Leveling Casters for Machine Tools: How to Choose the Right One

Putting a heavy machine on leveling casters comes down to three decisions: what the caster is doing under the base, how much load each unit must carry, and which CarryMaster model covers that load in the mount style your base accepts. Each decision is covered below, in order.

What a leveling caster does under a machine base

A leveling caster combines a wheel for rolling with a built-in leveler and a foot that bears on the floor, so a machine can be rolled into position and then stand on its feet.

In use, the machine rests on the leveler foot pads. That transfers the full load to fixed, stable contact points. Both functions share one mounting footprint on the machine base, which is the practical advantage over installing separate casters and separate leveling feet side by side.

For a broader overview of how leveling casters compare to other caster types and where each fits, see the leveling casters buying guide.

What leveling casters do not do: they are not a substitute for proper machine anchoring where codes or OEM requirements call for it, and they do not replace the base frame of the machine itself. The caster attaches to the base; the structural integrity of that base is the machine builder's responsibility.

How heavy a machine CarryMaster leveling casters can carry

The heaviest rating is 3,307 lbs per caster (AC-1800F, flange only). The heaviest stem leveling caster is 2,205 lbs (AC-1300S).

Those two figures define the top of the CarryMaster AC Series range. The full series spans from 110 lbs per caster up through 3,307 lbs, giving buyers a wide selection across light, medium, and heavy-duty machine bases. Browse the complete AC Series leveling casters for all current models and load ratings.

The practical upper limit for a four-caster base

Using the sizing method below on a four-caster base, the AC-1800F supports 3,307 x 3 / 1.5 = about 6,614 lbs of machine. The heaviest stem option, the AC-1300S, supports 2,205 x 3 / 1.5 = about 4,410 lbs. Above roughly 6,600 lbs on a four-caster base, the CarryMaster leveling range is not the right product.

Rated load figures across the CarryMaster leveling range

Model	Mount	Load per caster
AC-50F / AC-50S	Flange / Stem	110 lbs
ACP-200F / ACP-200S	Flange press / Stem press	441 lbs
ACT-400F / ACT-400S	Flange / Stem	441 lbs
AC-300F / AC-300S	Flange / Stem	551 lbs
ACT-800F / ACT-800S	Flange / Stem	882 lbs
AC-600F / AC-600S	Flange / Stem	1,103 lbs
APLC-700F	Flange press	1,543 lbs
AC-1000F / AC-1000S	Flange / Stem	1,764 lbs
AC-1300F / AC-1300S	Flange / Stem	2,205 lbs
AC-1800F	Flange only	3,307 lbs

One load figure is published per model. That figure is the load per caster.

Working out the load per caster

Divide the machine's total weight by three, then multiply by 1.5. That is the minimum per-caster rating you need, regardless of how many casters are under the base.

The reason for dividing by three rather than four is covered below. The 1.5 multiplier is a margin for uneven load sharing and real-world conditions, consistent with the method in the caster wheel load capacity guide.

Why three, not four

On any real floor, one of four casters may bear almost no load if the surface is not perfectly flat. The three-caster method ensures every unit is sized for the worst-case distribution, not the ideal one.

Dividing by four with no safety factor gives a falsely low per-caster number. In the first worked example below, dividing by four gives 1,250 lbs, which would wrongly accept the APLC-700F at 1,543 lbs or the AC-1000 at 1,764 lbs. Both fail once the correct method is applied.

Hypothetical worked examples

Example 1: 5,000-lb machine on four casters

5,000 lbs / 3 = 1,667 lbs. Multiply by 1.5 = 2,500 lbs per caster required.

• AC-1300F and AC-1300S rated at 2,205 lbs: fail (2,205 < 2,500)

• AC-1800F rated at 3,307 lbs: passes (3,307 > 2,500)

The correct model for this hypothetical machine is the AC-1800F (flange mount).

Example 2: 9,000-lb machine on four casters

9,000 lbs / 3 = 3,000 lbs. Multiply by 1.5 = 4,500 lbs per caster required.

4,500 lbs per caster exceeds the AC-1800F rating of 3,307 lbs. This hypothetical machine is out of range for the CarryMaster leveling caster series.

What to do when the math puts you out of range

If your calculation exceeds 3,307 lbs per caster, the AC Series is not the right product for that machine. Contact Zambus to discuss the application before purchasing.

What our published data does and does not tell you

Published data tells you the load per caster for each model. That is the number to use for model selection, and it is the number shown in the table above.

