Make a cart that can be used to haul tools and materials up an extension ladder to a roof, loft, balcony, or upper window of a building or to the deck of a keeled sailboat that is propped up on dry land. Note that some of the accompanying photos were staged for clarity of photographing, so not all safety precautions may be in evidence that would be in place during actual hauling of a load up a ladder.
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Unclesam

Step 1: Going Up!

This view shows details of the pony's lower construction. It is basically a three-legged chair, the third leg attached to the middle of the underside of the load platform ("seat"). The lower axle is positioned so that the plywood disks attached to the wheels are below the lower side of the load platform so long cargo objects can lay across the platform without interfering with the wheels. I made my pony's siderails 36" long from 2" by 3" wood (actual 1-1/2" by 2-1/2") sold at home centers as "studs." The lengths of the other components depend upon the distance between the side rails of your ladder. I connected the wood frame members together using wood glue and deck screws. My load platform is an 18" square of 1/2" thick plywood whose corners are notched out to clear the side rails, and glue and drywall screws fasten it. A couple small wood cleats were screwed to the back of the platform to restrain the bottom of a 5-gallon plastic bucket.
I chose 7" diameter plastic non-pneumatic lawn mower wheels running on two 1/2" steel axles secured with washers and push-on nuts. I made the 9" diameter wood wheel disks from 1/4" thick plywood fastened directly onto the sides of the wheels with drywall screws. A 45-degree chamfer on the inside of the outer rims of the disks keep them from riding up onto the ladder siderails.
Photo show details of the bracing underneath the load platform and attachment of the front, third leg.

Step 2: Ramps Transistion Pony Between Ladder Sections

Small plywood 30-degree ramps, having the same thickness as the ladder siderails, allow the pony's wheels to smoothly transition from one ladder section to the other. Ramps replace plastic caps on the top ends of side rails of the ladder's lower section whenever the pony is to be used.

Step 3: Clips Steady Ladder Feet

Homemade wire clips slipped through deck board cracks secure light ropes that prevent ladder feet from kicking out. If ladder rests on the ground, ladder feet can be put into shallow holes to keep them from moving.

Step 4: Snap Clips Secure Top of Ladder

Short ropes and clips snapped to heavy screw eyes prevent the top of my ladder from sliding sideways when I haul tools and materials up to my roof. Ropes are slack when first snapped in place but tighten when the bottom of the ladder is moved away from the house. The ladder ends up with its feet farther away from the house than is recommended for safe use, and that is why I take pains to secure the top and bottom of the ladder. The wide angle of the ladder allows less effort to pull up the loaded pony. Rope for hauling up the ladder is tied to the top rung, run down through a pully mounted on top of the pony, then back up to the top of the ladder and through the pully bolted to the top rung. Pulley allows pony to be raised and lowered either by someone standing below, or by someone above, on the roof, but back away from the edge.

Step 5: Pulley and Cleat Bolted to Top Ladder Rung

The hauling pulley and a cleat for tying off the hauling rope are bolted through the top rung of the ladder. They do not interfere with normal operation of the ladder so are left in place all the time.

Step 6: Pony Ready to Be Loaded

Pony sits level while bucket of material or tools or other things are loaded onto its load platform. Loaded pony is then tilted back against ladder, operator steps up over pony, climbs up ladder, then hauls up pony. Pulley attached to top of pony halves the amount of effort needed on the pulling rope. I chose 3/8-inch nylon rope, even though the weight of the load does not require it, because it is easier to grip.
This project was originally described in an article I had published in 15 Nov 2002 issue of MESSING ABOUT IN BOATS magazine.
U.S.