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|  MIL-T-62518A
hydraulic cylinders for actuating the booms and outriggers shall be provided with pilot check or
holding valves to prevent descent of the boom assembly and retraction of the outriggers in the
event of loss of hydraulic pressure. Means shall be provided to install pressure gages for testing
the hydraulic system pressure and relief settings. All surfaces of hydraulic ram piston rods shall
be chrome plated with sufficient thickness to withstand a 30-hour salt spray test in accordance
with ASTM B 117.
3.6.8.2 Hydraulic lines and fittings. Hydraulic lines shall be located for maximum ease of
removal and installation, or visual inspection for failure, and maximum protection from damage
during operation of the boom assembly. Flexible hydraulic hose or collector rings shall be used
where flexing of hydraulic lines is encountered and where installation of components requires a
flexible coupling. Standard straight thread, flared type fittings, fittings adapted to flared type, or
tapered pipe thread with dry seal fittings shall be furnished. Hydraulic lines and fittings shall be
air- and liquid-tight and shall be installed to prevent vibration and chafing. The system shall be
designed to prevent hydraulic transients. Provisions shall be made for bleeding air from the
hydraulic system and completely draining all hydraulic lines, when necessary. A manual type
bleeder shall also be provided as on-vehicle equipment on closed-center, non-self bleeding
systems. Hose assemblies and all seamless steel hydraulic line shall be adequate to provide the
rate of flow, temperature and pressures required to operate the system smoothly and efficiently.
Galvanized pipe and copper tubing shall not be acceptable.
* 3.6.8.3 Hydraulic pump. A hydraulic pump with necessary pressure and flow capacities to
operate all hydraulically powered components shall be provided. The pumping system shall
include an adjustable pressure relief valve, unloading valve or pressure compensator with a range
of adjustment which allows raising or lowering of the boom(s) and basket(s) with any working or
test loads specified herein. A readily visible pressure gage shall be provided on the discharge
side of the hydraulic pump.
* 3.6.8.4 Pump drive systems. The hydraulic pump shall be driven by a heavy duty power
takeoff unit attached to the truck chassis transmission. For emergency use, except when a
rechargeable electrical or auxiliary engine driven system is specified, an auxiliary hydraulic
pump, driven by an electric motor powered from the vehicle chassis electrical system, shall be
provided to rotate the turntable, retract the outriggers, lower the booms and place the booms in
stowed position in the event of primary power source failure. The system shall be equipped with
cut-in devices and controls at the basket(s) and at the lower control station. The system shall
provide adequate pressure and flow capacities for operation when the power takeoff driven
power source fails. When specified, in addition, to the power takeoff, the hydraulic pump shall
be driven by a rechargeable electrical system (see 3.6.9), or by an auxiliary engine (see 3.6.10).
Means of rapid conversion from one power source to the other, within the basket and from the
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