caution - Toro

Mow Circuit Cutting Deck Blade Braking
When the operator turns the PTO switch OFF or if a deck
is raised with the PTO switch ON, deck control manifold
solenoid valve (S) is de--energized causing logic cartridge
(LC1) to shift (refer to information in PTO Mow Circuit
in this section). This shifted cartridge allows oil
return out manifold port P2. At the same time, solenoid
valve (S) in its neutral position prevents any sense line
flow through the spool which causes the logic cartridge
LC2 to shift to its neutral position blocking return flow
from the deck motor and slowing the cutting blades (Fig.
10).
DECK
MOTOR
DECK MANIFOLD
M1
RV2
LC2
M2
RV1
S
G
LC1
P1
P2
The inertia of the rotating cutting blades, however, effectively
turns the deck motor into a pump causing an increase
in pressure as the flow from the motor comes up
against the closed logic cartridge (LC2). When this pressure
builds to approximately 600 PSI (41 bar), relief
valve (RV2) opens which allows a small amount of hydraulic
flow to return to tank through a manifold sensing
line (Fig. 11). This flow causes a pressure increase that
shifts logic cartridge LC2 to once again allow oil flow
from the motor (Fig. 12). When motor return pressure
drops below 600 PSI (41 bar), relief valve (RV2) reseats
and causes LC2 to close again blocking return flow from
the deck motor to further slow the cutting blades. This
action of the brake relief valve opening and the logic cartridge
shifting occurs several times in a very short time
frame as the blades finally come to a stop. Once the
blades have stopped, logic cartridge LC2 remains in the
neutral position to keep the deck motor from rotating.
DECK
MOTOR
Figure 10
DECK MANIFOLD
M1
RV2 RV1
M2
LC2
CD
S
G
LC1
P1
P2
CD
Figure 11
DECK MANIFOLD
G
M1
RV2
RV1
P1
DECK
MOTOR
LC1
S
M2
LC2
P2
CD
Figure 12
Hydraulic System Page 4 - 20
Groundsmaster 4100--D