KCPA

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KCPA SAMPLE Hydraulic SYSTEMS
Tom Korder kordertv_at_uiuc.edu
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Roméo et Juliette RAMP

• Two
• One , rated up to 5 GPM
• One
• One

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Roméo et Juliette RAMP
Ramp cylinders
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Roméo et Juliette RAMP
Ramp cylinders
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Roméo et Juliette RAMP
Hydraulics viewed from under ramp in trap room
cylinders
Flow divider
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Roméo et Juliette RAMP
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Roméo et Juliette RAMP
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Roméo et Juliette SLIPSTAGE

• Two
• One , rated up to 5 GPM
• One
• One

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Roméo et Juliette SLIPSTAGE
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Roméo et Juliette SLIPSTAGE
Slipstage in out position
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Roméo et Juliette SLIPSTAGE
Cable drum
Hydraulic motor
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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

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Shop-Built Hydraulic Trainer
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Closed Loop vs. Open Loop
pressure line
pressure line
Return line
Return line
pressure line
pressure line
Return line
exhaust
inlet
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DESIGNING A SYSTEM

• Determine System Parameters
• Perform System Calculations
• Choose System Components

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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?

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B. System Calculations

• FORCE / TORQUE
• lbs of force
• in lbs of torque
• SPEED / FLOW
• time for stroke
• time for rotation

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AREAPRESSURE / 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
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calculate AREAPRESSURE /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

load
cylinder
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examples AREAPRESSURE /force

• Force Pressure x Area
• Force (lb.) pressure (lb sq in) x area (sq in)
  
• 2 bore x ?? psi system pressure
• 1570 lb 500 psi x 3.14 (22x.7854) sq. in.
• 4710 lb 1500 psi x 3.14 (22x.7854) sq. in.
• 9420 lb 3000 psi x 3.14 (22x.7854) sq. in.

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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
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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
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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)

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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.

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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

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C. System Components
DCV (Directional Control Valve)
Other control devices (pressure,flow, etc)
Power unit (pump)
Actuator (cylinder)
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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

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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

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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

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CENTER CONFIGURATIONS
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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

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Mobile (Ag) style valves
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Industrial (Manifold) style valves
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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

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Mobile (Ag) style cylinders
Tie-Rod Cylinder
Welded Cylinders
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Industrial (NFPA) Cylinders
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OTHER CONTROL DEVICES

• Pressure Control (force)
• Flow Control (speed)
• Additional controls
• Safety Devices
• Additional filtering
• Electrics/Electronics
• Counterbalancing
• Flow dividing

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Recommended HIGH LEVEL 4000-5000
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Recommended LOW LEVEL 2000-2500
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Recommended Systems ADD-ONS

• Combine two systems
• Power Unit
• Second power unit
• Additional Valves
• Industrial-solenoid proportional w/ electronic
  card
• Actuators
• Additional cylinders
• Rotary actuator
• Accessories
• Flow divider
• More hoses

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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!!!

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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.
• .

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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
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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.

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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
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Counterbalance
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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
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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'. .

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Counterbalance Circuit 1
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An Introduction to HydraulicsUSITT-
Minneapolis 2003

• Notes available at
• http//www.nwmissouri.edu/7Epimmel/usitt/tech_pro
  d/TECH_PROD_INDEX.HTM
• Contact me at
• kordertv_at_uiuc.edu