TM 10-3950-672-10
HYDO. Hydraulic Oil. Oil in a hydraulic system serves as the power transmission medium, system
lubricant, and coolant. Selection of the proper oil is essential to ensure satisfactory system performance
and life. (See Hydraulic Oil Recommendations, paragraph 6-1.3.)
HYDO may be further described using a suffix as follows:
RO - Rust and oxidation inhibited oil
AW - A premium oil with antiwear additive
LT - Low temperature hydraulic oil
WPG. Water Pump Grease. This is a multi-purpose high pressure lithium soap base grease. The
following properties are recommended.
Dropping Point
240 (171 ) minimum
F
C
Water Resistance
Excellent
NLGI Grade
No. 2
WRL. Chemically neutral Wire Rope Lubricant used to prevent corrosion and reduce wear caused by
internal friction. OGL is sometimes suitable. WRL should be selected and applied in accordance with
operating conditions and recommendations of a reputable lubricant supplier. (See Wire Rope
Lubrication, paragraph 6-1.6.)
6-1.3
Hydraulic Oil Recommendations. New cranes come from the factory with Kendall Hyken 052, a type of
hydraulic fluid commonly known as Tractor Hydraulic Fluids. Tractor Hydraulic Fluids are intended to provide chatter-free
lubrication of wet brakes and wet clutches in addition to good gear lubrication and hydraulic performance.
Factory fill oil meets the optimum viscosity requirements through a temperature range from -5to 210
F
(-21to 99 ). When replenishment of the oil becomes necessary, or when replacement of the oil is required as a result
C
of contamination or operation outside the recommended temperature range for he factory fill oil, the following types of oil
are suitable under most operating conditions.
Tractor Hydraulic Fluids of suitable viscosity.
Good quality anti-wear hydraulic oils of suitable viscosity and specifically
formulated to provide chatter-free operation of wet brakes.
The most important factors in selecting an oil for hydraulic service are:
Viscosity.
Anti-wear additives.
a.
Viscositv. The oil must have proper viscosity to provide a lubricating film at system operating
temperature. Oil viscosity is important because it has a direct bearing on efficient transmission
of power. An oil must flow readily through the system with a minimum of pressure and flow loss.
Positive lubrication depends on viscosity. The oil must be sufficiently light to get between the
components machined surfaces, and maintain a lubricating film at system operating
temperatures. Cold weather start-up procedures should allow for a gradual warm-up until the oil
reaches a reasonably fluid state.
6-3
