Types of Casters: Swivel, Rigid, Wheels and Duty Classes

There are two basic types of casters: swivel casters, which rotate a full circle so the cart can steer, and rigid casters (also called fixed casters), which roll only in a straight line. Beyond that, casters differ by how they mount, how they brake or lock, what the wheel is made of and what duty class the rig is built for. The right combination comes down to your load, your floor and your environment.

This guide walks through each choice in the order we ask about them on a quote.

Swivel vs Rigid Casters

Swivel casters

A swivel caster has a raceway (a bearing between the top plate and the fork) that lets the wheel turn in any direction. The axle sits slightly behind the swivel center, so the wheel trails and lines itself up as the cart moves. Swivels make a cart maneuverable in aisles and tight corners.

Rigid casters

A rigid caster has no swivel: the wheel is held in a fixed fork and rolls forward and backward only. Rigid casters keep a cart tracking straight, resist drifting on slopes and are simpler, with fewer moving parts.

The common layout: two swivel + two rigid

Most push carts use two swivel casters at one end and two rigid casters at the other, like a shopping cart. The swivels steer and the rigids keep the cart going straight over long pushes.

• All four swivel gives the most maneuverability for tight spaces, but the cart is harder to keep straight, especially under heavy loads or on uneven floors.
• Long carts sometimes use other layouts, such as rigid casters in the middle with swivels at each end, so the cart can pivot near its center.
• Directional locks (below) let you switch a swivel caster to act like a rigid one when you need straight tracking.

Mounting: Top Plate vs Stem

Top plate casters bolt to the cart through holes in a flat plate. They are the standard for industrial carts and equipment from medium duty up. To replace one, measure the plate size, the bolt-hole spacing and the overall height from floor to mounting surface.

Stem casters attach with a single stem that goes into the leg or tube of the equipment. Common styles include threaded stems, grip-ring stems, grip-neck stems and expanding adapters for tube legs. Stems are typical on furniture, racks and lighter equipment with no room for a plate. To replace one, measure the stem diameter, length and style (or thread), plus overall height.

Brakes and Locks

• Wheel brake. Stops the wheel from rolling. The swivel can still rotate, so the cart stays put but can pivot. Styles include side brakes, tread brakes and cam brakes.
• Total lock. Locks both wheel rotation and the swivel at once. The usual choice for workstations, equipment stands and anything that has to stay firmly in place.
• Directional lock (swivel lock). Holds the swivel in a straight-ahead position so it rolls like a rigid caster. Useful when a cart needs to maneuver in one area and travel straight in another.
• Floor locks. A separate device on the cart that presses a pad against the floor when caster brakes alone aren’t enough.

Brake and lock options vary by manufacturer and series, and not every option is offered on every wheel size.

Wheel Materials Compared

Wheel material	Floor friendliness	Where it fits	Watch-outs
Rubber	High; quiet and cushioned	Hospitality, healthcare, light-to-medium carts on finished floors	Lower capacity than harder wheels; oils and heat can degrade it
Polyurethane	High	General industrial use on concrete; a versatile all-rounder	Check suitability for hot, wet or chemical exposure
Phenolic	Moderate	Smooth floors, heavier loads, some heat exposure	Hard and noisy; can chip on debris; not for wet areas
Nylon / polyolefin	Lower	Low push effort, moisture and many chemicals	Noisy and less forgiving on rough floors
Steel / cast iron	Low; hard on floors	Very heavy loads, high heat, rough industrial floors	Loud; can damage finished floors
Pneumatic	High; most cushioning	Outdoor and rough terrain, fragile loads	Punctures, pressure checks, lower capacity for its size

This is a general comparison. Specifications vary by manufacturer and configuration — confirm the rating with the manufacturer’s documentation. For a closer look at tread wheels, see our polyurethane casters, and for air-filled wheels read Pneumatic Casters: When Air-Filled Wheels Make Sense.

Duty Classes

Duty classes are informal categories whose cutoffs differ by manufacturer. Use them to narrow the search, then size by the actual per-caster rating.

• Light duty. Furniture, displays, office and light utility carts. Often stem-mounted, smaller wheels.
• Medium duty. Utility carts, hospital and food service carts, light manufacturing. Top plate or stem.
• Heavy duty. Industrial carts, racks and equipment that move loaded every day, with heavier forks and larger raceways. See heavy duty casters.
• Extra-heavy / kingpinless. Very heavy loads, tow lines and carts that take impacts at dock plates and floor joints. A kingpinless caster has no kingpin in the swivel to stretch or loosen under shock loads, so the swivel holds up better in hard service. See extra-heavy and kingpinless casters.

Douglas Equipment is a Colson Master Distributor, and we can also help compare options from other manufacturers when the application calls for it. For how capacity ratings are measured and how much margin to leave, read Caster Load Ratings Explained.

Casters by Application

• High-temperature casters. Ovens, bakeries and autoclaves, where wheel, bearings and grease all have to handle heat.
• Stainless steel casters. Washdown and corrosive areas where a plated steel rig would rust.
• Medical casters. Quiet wheels, smooth swivels and total locks for beds, carts and equipment stands.
• Food service casters. Washdown-friendly materials, sealed bearings and easy-to-clean designs for kitchens and processing areas.
• ESD and conductive casters. Conductive or static-dissipative wheels for electronics work. Confirm the wheel’s properties with the manufacturer’s documentation and check your full grounding path.
• Specialty casters. Spring-loaded, low-profile and other designs for unusual mounting or ride requirements.
• Custom caster assemblies. Rig, wheel, bearing, brake and mounting combined for an application a catalog part doesn’t cover.

For medical, food service or electronics applications, our team can help you obtain manufacturer documentation for your application.

How to Get the Right Quote

Send us these five things and we can recommend the right type of caster:

1. Load per caster. The weight of the cart plus its heaviest load, and how many casters it rides on.
2. Floor. Smooth concrete, epoxy, tile, rough or cracked concrete, asphalt, ramps, dock plates or thresholds.
3. Environment. Indoor or outdoor, washdown, heat, cold, oils, chemicals or debris.
4. Mounting. Top plate size and bolt-hole spacing, or stem type and size, plus the overall height you need. A photo of the existing caster next to a tape measure works well.
5. Quantity. How many casters, how many swivel vs rigid, and which brakes or locks you need.

Not sure what you have? Start with Find My Caster, then request a quote.

Frequently Asked Questions

What are the main types of casters?

Swivel and rigid. From there, casters are grouped by mounting, brakes and locks, wheel material and duty class.

What are rigid casters used for?

Rigid casters keep a cart moving in a straight line. They are usually paired with swivel casters so the cart steers at one end and tracks straight at the other.

Should I use four swivel casters?

Only if you need maximum maneuverability in tight spaces, since four swivels make a cart harder to push straight. Directional locks on two of them give you both options.

What is the difference between a top plate and a stem caster?

A top plate caster bolts on through a flat plate and is standard for industrial carts. A stem caster fits into a leg or tube with a single stem and is common on furniture, racks and lighter equipment.