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KCPA SAMPLE Hydraulic SYSTEMS. Tom Korder kordertv@uiuc.edu. Roméo et Juliette RAMP. Two – One –, rated up to 5 GPM One – One – . Roméo et Juliette RAMP. Ramp cylinders. Roméo et Juliette RAMP. Ramp cylinders. Roméo et Juliette RAMP.

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slide1

KCPA

SAMPLE Hydraulic SYSTEMS

Tom Korder

kordertv@uiuc.edu

rom o et juliette ramp
Roméo et Juliette RAMP
  • Two –
  • One –, rated up to 5 GPM
  • One –

One –

rom o et juliette ramp5
Roméo et Juliette RAMP

Hydraulics viewed from under ramp in trap room

cylinders

Flow divider

rom o et juliette slipstage
Roméo et Juliette SLIPSTAGE
  • Two –
  • One –, rated up to 5 GPM
  • One –

One –

rom o et juliette slipstage10
Roméo et Juliette SLIPSTAGE

Slipstage in “out” position

rom o et juliette slipstage11
Roméo et Juliette SLIPSTAGE

Cable drum

Hydraulic motor

shop built hydraulic trainer
Shop-Built Hydraulic Trainer
  • AC Power Unit (500 psi, 1-2 gpm)
  • Tie-rod and industrial cylinders
  • Low speed/high torque motor
  • Rotary Actuator
  • Industrial and Mobile valves
    • different actuations and centers
  • Flow, pressure, etc. valves
    • sandwich and in-line style
  • Pressure gauges and flow meter
  • Hoses with couplers, adapters
closed loop vs open loop
Closed Loop vs. Open Loop

pressure line

pressure line

Return line

Return line

pressure line

pressure line

Return line

inlet

exhaust

designing a system
DESIGNING A SYSTEM
  • Determine System Parameters
  • Perform System Calculations
  • Choose System Components
system parameters
System Parameters
  • What type of movement? (Linear or Rotary)
    • actuator type
  • How far does it travel?
    • Stroke, degree of rotation
  • How heavy is the object ?
    • total weight of all materials
  • What speed?
    • How fast of move? safe travel speed ?
    • How fast to get to full speed? , rpm
  • Other needed components?
b system calculations
B. System Calculations
  • FORCE / TORQUE
    • lbs of force
    • in lbs of torque
  • SPEED / FLOW
    • time for stroke
    • time for rotation
area pressure force
AREA–PRESSURE / force
  • Amount of force is determined by pressure pump can deliver
    • measured in psi – lbs per square inch

2000 lbs of force

6000 lbs of force

1000 psi

3000 psi

2”

actuator

2”

actuator

calculate area pressure force
F = P X A

force = pressure x area

Area = d2 x .7854

lb = psi x sq in

given a stated force needed

start with assumed area

pick a cylinder bore

start with assumed system pressure

as low as possible for safety

experiment with numbers until you find right combination

calculate AREA–PRESSURE /force

load

cylinder

slide20

examples AREA–PRESSURE /force

  • Force=Pressure x Area

Force (lb.) = pressure (lb sq in) x area (sq in)

2” bore x ?? psisystem pressure

  • 1570 lb=500 psix3.14 (22x.7854) sq. in.
  • 4710 lb=1500 psix3.14 (22x.7854) sq. in.
  • 9420 lb=3000 psix3.14 (22x.7854) sq. in.
multiplication of force
Multiplication of Force

F / A = P

242 x .7854 = 452 sq. in.

220 lb. / 452 sq. in. =

.48 psi

1442 x .7854 = 16286 sq. in.

.48 psi x 16286 sq. in. =

7817 lb. of force

flow speed
FLOW / Speed
  • rate of flow determined by pump delivery
  • flow determines speed of devices
    • measured in GPM - gallons per minute

5 seconds

10 seconds

5 gpm

2.5 gpm

2”

actuator

2”

actuator

calculate flow speed
calculate –FLOW / Speed

To Find Needed GPM

  • Flow=Area x stroke length x .26

time for stroke

  • gal./min. = sq. in. x in. x .26

sec.

  • Flow (gal./min.) = (area (sq in) x stroke length (in) x .26) / time for stroke (sec)
examples flow speed
examples –FLOW / Speed
  • Flow=Area x stroke length x .26

time for stroke

Flow (gal./min.) = (area (sq in) x stroke length (in) x .26) / time for stroke (sec)

2” bore x 36” stroke cylinder ; 30 seconds, 15 seconds, 10 seconds

  • .97 gpm=3.14 (22x.7854) sq. in. x 36 in. x .26

30 sec.

  • 1.95 gpm=3.14 sq. in. x 36 in. x .26

15 sec.

  • 2.93 gpm=3.14 sq. in. x 36 in. x .26

10 sec.

motor shaft speed
Motor Shaft Speed
  • Speed of the motor output shaft.

