Ch. 16 Introduction to Aerial Fire Apparatus Flashcards
3 Types of Aerial Devices
Aerial ladders
Elevating Platforms (telescoping, articulating, aerial ladder)
Water towers
Primary Features of Aerial Ladders
- Ladder- May be mounted on straight chassis in rear or mid-mount
- Trusses- Consist of assembly of bars or rods to form a rigid framework
- Base (bed)- Bottom section of the aerial device
- Fly Section- Second section that extends that extends beyond base
-Two most common materials are heat treated aluminum and alloy steel - Base Rails- Also called beams, lower chords of the aerial ladder to which the rungs, trusses, and other portions of ladder attach
- Rails- Called handrails is the top chords to which opposite ends of the trussing are attached
- Aerial ladders are built with “K-bracing” provide greater strength
Basics of Aerial Device Hydraulic Systems
Basics of Aerial Device Hydraulic Systems
-Have Four main compartments:
- Actuator- Transforms power into mechanical force
- Hydraulic Fluid- Is the medium by which the system transmits force
- Hydraulic Pump- Powered by the power-take-off (PTO) arrangement off the vehicle’s main engine
-load sensing piston pump, rotary vane or rotary gear positive displacement
- Hydraulic Reservoir- Supplies the hydraulic fluid that is moved in and out of the system
-Reservoir supply adequate amount fluid to operate system and to condition the fluid while it is stored
-Supply hose must withstand pressure 4 times greater than normal operating
-Valves start, stop, and direct flow of fluid of fluid to control pressure
-Check Valve- Prevents fluid from flowing back into system and is a safety feature
-Relief Valve- limit the pressure built up in system
-Selector Valve- Known as transfer or diverter valve
(Three-way valve directs fluid to stabilizer control or aerial device control)
-Hydraulic cylinders convert energy into linear mechanical force or motion
-Counterbalance Valve- Prevent undesirable motion of aerial device from established position
-power rotation of aerial turntable
Stabilizer Cylinders
aerial
-Outriggers
-Deploy any time aerial is raised and prevents truck from leaning or tipping
-Force arm outward and down to take weight of the truck off suspension
Aerial Device Hoisting Cyclinders
-Piston style cylinder
-Function to elevate the aerial device from stowed position
-Heavy, seamless steel outer shells bored to extremely smooth inside surface
-Often chrome-plated inside to resiste friction and wear
-Normal hydraulic pressure is from 850 to 3,000 psi
-Leak in system ladder must be lowered by manually bleeding pressure lines
-pivoting end fitted w/ trunnion to attach to anchor ear by the heel pin
Aerial Device Extension Cylinders
-Used in newly designed aerial devices
-Dual cylinders on base section to extend second section
-simply operate pulleys and cables that extend fly sections
Aerial Ladder Apparatus
(Ladder, Truck, Aerial, Stick)
-allows firefighters to easily climb and descend
-Length range from 50 to 137 feet
-Working height measured from ground to highest ladder rung
-Used for rescue, ventilation, elevated master streams, exposure protection, gaining access
-May be mounted on two or three axle, single chassis vehicle or tractor-drawn
-Tractor-drawn aerial apparatus (TDA)(Tiller Trucks) are equipped with steerable rear wheels on trailer
-More maneuverable than single straight vehicle
Requirements of All Elevating Platforms
- A platform leveling system required to keep parallel to groud
- Minimum floor area of platform- 14 square-inch
- Must have a rail completely enclosing the floor area with no opening under the railing greater than 24-incheas
- Kickplate is require at floor level and should be 4-incheas high
-Prevents firefighter’s feet from sliding off platform - Have two operator controls stations
-one at street level
-one in platform
-must also have backup hydraulic system - protective fog curtain on bottom of platform (75 gpm)
- Minimum load capacity of 750 pounds when fully extended with no water in piping
-drops to 500 pounds when charged - min discharge 1,000 gpm at 100 psi
- platforms 110 feet or shorter should be able to be raised from bedded position for maximum elevation and extension and rotated 90 degrees in 150 seconds or less
Aerial Ladder Platform
-Feature a work platform attached to the end of aerial ladder
-Working height measured from the ground to top surface of handrail
-Range 85 to 110 feet
-Most common straight chassis, three-axle vehicle with rear-mounted device
Telescoping Aerial Platform
- Primary difference- aerial ladder platforms are designed to allow climbing
- Equipped with small ladder attached to the boom
-Primarily an escape ladder for firefighter’s working in platform - Range from 75 to 100 feet
- Have two or more sections made of either:
Box Beam- consist of four sides of steel or aluminum welded together to form box shape with hollow center
Tubular Truss Beam- steel is welded to form box shape using cantilever or triangular truss design
Articulating Aerial Platforms
- Boom sections are connected by hinge, and fold and unfold like elbow
- ability to go “up and over”
-Range from 55 to 85 feet - Some manufactures developed both articulating and telescoping (combination)
-Range from 90 to 174 feet
Water Towers
-telescoping or articulating aerial devices
-primary function- deploy elevated master streams
-Designed so that their fire stream range starts from a few degrees below horizontal to nearly 90 degrees from ground
-Range from 50 to 130 feet
-Flow rate from 1,000 to 5,000 gpm
Quints
5 functions
- Derived from phrase “quintuple fire apparatus
- meaning has 5 major functions:
-Fire pump
-Water tank
-Supply and attack hose
-Ground Ladders
-Aerial device or elevated platform- able to operate as Engine Co., Ladder Co., or both
Cable System, Chains, Slides, and Rollers
- Third, fourth, and fifth sections of aerial device extend by cables and pulleys
- usually corrosion-resistant aircraft quality cables
- Made with very high strength steel called plow steel
-abrasion resistant - Aerials using a main cable drum can be operated mechanically, hydraulically, or electrically
Turntable
-Rotational structural component of aerial
-Provides continuous rotation on a horizontal plane
-Operates on a large shear ball-type bearing
-Gear teeth on turntable engage gears
