MAINTENANCE/SERVICE
66
Adjusting the Output Pressure of the
Spray Pump
The hydraulic centrifugal spray pump of the
MacDon sprayer has the capacity to output 150 psi
(1030 kPa) at normal operating engine speed. This
allows the sprayer to be used for a variety of
applications and with a variety of different nozzle
types. The plumbing system of the sprayer has
been designed to be used at these high pressures.
Adjust the output pressure of pump if the pressure
exceeds 150 psi (1030 kPa) or there is not enough
output pressure for the application. To adjust the
output pressure of the pump:
1. Locate the bypass adjusting screw on the side
of the hydraulic motor.
2. Start the engine. Allow the oil of the self-
propelled windrower hydraulics to be warmed
for approximately 10 to 15 minutes.
3. Add clean water to the tank. Prime the pump
and circulate water through the plumbing
system.
4. Adjust the reel speed control and conveyor
speed control dials to the optimum setting.
Increase the throttle to full engine speed.
5. Close the electric servo valve by depressing ‘-‘
on the MT-3405 rate controller for 30 seconds.
The rotary dial on the monitor must be pointed
to “FLOW RATE” to adjust the servo valve.
6. Close the agitation valve C. Close the valve to
the rinse nozzles if the sprayer is equipped.
Note the spray system pressure
7. Adjust the bypass screw by turning it
counterclockwise to decrease or clockwise to
increase the spray system pressure until the
maximum pressure is 150 psi (1030 kPa)
Spray Pump
Plumbing System
Bypass
Adjusting
Screw
A
B
C
