Telescope Circuit
TELESCOPE FUNCTION ONLY - WILL NOT OPERATE
CAUSE REMEDY
Load too great Move lever to first position, not “high
speed”. Reduce load or set boom length
before lifting load
Both port relief valves sticking See section on “Relief Valves”
Hose plugged or liner collapsed Replace hose
BOOM EXTENSION JERKY OR ERRATIC
CAUSE REMEDY
Inadequate grease on boom pad surfaces Lubricate boom where pads contact boom
Wear pads damaged Replace wear pads
Wear pads shimmed to boom too tight Reshim wear pads
Faulty counter balance valve Replace counter balance valve
Loose chain system Adjust chains as required
TELESCOPE CYLINDER EXTENDS BUT WILL NOT RETRACT
CAUSE REMEDY
Port relief valve sticking See section on “Relief Valves”
Hold valve malfunctioning Repair or replace
Internal leakage in cylinder See section on “Cylinder Leakage”
Extend valve malfunctioning Repair or replace
BOOM SECTIONS RETRACT UNDER LOAD
CAUSE REMEDY
“O” ring around hold valve damaged Replace “O” rings
Hold valve not seating properly Repair or replace
Telescope cylinder by-passing See section on “Cylinder Leakage”
407P/N 12261-683 REVISED: January 2015
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