Self propelled Sprayers

[Update: 12/3/14]-- The new location for the auto boom height sensors is a success.  There are limitations that were mentioned below.  We have been able to spray at 9-11mph without problem.  You just have to be ready to react when the rare situation presents itself.  The 275hp engine is adequate  with 1500gal load in our hills at 5-7mph; however, above that speed you can have issues.  The system safety sensors kick the transmission into neutral when over loaded.  Not nifty when climbing a 40% slope -- so, be aware of your terrain and how you approach it.  We have noticed that the transmission is finicky.  It goes to neutral if it senses a jerk or overload, and maybe other things.  We have less issues as we become familiar with the machine.  I run in cruise control all the time, including roading.  The system isn't tolerant of throttle hopping.  The cab is quiet at 1800rpm; however, in the hills, we need to keep the engine at 2000-2200rpm for the power --the fan for cooling the engine and hydraulics is a roar at high engine rpm.
[5/24/14 update:]-- Life on the sprayer has become more boring with less to do -- but we are doing a better job with less damage to crop and machine.  In the past, we placed the autoboom sensors at the joint where the outer wing boom flips over.  The center section has been lower than the wings giving a shallow [V] look from the front or back of the machine.  We have been using the manual outer wing switches to lift the outer boom to avoid ground strikes when transitioning from one slope to another.  Even in the "down" position the end boom of either wing seems seldom at the right height.    We got a lot of boom flare up as we traverse the ground. As the boom height is adjusted through the sensor it is magnified at the end of the boom (20+ feet farther out).  This has caused damage to neighboring crops, and in general doesn't look good spraying product and having the ends frequently 8-12 feet off the ground instead of 24-30".  The tall 40" stubble has worsened the situation since the sensors reflect from that material.  We have noticed some flop as the sensors pass from tall stubble into a wheel track.   We have changed this arrangement and I think we will like it.   
       The new autoboom arrangement:  a)--The center section has been lifted and blocked at 38" instead of  the original 28".  The blocks are for stability of the boom.   b)--the sensors have been moved out near the end of the wings.  Only two nozzles are beyond the sensors.  Those sensors are now normally set at 24-28" height instead of the earlier 32-35"height.  This has eliminated the need for manually controlling the outer boom to prevent ground strikes.  We have greatly reduced the wing flareups.  We can better judge the end of the boom  along a fence where the guidance system is inoperative.  The look from front or rear is a shallow inverted [V].  It looks better from the point of misting.  There is less need for watching and correcting height to prevent boom strikes.  We do go to the screen more frequently and adjust the sensor height.  I have run it as low as 16".  Two down sides to this arrangement:  1-- the hydraulics won't keep up with significant terrain change above 6mph., and 2-- if you need to manually control a wing, the auto boom has to be disabled on that side.   This normally only comes into play when you run the end of the boom (where the sensor is located) out into space over a near vertical bank.   
        We have a full year of experience now with this unit.  It is a great machine.  We like the capacity(100ac @ 15gpa).  We like the mobility (at 12' width we can move on the road without much concern, and we can go some distance for reload).  It's stable beyond any slope we will ever farm.  Our spray pack is an 02 model at 90'.  It has the rectangular box center frame instead of the newer parallel link center frame.  I think the parallel links are not as stable or as strong, and will likely be more prone to damage than the box frame in our hills.  I like the 90' boom.  We get good production, and now, with the new autoboom setup.  I think it will move around the field better with less trouble, and do a better job than the 120' booms that are making an appearance.  

[7/22/13 update:]-- We have divided the 90' boom into 9 sections with 4, 6, or 7 nozzles each.  This is better.  Even at 7 nozzles, the boom length is only 11.6 feet, so we can pick up small strips going down the center line on the GPS screen -- a lot easier than trying to guess on the screen where the end of your boom is situated.
     While spraying out a CRP field we noticed that going one direction we left a 4 foot skip in places on our hill sides.  Going the other direction we left no skip.  It turns out that we need to zero out our tilt correction that is part of the smart-steer system.  Without Smart-steer we watched the screen and tried to keep a 5-7' overlap with a setting of 100% boom width.  We had few skips and they showed accurately on the coverage map following an application.  With smart-steer I notice that it tries to keep the overlap 0.2-0.6 feet.  At this point in time the coverage map is not accurate.  When you go back to spray out the visible skips they don't show up on the application map.   It's obvious we need to adjust some settings so skips show accurately.
      Our overlap settings currently are as follows:  We have shortened up our 90' boom 20" (one nozzle), and left no overlap settings for the individual booms.  This evening I started the system up and hopefully corrected the tilt.  To do that I tapped the steering symbol on the Viper and tapped through the screens to the 3D screen and followed the directions for adjusting the tilt.

[5/21/13 update]-- We have 1000 acres sprayed with the GVM.  This is an impressive machine.  The smart-steer is responsive and holds the line very well.  The auto-boom holds the spray boom stable at the desired height.  We have 8 years experience with accu-boom (auto sectional on/off) and love it.   Although the GVM  is better than I ever imagined,  it currently has more overrun than our 100' pull sprayer with it's 7 sections controled by accu-boom.  We need to divide our current five section 90' boom into 7, at least, or maybe 9 sections.  The greatest return for the precision buck is accu-boom.  Hopefully the smart-steer will help a little to reduce overrun.  

