Fluid Power Final Flashcards
Define fluid power
a type of system that uses energy to do work, by using a prime mover to drive a pump that presurizes a fluid, which is transferred through pipes & hoses to an actuator
6 basic components in a hydraulic circuit.
reservoir/tank
pump
prime mover
actuator
valves
piping
Reservoir?
holds oil
Pump?
forces oil through system
Prime mover?
drives pump by electric motor/other power source
Valves?
control oil direction, pressure, and flow rate
Actuator?
converts oil pressure to mechanical force/torque
Piping?
carries oil
Difference between a hydraulic system and a pneumatic system.
hydraulic - liquid
pneumatic - air
List the 3 systems that use energy to do work.
mechanical, electronic, hydraulic
Hydraulic v pneumatic actuator movement?
hydraulic more accurate
Hydraulic v Pneumatic operating pressure?
Operating Pressure – hydraulic is more
Hydraulic v Pneumatic actuator speed?
Actuator speed – hydraulic is less
Hydraulic v pneumatic component weight?
Component weight – Hydraulic is heavier
Hydraulic v pneumatic cost?
Cost – Hydraulic more expensive
advantages of fluid power over mechanical power systems.
Remote control, complex mechanical lineages eliminated, instantly reversible motion, automatic protection & instant lubrication
List the advantages of mechanical power systems over fluid power systems.
No oil leakage problems, no danger of bursting of hydaulic lines, no fire hazard
Pascal’s Law?
Force on a confined fluid results in equal pressure in all directions
Force (lbs) = Pressure (psi) x Area (in^2)
How to find Full Area?(cap side)
pi x diameter^2/4
Annular Area?
Full area - Rod area
Volume?
Area x stroke length (in^3)
Extension force?
system pressure x full area
Retraction force?
system pressure x annular area
How to convert volume in cubic inches to gallons?
divide by 231
pump output power?
pump output power (hp) = flow rate (gallons/min) x Pressure (psi)/1714
the amount of energy required to lift 550 lbs one foot in one second
hp
is the amount of work that can be done in a certain amount of time, or the Rate of work
power
the force that tends to cause a rotation
torque
the motion of a load through a distance in something useful being done
work
defined as the ability to do work
energy
3 types of positive displacement pumps
gear, vane piston
Define displacement.
Volume of oil required for the motor shaft to turn 1 complete rotation
Define Nominal flow rate
theoretical amount of oil supplied by the pump at a given rotation speed. Equal to 1 pump displacement multiplied by rotation speed
Define slip value
Indicates the amount of oil that does not reach the pump output for a given increase in pump pressure.
4 basic applications of accumulators
backup power, auxiliary power, hydraulic shock absorber, leakage compensator
5 probable causes that should be investigated when actuator fails to move
bad actuator
bad pump
DCV fails to shift
system pressure low
actuator load is excessive
4 advantages of hydraulic motors over electric motors
uni/bi directional
instantly reversible
absorb severe shock loading
smaller & respond faster
Hydraulic pumps create ______ not ___________
flow/pressure
Resistance to _____creates _______
flow/pressure
_______ determines actuator speed
flow
___________determines actuator force
Pressure
The speed of a hydraulic motor is a function of the circuit_____
flow
The output force of a hydraulic motor is a function of the circuit _____
pressure
