JMI Heavy-Duty Medium Universal Wheeley Bar — Telescope Dolly

Product Overview

The JMI Heavy-Duty Medium Universal Wheeley Bar is the middle span in JMI's heavy-duty Universal line and the one that fits the widest set of common German equatorial tripods. It carries 300 lb total — tripod, mount, OTA and accessories combined — on a welded steel frame, and adjusts to tripods measuring 34″ to 42.5″ tip to tip. Foot receptacles have a 2-3/4″ inside diameter and take feet up to 2-3/4″ across. Leveling is on 5/8″ heavy-duty screws. It is offered here in two configurations: the standard bar on 5″ polyurethane locking casters, and the same bar supplied with JMI's 10″ all-terrain pneumatic wheel package and tow handle. Made in the USA.

Who It's For

This is a good match if you keep a loaded mount and optical tube assembled between sessions and want to roll the whole thing out rather than rebuild it; if the tripod measures between 34″ and 42.5″ foot to foot at observing height; and if the rig, counterweights and imaging train together come in under 300 lb. The 5″ caster configuration suits a route over concrete, asphalt or pavers; the 10″ pneumatic configuration suits a route that crosses grass, gravel, mulch, sand or a lawn-to-driveway transition.

Key Features & Design

• 300 lb load rating: Covers the tripod, mount, counterweights, optical tube and the full imaging train together.
• 34″–42.5″ tip-to-tip range: The broadest-fitting span in the heavy-duty Universal series.
• 2-3/4″ foot receptacles: Sized for the larger feet on heavy equatorial tripods, up to 2-3/4″ in diameter.
• 5″ polyurethane locking wheels: Standard equipment on the caster configuration, and they cross expansion joints and cracked concrete without stalling.
• 5/8″ heavy-duty leveling screws: The heavier thread matched to the 300 lb rating.
• 10″ all-terrain option: Six 10″ pneumatic wheels — two front swivel and four rear in dual-inboard pairs — with a tow handle, raising the mounted scope about 3¼″ over the factory caster setup.
• Welded steel frame: Powder-coated welded steel, made in the USA; the bar itself ships at 50 lb.

Mechanical Design

The bar is a welded steel spider with adjustable arms, each ending in a cup that captures one tripod foot. Nothing bolts to the tripod — the mass of the loaded rig seats the feet and holds the geometry. Each arm carries a locking caster and a 5/8″ leveling screw. Rolling is done on the wheels; at the observing position the leveling screws thread down until they take the load off the casters, putting the rig on rigid steel feet rather than rubber and levelling the base on a sloped pad. The 10″ pneumatic package replaces the factory casters with a six-wheel arrangement, two swivel wheels at the front and four in dual-inboard pairs at the rear, which spreads the footprint and keeps the wheels from sinking on soft ground; the supplied tow handle gives a pulling point clear of the tripod legs.

Recommended Uses

• Rolling a fully assembled imaging rig from a garage bay onto a driveway or concrete pad every clear night.
• Crossing a lawn between the house and a back-yard observing site with the 10″ pneumatic package.
• Moving a heavy German equatorial tripod with counterweights, optical tube, camera and dew control still fitted.
• Repositioning a rig mid-session to clear a tree line or a neighbour's roof.
• Returning a telescope to a marked pad position night after night with alignment and cabling untouched.

Compatibility and Accessory Notes

Fit is set by the tripod's tip-to-tip measurement at observing height, taken between any two feet: this bar covers 34″ to 42.5″. The receptacles are 2-3/4″ inside diameter and take feet up to 2-3/4″. Narrower tripods are covered by the Heavy-Duty Shorty at 26.25″–31.25″ and wider ones by the Heavy-Duty Large at 49″–56.5″, both rated to the same 300 lb. This bar uses 5/8″ leveling screws, so the 5/8″ versions of JMI's 10″ pneumatic wheel upgrade, tow handle, speed-dial drill adapter, replacement leveling screws and soft-ground feet are the matching parts; accessories listed for 1/2″ leveling screws belong to the standard-duty bars. Tie-down bracket kits are sold separately. Tell us the make and model of your tripod and we will confirm the fit and the right wheel configuration.

Good to Know Before You Order

• The two options differ only in wheels. The 5″ Caster option is the bar as JMI builds it; the 10″ Pneumatic option is the same bar supplied with the 10″ all-terrain wheel package and tow handle, which ships as a second carton.
• The 10″ package changes the working height. It raises the mounted scope about 3¼″ over the factory caster setup, which shifts the eyepiece position and the tip-to-tip figure to measure against.
• Doorway clearance with the 10″ tires. JMI's published allowance is a doorway at least 3″ wider than the tip-to-tip distance.
• The 300 lb rating is for everything on the bar. Tripod, mount, counterweights, optical tube, cameras, dew heaters and power supplies all count toward it.
• 5/8″ leveling screws set the accessory version. The 1/2″ accessories in the JMI range fit the standard-duty bars rather than this one.
• Shipping weight. The bar ships at 50 lb; the 10″ wheel package adds a further 35 lb in its own carton.

Frequently Asked Questions

Is it difficult to set up?

The frame arrives welded and ready. Setup is a matter of opening the arms to the tripod's tip-to-tip measurement, lowering the feet into the cups, and running the 5/8″ leveling screws down once the rig is parked. The 10″ wheel package bolts on in place of the factory casters using the supplied hardware, and nothing on the tripod is drilled or modified either way.

How is tip-to-tip distance measured?

With the tripod at observing height, the measurement runs between any two foot tips. This bar covers 34″ through 42.5″.

Which wheel option suits my site?

The 5″ polyurethane casters roll on concrete, asphalt, pavers and cracked driveways. The 10″ pneumatic wheels are built for grass, gravel, mulch, sand, rough pavement and lawn-to-driveway transitions.

Can the 10″ wheels be added later?

Yes. The 10″ pneumatic package is also sold on its own in the 5/8″ leveling-screw version, which is the one that fits this bar.

Does polar alignment survive the trip?

The tripod is never taken apart, so alignment, cable routing and counterweight position stay as they were. Marking the tripod position on the pad reproduces the same alignment closely on the next run.

Bottom Line

In short: a 300 lb welded steel dolly on 5/8″ leveling screws that fits tripods spanning 34″ to 42.5″ tip to tip, supplied either on 5″ locking polyurethane casters for hard ground or with the six-wheel 10″ pneumatic package and tow handle for grass and gravel. Made in the USA.