How to Identify an Implement Hub and Match It by Hub Number

When an implement hub wears out, the fastest way to the right replacement is the hub number. On Southwest Wheel's implement hubs, a number such as AG-H3066600-2ZHA identifies the hub, its bolt pattern and its matching spindle. Every character counts, including the suffix at the end, because two hubs with the same bolt pattern can take different bearings and different spindles.

This guide explains how to record the hub number on your equipment, what the parts of the number tell you, how to match a spindle to it, and what to measure when no number can be found.

Key takeaways

• Record the complete hub number. Write down every letter and digit, including the suffix after the last dash. Do not round it off or drop characters.
• The bolt pattern alone does not identify a hub. Southwest Wheel carries five different 6 on 6 in. implement hubs, and each takes its own spindle.
• The suffix tells you how the wheel attaches. A 1 before ZHA means a threaded hub that uses lug bolts; a 2 means a studded hub that uses standard lug nuts.
• WS at the end means the spindle is included. A hub number ending in ZHA is a complete hub assembly; the same number ending in ZHAWS adds the matching spindle.
• No number? Measure. Bolt pattern, pilot, bearing numbers, and spindle diameter and length together narrow the choice to one hub.

Terms used in this guide

• Hub number: The complete part number of the hub, for example AG-H3066600-2ZHA.
• Suffix: The characters after the last dash, such as 2ZHA or 2ZHAWS.
• Hub reference: The short hub number used on older equipment and in older parts lists, such as 12-4, 30-6 or 60-8B. It is built into the hub number.
• Bolt circle: The diameter of the circle that passes through the center of each stud.
• Pilot: The diameter of the hub's raised center that the wheel's center bore fits over. The hub pilot and the wheel's center bore are separate dimensions.
• Spindle number: The part number of the matching agricultural spindle, for example SP-306175NWC-120.

Step 1: Record the complete hub number

Hub numbers are generally cast into the hub on the backside, between the studs. Clean that area with a wire brush so the characters are readable, and check any parts records you have for the equipment. Copy the number exactly as written, letter for letter. A number that is one character off can point to a different hub with different bearings or a different spindle.

An older hub may show only a short hub reference, such as 12-4 or 30-6, sometimes followed by letters, as in 12-4LM. Record that too. The table near the end of this guide matches each hub reference to its current hub number.

If you find a number, also note the bolt pattern and pilot so you can confirm them against the replacement. If you cannot find a number, skip to Step 5.

Step 2: Read the hub number

Every part of an implement hub number has a meaning. Here is AG-H3066600-2ZHA, read left to right:

The 1 or 2 is easy to check on the equipment. If the wheel is held on by lug bolts that screw into the hub, the hub is threaded (1). If studs stick out of the hub and the wheel is held on with standard lug nuts, the hub is studded (2). The hub reference is an identifier, not a load rating; check the capacity on the hub and spindle you select rather than estimating it from the number.

Step 3: Choose a hub with parts or a hub with spindle

A hub with parts, ending in ZHA, comes complete with bearings, seal and dust cap, and the spindle is sold separately. Choose it when the spindle on the equipment is in good condition and is the correct match for the hub.

A hub with spindle and parts, ending in ZHAWS, comes complete with bearings, seal and dust cap plus the matching spindle. Choose it when the spindle is worn or damaged, when you are building a new wheel end, or when you are not sure the existing spindle matches. For example, AG-H3066600-2ZHA is the hub with parts, and AG-H3066600-2ZHAWS is the same hub with spindle SP-306175NWC-120 included.

Step 4: Match the spindle to the hub number

Each agricultural spindle is made for one hub number. Spindle SP-306175NWC-120 fits hub AG-H3066600-2ZHA; spindle SP-356200NWC-130A fits hub AG-H3566600-1ZHA. Pick the spindle by the hub it names, not by the bolt pattern of the wheel.

The spindle number also carries useful dimensions. In SP-306175NWC-120, 306 is the hub reference, 175 is the 1.75 in. bar stock diameter, NWC means the spindle nut, washer and cotter pin are included, and 120 is the 12 in. overall length. Use those numbers to double-check a spindle you have in hand, then confirm the diameter, length and overall length on the spindle you order.

