Aerial Hydraulic Theory Flashcards
Why is there remote starter button for?
In case engine stalls during aerial operation
All control levels in neutral position should register between___ and ——
60 and 125 pounds
What pressure when control levers are moved to position requiring high pressure is between ___ and ___
800 and 900
What gauge shows the the height reached when at approximately 80 degrees from horizontal?
Ladder extension indicator guage
What does the ladder load indicator show?
The actual stress (bend) on upper and lower beam when the ladder beam when the ladder is supported or unsupported
What are the 4 levels of load indicator?
Right to Left
DangerRED
Indicates excessive stress due to nozzle reactions
Downward prsssure on ladder when supported
Safe GREEN
Safe operating conditions
Caution YELLOW
Ladder when extended at low angles
Danger RED
Excessive stress on ladder when extended at low angles
Aerial turntable reference
Turns table constructed of steel plate electricity welded into a section great strength and rigidity.
On bottom are machine ball races which register with similar races in a large diameter heavy steel ring bolted to the chassis frame. A large number of hardened steel balls in races carry weight of ladder and mechanisms, THUS PERMITTING FREE ROTATION of turntable.
How do you lubricate the turntable?
Grease fitting for lubricating ball races top of turntable near the rear. Rotate turntable slowly while lubricating to distribute grease
How to use turntable by hand
Open valve rotation bypass
Remove cap and attach crank to square shaft
Reverse to be operated by power again
Rotation Lock reference
Be sure the rotation lock is released towards the operator before attempting to rotate the turntable
What are automatic limit stops?
Prevent over travel in hoisting lowering and extending
Hoist limit consist of a rod connector to a link at the base of ladder 2 collars are held in place with a set screw
The extension limit consist of a disc engage a floating lever on disc shaft . The disc driven by worm gears from extension drum. Floating lever is connected by a link , lever, collar to extension control valve
What are limits of the hoisting, lowering ,extension and retraction stops?
Hoisting adjusted to stop when angle of inclination is 85 degrees from frame of truck
Lowering to stop settle gently in bed
Extension when second section second rung of lower head block is about 1 1/2” to 2”above lower lock pawls
Retraction stop second section 3”-4” inches above rubber bumpers
Stops should be checked after ladder has been operated few times to warm up oil
When is rotation bypass valve may be necessary?
In case system failure or in conjunction with water tower operation
How do you check hydraulic system?
Close test valve
Press manual throttle control button
Should be 800-900psi if it varies 50 pounds from setting contact shops
How does hydraulic relieve valve work?
Ground position type one end has cone shaped extension rests against hardened steel seat in valve body held by initial springs 60-125psi
High pressure 800-900psi controlled by pilot valve also held by spring tension
