Toro Groundsmaster 4500-D Series Service Manual page 138

Cutting Deck Blade Braking (continued)
Hydraulic System: Hydraulic Flow Diagrams
shift. The shifted relief valve removes the flow path from the orifice at the logic
cartridge, causing the logic cartridge to shift and block the return oil path from
the deck motors (Figure
The inertia of the rotating cutting blades, however, effectively turns the deck
motors into pumps causing an increase in pressure as the flow from the motors
comes up against the closed logic cartridge (LC). When this pressure builds to
approximately 104 bar (1500 PSI), the relief valve opens which allows a small
amount of hydraulic flow past the relief valve
pressure increase that shifts the logic cartridge to once again allow oil flow from
the deck motors (Figure
PSI), the relief valve re-seats and causes the logic cartridge to close again,
blocking return flow from the deck motors to further slow the cutting blades. This
action of the 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, the logic cartridge remains in the neutral position to
keep the deck motors from rotating.
52).
(Figure
54). When return pressure drops below 104 bar (1500
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53). This flow causes a
Groundsmaster ® 4500-D/4700-D
19245SL Rev A