These carts generate lots of unnecessary heat from the fan circuit because the JD setup is silly. Our recent newsletter on our Smallaire Heat Exchangers for JD air drills describes JD battling the heat buildup by converting drills to run Power Beyond for the rockshaft downforce, but there’s a much easier fix, we recently discovered.
JD returns the fan hydraulics thru an SCV remote, which generates a ridiculous amount of heat (almost as much as the rockshaft circuit!). Nearly all the heat generated by the fan circuit can be eliminated by instead returning it into a high-volume low-pressure return, a.k.a. “motor return port” (this cuts backpressure from 300 psi to 50 psi, which is also better for the fan motor).
The following document spells out in great detail what this is, and where it’s located for various tractor models: http://www.greatplainsmfg.com/manuals/pdf/CDMR101209.pdf — scroll down a few pages.
[ Edit: late-model JD articulated 4WD tractors don’t have motor-return ports, but there is a low-pressure dump port below the rear of the cab — call or email us if you need a drawing of where this is. ]
Nearly all Aussie air cart manufacturers use this method of returning the fan oil thru a motor return port, as do most air drill mfgrs in North America. Our Smallaire rep in Australia has done this conversion to a JD 1910 cart, and it works great. Exapta’s hydraulic expert believes the JD setup was originally designed for convenience of connecting to the tractor as not all tractors have this extra port, although he concurs that their setup doesn’t make sense for the majority of situations. So, for the cost of a couple of hydraulic fittings, you can reduce the heat buildup on your JD air drill by 30 – 35%.
[ Edit: If you have a JD tractor with ‘High-Flow’ hydraulic capacity, there’s another trick to dramatically cut heat. These tractors actually have 2 hydraulic pumps, which serve different SCVs (one pump serves SCVs 1 & 2, the other serves SCVs 3 & 4). Hook up your drill so that the high-flow (e.g., the fan) is on a different pump than the high-pressure (e.g., rockshaft, UniForce). This will knock 20 – 30F off the temp, and sometimes provides more heat reduction than rerouting the fan return. ]
If your hydraulic oil still isn’t cool enough (aiming to be well under 185), our Smallaire Heat Exchanger will knock the temp down by another 30 F degrees. Oil coolers and heat exchangers are still very popular with owners of all the other air cart brands that are set up correctly on the fan return. Our Smallaire Heat Exchanger provides other benefits beyond merely cooling the oil — it greatly reduces gunk buildup (from moisture, fertilizer dust, and seed treatments) inside the drill’s air lines by warming the air. Flexi-coil has offered a similar setup for many years, and air drill owners who’ve installed them report far less gunk buildup in their air system compared to without the setup.
