How it connects
Trolley wheels insert into and ride atop the curved interior contour or tubular slot of a hollow round track, providing rolling support and guidance under gravity load.
Male and female halves
Male (roller/trolley wheel assembly) riding within or atop female (round tubular track profile).
Usually connects to
- Tubular round barn door track / rail (e.g. CannonBall round track, National #3 round rail)
Common sizes
- Typically sized for standard agricultural round track profiles (around 2 to 2-1/4 inch diameter tubular round rail, supporting 300 to 600 lbs per door).
Where it is used
Agricultural buildingsBarns and shedsPost frame sliding doorsCommercial exterior sliding doors
Variations
- Delrin/polyoxymethylene plastic wheels
- Steel wheels
- Ball bearing vs bronze bushing
- Flexible apron vs offset threaded bolt hanger
How to recognise it
Recognised by tandem (two or four) convex-tread Delrin or steel wheels mounted on a hinged/swivel trunnion frame with a hanging bolt or apron plate, contoured to roll on curved tubular track.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| Box rail trolley wheel | Box rail trolleys feature flat or cylindrical wheels running along the flat bottom flanges of an enclosed rectangular box track, whereas round rail trolley wheels have contoured convex treads designed for cylindrical round track. |
Also called
Round rail trolleyRound track hanger rollerRound track trolley rollerSliding barn door round rail wheel
Good to know
Often referenced under proprietary or industry-standard round rail systems such as CannonBall:HNP or National Hardware #3 round track.
Related connections
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