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At CasterHQ we stock over 25,000 caster and wheel SKUs and field keyed-vs-bored questions every week. The wrong choice means either a drive wheel that slips on day one or an unnecessarily expensive idler. This guide gives you a straight answer backed by 15 years of real application data so you can spec the right wheel the first time.
What Is a Keyed Wheel?
A keyed wheel has a rectangular slot — called a keyway — machined into its bore. A small steel key sits half in the shaft's keyway and half in the wheel's keyway, creating a mechanical interlock. When the shaft rotates, the wheel rotates with it at exactly the same speed, with zero slippage. This is called positive torque transfer.
Keyway dimensions follow ASME B17.1, which specifies key widths, heights, and tolerances based on shaft diameter. A 1-inch shaft typically uses a 1/4-inch square key. Because the standard is universal, you can source replacement keys from any industrial supplier and expect a proper fit.
We see keyed wheels most often in drive systems: powered conveyors, automated guided vehicles (AGVs), motorized carts, and any application where a motor or gearbox must transfer rotational force through the wheel. If you are building or specifying a powered conveyor line, our keyed drive wheels collection is the starting point.
What Is a Bored Wheel?
A bored wheel has a smooth, cylindrical bore — no keyway, no splines, no flats. It slides onto a shaft and is held in position axially by set screws, snap rings, retaining rings, or a press-fit between the bore and the shaft.
Because there is no mechanical interlock for rotation, the wheel spins freely around the shaft. That is the point. In an idler position — where the wheel is not driven by a motor but rolls passively under load — free rotation is exactly what you want. Forcing a keyway into an idler wheel adds cost, adds a failure point, and accomplishes nothing.
Typical applications include gravity conveyors, non-driven cart wheels, guide rollers, and tensioner pulleys. If you are outfitting a manual cart or gravity line, browse our shop wheels for bored options in polyurethane, nylon, rubber, and phenolic.
Key Differences at a Glance
The core distinction is simple: keyed wheels transfer torque from shaft to wheel; bored wheels allow free rotation on the shaft. Everything else — cost, installation complexity, failure modes — follows from that single difference. If the wheel must be driven, key it. If it rolls freely, bore it.
Keyed vs Bored Wheel Comparison
| Feature | Keyed Wheel | Bored Wheel |
|---|---|---|
| Torque Transfer | Positive mechanical lock — zero slippage | None inherent; relies on friction or set screws |
| Installation | Requires keyway alignment, key insertion, and securing hardware | Slide on, secure with set screw or retaining ring |
| Cost | Higher — additional machining for keyway (typically 15-30% more) | Lower — standard bore, minimal machining |
| Best Applications | Drive wheels, powered conveyors, AGVs, motorized equipment | Idler wheels, gravity conveyors, carts, guide rollers |
| Load Capacity | Handles high-torque loads without slipping | Handles equivalent static/radial loads; not suited for torque transfer |
| Replaceability | Must match keyway size and shaft diameter exactly | Any wheel matching bore diameter fits the shaft |
| Axle Requirement | Shaft must have a matching keyway (per ASME B17.1) | Smooth shaft — no keyway needed |
| Failure Mode | Key shears under extreme overload (protects gearbox) | Set screw loosens or bore wears, causing axial drift |
When to Choose Keyed Wheels
Choose keyed wheels whenever the wheel must transmit rotational force. Specific scenarios include:
- Powered conveyor drive rollers — the motor drives the shaft, the key drives the wheel, and the wheel moves the belt or product.
- AGV and AMR drive wheels — autonomous vehicles need zero-slip torque transfer for accurate navigation and odometry.
- Motorized carts and tuggers — any wheel connected to a drive motor or gearbox output shaft must be keyed to avoid energy loss and slippage under load.
- High-torque industrial equipment — if the wheel sees more than 50 ft-lbs of continuous torque, a set screw alone will not hold. A keyed connection is required.
For material selection guidance on drive wheels, see our caster and wheel materials guide.
