Service Manual

Topdresser 1800 & 2500 Hydraulic SystemPage 3 – 13
Topdresser 2500 Operation: Switch On
While being towed in the forward direction with the Top-
dresser control handle switch in the ON position, the
wheel motors act as pumps to provide hydraulic flow for
the system. Flow from the wheel motors is directed to
the control manifold (through two ports A1). Energized
solenoid cartridge valve (S1) diverts flow from the man-
ifold (out port M1) to the brush motor and then to the con-
veyor motor.
Hydraulic flow causes rotation of both the brush motor
and the conveyor motor which are connected in series.
The brush is driven directly by the hydraulic brush motor.
The conveyor belt is driven by the hydraulic conveyor
motor with a chain reduction. Operating pressure is lim-
ited by the system relief valve (R1) located in the control
manifold.
Flow from the conveyor motor is directed to the charge
motor/pump assembly causing the charge motor to ro-
tate. The charge motor rotation in turn rotates the
charge pump which provides charge flow to fill the hy-
draulic system to the wheel motors. Charge pressure is
limited by the charge relief valve (R2) located in the con-
trol manifold.
Because hydraulic flow is developed by the wheel mo-
tors, the hydraulic system automatically compensates
for changes in ground speed to produce even applica-
tion rates even though ground speed fluctuations may
occur.
An optional brake kit is available for the Topdresser 2500
that uses a solenoid cartridge valve (S2) to cause hy-
draulic flow to bypass the brush and conveyor motors
when the brakes are applied. Oil flow is directed to the
main relief valve causing a pressure increase to slow the
wheel motors and, therefore, the machine when brak-
ing.
Hydraulic
System