Topping off a fighter jet’s hydraulic system on the flight line isn’t the same job as topping off a car \u2014 the fluid has to arrive free of both particulate contamination and entrained air, because either one can compromise an actuator that’s expected to work exactly right the first time, every time. Neometrix’s HST 300U Hydraulic Refilling Trolley is a compact, towable ground support unit that pressurizes, de-aerates, filters, and transfers hydraulic fluid at up to 300 bar and 100 L\/min per circuit \u2014 in a single mobile pass.<\/p>\n
Twin 50-litre nitrogen bottles at 220 bar service pressure pressurize the dual-chamber reservoir to drive fluid transfer, rather than relying on an electric pump. On an airfield apron \u2014 where fuel vapor, dust, and unpredictable power access are all realistic conditions \u2014 a nitrogen-driven system removes the ignition risk and power-dependency that come with an electrically driven pump, while still delivering up to 100 L\/min per circuit.<\/p>\n
An engine-driven vacuum pump extracts dissolved air and moisture from the hydraulic oil down to under 200 mbar absolute before it ever reaches the aircraft. Entrained air that isn’t removed before transfer doesn’t just sit inertly in the fluid \u2014 it compresses under pressure and can cause cavitation or hydraulic lock once the system is back in operation, a failure mode that filtration alone does nothing to prevent.<\/p>\n
Two independent hydraulic circuits can be serviced simultaneously from the trolley’s twin 70-litre SS304L chambers, reducing aircraft downtime during depot-level maintenance where multiple hydraulic systems \u2014 primary flight controls and utility hydraulics, for instance \u2014 often need attention in the same maintenance window.<\/p>\n
Bypass and mainline 3 \u00b5m absolute filter stages strip particulates and varnish from the fluid before it reaches the aircraft, holding a cleanliness level \u2014 ISO 4406 Class 18\/16\/13 \u2014 that matters directly to actuator and servo-valve life downstream. Redundant relief valves and burst discs on both the nitrogen and hydraulic circuits, plus over-temperature shutdown and an emergency-stop circuit, protect both the equipment and the operator throughout.<\/p>\n