When to Choose Bored Wheels
Choose bored wheels whenever the wheel rolls freely and is not connected to a power source:
- Gravity conveyors — product weight and incline provide the motive force; wheels just need to spin.
- Idler positions on powered conveyors — the drive end is keyed, but non-driven rollers use bored wheels to reduce cost and simplify maintenance.
- Manual carts, dollies, and platform trucks — human-powered movement does not require torque transfer through the wheel bore.
- Cost-sensitive applications — when budgets are tight and the application does not demand torque transfer, a bored wheel saves machining cost on every unit.
Common Industries and Applications
We supply keyed and bored wheels across a wide range of sectors. In manufacturing, keyed drive wheels power conveyor lines that move parts between CNC stations, while bored idler wheels support the return side of the belt. Warehousing and distribution facilities use keyed wheels on sortation drives and bored wheels on gravity take-away lines.
AGV and robotics integrators specify keyed polyurethane drive wheels for traction and odometry accuracy. Food processing plants need both types — keyed for washdown-rated powered conveyors, bored for gravity roller sections — often in stainless-steel-compatible materials. Browse our full range of industrial casters for heavy-duty options across all of these sectors.
- Keyed wheels lock onto the shaft and transfer torque — required for any driven application.
- Bored wheels spin freely on the shaft — ideal for idler, gravity, and manual-push applications.
- Keyway dimensions are standardized under ASME B17.1; always match the key size to the shaft diameter.
- Using a keyed wheel where a bored wheel suffices wastes money. Using a bored wheel where a keyed wheel is needed causes slippage and equipment failure.
- When in doubt, call us at 844-439-4335 — we will spec the right wheel for your application in minutes.
Need Keyed Drive Wheels or Bored Wheels?
CasterHQ stocks keyed and bored wheels in polyurethane, nylon, rubber, and more. Our engineers help you match the right wheel to your shaft and application.
Shop Keyed Drive Wheels Call Us: 844-439-4335Frequently Asked Questions
What is the difference between a keyed and bored wheel?
A keyed wheel has a machined keyway in its bore that interlocks with a key on the shaft, creating a positive torque connection. A bored wheel has a smooth bore and spins freely on the shaft. Keyed wheels are used in drive applications; bored wheels are used in idler and gravity applications.
Can I replace a keyed wheel with a bored wheel?
Only if the wheel is in a non-driven position. If the wheel must transmit torque from a motor or gearbox, a bored wheel will slip on the shaft and the system will fail. For idler positions, swapping a keyed wheel for a bored wheel is fine and may save cost.
Which is stronger — keyed or bored?
Both can handle equivalent radial (weight) loads. The difference is torque capacity. A keyed wheel handles far more rotational force because the key distributes torque across the keyway walls. A bored wheel with a set screw has limited torque capacity — the set screw is the weak link. For ANSI/AGMA-rated torque values, refer to the shaft and key size tables in ASME B17.1.
What axle size do I need for a keyed wheel?
The axle (shaft) diameter must match the wheel's bore diameter, and the shaft must have a keyway machined to the same width and depth as the wheel's keyway. Standard key sizes per ASME B17.1 include 3/16-inch key for 3/4-inch shafts, 1/4-inch key for 1-inch shafts, and 5/16-inch key for 1-1/4-inch shafts. We stock keyed wheels for the most common shaft sizes — contact us if you need a custom bore.
Are keyed wheels more expensive than bored wheels?
Yes, typically 15 to 30 percent more, depending on material and size. The added cost comes from the extra machining operation to cut the keyway. For drive applications, this cost is justified — a slipping bored wheel will cause far more expense in downtime and damage than the upfront cost of a keyed wheel.
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Shop All CastersCall 844-439-4335Jordan Wilson
Founder of CasterHQ.com. Works directly with engineers, MRO buyers, and procurement teams across material handling, healthcare, food service, aerospace, and OEM. CasterHQ stocks Albion, Hamilton, P&H, Colson, Faultless, and the in-house Durastar series from a Texas warehouse and retrofits OEM fitments from dimensional drawings when brands discontinue parts.