I get a lot of people asking me why the cart was designed so that the wheels protrude slightly above the bed of the cart; “Wouldn’t it allow more space for the bed of the cart if it were above the wheels?”
Another question I get, not quite as frequently, is “doesn’t the bed need to be bolted down?” Today I got a question something like that, but also asking why I use plywood instead of expanded metal permanently welded in place.
These are both good questions and design changes that you might decide to make. Below is my response, as well as a few ideas for folks who are farming on slopes, or who need to go up (and especially down) steeper sections.
The platform is at the level that it is at because it is just below the height that a deep harvest tote typically hangs from a harvester’s hands when they carry it. This makes the cart easier to load, even though you have to deal with the wheel. In my experience it hasn’t been a problem. Using 20” wheels on the same platform will ride below the platform and only drop the cart 3″, or you could extend the forks if you want which would raise the bed about 4″. The higher the platform, the harder it is to load, and the less stable it is on hills, but the more clearance you have to roll over plants.
The platform is removable because we use it for more than just a cart, it’s also used with a different attachment to mark beds, and I have other attachments I’m wanting to develop for it that would make it a more modular tool. It’s also easier to store without the top on, and we make different tops for different uses sometimes (harvest, vs. toting compost etc.). Plywood, even untreated, has lasted for years with no problems for us, although we do store the cart out of the rain when not in use. Storing in the rain is harder on the wheel bearings than the plywood. It’s cheap, light, and easy to work with. It also doesn’t sag like expanded metal and it has soft edges and doesn’t wear on the harvest totes. There are some expanded metals that might be good, or some applications it might be better for. Also, note that the plywood extends beyond the front and back of the frame overhanging a little on either end.
Two other things you might consider on a farm with significant hills. With hills, going down with a load can be a little tricky with heavy carts. You can use the legs as a kind of friction brake, but it’s not the best. Worksman Cycles sells very heavy duty bicycle wheels that also have drum brakes. You’d need to figure out a way to hook up the brake arm and cable and to mount a brake lever but I don’t think it would be too difficult (I have plans to do this at some point). Also, at Skyline Farm, where one of the early carts has been in service for about 7 years now, they’ve found that the cleat isn’t enough for them to keep bins from sliding off the sides on some of their slopes so they’ve added short sides to the cart platform. The bed still simply lifts off the frame so the frame can be used with the bed marker as well, but essentially the cleats on the sides are a little higher. Again, this makes it harder to load but they like this modification in their conditions.
On relatively flat ground I really like having low cleats and almost never have totes slide off. The exception is when a tote isn’t placed right up against the cleat and it slips while the cart is moving with enough momentum to tip over the cleat (or if it’s sloppily placed on top of the cleat). The cleats I use are only about 1″ high.
I also want share some comments from Jeff Benton who built one of these carts a few years ago and made some modifications. It’s fun to see how people are modifying these and making little additions or subtractions. Here are Jeff’s thoughts:
Overall, the cart has been great and been very heavily used.
- Asymmetry: Since the bike tires I had (and the one’s I’m likely to get in the future) were from one bike, I decided to accommodate a front and back wheel (spaced wider for the cassette) instead of two front wheels. This just means that the width of one of the forks is about 1.25 inches wider. Pretty subtle change.
- Instead of keeping the frame supporting the plywood flat, I stacked the right and left side on top of the front and back supports. My goal was to eliminate the need for wooden supports underneath the plywood platform while also creating a lip on the top side to prevent crates from sliding into the tires. What I didn’t realize was how much more pressure that put on the plywood with supports only on two sides. Also, the side lip isn’t very big since the steel is not too much thicker than the plywood base. I think I would eliminate this variation on the next model.
- Wire Basket: I took some of the thick metal wire from some old political sign supports to make a basket in some of the dead space. I attached it to the outside of the frame so that no one gets cut by sharp edges when reaching in. I find this is a very helpful addition for carrying various things out to the field that otherwise my be clumsy like water bottles, hand-tools, rubberbands, gloves, etc. I feel it also gives those items a much better chance of making it back from the fields at the end of the day.
- Additional Plywood Toward Handle: This removable piece is great for getting about 3 more transplant trays per load. It does make the load heavier since the weight isn’t over the wheels, but for transplant trays, that’s usually not a big issue.
- Rolling Dibble Maker: I took your idea for the row marker and tried to add dibble too it using some of the scrap steel from the frame. It doesn’t seem to work very well. My intention was to be able to roll it down bed covered in black plastic to punch whole for 3 rows at a staggered 12″ spacing. But I made the dibbles too long and they don’t penetrate all the way down, so my spacing ends up being closer to 17″. An easy fix, but then I took a step back and realized how few beds are actually 3 rows at 12″, so I decided to not pursue this any further for now.
The biggest limitation of the cart design that I’ve come across is in the ability to add things to it. As I’ve started trying to work out ways of attaching things like a second platform or taller side walls, I feel like my options are pretty limited. I think there is a lot of opportunity in the spaces on the sides, occupied partially by the wheels and in my case a wire basket, to creating some placeholders for more accessories. I’ve included an image in the album to show you what I mean. I haven’t sat down and really designed it yet, but I think that will be one of the first big edits I do next winter.
You can see photos of Jeff’s cart on his picasa album
Two responses to Jeff’s ideas: one is that using a rear bicycle wheel on one side opens up some interesting possibilities for a kind of PTO (power take off) and maybe ground driving something like a spreader. I’ve gotten the comment about things being hard to attach a number of times. Building it with something like Telespar might be a solution (although it’s heavier and more expensive). I don’t find it a problem as I’m fine with just clamping things over the square tube, either with square u-bolts or even just making brackets that slip over the square tube and friction fit or hang on by gravity. So far attachment I’ve made has just used a bracket that allows the attachment to just drop onto the square tube and then be lifted off, no tools needed. I kind of think of the frame of the cart a bit like tool bars on a cultivating tractor so at some point I’ll probably have some attachments that require pins to hold them in place as well.