Cub Cadet 8354 Service Manual page 244

CHAPTER 9 8354/8404
B. Delivery Phase
(1) Control Spool
(2) Regulator Piston
(3) Check Valve
(6) Fixed Throat
(7) Safety Valve
(15) Chamber
(17) Hole
During this phase the control valve supplies the oil on
pressure to the cylinder and it consequently lifts the
arms.
The control spool (1) is in such a position to connect
the chamber (15) with the oil coming from the pump
through the annular duct (19) and holes (20) and (21).
In this way, chambers (15) and (22) have the same
pressure and the small regulator piston (2) closes dis-
charge holes (17) due to the upward push of return
spring.
The oil on pressure flows to the cylinder through the
annular duct (19), it enters the hole (20) through the
fixed throat (6) and the variable throat made by the con-
trol spool (1) with the hole (21), it opens the check
valve (3), it enters in annular duct (18) and flows into
the cylinder chamber (23).
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(18) Annular Duct
(19) Annular Duct
(20) Hole
(21) Hole
(22) Chamber
(23) Cylinder Chamber
The small regulator piston (2) adjusts the oil flow to
the cylinders because chambers (15) and (22) are sub-
ject to the difference of pressure made by the oil pas-
sage through the fixed throat (6) and the variable throat
made by the control spool (1). Depending on its up-
ward movement caused by the internal levers of power
lift.
The excessive flow is deviated at the lifting pressure by
holes (17), in this way it regulates the maximum lifting
speed and allows a slow starting and arrival of arms.
In this phase the maximum lifting pressure is controlled
by the safety valve (7) that is connected to the annular
duct (19) through holes (20) and (21).
615W912A
D615-W02 May-2003