Step 5: No hub number? Measure and record these details

If the number is missing or unreadable, do not choose a hub by appearance. Record:

• Bolt pattern: Count the studs and measure the bolt circle. On 4, 6 and 8-lug hubs, measure from the center of one stud straight across to the center of the opposite stud. On a 5 on 5-1/2 in. pattern, adjacent stud centers should measure 3-1/4 in.
• Pilot: Measure the hub's center pilot. Implement hubs pair 4 on 5 in. with a 3-5/8 in. pilot, 5 on 5-1/2 in. with 4 in., 6 on 6 in. with 4-5/8 in., and 8 on 8 in. with 6 in.
• Bearing numbers: Read the numbers on the inner and outer bearing cones.
• Spindle: Measure the spindle diameter, spindle length and overall length.

The bolt pattern narrows the search to one group of hubs. The bearings and spindle identify which hub in that group you have. The 6 on 6 in. group shows why all of these details matter:

All five share the same bolt pattern and pilot. AG-H3066600-2ZHA and AG-H6116600-1ZHA even use the same bearings and the same spindle diameter, yet their spindles differ in length. Bearing numbers alone are not enough; measure the spindle as well.

Implement hub numbers by bolt pattern

Each hub is also available with its spindle; add WS to the end of the hub number. The wheel must match too: implement wheels in these patterns have center bores of 3.62 in. (4 on 5 in.), 4 in. (5 on 5-1/2 in.), 4-5/8 in. (6 on 6 in.) and 6 in. (8 on 8 in.).

Check the rating before you order

Implement hub and spindle ratings are based on a 20 mph maximum speed, the recommended wheel offset and a single-wheel application. A wheel end is only as strong as its lowest-rated part, so compare the ratings of the hub, spindle, wheel and tire you plan to use, and size the parts for the load on that wheel.

Checklist before ordering

• Complete hub number, including the suffix, copied exactly, or the older hub reference.
• Threaded hub with lug bolts (1) or studded hub with standard lug nuts (2).
• Hub with parts (ZHA) or hub with spindle and parts (ZHAWS).
• Bolt pattern: stud count and bolt circle.
• Hub pilot, and the center bore of the wheel that will mount on it.
• Inner and outer bearing numbers.
• Spindle number, or spindle diameter, length and overall length.
• Ratings of the hub, spindle, wheel and tire for the load and the 20 mph limit.

FAQ

Can I order a hub using only the bolt pattern?

No. Several hubs share each bolt pattern. The 6 on 6 in. pattern alone covers five different hubs with different bearings and spindles. Use the complete hub number, or measure the bearings and spindle.

What does WS mean at the end of a hub number?

WS means the hub comes with its matching spindle along with the bearings, seal and dust cap. The same number without WS is the hub with parts, with the spindle sold separately.

Does the 1 or 2 before ZHA matter?

Yes. A 1 is a threaded hub that uses lug bolts, and a 2 is a studded hub that uses standard lug nuts. The same hub reference can come either way, so match the replacement to the hub you have; do not substitute a hub that differs by that character.

My old hub only shows a number like 30-6. Which hub is that?

That is the hub reference. Find it in the hub number table above; 30-6 is AG-H3066600-2ZHA. Then confirm the bolt pattern and whether the hub is threaded or studded before ordering.

Can I reuse my old spindle with a new hub?

Only when the spindle is in good condition and is the spindle made for that hub number. If you cannot confirm both, order the hub with spindle and parts.

References

• TRP International, LLC. Agricultural Components catalog: implement hub and spindle part number breakdown, hub and spindle specifications, and load capacities.
• French and Hecht implement hub part numbers: the older hub references, such as 12-4LM and 30-66LM, used on older equipment and parts lists.
• Southwest Wheel product specifications for implement hubs, hubs with spindles, and spindles.

Related guides

• How to Choose Implement Wheels, Hubs, and Spindles
• How to Measure an Implement Wheel Bolt Pattern and Center Bore

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