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|  MIL-S-45152H
continuous full width ramp and loading approach to the semitrailer deck. A locking arrangement
shall be provided to enable the gooseneck to be held erect in a fixed gooseneck position.
3.8.4.1 Hydraulic folding gooseneck. Class D folding gooseneck semitrailer shall be
furnished with a hydraulically operated folding gooseneck mechanism and a self-contained
hydraulic power system. Folding and unfolding operations shall be capable of being performed
without outside power or mechanical assistance. Means shall be provided to prevent damage to
the kingpin with the gooseneck in the prone position. Any locking pins shall be of the captive
type or shall be secured to the semitrailer with corrosion-resistant chains or cables. A
self-contained hydraulic system shall be installed on the semitrailer.
3.8.4.2 Hydraulic system. The hydraulic system shall consist of an engine, hydraulic pump,
hydraulic cylinders, hydraulic fluid reservoir, control and relief valves, filters, hoses, piping,
fittings and all other components required to actuate and control the hydraulically powered
gooseneck (and for class D, the landing legs, when landing legs are furnished). The cylinders
shall be designed to travel slower in the lift mode than in the retract mode.
3.8.4.3 Hydraulic pump. The hydraulic pump shall be capable of delivering a flow rate at
maximum system operating pressure which is adequate to provide for a minimum system flow
rate of 3 gallons per minute (gpm).
3.8.4.4 Hydraulic fluid and filter. A full-flow hydraulic filter, having a filter rating no
greater than 25 microns shall be installed in the hydraulic system. The hydraulic fluid shall be of
a noncorrosive type with characteristics to withstand a temperature range from minus 40 to
plus 275 degrees Fahrenheit (F). The hydraulic fluid shall conform to SAE standards.
* 3.8.4.5 Hydraulic reservoir. The hydraulic reservoir shall have sufficient capacity to hold
the maximum volume of fluid required for the system plus a minimum of 20 percent reserve.
Further, in no case shall the reservoir capacity be less than four gallons. The reservoir shall be
vented by a separate vent or through the filler cap. The vent shall be fitted with a filter element.
A corrosion-resistant plate conforming to composition A (class l or 2) or composition C of
MIL-P-514, indicating the type of hydraulic fluid to be used, shall be installed near the filler cap.
3.8.4.6 Hydraulic lines and fittings. All hydraulic tubing, hosing, and fittings shall conform
to applicable SAE standards. A minimum number of fittings, joints, and connections shall be
used to prevent excessive back pressure, clogging, and leakage. All hoses and fittings shall be
capable of withstanding a bursting pressure of four times the working pressure and a maximum
proof pressure of at least two times the working pressure. Hoses shall have physical qualities
equal to or conforming to SAE J517 (100 R1), as applicable. Hoses shall be protected against
chafing through utilization of supports and protective devices.
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