KCPA SAMPLE Hydraulic SYSTEMS Tom Korder [email protected]

KCPASAMPLE Hydraulic SYSTEMS

Tom [email protected]

16-Nov-02USITT Hydraulics TV Korder 2

Roméo et Juliette RAMP

• Two –

• One –, rated up to 5 GPM

• One – One –

2 2” bore x 36” stroke, double-acting, tie rod cylinders

$90 / $180

1 Flow divider - rated to 5 GPM $150

1 solenoid actuated/closed center/ industrial style valve

$120

1 ½” x ¼” x ¼” npt medium pressure Tee $40

4 ¼” npt x 36” 4000 psi hoses $20 / $80

2 ½” npt “pioneer” style couplers $18 / $36

2 ½” x 25’ 4000 psi hoses w/ couplers $40 / $80

TOTAL $700


Ramp cylinders



Ramp cylinders



cylinders

Flow divider


Hydraulics viewed from under ramp in trap room






Roméo et Juliette SLIPSTAGE

• Two –

• One –, rated up to 5 GPM

• One – One –

1 Low speed/high torque motor $250

1 Stock – cable drum drive unit NC

1 solenoid actuated/float center/ industrial style valve $120

1 sandwich style flow control valve, both A&B $200

2 ¼” npt “pioneer” style couplers $18 / $36

2 ¼” x 50’ 4000 psi hoses w/ couplers $60 / $120

TOTAL $726





Slipstage in “out” position



Cable drum

Hydraulic motor


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


Shop-Built Hydraulic Trainer


Closed Loop vs. Open Loop

Return line Return line

exhaustinlet

pressure linepressure line

pressure linepressure line

Return line


DESIGNING A SYSTEM

A. Determine System Parameters

B. Perform System Calculations

C. Choose System Components


A. 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

• FORCE / TORQUE– lbs of force– in lbs of torque

• SPEED / FLOW– time for stroke– time for rotation


AREA–PRESSURE / force

• Amount of force is determined by pressure pump can deliver– measured in psi – lbs per square inch

2”actuato

r

1000 psi 3000 psi

2000 lbs of force

2”actuato

r

6000 lbs of force


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

cylinder

load


examples AREA–PRESSURE /force

• Force = Pressure x AreaForce (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.


Multiplication of Force

F / A = P242 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

• rate of flow determined by pump delivery

• flow determines speed of devices– measured in GPM - gallons per minute

2”actuato

r

5 gpm 2.5 gpm

5 seconds

2”actuato

r

10 seconds


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• Flow = Area x stroke length x .26

time for strokeFlow (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• 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


DCV (Directional Control Valve)

C. System Components

Power unit (pump)

Actuator (cylinder)

Other control devices

(pressure,flow, etc)


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• 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

• Actuation method– manual, electrical, or fluid

• Rating– flow and pressure

• Center style– closed, open, float, or tandem

• Style of construction– mobile or industrial


CENTER CONFIGURATIONS


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


Mobile (Ag) style valves


Industrial (Manifold) style valves


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

Welded Cylinders

Tie-Rod Cylinder


Industrial (NFPA) Cylinders


OTHER CONTROL DEVICES

• Pressure Control (force)

• Flow Control (speed)

• Additional controls– Safety Devices– Additional filtering– Electrics/Electronics– Counterbalancing– Flow dividing


Recommended– HIGH LEVEL $4000-$5000

Power Units

1 power unit 5-7 GPM 1000–3000 psi 3 Ø 240 AC volts $1300

1 hand pump 5000 psi $200

Valves

1 ea tandem, closed, open centers industrial style manual actuation $360

1 ea tandem, closed, open centers industrial style solenoid actuation $360

Actuators

1 High Torque, Low Speed Motor $250

1 ea Tie-rod cylinder Min. 3000 psi 2” bore x 24” stroke

2” bore x 36” stroke

$70

$90

1 Telescoping cylinder Min. 3000 psi Equal to trap depth $700

4 Single-acting cylinders (ram) 1” bore x 2” stroke $200

Accessories

stack style valves counterbalance flow, pressure $500

Hoses with connectors $250


Recommended– LOW LEVEL $2000-$2500Power Units

1 AC power unit 1-2 GPM 500–1000 psi 1 Ø 120/240 $500

1 hand pump 5000 psi $200

Valves

1 ea tandem, closed, open centers Mobile style manual actuation $240

Actuators

1 High Torque, Low Speed Motor $250

1 ea Tie-rod cylinder Min. 3000 psi 2” bore x 24” stroke

2.5” bore x 48” stroke

$70

$110

4 Single-acting cylinders (ram) 1” bore x 2” stroke $200

Accessories

inline style valves – 1 flow, 1 pressure, 1 counterbalance

$250

Hoses $250


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


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(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 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

actuator

load

A

B


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 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

in

out pilot

pilot


Counterbalance


Counterbalance valve

in

outpilot

pilot

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.


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'. .


Counterbalance Circuit #1

““An Introduction to Hydraulics”An Introduction to Hydraulics”USITT- Minneapolis 2003USITT- Minneapolis 2003

Notes available athttp://www.nwmissouri.edu/%7Epimmel/usitt/tech_prod/TECH_PROD_INDEX.HTM

Contact me at:

[email protected]

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

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

mailto:[email protected]

mailto:[email protected]

Documents

KCPA SAMPLE Hydraulic SYSTEMS Tom Korder [email protected]