FOUR-WHEEL FUN

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To form the seat-back frame, bend both a 30 1/2" and a 35" conduit section into the shapes indicated, then weld the wider piece to the upper surface of the frame rails (1" forward of the crossmember) at an angle of 60°. The narrow hoop mounts atop that at an 85° bias to the chassis. Then the seatback strut, along with the 4 1/2" 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 1/2" pipe coupling welded to each half of a longitudinally split section of 11/4," EMT, then capped at each end with 1 1/2" to 3/4" pipe bushings. The threads within the center hole in each reducer must be filed out if it's to accept the shank of a 3/4" nipple.

The handle is nothing more than a section of 1" conduit equipped with 3/4" X 14" upper grip bar and a 1" X 7" pivot shaft-at the lower end-made from a scrap of mechanical tubing (this piece can be replaced with a length of 4 3/4," pipe if you don't mind filing its outer surface a bit). A 3/16" X 1 1/2" X 7" hunk of flat metal welded perpendicularly to the midpoint of the pinion functions as the drive lever, and the 1" shaft rides inside a pair of 1" X 2 1/4," 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" piece of 1/2" EMT, then a 2 1/2" washer and3/4" X 3 3/4" pipe nipple combination to the center of, and perpendicular to, the 1" X 30" conduit axle. A 27" length of 1/4," 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" stretch of 3/4" conduit run through the housing. The front wheel hubs ride on the shaft and are held in place with 1/4" bolts pinned through the tube's ends.

To attach the front assembly to the steering hub, just slip the 3/4" pipe center pivot through the two bushings in the coupling and lock it in place with a large washer and 3/4" pipe cap.

The drive and brake mechanisms also work on a sleeve-within-a-sleeve principle. The 3/4" X 17 1/2" drive axle shaft utilizes a 3/16'' X 1 1/2" X 5" flat metal crank throw (a 2 1/2" washer, welded in place 1" from that bar, makes a good walk stop). The braked (right side) wheel is fastened to a 3/4" shaft that houses-and is bolted to-a 1/2" X 17 1/2" pipe, which is then connected to a 5 1/2" 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.

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