SkyTrak 6036 Service Manual - Manual (Page 164)

Section 9 Hydraulic System
9-14 Model 6036/6036T S/N 9B0500 thru 14833
Fig. 9.10 Electronic Control Boom Raise/Lower Circuit
RIGHT BOOM HOIST
CYLINDER
LEFT BOOM HOIST
CYLINDER
PILOT
FILTER
BYPASS
VALVE
OUTLET EXTEND/RETRACT
WORKING SECTION
RAISE/LOWER
WORKING SECTION
PRESSURE
COMPENSATED
INLET
TANDEM PUMP
30
GPM
15
GPM STRAINER
RETURN FILTER
RESERVOIR
C2 C1
P T
LOWER RAISE
CENTER
TO BOOM
EXTEND/RETRACT
CYLINDER LOWER
PWM
RAISE
PWM
CONTROL VALVE
RAISE
LOWER
COMPENSATOR
VALVE
PILOT VALVE
200 PSI
COUNTERBALANCE
VALVES
INLET RELIEF VALVE
2650 PSI
NOTE: Shifting the raise/lower working section
spool manually by moving the optional valve lever
away from the control valve will also actuate the
hoist cylinder to lower the boom.
The counterbalance valve in each boom hoist
cylinder serves another main function for safety
purposes. This function can be described as
follows:
• Should any of the hydraulic lines going to
either boom hoist cylinder fail, there will be
a loss of hydraulic system pressure to the
cylinder(s).
Example: If there was a
hydraulic line failure in the pressurized
lowering line during lowering, the counter-
balance valve would lose pilot pressure
closing off flow returning to the reservoir.
The oil in the base end of the cylinder
would then be trapped, which would
immediately stop boom lowering and
prevent an elevated load from falling to the
ground uncontrolled. The load can be
lowered safely to the ground by following
the “Emergency Boom Lowering” proce-
dures in your Owners/Operators Manual.
IMPORTANT: DO NOT attempt to reset the
counterbalance valve cartridges. In the event that
the counterbalance valve cartridges were disabled
for emergency boom lowering or any unauthorized
adjustments are ever made to these cartridges,
remove and replace both cartridges with new
parts. Failure to replace these cartridges with new
parts may alter the holding characteristics of the
counterbalance valves creating an unsafe condi-
tion for machine operation.
PULSAR
SOLENOID
PULSAR
SOLENOID
MK0310