Aerial Device Classification: Features and Requirements

Posted on Apr 6, 2025 in Technology

  • Aerial Device Classification: Must reach at least 65ft above grade.
  • Quint (50–75): Tank & Pump Size – Supply/Attack Hose Lines – Ladders & Waterways.
  • Water Tower (50–130): Below Horizontal to 90° & flows 1000gpm.
  • Articulating Aerial Platform (55–85): Boom Sections with hinge. Up & Over.
  • Aerial Ladder Apparatus (50–135): Most Common /WH: Ground to highest rung.
  • Combo Telescoping/Articulating Aerial Device (90 – 174)
  • Aerial Ladder Platform (85–110): Straight-Chassis 3-axle, rear-mounted type.
  • *WH: Ground to top of Railing @ Max Extension & Elevation.
  • Telescoping Aerial Platform (75–100): 2 or more sections Box-Beam/Tube Truss.
  • Requirements of all Platforms: Floor 14ft² – 4” high kickplate.
  • Railing no more than 24” opening – 2 gates below top railing.
  • Fog Curtain Nozzle underneath: 75gpm – 2 Control Stations – Communications Between.
  • 110ft – Must be raised, Max Elevation & Extension & Rotate 90° in <150 seconds.
  • Minimum Load capacity 750lbs fully Extended @ any Elevation & pump 1000gpm any position.
  • *Minimum Load drops to 500lbs when piping is charged.
  • 1 or 2 permanently mounted Master Stream Nozzles & Backup Hydraulic System.
  • Primary Features of Aerial Devices – Heat Treated Aluminum Alloy/ Steel.
  • Base: Bottom Section. Fly: 2nd & subsequent sections extend past base. Rungs: Between the two base rails. Used as steps.
  • Base Rails (beams): Lower Chords. Rungs, Trusses, etc. are attached.
  • Rails (Handrails): Top Chords. Opposite ends of trussing attached.
  • Hydraulic System: Fluid: Transmits force (>3500psi) Incompressible.
  • Pump: Positive Displacement (rotary vane or gear). Creates Force on fluid.
  • Reservoir: Conditions fluids while stored in tank.
  • Valve: Mechanical passage controls, starts, stops, regulates & directs fluid flow.
  • Check Valve: Automatic Valve allows flow only 1 direction. Safety feature in case of leak.
  • Relief Valve: Limit built up pressure. Prevent damage from overpressure.
  • Counter-Balance Valve: Prevent unintentional motion of aerial.
  • Selector Valve (transfer/diverter): 3-way that directs fluid to Stabilizer OR Aerial Control. One of most important valves. Prevents simultaneous use.
  • Actuator Valve: Controls flow of Hydraulic fluid to Hydraulic Cylinders.
  • Monitor Valve: Multi-directional valve controls flow of Hydraulic oil through System.
  • Stack Valve: Multi-directional valve used in aerial Hydraulic System.
  • Actuators (cylinders): Convert fluid power to Mechanical Force.
  • Hydraulic Cylinders: Used for Elevation, Extension, Telescoping & Stabilizers. *Are Double-Acting.
  • Double-Acting Cylinders: Receive oil from both ends. Force created both directions.
  • Auxiliary Hydraulic Pump: Provide all same motions, but should be limited to bedding if failure occurs. Operate 1min with 1min rest.
  • Stabilizer Cylinders: Prevent apparatus from tipping over when raised.
  • Hoisting (Elevating/Lift) Cylinders: Elevate aerial from stowed position.
  • Piston Rods: Chrome-plated rods inside each Cylinder. End has a Trunnion.
  • Trunnion: Pivoting end of Piston Rod anchored to aerial or turntable anchor ear by a heel pin. Transmits force of hydraulic fluid in cylinders to aerial.

*The larger the piston area, the more upward force produced 850-3500psi

  • Extension Cylinders: Dual-Cylinders fitted on Base section to extend Fly sections.
  • Turntable: Rotational Structural component. Provides continuous rotation.
  • Control Pedestal: 3 ½ft tall. Driver/Operator has clear view of tip & workers. Has 3 control levers from left to right (Extension, Rotation, Elevation).