Lawn Seeder/Fertilizer-Electric Ground Drive Conversion

[npalen]

The attached shows a Gandy seeder with 12 VDC drive for the seed metering. I wonder how accurate this type of seeding would be given that it would be difficult to maintain a ground speed consistent with the seeding rate dictated by the constant speed electric drive for the seeding rate metering.

Given that many compact utility tractors are hydrostat drive, would it be reasonable to think that a variable speed DC drive controlling the motor on this type of seeder could be matched to ground speed using a potentiometer connected to the pivot of the hydrostat pedal?

I realize that a metering system of this type would have to be calibrated like any other, but the ground speed of a hydrostat in a given gear range would seem to be fairly consistent/repeatable to pedal position assuming that the engine RPM is enough that the ground speed is consistent.

Would enjoy hearing input from you guys as I've often wondered if there could be a more accurate way for homeowners/landscapers to drop seed and fertilizer consistent with ground speed rather than relying on gravity drop for example. It would seem, from a cost versus performance standpoint, that an electric drive synchronized with ground speed could be very competitive in lieu of chains, sprockets etc.

 

[npalen]

https://www.amazon.com/tatoko-Controller-Forward-Brake-Reverse-Ajustable-Potentiometer/dp/B07Y73MN5R/ref=sxin_16_pa_sp_search_thematic_sspa?content-id=amzn1.sym.b245e49f-68a4-4489-b1f9-81f4034255f5%3Aamzn1.sym.b245e49f-68a4-4489-b1f9-81f4034255f5&cv_ct_cx=12v+dc+motor+controller&keywords=12v+dc+motor+controller&pd_rd_i=B07Y73MN5R&pd_rd_r=7a284c4f-2fc7-4fa7-8056-e54a2bfea485&pd_rd_w=z05JY&pd_rd_wg=7J6qV&pf_rd_p=b245e49f-68a4-4489-b1f9-81f4034255f5&pf_rd_r=CMAT3XVVJN00RQSWN843&qid=1657751255&sr=1-1-a73d1c8c-2fd2-4f19-aa41-2df022bcb241-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExUFoxVzYzMjBJWDVXJmVuY3J5cHRlZElkPUEwNzMwMDQyMjdKVTBaS0xQVVBVVyZlbmNyeXB0ZWRBZElkPUEwNzkwMTY4N0JMSEpHVkNSSjFCJndpZGdldE5hbWU9c3Bfc2VhcmNoX3RoZW1hdGljJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

This is a simplified example of a controller to vary the speed of the seed metering via the 12 VDC motor. The pot shown would be controlled by the hydrostat pedal. The trick, as I see it, would be to proportionately synchronize the meter speed with the ground speed resulting from the hydrostat position.

Edit: A second pot that would function to set the seeding rate would be required. Running a seed rate calibration test would also be required just as with a ground drive metering system.

Edit II: Just talking to myself here so far but hopefully some of you electronics gurus will weigh in. I realize that the relationship between the groundspeed, whether gear or hydrostat controlled, will need to be linear or 1:1 with the "throttle setting" to get consistent metering That would be less important if the ground speed is consistent and similar to when calibrating.

I feel that controlled metering is important when applying lawn and sports field fertilizer also. Most lawn broadcast spreaders using their on/off flow gate are crude applicators at best considering that ground speed can vary greatly stopping and starting, going around obstacles etc. Slowing ground speed suddenly ups the rate and the slowing spinner deposits that higher rate on a smaller width!

 

[npalen]

This thread must have bad breath! Actually probably a bit wordy which tends to discourage readers.
I don't mind talking to myself but a bit worrisome when I start answering myself.

 

[dieselscout80]

Would it be easier to use a wheel on the seeder with a sensor for the speed and therefore self-contain the speed control system on the seeder.

 

[npalen]

Would it be easier to use a wheel on the seeder with a sensor for the speed and therefore self-contain the speed control system on the seeder.

That would be another approach that has some merit. Someone might say, however, just as well drive the metering shaft off the wheel chain drive as normal.

Another thought regarding the original idea above would be to also control the "gate" setting "on the fly" with a servo actuator. Most ground driven seed/fertilizer metering systems utilize both metering shaft RPM as well as the gate setting to control the rate.

I'm suggesting that a metering system could utilize a constant speed drive on the metering shaft as well as the servo controlled gate all electric driven with the hydrostat pedal or throttle position as the input. Both would be de-energized when the tractor comes to a stop.

I'm really not trying to find a solution to a nonexistent problem, here, even though it may seem that way. Just trying to think "out of the box" a little.