[5/13/13 update]-- We have changed the wing cylinder lift point to give significant additional lift.  A test run through one of our sharpest "V" shaped draws indicates that we should not have any ground strikes with the sensor controlled inner portion of the wing.  The outer wing portion will need tending and that is OK.  There is no reason to grip the joy stick; so, the operators fingers can rest comfortably over the outer wing control switches on the console for quick reaction to slope change.  Monitoring, lifting, and lowering the outer wings will become second nature with a little experience.
      We have changed the fence-row tip to a TOC80 high volume tip giving an additional 30' of reach.  This tip operated at 40psi, traveling 5mph, closely matches the turbo twinjet 04's (red) on the booms at 24-25gpa.  This tip, along with the suspended boom, allows us to extend out over non-crop areas farther than in the past.  If we find that we actually need a fence row tip, we will modify the bracket too accommodate both the TOC80 and a smaller turbo twinjet 04 tip, or an 02.5 tip.

   [5/5/13]-- Past observations and concerns: --- There are several self propelled sprayer manufacturers to choose from, and more coming into the market.  --It may be a challenge to get a good job from self propelled sprayers.  A consistent height appears difficult to achieve.  Every spray job I have observed showed frequent ground strikes, and booms 6-10 feet off the ground.  --- The sprayers don't maintain a consistent speed.  They appear to be racing over the fields with booms a flopping.  ---By mounting skinny tires they do offer the potential to spray a fungicide late in the growing year as an alternative to an airplane. --- We have had five custom applications in the past 3yrs and I would classify all as failures:  three from not doing the job timely, one from a contaminated tank, and the last was from poor plant coverage.

      The decision was made to own one of these units.  The stripper header has made our pull sprayer obsolete, and the custom operators don't appear to be an option for us.  The question is -- can we find a unit we can afford.  Since we are not dealing with row crops and a mechanical drive is likely to work better in our hills than a hydraulically driven unit, a GVM Prowler is our preference.
        The Lord was with us on this project.  Although we did research GVM, self-propelled units are complex machines and there were questions we never thought of asking.  In the end, we have a late model, low hour machine with all the electronic gadgetry, for less than 25% new cost -- still a lot of money!   It all came together May 1st with our first field application.

Unit specifications:   2007 GVM chassie with a 6.7 Cummings engine developing 275hp, 10 speed Funk power shift transmission, front axle steer, four wheel drive with locking differentials.  The chassie came equipped as a combo-unit, meaning the wiring harness and hydraulic system was designed for either the spray kit or the spreader kit.  The chassie came with a 9.5 ton Fusion stainless steel two product spreader kit.  We purchased the spray kit separately. 

     The spray kit is a 2002, with a self cleaning 1500 gallon stainless steel tank, 90 foot booms equipped with nozzle bodies that have five ports, on 20" centers.  The solution pump is a hydraulically driven centrifugal that delivers up to 190gpm, and can be used to fill the tank without the aid of a transfer pump.  It also is equipped with a stainless steel inductor that allows you to introduce chemical into the system without any additional support equipment.

     The electronics include:  SmartTrax (auto-steer) by Raven, Auto-Boom (sonic height control for the 90' suspended boom) by Raven, Acu-Boom (GPS controlled on/off for a 5 section boom) by Raven, a single product node (product application rate control) by Raven, and cruise control (for maintaining a constant speed).   All control is done through a Raven Viper Pro touch screen monitor with mapping capability.

        Pic's above are from the first hour of product application.  AMAZING!!  We loaded up 1250 gals of product and started out.  All of the controls functioned as advertised.  At 7.5mph, the ride was comfortable, plenty of power for the hills, the booms stayed at the programed height and were steady (not flopping around).  The 12' width of the unit felt solid and stable on our slopes.  The back rack (which carries the booms) has no stabilizing cylinders, or shock absorbers that some of the newer units feature to control the boom flop when traversing uneven terrain at application speed.  The AutoBoom system mitigates much of the need for those features.  Field speed probably plays a major role as well.  Most of the units I have observed have been operating in the 12-15mph range when applying herbicides -- not the 7-8mph that we are currently doing.

        Most of my concerns about these self propelled, suspended boom spray units disappeared after the first day of spraying.  The only question left is the coverage?  That judgement will be left to the end of the season when we re-evaluate the system.  My early thought after watching the application on the first 500ac, is that it will be better than our pull sprayer --> more solution per acre, fewer tracks, less dust, more consistent speed.   We will do nearly all of our spraying at 12.5 gpm.  We have equipped the unit with 04 turbo-TeeJet (red) with duel spray pattern.  This looks like it will be the principal nozzle.  It's designed to operate in the range of 20-90 psi.  This gives us application rates ranging from 12.5-24.0 gpa.  We have also equipped the unit with 2.5 turbo-TeeJet (purple) duel pattern nozzles for our chem-fallow.  With these tips applying 12.5gpa, we will be traveling in the 4-6mph range for better dust control.   The unit came with two sets of air induction tips, one very fine droplet, and one very course droplet.  It's questionable whether we will use them.

     Adaptations to consider:  1--reposition the wing lift cylinder for more wing lift.  We do need to lift the wings to a greater angle for the transition between the flats and slopes in many areas of our fields.  2--possibly go from 5 to 9 boom sections for less product over-run???  3--put another AutoBoom node in to control height of the outer wing??--> we don't know it that is even possible at this time regardless of cost.  That would make this unit nearly independent from operator input as the unit follows along a line.

       This pic shows how we received the chassie with the Fusion stainless steel dry spreader box and the tinted glass from Tennessee last January.  Fortunately the glass tint was a film that came off easily.  We have not taken the time yet to check out the spreader.  It does have a two product node for GPS control through the Raven Viper Pro monitor.  It looks to be in excellent shape.  Once we find out it's condition, we will  probably offer it for sale since we currently don't have a use for it.