Great Plains NP3000A Operator Manual - Manual (Page 98)

94 NP3000 and NP3000A Table of Contents Index Great Plains Manufacturing, Inc.
407-613M Table of Contents Index 2014-04-22
Ground Drive: Setting Relief Valve
A relief valve is plumbed after the ground drive pump
outlet to protect the manifold and pump from excessive
pressure. Any product that activates the relief valve
discharges from the dump line
.
To set relief valve:
Refer to Figure 62
1.
Unlock plastic jam nut from relief valve knob .
2. Unscrew knob counter-clockwise until it loses
contact with internal spring.
3. Screw knob clockwise two turns. Start at this setting.
4. While operating in the field, observe manifold
gauge
, and watch for relief valve discharge .
5. If valve is dumping product and gauge reads under
65 psi, stop tractor and turn knob clockwise (looking
down)
1 ⁄
4
turn. Continue operating at normal field
speed. Repeat this step as needed until no product
is discharged from relief valve.
6. If pressure gauge reads above 65 psi, change to a
larger orifice. Go to step 2. Repeat steps.
Ground Drive: Set Pump Drive Range
Refer to Figure 63
Two Driving sprockets are provided for the pump:
Low Range: 15T
High Range: 47T
The choice of Driving sprocket depends on the
application rate desired. The pump adjuster dial (see
Figure 64
) must be in the range 2-to-10 for consistent
pump rate.
Use the rate chart on page 89 to determine which Range
to use for the rate desired.
For applicators with optional variable rate capability,
choose the sprocket which, at dial setting 10, provides a
rate higher than the maximum you intend to use. If Low
range suffices, use it for reduced pump wear.
To change Driving sprocket:
1. Loosen the bolt securing the rear idler . Slide the
idler forward. Lift the chain off the lower Driving
sprocket.
2. Remove pins at the storage and Driving shafts.
3. Exchange sprockets. Re-pin.
4. Re-engage idler for slack of 3 ⁄
8
inches (9 mm) in the
longest chain span .
Figure 62
Fertilizer Relief Valve
31729
L25
L26
L24
2
3
{
L25
L26
2 3
L24 L26
Figure 63
Pump Range Sprockets
31656
5
3
4 1
2
6
1
2
3
4 5
6