Verifying Plate Dimensions, Bolt-Hole Spacing and Swivel Offset Before Ordering a Replacement Caster

Measure the old caster before you contact anyone

A replacement is matched on bolt pattern, wheel diameter and load rating to the original spec 8 . Because two plates of the same nominal size can carry hole patterns roughly 5 mm apart, and that difference alone stops the bolts going in, a measured record is the only basis you can order against 17 .

Measure the caster still on the equipment where possible, and note the mounting type first — it decides which of the remaining dimensions you need 15 .

• ✓Record wheel diameter, wheel width, overall height and swivel radius for every caster on the unit.
• ✓Note the mounting type — plate, stem or bolt-hole — before measuring anything else.
• ✓For a plate mount, record plate length × width, the distance between holes and the hole diameter.
• ✓Check hole or slot size and bolt clearance against the equipment surface, not just the caster.
• ✓Keep the record as a drawing: wheel diameter and width, overall height, offset, swivel radius, plate and bolt-hole dimensions, bracket thickness, bearing and rating.

Screen out quotes whose plate and hole data do not match

A plate-mount caster is defined by three numbers: plate length × width, the distance between the holes, and the diameter of each hole 15 , 16 . If a quotation omits any of them, you cannot confirm the fit, and the omission is a reason to hold the quote rather than a detail to chase later.

Plate and stem mounts need different measurement sets, so a quote written for a stem caster tells you nothing about a plate replacement 15 , 27 . Ask the supplier to state the plate and hole figures on the quotation itself, in the same units you measured.

Published plate sizes vary widely between models — one product lists a 4" × 4-1/2" plate on a 3" × 3" bolt pattern 1 , and another a 3-7/8" × 2-11/16" plate on roughly 2-13/32" × 1-15/32" hole spacing 16 — which is why no single pattern can be assumed.

The sources set no acceptable tolerance on these dimensions, so treat any quoted figure as nominal until the supplier confirms it.

Measure swivel offset and swivel radius separately

Offset, also called lead, is the horizontal distance from the swivel centerline to the wheel centerline; the two words describe the same measurement 2 , 5 .

Swivel radius is a different dimension: it runs from the swivel or raceway centerline to the furthest edge of the wheel and defines the space the caster needs to rotate a full 360 degrees 6 , 26 , 27 . Measure both, because one governs the load path into the plate and the other governs clearance.

Offset creates a moment at the mounting plate equal to caster load times offset, so plate thickness and bolt grade should be checked against that moment rather than vertical load alone 2 , 5 . A 2,000 lb caster with 2 inches of offset produces 4,000 in-lb at the plate 2 .

If you change wheel diameter or offset on a replacement, the moment changes with it, and the existing plate and bolts may no longer be sized for it 5 .

Swivel radius is the figure to compare against the equipment envelope: if the replacement sweeps a larger arc than the old caster, it will foul on the frame or on adjacent structure 26 , 27 .

Fix the per-caster load rating and the wheel spec it depends on

Load per caster is total load divided by the number of casters, then adjusted by a safety factor 3 , 9 , 19 , 20 . The method is consistent across sources; the multiplier is not, so choose one for your application and write it into the specification instead of letting a supplier pick silently.

An 800 kg piece of equipment on four wheels gives 200 kg per wheel, and a 1.3–1.5 factor raises the selection baseline to 260–300 kg per wheel 20 . Record the wheel diameter, tread width, material and bearing type alongside the rating, because the rating is only meaningful for that combination.

The sources do not publish a complete wheel material and bearing selection table, so ask the supplier to state which wheel and bearing the quoted capacity applies to.

Confirm fasteners and their specification in writing

Fastener inclusion is not automatic. One plate caster listing states "Includes Mounting Fasteners: No", which means the bolts have to be sourced separately 14 .

Ask per SKU or per quotation rather than assuming a house rule, and get the answer in writing before the order is placed 14 , 33 .

• ✓Confirm whether mounting fasteners are included for the exact SKU quoted.
• ✓Ask the supplier to state bolt size, thread and grade for the mounting holes.
• ✓Ask for the recommended tightening torque for those bolts.
• ✓Confirm what else the quotation covers — sample cost, tooling, packaging, test reports, lead time and order quantity.

Match certification and environment features to the application

Washdown and food-service use calls for a stainless rig and hardware with sealed swivel and bearings, and NSF-listed models where food contact applies 7 .

Medical equipment under FDA and IEC 60601 requirements calls for total lock as a minimum and central lock as preferred, scaffolding under OSHA 29 CFR 1926.452(w)(2) and EN 1004-1:2020 requires positive wheel and/or wheel-and-swivel locks on all casters, and food service under NSF/ANSI Standard 2 recommends total lock for prep surfaces 30 .

Ask the supplier to name the standard the product is listed to, rather than accepting a general compliance statement.

One supplier states its stainless line meets USDA, FDA and NSF standards 13 , but no source in this set establishes which certification is mandatory for a given replacement application, so the requirement has to come from your own governing standard or your quality function.

Screen the commercial terms before you commit

No source in this set publishes lead times, minimum order quantities or price-break quantities for replacement casters, so ask for each explicitly and treat any figure you receive as specific to that supplier and that order.

Suppliers describe their own commercial positions differently — one states it supplies directly with no middleman markup and offers small MOQ options 31 , another stocks several brands and offers fitment help on non-standard casters 3 — and neither statement tells you what your order will cost or when it will arrive.

Normalise the specification before comparing prices: ask every supplier to quote against the same load, wheel diameter, brake mode, mounting dimensions, tread requirement, quantity and documentation request, because a quotation that includes a different lock or mounting design is not comparable 33 .

Where the sources disagree on the safety factor

The sources agree on the calculation method but not on the multiplier, so the figure you apply changes the rating you order. Pick a factor for your application, record it in the specification, and ask the supplier to confirm the rating was derived on that basis.

What the sources do not establish

• No source gives acceptable measurement tolerances for plate dimensions or bolt-hole spacing, so you cannot specify how close a quoted plate must be to your measured one.
• No source gives bolt size, thread, grade or torque values for mounting hardware; these must come from the supplier.
• No source gives a universal plate dimension or bolt-hole pattern standard, so no plate size can be assumed to fit.
• No source gives specific lead times, MOQ numbers or price-break quantities for replacement casters.
• No source establishes which certification is mandatory for a given replacement caster application.
• No source gives a numeric relationship between swivel offset and overall height or mounting height.
• No source gives a complete wheel material and bearing type selection table, so the wheel and bearing behind a quoted rating must be confirmed with the supplier.
• No source establishes a single mandatory safety factor or divisor for the per-caster load calculation.