HYDRAULIC SYSTEM RT765E-2 SERVICE MANUAL
2-8
Published 9-04-2014, Control # 422-08
Also, check the valve for rust. Rust or dirt collecting on the
valves can prevent free movement of the spool, and keep it
from the true center position. Excessive system pressure
can create both internal and external leaks in valves that are
otherwise sound. Only qualified technicians using the correct
equipment should make pressure adjustments when
pressure adjustments are needed.
Visual Inspection of Hoses and Fittings
Visually inspect hoses and fittings once a month or every 250
hours for the following:
• Leaks at hose fitting or in hose
• Damaged, cut, or abraded cover
• Exposed reinforcement
• Kinked, crushed, flattened, or twisted hose
• Hard, stiff, heat cracked, or charred hose
• Blistered, soft, degraded, or loose cover
• Cracked, damaged, or badly corroded fittings
• Fitting slippage on hose
• Other signs of significant deterioration
If any of the above conditions exist, evaluate hose
assemblies for correction or replacement. For replacement
of hose assemblies, refer to your Manitowoc Crane Care
Parts Manual.
At the same service interval, visually inspect all other
hydraulic components and valves for the following:
• Leaking ports
• Leaking valve sections or manifolds and valves installed
into cylinders or onto motors.
• Damaged or missing hose clamps, guard, or shields.
• Excessive dirt and debris around the hose assemblies.
If any of these conditions exist, address them appropriately.
All hydraulic hose assemblies are recommended to be
replaced after 8000 hours of service life. Working conditions,
ambient temperatures and high duty circuits can affect
service life of hose assemblies and must be taken into
account when inspecting and replacing hoses. High duty
circuits can include, but are not limited to, outriggers,
hoist(s), boom lift, swing, pump suction and discharge to
directional valves and directional valve return to the
reservoir.
Hydraulic hose assemblies operating in a temperature
climate zone “C” (Table 2-1)are recommended to be
replaced after 8000 hours of service life.
Hydraulic hose assemblies operating in climate zones “A”
and “B” (Table 2-1) with high ambient temperatures, could
see hose service life reduced by 40 to 50%, therefore, it is
recommended to replace these hoses after 4000 to 5000
hours of service life.
Hydraulic hose assemblies operating in climate zones “D”
and “E” (Table 2-1), cold climates, should expect a degrade
of mechanical properties, long term exposure to these cold
temperatures will negatively impact service life. Therefore it
is recommended for these hoses to be inspected thoroughly
as service life may be less than 8000 hours.
Table 2-1
CAUTION
Ensure that the hydraulic hose is depressurized before
loosening the connections.
Zone Classification
A Tropical Moist: All months average above 18° C. Latitude 15° - 25° North and South
B Dry or Arid: Deficient precipitation most of the year. Latitude: 20° - 35° North and South
C Moist Mid-Latitude: Temperature with mild winters. Latitude: 30° - 50° North & South
D Moist Mid-latitude: Cold winters. Latitude 50° - 70° North & South
E Polar: Extremely cold winters and summers. Latitude: 60° - 75° North & South
Reference Only
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