Hydraulic Systems Flashcards
What is a hydraulic system?
A drive or transmission system that uses pressurized fluid to power hydraulic machinery such as cylinders or hydraulic motors
System exerts a large amount of force
Hydraulic systems are run by a…
Power take off
Aerial PTO and Master switch
Activate one at a time
Park brake must be set
Wheels straight
Transmission in neutral
The PTO transfers power from the ____ and diverts it to the ____.
transmission, hydraulic pump
Quint PTO Activation
Always engage Aerial master and Aerial PTO before engage pump
Generator should not be engaged above idle
Plan ahead and prepare your rig for any situation
Hydraulic Systems…
on aerials are closed. This means that fluid circulates through all components and back to reservoir.
Variable displacement pump…
similar to what is used in the aerials. Basis of this design is the fluid can be metered based on how much fluid is required. At a fixed RPM, the pump can go from barely moving any fluid to moving enough fluid to generate pressure in the system.
Relief valves…
All systems are equipped with relief valves to prevent over pressurization and send fluid back into the reservoir. this prevents damage to the system.
Double acting hydraulic cylinders
Create power by fluid under pressure against a surface area
Fluid ports on each side of cylinder
Seals at the piston end and rod end to prevent leakage
Ladder extension rams…
Smeal uses hydraulic rams and cables
One on each side of ladder
One can fail and the other can still operate ladder
Hydraulic rotation motor…
Rotates turntable
Hydraulic motor is attached to a planetary gear box
Gearbox output shaft has pinion which drives against ring gear on turntable
Smeal have turntable brakes when ladder lock is engaged, brakes inhibit ring gear from turning
Outrigger control valves…
Switches send electrical signals to a solenoid on the valve
Valves used are DCV’s and allow no adjustment
Valve is on off or on position
Located at the rear of the aerial
Check valves…
Used on all cylinders
Prevents back flow of oil
Ladder control levers…
Self centering
Diverts oil to hydraulic equipment
Are a proportional valve
Diverter valve…
Diverts fluid from outriggers to aerial device
Both cannot function at the same time
