Toro 4100-D Mow Circuit Cutting Deck Blade Braking, Hydraulic System Groundsmaster 4100--D

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 car- tridge (LC1) to shift (refer to information in PTO Mow Cir- cuit 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).

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 logic cartridge (LC2). When this pres- sure 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. 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 car- tridge 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 MANIFOLD		G
M1	RV2	RV1	P1
DECK			LC1
MOTOR
			S
M2	LC2
			P2
			CD

Figure 10

	DECK MANIFOLD		G
M1	RV2	RV1	P1
			LC1
DECK
MOTOR
			S
M2	LC2
			P2
			CD

Figure 11

	DECK MANIFOLD		G
M1	RV2	RV1	P1
DECK			LC1
MOTOR
			S
M2	LC2
			P2
			CD

Figure 12

Hydraulic System Page 4 -- 20 Groundsmaster 4100--D