#ExactApply
Assessment: Thoughts on ExactApply Auto Select (PWM Version)
The classic (non-PWM) Auto Select on ExactApply works like a conventional three-tiered system (3TS): it switches between A only, B only, or A+B based on pressure/flow changes as speed varies—essentially the same as any pressure-regulated automatic nozzle switching setup.
In non-PWM mode, for our typical broadacre rates of 80–100 L/ha, I see no real advantage over a well-optimised fixed pulsing setup (A only, B only, or A+B manual). Duty Cycle (DC) alone handles speed variations efficiently, keeping droplet size and pattern consistent at constant pressure. When rates or spray qualities need changing, a quick console switch does the job—no need for auto-switching.
John Deere's more recent PWM-enabled Auto Select Pulsing is a step forward: it allows automatic nozzle switching (A, B, A+B) while pulsing stays active (constant pressure), and the algorithm factors in Duty Cycle alongside speed/flow demand to optimise performance.
What advantages does this offer in practice?
The starting point for any 3TS/AutoSelect nozzle selection is the same: choose a pair that comfortably delivers your maximum rate at maximum speed without excessive DC.
Example: For 100 L/ha at 25 km/h on ExactApply, you'd need an effective 06 equivalent in A+B (e.g., ~3.5 bar at 80% DC). That often means an 02 + 04 combo as your only realistic pairing for Auto Select (to enable both on at peak demand).
The 02 alone is practically useless at your rates—it's too small and would rarely engage.
The 04 alone maxes out around 60 L/ha (3 bar, ~78% DC) or pushes to ~70 L/ha at 91% DC—still short for your common 80–90 L/ha work.
Result: For the majority of applications (80–90 L/ha), the system ends up frequently re-engaging the 02 (the smaller nozzle) to meet demand. That forces the nozzle pair into a suboptimal lower Duty Cycle.
Given that high-rate work dominates most broadacre jobs, Auto Select Pulsing isn't as efficient as sizing a dedicated fixed combo (e.g., matched 04s or 03s in A+B for V30 Hz pulsing) or a single larger nozzle. You get cleaner, more consistent operation with fewer unnecessary switches and better average DC across the board.
In summary: The PWM Auto Select is a nice evolution for highly variable-rate jobs, Multi-Rate sections, or extreme speed swings—but for consistent 80–100 L/ha broadacre spraying, a manual pulsing setup with optimised fixed nozzles usually wins on simplicity, reliability, and real-world performance.
Regards - Dave
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