What the published data covers

For each CarryMaster leveling model, CarryMaster publishes:

• Load per caster: the rated maximum per unit, used for model selection

• Unit weight: the weight of the caster itself

• Overall dimensions: height, width, and depth of the assembled unit

• Stem thread or plate size and hole pattern: the exact mounting interface, available as downloadable diagrams

• Material of each part: wheel material, frame material, foot pad material, and hardware

What is not published

CarryMaster does not publish the following for its leveling casters:

• Any rolling or separate load rating beyond the single published figure

• Leveling adjustment range or travel

• Deflection under load

• Any performance figure related to machine accuracy or the machine's operating environment

Off-center loading

If a machine's center of gravity sits significantly to one side of the base, the casters on that side carry more than an even share. The three-caster sizing method partially compensates for this, but an extreme offset may require a custom analysis.

A common example is a CNC machine with a heavy spindle head or a large rotary table mounted to one side. In those cases, the two casters nearest the heavy side may carry a disproportionate share of the total load. If the offset is significant, calculate the approximate load distribution before selecting a model, or contact Zambus with the machine layout for guidance.

Floor condition

An uneven, cracked or contaminated floor changes how load shares between casters and how each foot sits. Inspect the floor where the machine will stand and address significant damage before relying on the casters to hold the machine in place.

Stem or flange on a machine base

The right mount type is determined by what the machine base already has, not by preference. Stem mounts thread or press into a pre-drilled hole in the base frame; flange mounts bolt to a flat plate on the underside of the base.

Stem mounts

A stem caster installs into a single hole, which makes it the simpler retrofit option when a base has existing threaded inserts or round holes of the right diameter. The catalog ceiling for stem-mount leveling casters is 2,205 lbs per caster (AC-1300S).

Stem casters are well suited to:

• Light and medium-duty machines (under roughly 4,400 lbs total on a four-caster base)

• Bases with existing round holes or threaded inserts

• Applications where drilling a bolt pattern is not practical

Flange mounts

A flange caster bolts to a flat surface using a four-hole bolt pattern. The AC-1800F at 3,307 lbs is only available in flange configuration.

Flange casters are the correct choice when:

• The machine exceeds 4,400 lbs total on a four-caster base

• The base has a flat welded plate or fabricated foot pad at each corner

• The application requires the highest available load rating

Mixed configurations

Some machine bases have a combination of hole types, or a fabricator can add flange pads to an existing base. If your base does not currently accept the mount type you need, that is a fabrication question for whoever built or will modify the frame.

When adding flange pads to a stem-hole base, the pad must be welded or bolted securely enough to transfer the full caster load into the base frame. A pad that is tack-welded or only surface-mounted is not a reliable substitute for a properly engineered flange surface. Confirm the pad design with a qualified fabricator before installing high-load flange casters on a modified base.

For a detailed comparison of stem and flange mount geometry and installation considerations, see the stem vs. flange caster guide.

Wheel material and shop floors

The wheel material affects how the machine rolls and how the wheel holds up over time. Leveling models in the AC Series use PA6 nylon wheels. The AC-1800F uses an MC nylon wheel.

PA6 nylon is a hard material that rolls well on smooth, sealed, or epoxy-coated concrete.

At the top of the range, other parts change too. The AC-600S has an NBR rubber foot pad while the AC-1800F uses a die-cast aluminum (ALDC12) foot. Read the Materials and Treatments table on the individual model page before specifying, particularly for the higher-load models.

For a full breakdown of wheel materials across caster types, see the caster wheel materials guide.

A short specification checklist

Before selecting a model, confirm each of these items. Every one of them affects which caster is correct.

Item	What to confirm
Machine weight	Total weight including the base frame, tooling, fixtures, coolant, and any material loaded into the machine
Number of casters	Usually four; confirm before calculating load per caster
Per-caster load	Machine weight / 3, then x 1.5
Mount type	Stem (hole diameter and thread) or flange (bolt pattern and plate size)
Wheel material	PA6 nylon for most applications; MC nylon on the AC-1800F
Floor condition	Smooth, cracked, coated, or contaminated
Operating load	Use the heaviest realistic condition, not the bare machine weight

If any item on this list is uncertain, resolve it before purchasing. An undersized caster is not a minor inconvenience; it is a safety and equipment risk.

Browse the full CarryMaster leveling casters range or contact Zambus at (973) 777-4922 for help matching a model to a known machine weight and mount type.

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Frequently Asked Questions

What is the heaviest load a single CarryMaster leveling caster is rated for?

The AC-1800F carries 3,307 lbs per caster and is available in flange mount only.

That rating is the single published load figure for the model.

The AC-1800F is the only CarryMaster leveling caster that reaches this rating. No stem-mount model in the AC Series comes close; the heaviest stem option is the AC-1300S at 2,205 lbs. If your calculation requires more than 3,307 lbs per caster, the AC Series cannot safely carry the machine.

Can I use stem-mount leveling casters on a machine heavier than 4,400 lbs?

