JLG 740AJ, Руководство по обслуживанию и ремонту

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SECTION 5 - BASIC HYDRAULIC INFOR M ATION AND SCHE M ATICS
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Table 5-3. Actuator Response Is Sluggish
Item Description Action
Check external system relief valve setting. Low external relief valve setting will slow down system. Adjust external relief valve setting per manufacturer’s rec-
ommendations. External relief setting must be above Pres-
sure Compensator setting for proper operation.
Check Pressure Compensator and LS control setting. Low Pressure Compensator setting will prevent the pump
from achieving full stroke. Low Load Sense setting will
limit output flow.
Adjust Pressure Compensator and Load Sense setting.
Refer to Adjustments.
Check Load Sense control signal pressures. Incorrect Load Sense signal will not allow pump to operate
correctly.
Inspect system, ensure that proper Load Sense signal is
transmitted to the pump.
Internal system leaks. Worn internal parts will not allow the pump to operate
properly.
Refer to Authorized Service Center for repairs as required.
Hydraulic fluid viscosity above acceptable limits. Hydraulic fluid viscosity above acceptable limits or low
fluid temperature will not allow the pump to fill or control
to operate properly.
Allow system to warm up before operation or use fluid with
the appropriate viscosity grade for expected operating
temperatures.
Check external system valving. Malfunctioning valving may not allow system to respond
properly.
Repair or replace system valving as required.
Check pump case pressure. High case pressure will cause the system to be sluggish. Correct case drain line restrictions.
Check pump inlet pressure / vacuum. High inlet vacuum will cause low output flow. Correct inlet pressure conditions.
Table 5-4. System Operating Hot
Item Description Action
Check fluid level in reservoir. Insufficient volume of hydraulic fluid will not meet cooling
demands of system.
Fill reservoir to proper level. Verify proper size of reservoir.
Inspect heat exchanger. Check air flow and input air
temperature for the heat exchanger.
Insufficient air flow, high input air temperature, or under-
sized heat exchanger will not meet cooling demands of the
system.
Clean, repair, or replace heat exchanger as required. Verify
proper size of heat exchanger.
Check external system relief valve setting. Fluid passing through relief valve adds heat to system. Adjust external system relief valve setting per manufac-
turer’s recommendations. External relief valve setting
must be above Pressure Compensator setting for proper
operation.
Check pump inlet pressure / vacuum. High inlet vacuum adds heat to system. Correct inlet pressure / vacuum conditions.