake type, not by the number itself.

The 400 series construction facts worth knowing

The construction of the 400 series is what the cross numbers are pointing at, and it is worth understanding what you are buying before you start comparing numbers.

Our published product description is specific. The internal gears are heat-treated steel alloy, which gives the adjuster its strength and wear resistance over the service life. The adjuster is compatible with all major brand clevises, which removes a common reason a part returns as “wrong fit”: the clevis on the chamber side. Lubrication is handled with a straight grease fitting type, positioned for convenient access, because an adjuster that cannot be serviced in the yard will not be serviced in the yard. The linkages are protected against the elements, and the unit is published for steer axle standard applications, with the clearance-sensing version keeping the brake unaffected by drum deflection or thermal expansion, and its control arm giving flexible application coverage for standard drive axle brakes.

It also helps to remember what the part does. An automatic slack adjuster works as a lever between the actuator or the spring brake chamber and the camshaft, and it compensates for the gradual wear of the brake drum and the shoe lining while keeping pace with the actuator’s stroke. The clearance-sensing type adds what older designs could not: it measures the actual clearance rather than assuming a fixed amount of wear, so thermal expansion and deflection do not push the brakes into contact.

The attribute set to put on the spec sheet

Our published product attributes for this family are worth carrying into a purchase order, because each constrains something a distributor ends up answering for.

The fitment families published alongside these parts are worth noting too, because they are where the thread lives: our catalogue carries adjuster references for 1-1/4″-24 and 1-1/2″-28 thread families under the Meritor line, and 400-series references of our own including 400-10216, 400-20236 and 400-20228. A cross number tells you what the part is called; the thread and the caging position tell you what it bolts to.

What the factory can evidence

Our own published position, so a buyer can check it: Shaoxing Fangjie Auto Accessory Co., Ltd. was founded in 2003 and integrates parts R&D, manufacturing, sales and service. The site covers more than two acres with a building area of more than 20,000 square metres. There are more than 100 employees, including more than ten management teams, more than ten foreign trade teams, a professional R&D team of five people and five quality management personnel. Production runs on large-scale machining centres and CNC machine tools with an annual output of more than 500,000 sets. Certifications include the IATF/TS16949 quality management system and national high-tech enterprise recognition.

The part I would point a technical buyer at is the product testing laboratory. The published equipment list includes contour roughness meters, coordinate measuring machines, ultrasonic metallographs, automatic gap detection platforms, torque adjustment detection platforms, sand and dust test boxes, salt spray test boxes and temperature and humidity detectors. An adjuster fails in millimetres and in how it behaves after heat, dust and corrosion, so the gap detection and torque platforms matter more than any product photograph.

Commercially, 80% of the company’s products are exported to Europe and America, with long-term relationships maintained with customers in more than 100 countries.

The commercial envelope before you quote

Our published product page already sets out the terms a buyer needs before a quotation: lead time is banded by order quantity, with the smallest and middle bands published and the largest volume band negotiated, and a wide set of delivery terms is accepted, from FOB and CFR through CIF, EXW, DDP and courier. Samples are available, a one-year warranty applies, and the reference price structure is published for the current configuration. Minimum quantities, current prices and delivery slots are confirmed per configuration, so request them for the model, finish and destination rather than working from a general figure.

Two practical points for a distributor. The first is that the packing and colour choices sit on the same order as the cross number, so fixing artwork and pack early avoids a second trip through the sample stage. The second is that a warranty claim in this product group is only as strong as the reference number and the document, worth telling customers at the point of sale rather than at the point of failure.

For a specific cross reference, a fitment confirmation or a sample request, our brake parts engineers are the route to a documented answer.

Frequently asked questions