When your safety and the safety of others is at stake, you need to use the right part for the right job, with no substitutions. Nowhere is this more apparent than when towing large pieces of equipment from here to there. If you think common bolts can serve as replacements for clevis pins, then you could be dangerously mistaken.
Clevis pins are specific fasteners that allow motion in one direction while limiting it in other. The parts of a clevis pin assembly are the tang, the clevis pin, and a cotter pin. The tang is a horseshoe shaped piece of metal with holes drilled in the “arms” to accept the clevis pin, which is then locked in place by the cotter pin. To visualize this, think of the front of your bicycle frame. The frame is the tang, and the clevis pin is the axle passing through both arms. This allows your wheel to move in one direction, around the axis of the clevis pin (axle). You can steer, but only by moving the entire assembly.
While clevis pins may look like carriage bolts or even regular bolts, there are a few crucial differences. First and most significant, the clevis pins have cross drilled holes on the opposite end of the head. Cotter pins slide through these holes and lock in, so that the assembly can remain intact. Second, unlike regular bolts and other threaded rods, clevis pins are smooth all along their usable length (the part between the arms of the tang). You may be able to smooth down bolt threads with a deburring tool, but you will never achieve the uniform and useful smoothness of a true clevis pin. And third, clevis pins are manufactured to withstand shearing forces, unlike bolts, which are only designed to handle tension loads.
Substituting a regular bolt for a clevis pin when towing a large piece of equipment is a recipe for disaster. A clevis pin assembly is machined as a set, with a precision fitting pin. Even if you have a bolt that fits perfectly the first time, the threads will quickly wear away and loosen the fit. So without the means to secure the bolt, as a cotter pin does with a clevis pin, the bolt could easily work upwards and disengage. Securing the bolt with a nut on the bottom will be of little help, since the rotational force of the hitch during turns will work the nut loose before you make your second turn. And that all assumes that the bolt does not simply snap from the shear forces applied to it.
Never compromise when it comes to safety. In addition to preventing injury and death, the right part for the right job will also make the job more efficient, more reliable, and much easier to finish.