Mr. Rawles,
I’m interested in building a supplies carrier for moving larger loads over distances. Sort of a trailer for humans. I have nothing specific in mind other than using discarded solid wheels from wheelchairs. They are quite sturdy. I have access to discarded wheels at no cost. My questions involve use of materials – welded steel (heavy), aluminum (expensive and hard to scrounge), PVC (durability) and, of course, the size. Two wheels or four? Ideal dimensions? Do you have any suggestions or a reference that might be helpful? I realize there are many variables and the largest would be the terrain to be covered and the load carried. I’m just looking for ideas at this time. Thank you for your consideration of my question, and the wealth of information on your blog. – C.G.
JWR Replies: I generally prefer aluminum frames for utility carts. PVC is light, but prone to breakage. Aluminum tubing bends if overloaded, but PVC shatters. If you do some searching, you can often find random length aluminum tubing for near scrap metal prices. (Although, admittedly, even scrap metal prices are currently quite high.) One possibility is a “want to buy/want to trade” ad on your local Craig’s List web site. Another possibility is to contact custom bicycle frame makers in your area. They nearly all have an “oops pile” of pieces that were cut to the wrong length or that had a hole drilled in the wrong place. (You can cobble together various short sections with sleeves. Aluminum tubing can be glued with a product called JB Weld, available at auto parts stores.) Bike frame makers might also have an under-utilized pile of stock that has a diameter or wall thickness that they no longer use with their current designs. Who knows? When you call and ask about their extra tubing and mention what you have in mind, they might be captivated and offer to sell you some stock tubing at, or near, their replacement cost.
If using PVC water pipe, use at least Schedule 40 thickness. Unfortunately, to achieve the necessary strength, you will probably need 1-1/4 inch diameter Schedule 40 PVC, which is fairly expensive, as are 1-1/4″ sleeve and elbow fittings. In my experience, the highest stress point on the frame will be where the axle meets the frame. Do not drill the PVC tubing at that point. Instead, fabricate an angled axle mounting brace that will distribute the stress from the axle over a wider area on the PVC frame. Doing so will double the weight capacity of your cart. If using PVC, keep in mind that unless you drill holes in the framework, the hollow space inside the frame can do double duty for storing fluids, or as watertight storage for metal parts or rolled documents. So be clever, plan ahead, and use a threaded end cap at at least one point–preferably on the front of the frame, so you can tip the frame forward to pour out the contents. Conceivably, with the right fittings the framework could also be used to hold slightly compressed gasses, but perhaps it might be too tempting to transport something flammable or explosive.
For rough terrain and narrow trails, nothing beats a narrow two man cart design, (one two or three wheel) such as those used for deer hauling. For one man hauling, two wheeled carts configured like a garden cart (including foldable variants) are usually best, but these of course require trails at least the width of the wheel base. (Similar carts are used for deer hauling.) Another approach has been suggested for infantry troops (the Darby Cart). There are cargo and casualty stretcher variants. For the heaviest loads, a two man, four wheel cart is apropos.
As with my previously posted advice on wheelbarrows, I recommend foam filled tires for both garden and utility carts.