Speed =___flow x 231_____

motor displacement

    • shaft speed in RPM
    • flow in GPM
    • displacement in cubic inches per revolution
    • 231 = cubic inches in a gallon
c system components
C. System Components

DCV(Directional Control Valve)

Other control devices

(pressure,flow, etc)

Power unit (pump)

Actuator (cylinder)

mobile vs industrial
MOBILE vs. INDUSTRIAL
  • Industrial
    • closer tolerances, more expensive, valves are modular
  • Mobile
    • also known as agricultural, rugged/basic construction, more plumbing/hoses, less expensive
  • Suggestion
    • Mobile actuators, Industrial valves
power unit
POWER UNIT
  • Preassembled vs. Shop assembled
  • System Flow
    • GPM – gallons per minute
  • System Pressure
    • psi – pounds per square inch
  • Voltage
    • 110vac or 220vac
    • 1 or 3 
  • Reservoir size
    • gallons
dcv directional control valve
DCV directional control valve
  • Actuation method
    • manual, electrical, or fluid
  • Rating
    • flow and pressure
  • Center style
    • closed, open, float, or tandem
  • Style of construction
    • mobile or industrial
center configurations31
CENTER CONFIGURATIONS
  • Closed or Blocked
    • when operating 2 or more branch circuits from one pump, where more than one must operate at one time
  • Float
    • cylinder is free to "float", piston can be pulled or pushed by an external force, sometimes used for Hydraulic motors
  • Open
    • motor" spool , minimizes circuit shock when controlling a motor, not recommended for cylinders
  • Tandem
    • popular for low power systems, provides free flow path for "pump unloading", simple/economical way to unload, holds cylinder against drift
actuator
ACTUATOR
  • Action Needed
    • Linear, Rotary limited motion, Rotary continuous motion
  • Amount of action needed
    • stroke length, degree of rotation, speed
  • Force in both directions or only one
  • Force / Speed
    • Bore/Displacement, Pressure, GPM rating, Port sizes
  • Mounting Method
mobile ag style cylinders
Mobile (Ag) style cylinders

Tie-Rod Cylinder

Welded Cylinders

other control devices
OTHER CONTROL DEVICES
  • Pressure Control (force)
  • Flow Control (speed)
  • Additional controls
    • Safety Devices
    • Additional filtering
    • Electrics/Electronics
    • Counterbalancing
    • Flow dividing
recommended systems add ons
Recommended Systems – ADD-ONS
  • Combine two systems
  • Power Unit
    • Second power unit
  • AdditionalValves
    • Industrial-solenoid proportional w/ electronic card
  • Actuators
    • Additional cylinders
    • Rotary actuator
  • Accessories
    • Flow divider
    • More hoses
safety rules
SAFETY RULES
  • Understand the basic principle and be familiar with components of the system.
  • The pressure in the system should never exceed the rated pressure of the lowest rated component.
  • Be certain all interfaces to the fluid power system are adequate in strength.
  • Never work on system under pressure.
  • Test all circuitry with low pressure before the load is attached.
  • Use only the pressure required to achieve the effect.

an obstruction, overload, or added friction will stall the system until you fixed the problem

  • Use common sense!!!
jack miller
Jack Miller

(following this slide are new slides that address these topics, these were not included in original workshop presentation)

  • Pump does not produce pressure.
  • Always use a Counterbalance valve if you have a load over the cylinder.
  • Be certain all interfaces to the fluid power system are adequate in strength.
  • …………………………………….
pressure
PRESSURE

load

  • pressure is created whenever the flow of a fluid is resisted
    • A. load on actuator
    • B. resistance or orifice in the piping
  • pump DOES NOT create pressure
    • it has the ability to push against a certain pressure

A

B

actuator

counterbalance valve
COUNTERBALANCE VALVE
  • counterbalance valve is an improved pilot operated check valve
  • the opening pressure of a pilot operated check valve depends on the pressure (applied by the load) behind the valve
  • the opening pressure of a counterbalance valve depends on the spring pressure behind the valve.
counterbalance valve45
Counterbalance Valve
  • dynamic performance of balance valve is many times better than the performance of a pilot operated check valve
  • balance valve is applied as a 'brake valve' in order to get a positive control on a hydraulic cylinder or motor with a negative load
    • small crane systems
    • elevator
    • scissor lifts

out

pilot

in

pilot

counterbalance valve47
Counterbalance valve

Left side of DCV is activated, cylinder will make its 'OUT-stroke‘, oil flows through integrated check valve.

To lower cylinder, the right side of DCV is activated. From that moment on pressure is built up at the rod side of the cylinder. This pressure opens the balance valve & the oil at the bottom side of the cylinder flows through the balance valve & DCV back to reservoir.

out

pilot

in

pilot

counterbalance valve48
Counterbalance valve

To lower cylinder, the right side of DCV is activated. From that moment on pressure is built up at the rod side of the cylinder. This pressure opens the balance valve

The oil at the bottom side of the cylinder flows through the balance valve & DCV back to reservoir

As the load helps lowering the cylinder, the cylinder might go down faster than the oil is applied to the rod side of the cylinder (the cylinder isn't under control at that moment).

However, the pressure at the rod side of the cylinder and therefore the pilot pressure on the balance valve will decrease and the spring moves the balance valve to the direction 'close' as long as it finds a new 'balance'. .

an introduction to hydraulics usitt minneapolis 2003

“An Introduction to Hydraulics”USITT- Minneapolis 2003

Notes available at

http://www.nwmissouri.edu/%7Epimmel/usitt/tech_prod/TECH_PROD_INDEX.HTM

Contact me at:

kordertv@uiuc.edu