Cub Cadet 8454 - Manual (Page 208)

CHAPTER 6 8454
6-14 D569-W02 May-2003
b. Delivery Phase
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 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) close 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).
The small regulator piston (2) adjust the oil flow to the
cylinder because chambers (15) and (22) are subject
to the difference of pressure made by the oil passage
through the fixed throat (6) and the variable throat made
by the control spool (1), depending on its upward move-
ment caused by he 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).
569W611A
(1) Control Spool
(2) Regulator Piston
(3) Check Valve
(6) Fixed Throat
(7) Safety Valve
(15) Chamber
(17) Hole
(18) Annular Duct
(19) Annular Duct
(20) Hole
(21) Hole
(22) Chamber
(23) Cylinder Chamber