GREAT PLAINS YP4425A, Operating Manual, Page: 45 / 170

YP4425A Table of Contents Index Operating Instructions 41
2018-07-30 Table of Contents Index 401-805M
Air System Overview
The hydraulic fan supplies air for both seed delivery
and meter operation. Fan rpm is operator-adjusted
(page 43) via the tractor’s hydraulic flow control, and
reported by the seed monitor system. The rest of the
system is fully automatic.
At the split air manifold , a rotary actuator operates
a vane, under the control of software in the WSMT ,
which regulates the air diverted to the meter
pressurization system
.
Air not used for metering (typically just under half of it)
flows to the air box
for bulk seed delivery. Air pressure
in the seed delivery system is not presently reported.
The meter pressurization air has priority, and can take all
the air.
Several rows have lines to sample metering air
pressure, which is measured in a sensor chamber .
The sensor reading is fed back to the WSMT for
closed-loop pressure control. No operator adjustment is
required for the metering air system.
At the air box , air is mixed with seed from the bulk
hopper or PROBOX
®
, and flows out air box manifold
ports into primary seed hoses to the rows. Y-tubes
(not shown) may split primary hoses into secondary
hoses to rows.
An air release screen above each Air-Pro
®
meter
vents the delivery air. The vent has two functions:
1. It releases delivery air while retaining the delivered
seeds.
2. It is a passive control gate for bulk seed delivery.

It takes about a minute to initially fill the meters.
Separate pressurization tubes provide the air to the
meters that holds the seed in disc cells until released to
the seed tubes
.
A detector in each seed tube reports seed passage to
the seed monitor system, which reports counts and rates
on the console
.
There are console menus for adjustment of metering air, and
manual fall-back modes.
1
2 3
4
5
In the case of insufficient fan air, or significant seed delivery air
leaks, seed flow may be irregular or stop.
6
Meter Pressurization is displayed by a mechanical gauge, and
by sensors connected to the seed monitor system. As these
sensors measure pressure at similar locations, they generally
agree.
7
8
9
If seed delivery air flow is insufficient, the indication will be low
seed rate alarms. If fan speed and direction are as
recommended, check for air leaks in the seed delivery system.
10
11
When the meter inlet is filled, and seed fills the tube above the
inlet, the screen becomes blocked by seed, shutting off air flow
to that meter. As the meter consumes seed, the screen
becomes exposed, air resumes flowing, carrying more seed
from the air box manifold to the meter.
12 13
Several rows have pressure sensor ports for the meter
pressurization system.
14
15
16