No. The heaviest stem-mount leveling caster in the CarryMaster AC Series is the AC-1300S at 2,205 lbs per caster, which limits a four-caster stem-mount base to roughly 4,400 lbs after applying the correct safety factor.

A machine heavier than 4,400 lbs on four casters requires a flange-mount model. The AC-1300F (flange, 2,205 lbs) and AC-1800F (flange, 3,307 lbs) both exceed the stem-mount ceiling. If your base currently has stem holes, a fabricator can weld or bolt flat mounting pads to the frame to accept flange casters.

The stem-mount ceiling is a catalog fact, not a conservative interpretation. There is no stem-mount option in the AC Series above 2,205 lbs.

Why divide a machine's weight by three instead of four when sizing casters?

Dividing by three accounts for the fact that a four-legged object on an uneven floor can rock on three contact points, leaving the fourth with very little load.

In practice, no shop floor is perfectly flat. Even small variations in floor height, or slight differences in how each leveling foot is set, can cause one caster to bear significantly less than one-quarter of the machine's weight. If you size for four equal shares and one caster ends up carrying close to one-third of the total, you have overloaded it.

The divide-by-three method sizes every caster as if it might carry one-third of the total load. Combined with the 1.5 safety factor, this gives a meaningful margin against the worst-case distribution without requiring you to measure your floor or calculate the exact load on each corner.

Do more than four casters let me put a heavier machine on leveling casters?

There is no published rule for bases with more than four casters. On an uneven floor, more casters do not reliably share load, so you cannot assume that adding casters raises the effective ceiling. Do not apply the four-caster sizing method to a six-caster base and expect the result to be conservative.

If your machine exceeds the four-caster range and you are considering a different base layout, ask Zambus before specifying. The load distribution on non-standard bases depends on geometry, floor condition, and how the feet are set, none of which can be resolved from a catalog alone.

Should the weight of tooling, fixtures and coolant count toward the caster load?

Yes. The caster load calculation must include everything the machine carries when it is in its heaviest operating condition.

Machine weight as listed in an OEM spec sheet typically refers to the bare machine without tooling, a full coolant reservoir, loaded fixtures, or material staged on the machine. In production conditions, that additional weight can be substantial. A machining center with a full coolant tank, a loaded tool magazine, and a heavy fixture on the table can weigh significantly more than its published base weight.

Use the heaviest realistic operating condition as your sizing figure, not the bare machine weight. If you are unsure of the fully loaded weight, the machine OEM or a rigging company can provide a measured figure.

Are leveling casters the same as leveling feet or machine mounts?

No. Leveling casters and leveling feet are different products that serve different purposes. Zambus sells leveling casters and does not sell standalone leveling feet or machine mounts.

A leveling foot is a fixed mount, typically a threaded pad or bolt, that holds a machine stationary at a set height. It has no wheel and does not allow the machine to be moved once set.

A leveling caster adds a wheel to the leveling function, so the machine can be rolled into position and then stand on its feet in place. The two product types are not interchangeable: a leveling foot cannot make a machine mobile, and a leveling caster is not a substitute for a leveling foot where a fixed mount is required by the machine builder or applicable codes.

Do CarryMaster leveling casters reduce machine vibration?

No. CarryMaster does not publish vibration performance for its leveling casters.

If your machine requires isolation from floor-borne vibration, or if the machine generates vibration that must be contained, that is a separate engineering requirement. The machine builder's installation guidance is the correct starting point for isolation requirements.

If vibration is a concern in your application, raise it with Zambus before specifying. The answer may involve a different product category entirely.

What happens if a leveling caster is loaded above its rated capacity?

The published load rating is the limit. Exceeding it puts the caster outside what the product is rated for.

The 1.5 safety factor in the sizing method exists precisely so the actual load on each caster stays below the rated limit under real-world conditions.

Overloading a caster creates a risk of failure. Size correctly before installation.

Where do I find the dimensions and mounting pattern for a specific CarryMaster model?

Every model page lists weight, dimensions, and mounting details. DWG, PDF, and STEP diagrams are available on the CarryMaster product diagrams page.

The diagrams page is the correct reference for fabrication and installation. Do not rely on catalog thumbnails or product page images for precise dimensions.

If a drawing for a specific model is not immediately visible, contact Zambus directly for the file.

What information should I have ready when asking Zambus to help specify casters for a machine?

Have the machine's total weight (fully loaded), the number of casters, the mount type the base accepts, and the floor type.

Those four items are the minimum needed to identify a candidate model. Beyond that, it helps to know the wheel material preference if you have one, any environmental factors such as chemical exposure, and how frequently the machine will be repositioned. If the machine has an unusual center of gravity or the base geometry is non-standard, a sketch or photo of the base mounting points speeds up the conversation.

Having the machine's OEM spec sheet available is useful but not required if you have the key figures listed above.