2nd Half Second Semester Flashcards
Gerotor
black ring around motor
Wider gerotor, more surface area, more torque
Function of Oil
Transmits energy/power
Double Acting Cylinder
2 directions
Reservoir Purposes
- Hold oil
- helps cool the oil
- places for extra oil to go
- allows oil to rest, foreign matter in oil allowed to sink to bottom of reservoir
Advantages of Hydraulics
- Variable Speed
- Very Easily Reversible
- Overload (easy to avoid, won’t even try)
- Usually components are smaller, size matters
- Can be stalled without hurting anything
- Quiet (the actuator) - can separate loud vs. quiet parts
Cubic inches of a gallon (magic number)
231 cubic inches of a gallon
How determine torque in rotary actuator?
Torque determined by pressure & area oil is pushing -load on motor determines pressure because it’s resisting flow of oil into actuator -area & psi tell torque = load
0.0007 assumes?
80%
Reducing coupling
up
Converts smaller to bigger pipe
Proportional Valve
Electrical directional control that can control flow, can move spool cooly under control
Every system should have a _____
Filter
Union
Can move sections of pipe without twisting pipe
What does gauge read in Tandem Center?
Zero
Cavitation
not getting enough fluid for what the pump wants
Symptoms that air might be in oil
Noisy, things don’t operate the way they should
Why does cylinder slow @ end of stroke?
Air cushion
-Retract is faster because less area to push oil into when cylinder is extended
How heavy is gallon of oil?
6#’s
Precharge
when charging up accumulator
What does flow control do?
Controls the speed of the actuator
Which flow control method is preferred?
Meter Out
Don’t use bypass, will pull oil out because it’s the pass of least resistance
Proper name of Tandem Center/all control valves
“4 way direction lever operated spring tandem center conrol valve”
Figure out amps in system
746 watts/HP
flow gauge says 2 gpm @ 300psi 2gpm*300psi*0.0007=0.42
- 42*746=313.32
- 32/120=2.6 amps
What happens when we compress compressible fluid?
If compress 1/2, pressure will double
Nitrogen is compressible fluid, oil is not
Decrease volume by 1/2, pressure will double
3 options for flow control
- Meter In
- Meter Out
- Bypass
Single Acting Cylinder
-Retract by a spring, gravity, a person, etc -forklift mast, pallet jack
Why would pressure gauge differ from flow gauge?
Pres. Relief Valve is setting the pressure, some flow being diverted @ PRV, going back to tank, that’s why pressure gauge <flow>
</flow>
Tubing is measured in ______
OD
Another name for motor
Rotary Actuator
Issue with motors in SERIES?
Different loads will cause motors to have different speeds
Motor with lighter load will be driving system
Pipe is measured in ____
ID
Velocity
Displacement over time & a direction
Pascal’s Law
Pressure applied on a confined fluid is transmitted undiminished in all directions, and acts with equal force on equal areas and at right angels to them
How pipe fits together
Pipe fittings threaded, leaking will happen
- can use teflon tape to seal area off
- threads on pipe are tapered a bit so more it goes in, tighter it gets
Rods should be in _____
Tension
Rods can buckle in compression
What type of center with >1 valve?
Closed center or power thru
3 Types of Working Lines
- Suction or Pump Inlet
- Pressure
- Return
Accumulator Gas
use inert gas, Nitrogen
How tubing fits together
metal to metal seals on surface, nut forces them together, no seal
Drain Lines
-Short Dashes -takes supplemental leakage and puts it back into reservoir
H-series motor Side Load
Perpendicular to shaft
How to measure flow in system?
Flow Gauge
Why don’t we want 90-degree corner?
Because turbulent flow
Pilot Lines
-Long Dashes -Transmits data (pressure) to pressure relief valve -always have one on the pressure line
Control Valve Direction Cheat Sheet
First box: Up-down
Third Box: Top Left to Bottom Right; TR-BL
What type of Lever is hydraulics?
1st Class Lever
3 Types of Lines
- Working Lines 2. Pilot Lines 3. Drain Lines
Energy Triangles
Determines which direction energy is going
Accumulator
We use it for storage, overflow
adds flow to the system
Can add flow to system for a period of time
H-series motor Thrust Load
Load parallel to shaft
Stop Tubes
Put on inside to limit extend
Put on outside to limit retract
Extend vs. Retract Cylinder
Extend will have more force than retract
Issue with motors in PARALLEL?
Wouldn’t work, pressure would go to path of least resistance, motor with lightest load would run; heavier motor may not run
- Could use this on wagon unit, connected together by floor gives it commonality
- would put chain b/t motors so they can run together at same speed
How heavy is gallon of water?
8#’s
Tandem Center
Low system pressure due to no resistance of flow
-keeps oil moving, pump to tank
HP Actual Formula
GPM*PSI*0.0007
Bang Bang
Solenoid operated control valve
Reducing bushing
Down
Converts bigger to smaller pipe
Working Line Velocity
7-20 fps
Check Valve
Free flow 1 way, control flow other way
<o>
<p>Flow pushes ball against arrow, blocks</p>
<p>Put on both ends so it meters out</p>
</o>
3 places filter can go
-
Before Pump
* Not seen often as it restricts pump but good for filtering - After Pump
- Pro: Catches crap before it goes out in system
- Con: must be designed to withstand pressure of system
- Going into Reservoir (end of system)
- Pro: Doesn’t restrict flow, really cheap
- Con: worst possible position, crap has already flowed through system
Pump Inlet Velocity
2-4 fps
Directional valves we use have _____ ways
Four Ways
Open Center
- Pressure is whatever it takes to get oil back to tank
- Can have cylinder creep
Aeration
Air in oil
What type of valve is pressure relief valve?
Infinite Position valve
HP theoretical formula?
(GPM*PSI)/1714
Directions in control valve
Left Box: P-A; B-T
Right Box: (BL-TR) P-B
(TL-BR) A-T
3 Hydraulic Motors
- Gear
- Vane
- Piston
