Service Manual

Groundsmaster 4500--D/4700--DHydraulic System (Rev. A) Page 4 -- 16
Cutting Deck Blade Braking
When the operator turns the cutting decks OFF, propor-
tional relief valve (PRV) shift occurs in the deck control
manifold (Fig. 15). This shifted valve allows oil return to
the oil cooler and gear pump. Hydraulic pressure is re-
duced to the cutting deck motors which begins to slow
the cutting blades and also allows the manifold relief
valve(RV)toshift.
The inertia of the rotating cutting blades increases pres-
sure of the oil return to the deck control manifold. This
pressure increase along with the orifice in the manifold
and the shifted relief valve (RV) cause logic cartridge
(LC1) to shift (Fig. 16). The oil from the deck motors is
finally directed through the orifice and to relief valve (RV)
which bleeds the residual pressure in the circuit and al-
lows the blades to stop in a controlled manner (Fig. 17).
Figure 15
TO OIL
FROM
TO DECK
FROM
COOLER
GEAR
PUMP
DECK
MOTORS
MOTORS
ORIFICE
Figure 16
TO DECK
FROM
DECK
MOTORS
MOTORS
TO OIL
FROM
COOLER
GEAR
PUMP
ORIFICE
Figure 17
TO OIL
FROM
TO DECK
FROM
COOLER
GEAR
PUMP
DECK
MOTORS
MOTORS
ORIFICE