5″ Lockable Caster Wheels Upgrade for JMI Wheeley Bars, Triangle Style for 8″, 10″ & 12″ Dobsonians

The JMI 5″ Lockable Caster Wheels Upgrade (Triangle-Style) swaps the small factory 2⅜″ casters on a JMI Triangle-Style Wheeley Bar for three 5″ polyurethane wheels with full-locking brakes — smoother rolling on hard surfaces and a platform that stays planted once positioned. Made in the USA by JMI (CXB Astro family).

Product Overview

Three 5″-diameter polyurethane caster wheels, Triangle-Style mounting plates, and all hardware. The larger diameter rolls smoother over expansion joints and small obstacles than the factory casters, the polyurethane tread is gentler on finished concrete and garage epoxy, and each wheel's brake locks against both rotation and swivel — step the lever and the Dobsonian platform stops dead.

Who It's For

Owners of a JMI Triangle-Style Wheeley Bar (8″/10″/12″ Dobsonians) who roll on hard, smooth surfaces — a garage floor, driveway, observatory pad, or smooth pavement — and want a quieter, smoother roll plus brakes that hold the rocker box stationary at the eyepiece.

Key Features & Design

• 5″ polyurethane wheels: Roll smoother over joints and small obstacles; gentler on finished floors than hard-rubber casters, and won't leave black scuff marks.
• Full-locking brakes: Each wheel locks against both rotation and swivel, so the platform stays put — even on a slight slope — while you observe.
• Triangle-Style mounting plates: Sized for the Dobsonian platform frame; complete with hardware.
• Raises the platform ~6⅜″ off the ground (manufacturer spec).

Compatibility and Accessory Notes

• Designed for the JMI Triangle-Style Wheeley Bar for 8″, 10″, and 12″ Dobsonians — fits the entire Triangle-Style range.
• The wheels are the same polyurethane, lockable design as the Universal-style 5″ upgrade, but the mounting plates are Triangle-Style-specific and won't interchange.
• Pairs naturally with the Triangle-Style Leveling Screws + Hardware kit for the full ground-game.

Important Limitations

• Hard, smooth surfaces only: Concrete, asphalt, garage epoxy, tile. These wheels do not excel on grass, gravel, mulch, or sand — the diameter still catches on rough ground.
• Not compatible with Universal-style Wheeley Bars (different frame — use the Universal 5″ upgrade) or Sky Trekker models.
• Wheel upgrade only — leveling screws are not included (see the Triangle-Style Leveling Screws + Hardware kit).

Frequently Asked Questions

Will this fit my Universal-style Wheeley Bar?
No — the mounting plates are sized for the Triangle-Style frame. The wheels are the same design as the Universal version, but won't mount on a Universal bar. Order the Universal-style 5″ upgrade instead.

Does the lock actually keep the platform from moving?
Yes — each brake holds against both wheel rotation and caster swivel. With all three engaged, the platform stays put even on a slight slope, keeping the rocker box stationary for manual tracking.

Will the polyurethane wheels mark my garage floor?
No — polyurethane is the standard choice for indoor-rolling equipment because it doesn't leave the black scuff marks hard-rubber casters do.

Can I use these on grass or gravel?
Not well — 5″ polyurethane wheels are for hard, smooth surfaces. Off-pavement use on a Triangle-Style platform needs larger pneumatic wheels (special-order; contact CXB Astro).

Bottom Line

A USA-made set of three 5″ locking polyurethane casters, with Triangle-Style mounting plates, that make a Dobsonian dolly roll smoother and quieter on hard floors and lock solidly in place. Triangle-Style only, hard-surface only; pairs well with the Triangle leveling kit.