Jim - 12/29/2009 21:22 I don't want to get involved in an online debate/beauty/pissing contest. However: tried dawn, did not like them to heavy. then put thompson wheel very good did not bounce like the factory wheel because the factory wheel is to heavy and cause compaction does not make sense to me. "did not bounce like the factory wheel because the factory wheel is too heavy" heavy things generally don't bounce as much as lighter things...??? The Dawn Curvetine II weighs approximately what the JD stock wheel does. Our
Dawn wheel differs in that it has teeth. The same weight as the OEM wheel is then focused on several teeth rather than a larger wedge in contact with the soil at any given time. These teeth "chip in" the seed slot sidewall created by the angled single disc opener on these drills. By concentrating the force on intermittent teeth the slot is alternately loosened, filled, and firmed. Sort of like planting beans in a garden. I take seeds out of a bowl and poke them into the ground for good seed to soil contact, then scoot loose soil in around it. These drills are used in a wide range of conditions basically ranging from potting soil to concrete. We have a broad continuous shoulder on the Curvetine II, just behind the teeth, to keep the teeth and wheel from going too deep in some conditions. With this combination of weight concentrated on curved teeth (which tend to extract themselves with minimal soil disturbance as they roll) and a broad continuous shoulder to act as a depth band and continuous closer is unique and patented. We find that in many conditions the Curvetine II can be run at much lower closing wheel arm spring tension settings than the standard wheel with its large continuous surface area. Running at lower arm spring pressure can logically reduce wear on the closing wheel arm bushings. As far as bearing location, we have different hub arrangements for the various generations of 750-1850 closing wheel arm designs. Most of our versions use Timken brand tapered roiller bearings and CR triple lip seal and are regreaseable. We just came out with a new version of our Supercap which has a lip protecting the zerk from rocks so the fitting can be left in Curvetine closers for those wanting to grease more frequently.... Here's a picture on a 750. Suggestion: try a couple row each of several designs and go with the one that works best in your conditions in Ohio.
Jim at Dawn Jim and "cajun": I think the OEM smooth cast wheel bounces so badly because it is smooth -- no teeth / spokes to engage the soil to dampen down the bouncing action. However, the heaviness of the JD wheel may be a contributing factor: Jim points out that heavy objects don't bounce as much as light ones, which is true for most objects -- however, what we have here is a weight on an arm that compresses a big torsion spring at the upper end when it bounces, and a soil surface (in no-till) that tends to cause objects to bounce off of it. So, once the bouncing motion begins (for instance, by a stalk catching the wheel/arm), it may be perpetuated or even accentuated by the spring as well as the soil properties. For instance, this is the reason that despite car/pickup wheels being fairly heavy, you need shocks as well as coil springs to help keep the wheel firmly on the road. But I don't have a PhD in physics or engineering . . . . Also, the bouncing action of any of these wheels occurs mostly at faster ground speeds -- e.g., over 6 or 7 mph. In any event, all reports that we've heard at Exapta is that the Thompson wheel bounces dramatically less than OEM smooth wheels or competitor spoked designs in side-by-side testing. Cajun -- Thanks for the kind words on the Thompson wheels! | 
750 drill rebuild and closer options
