Filter
Top Products
Rev. B
Groundsmaster 3505--D Hydraulic SystemPage 4 -- 11
Cutting Unit Circuit
Mow
A two sectiongear pumpis directlycoupled to thethe hy-
drostat which is driven by the engine. Gear pump sec-
tion (P1) supplies o il flow to the cutting unit circuit
through the manifold block and to the cutting unit mo-
tors.
Solenoid v alve (R1) in the manifold block is de--ener-
gized when either the PTO switch is in DISENGAGE or
the transport/mow slide is in TRANSPORT. When de--
energized, solenoid valve (R1) by--passes flow from the
cutting unit motors. Flow returnsto gear pump (P1) inlet.
Solenoid valve (R1) is energized when the PTO switch
is in ENGAGE and the transport/mow slide is in MOW.
When energized, solenoid valve (R1) allows gear pump
(P1) flow out manifold block port M1 to the cutting unit
motors. When solenoid valve (R1) is energized, brake
relief cartridge (BV) is shifted (opens) to allow oil return
from the cutting unit motors.
Oil flows through the left, right and then rear cutting unit
motors as it turns the motors. The oil then returns
through manifold block port (M2), the oil cooler, the oil
filter and to gear pump (P1) inlet.
If cutting unit circuit pressure exceeds relief pressure of
3200 PSI (221 bar), solenoid valve (R1) shifts to allow
circuit pressure relief.
Cutting Unit Blade Braking
When the solenoid valve (R1) is de--energized as the
PTO switch is DISENGAGED, brake relief cartridge
(BV) shifts to its closed position, blocking return flow
from the deck motors and slowing the cutting blades
The inertia ofthe rotating cutting blades,however, effec-
tively turns the deck motors into pumps causing an in-
crease in pressure as the flow from the motors comes
up against the closed brake relief cartridge (BV). When
this pressure builds to approximately 1500 PSI (103
bar), brake relief cartridge (BV) opens which allows hy-
draulic flow to return to tank and reduces return pres-
sure. When return pressure drops below 1500 PSI (103
bar), brake relief cartridge (BV) reseats to further slow
the cutting blades. This action repeats several times in
a very short time frame as the blades finally come to a
stop. Once the blades have stopped, brake relief car-
tridge (BV) remains seated to keep the deck motors
from rotating.
Hydraulic
System