Lit. No. 28270, Rev. 00
July 1, 2005
59
STRIKING AN OBJECT WHILE PLOWING FORWARD – HYDRAULIC
QUILL
M
LEFT
RIGHT
3500 PSI
3500 PSI
4000 PSI
4000 PSI
1750 PSI
S6
S3
S1
S5
S4
S2
(C)
(D)
(A)
(B)
LIFT
FORCE APPLIED
WHEN PUSHING
FORCE APPLIED
WHEN PUSHING
RELIEF VALVE
SECONDARY
RELIEF VALVE
SECONDARY
P/O
CHECK
VALVE
P/O CHECK
VALVE
SECONDARY BLOCK ASSY.
PRIMARY BLOCK ASSY.
VALVE
RELIEF
PRIMARY
PRIMARY
RELIEF
VALVE
VALVE
RELIEF
PUMP
P/O
CHECK
VALVE
P/O
CHECK
VALVE
SV08-43
S3
ON
ON
ON
ON
SV08-2004
S1
ON
MOVEMENT
BLADE
RAISE
LOWER
SCOOP
VEE
SV08-30
S6
ON
ON
RIGHT
EXTEND
RIGHT
RETRACT
LEFT
RETRACT EXTEND
LEFT
S4
SV08-30
ON
ON
SV08-40
S2
ON
ON
ON
ON
SV08-40
S5
ON
ON
MOTOR
M
ON
ON
ON
ON
ON
ON
ON
ON
ON
ANGLE
RIGHT
ANGLE
LEFT
System Response
1. Hydraulic fluid is trapped in the
base end of the right ram by the
right primary relief valve, right
secondary relief valve, and P/O
check valve (D). Hydraulic fluid is
trapped in the base end of the
left ram by left primary relief
valve, left secondary relief valve,
and P/O check valve (C).
2. When the snowplow contacts an
object on the front side of either
wing, the force of the impact
increases the hydraulic pressure
in the base end of one ram.
When the pressure exceeds
3500 psi, the ram's primary relief
valve opens allowing some of the
hydraulic fluid to move from the
base end to rod end of the same
ram.
3. Due to the unequal displacement
of fluid between the base and rod
ends of the ram, hydraulic
pressure continues to increase.
When the pressure exceeds
4000 psi, the ram's secondary
relief valve opens allowing the
remaining hydraulic fluid back to
the reservoir.
