You can build this! Click on this diagram to enlarge.
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Two-wheelers don't have to be the only game in town. This isn't news to those who spent their fun-filled youth pumping the daylights out of a pipe-and-wheel contraption that was called an Irish Mail cart. Well, here's a modern version of that pump scooter, and it can be built with electrical metallic tubing (EMT) and some odds and ends.
The necessary tools include a small welder and two different tubing benders (to handle ½ - and 1-inch EMT), as well as a hacksaw, an electric drill with bits, a screwdriver, a round file, a measuring tape, a pipe wrench and a coping saw. If you're purchasing new electrical conduit (in 10 lengths), you'll need two complete 1-inch sections, one ¾ -inch piece and three ½ -inch lengths to handle most of the job. Also required are an additional 2 feet of the ½ -inch size and an 8-inch length of 1 ¼ -inch tubing. The two-piece seat can be cut from a single 20-by-28-inch slab of plywood.
The chassis is made from two 58-inch lengths of 1-inch conduit which are bent to the same contour, then joined to form a sort of paddle shape. To curve these sections properly, choose one and — starting at either end — measure off 4 inches. Make a 90-degree bend at that point, which should take up about 10 inches.
Mark off 5 inches more, start a 45-degree arc (this one uses up 5 inches), leave an 8-inch straight section, form the final 45-degree curve, and then determine the length of the remaining leg (it should be about 21 inches).
Once you've curved a pair of the tubular side rails, join them by temporarily placing your 1 ½ -inch pipe coupling between the parallel front tubes as a spacer, then welding the butted rear tips to each other. Use a scrap of 1-inch-diameter mechanical tubing (or filed-down ¾ -inch pipe) inside both parts to serve as a bridge.
The rear axle housings are welded to the chassis next, and these should be positioned so they intersect the right-angle bends at midpoint and are equally divided by the joint. A 2 ½ -inch section of ½ -inch conduit holds each one to the frame at the inner ends, but since the goal is to mount the housings true for proper wheel alignment and camber, these stubs may have to be made slightly longer or shorter to suit your individual chassis.
The rest of the frame components are made from ½ -inch EMT, which can be fine-trimmed as necessary. A 20-inch cross-member fastens between the side rails at a point 10 ½ -inch in front of the butt joint at the rear. Then two 90-degree pieces — one 9 inches and the other 24 inches in total length — are similarly arranged to help support the plywood seat.
To form the seat-back frame, bend both a 30 ½ -inch and a 35-inch conduit section into the shapes indicated, then weld the wider piece to the upper surface of the frame rails (1 inch forward of the crossmember) at an angle of 60 degrees. The narrow hoop mounts atop that at an 85-degree bias to the chassis. Then the seatback strut, along with the 4 ½ -inch rear support, is fastened in place to lock the axle housings to the seat structure.
At this point, complete the steering hub and pump handle. Both of these parts have to be adjustable, so they're designed to slide within the parallel front frame rails as necessary, and can be held in place with hose clamps. The hub is simply the 1 ½ -inch pipe coupling welded to each half of a longitudinally split section of 1 ¼ -inch EMT, then capped at each end with 1 ½ -inch to ¾ -inch pipe bushings. The threads within the center hole in each reducer must be filed out if it's to accept the shank of a ¾ -inch nipple.
The handle is nothing more than a section of 1-inch conduit equipped with ¾ -by-14-inch upper grip bar and a 1-by-7-inch pivot shaft — at the lower end — made from a scrap of mechanical tubing (this piece can be replaced with a length of 4 ¾ -inch pipe if you don't mind filing its outer surface a bit). A 3/16-by-1 ½ -by-7-inch hunk of flat metal welded perpendicularly to the midpoint of the pinion functions as the drive lever, and the 1-inch shaft rides inside a pair of 1-by-2 ¼ -inch EMT stubs. These stubs are clipped to the chassis rails with half sections of 1 Y" conduit and hose clamps.
A buttress front axle allows easy foot steering, and it's made by welding a 3-inch piece of ½ -inch EMT, then a 2 ½ -inch washer and ¾ -by-3 ¾ -inch pipe nipple combination to the center of, and perpendicular to, the 1-by-30-inch conduit axle. A 27-inch length of ¼ -inch reinforcing rod trusses the assembly, and two angle iron sections, fastened to the ends of the housing and tilted toward the rider, form modest footrests. The axle itself is merely a 40-inch stretch of ¾ -inch conduit run through the housing. The front wheel hubs ride on the shaft and are held in place with ¼ -inch bolts pinned through the tube's ends.
To attach the front assembly to the steering hub, just slip the ¾ -inch pipe center pivot through the two bushings in the coupling and lock it in place with a large washer and ¾ -inch pipe cap.
The drive and brake mechanisms also work on a sleeve-within-a-sleeve principle. The ¾ -by-17 ½ -inch drive axle shaft utilizes a 3/16'-by-1 ½-by-5-inch flat metal crank throw (a 2 ½ -inch washer, welded in place 1 inch from that bar, makes a good walk stop). The braked (right side) wheel is fastened to a ¾ -inch shaft that houses — and is bolted to — a ½ -by-17 ½ -inch pipe, which is then connected to a 5 ½ -inch pulley. The right axle shaft uses an anti-slide washer, as does the drive axle, and it's carried inside the axle housing as well.
A one-wheel brake is all that's needed for this simple "pump-about," and that can be worked out by tacking a 1-by-9-inch EMT housing to the upper part of the chassis just behind the crossmember. Two more conduit sections, welded at a right angle, provide a brake handle and shaft. Once this control is slipped into place and a small spacer and stop are installed, a 27-inch length of strapping band is fastened between the brake shaft and crossmember, with the pulley nestled in the loop created. In practice, this arrangement works reasonably well, since a good deal of tension can be drawn on the strap through the mechanical advantage of the small pivot. But the system performs even better if the pulley groove itself is covered with a steel band, and the inner side of the steel loop is then faced with a strip of "grabby" rubber matting to act as a brake shoe.
All the cart's wheels can be fabricated from EMT scraps and discarded bike rims, since regular spoked wheels probably couldn't stand up to the side thrusts placed upon them by a "four-footer." To make sturdy units, use 1-by-4-inch conduit hubs, centered within the rims. For each one, cut five ½ -inch spokes to length (from 7 to 7 1/8 inches long, depending on the rim). Lay the rim on a slab of plywood, mark its circumference, and then bore a hub-holding hole dead center. By using spacer blocks to lift the rim and spokes to the hub's midlevel, you can tack all of your parts in place first and can finish welding them when you're satisfied with the assembly.
As soon as the wheels are bolted on the axle shafts (short lengths of vacuum-cleaner hose make nice grease covers to fit over the axles between the hubs and the housings), you can complete the pumper by fastening the seat boards and the connecting rod in place. To keep the driving force aligned along the axis of the cart, the ½ -by-29 ½ -inch rod has a small offset in it about 4 inches from the crank (rear) end. A 1-inch-long piece of ½ -inch conduit welded to the end of the connecting rod serves as a wrist sleeve through which the driving mechanism can be bolted to the crank throw. At the front end of the rod, a ½ -inch nut allows for the installation (and adjustment) of an eyebolt, or — if you have expensive tastes — a Heim joint.
With everything welded, bolted and screwed in position, you can paint your Irish Mail cart chariot. The final step can be tricky: trying to keep the children off this four-wheeler until the paint dries!