MIL-S-46777 Semitrailers, Dump, Commercial, General Specification ForThis specification covers various sizes of rear dump semitrailers. The dump semitrailers are operated by the truck-tractors hydraulic system, unless the self-contained engine driven hydraulic option is required.

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MIL-S-46777C

(a)        Truck-tractor hydraulic hose type, whereby hydraulic hoists pressure is provided from the towing truck-tractor's hydraulic system (see 3.7.1(a) thru (h)).

(b)    Self-contained type, whereby the complete hoist system is mounted on the

semitrailer with a gasoline or diesel engine (see 3.8) driving the hydraulic pump

(see 3.7.1 (a) and (c) thru (h)).

3.7  Hydraulic system.  The dump body shall be actuated by a front mounted telescopic ram hydraulic hoist system having a minimum class number specified in the specification sheet's TBEA Hoist Classification, and a minimum ton rated capacity as specified in the specification sheet.  The hydraulic hoist system shall be as follows:

(a)        Provide the complete hydraulic system having all components as recommended by the hydraulic pump hoist cylinder manufacturer's recommendations:

(1)        Operate with rated payload without binding, malfunction, or permanent deformation.

(2)    Provide a fail-safe system protected from accidental lowering due to any

hydraulic system failure other than telescopic cylinder.

(3)    Capable of withstanding minimum proof pressure without leakage as

recommended by the pump manufacturers.

(4)    All components and lines cleaned and free of foreign matter.

(5)    Hydraulic oil approved by the pump mfgr. for severe heavy-duty service.

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