Toro 4000-D 用户手册

Groundsmaster 4000--D/4010--D

Hydraulic System

Page 4 -- 20

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, PTO manifold sole-

noid valve (S) is de--energized causing bypass cartridge

(LC1) to shift (refer to information in Mow Circuit in this

section). This shifted cartridge allows oil return out man-

ifold port P2. At the same time, solenoid valve (S) in its

neutral position prevents any sense line flow through the

spool which causes the brake cartridge (LC2) to shift to

its neutral position blocking return flow from the deck

motor and slowing the cutting blades (Fig. 11).

The inertia of the rotating cutting blades, however, effec-

tively turns the deck motor into a pump causing an in-

crease in pressure as the flow from the motor comes up

against the closed brake cartridge (LC2). When this

pressure builds to approximately 600 PSI (41 bar), relief

valve (RV2) opens which allows a small amount of hy-

draulic flow to return to tank through a manifold sensing

line (Fig. 12). This flow causes a pressure increase that

shifts brake cartridge (LC2) to once again allow oil flow

from the motor (Fig. 13). When 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 brake cartridge

shifting occurs several times in a very short time frame

as the blades finally come to a stop. Once the blades

have stopped, brake cartridge LC2 remains in the neu-

tral position to keep the deck motor from rotating.

Figure 11

PTO

MANIFOLD

PUM

Figure 12

PTO

MANIFOLD

Figure 13

PTO

MANIFOLD

LOW