Sizing criteria for cylinders and servocylinders - ATOSdb95b641-9889-4ff4-bb91-f3ae691f4a2b/B015.… · SWCis a smart software for fast and efficient design of Atos hydraulic Cylinders

SWC is a smart software for fast and efficient design of Atos hydraulic Cylinders & Servocylinders, available for download at www.atos.com in 4 languages: English, Italian, French, German. The codes’ assisted selection and the cylinder’s sizing module drive the user to identify the bestsolution for any application. The 3D tool permits then to include the cylinder’s model into machines or systems overall mechanical design.

2 HYDRAULIC FORCES AND DYNAMIC LIMITS

B015

1 SWC Cylinders Designer

2.1 Hydraulic forcesTo ensure the correct cylinder functioning it is necessary to check that the hydraulic force Fp is upperthan the algebraic sum of all the counteracting forces acting on the cylinder:

Ff are the friction forces of the system, m.a the inertial forces and m.g the weight force (only for ver-tical loads). For gravity acceleration consider g = 9,8 m/s2.For Fp values refers to section , otherwise Fp, A1, A2 and speed V can be calculated as follow:3

The table below reports the push/pull sections and forces for three different working pressures.

3 SIZING

Once the push/pull forces are known, the size of the hydraulic cylinder can be choosen from the table below. The values have been determined using theformulas in section .2

Sizing criteria for cylinders and servocylinders

Table B015-15/Ewww.atos.com

Bore [mm]

Rod [mm]

A2 Pulling area [cm2]

50403225

126,5

6,5

63 80 100

18 14 22 183,8 2,4 4,2 10,0

22 28 22 28 36 28 36 45 36 45 56 45 56 708,8 6,4 15,8 13,5 9,5 25,0 21,0 15,3 40,1 34,4 25,6 62,6 53,9 40,1

3,8 2,4 4,2 10,0 8,8 6,4 15,8 13,5 9,5 25,0 21,0 15,3 40,1 34,4 25,6 62,6 53,9 40,1

6,0 3,8

9,4 5,9

10,4

16,3

6,8

10,6

16,0

25,1

14,0

21,9

10,3

16

25,3

39,6

21,6

33,7

15,1

23,6

40,0

62,5

33,6

52,5

24,4

38,2

64,1

100,2

55,0 41,0 100,2 86,3 64,1

85,9 64,1 156,6 134,8 100,1

p=100 bar

p=160 bar

p=250 bar

Pull force[kN]

Bore [mm]

Rod [mm]

A2 Pulling area [cm2]

160140

98,1

98,1

200 250 400

56 70 90

84,2 59,1

90 70 90 110 110 90 110 140 140 180 180 220 220 280

90,3 162,6 137,4 106,0 159,4 250,5 219,1 160,2 336,9 236,4 549,8 424,1 876,5 640,9

84,2 59,1 90,3 162,6 137,4 106,0 159,4 250,5 219,1 160,2 336,9 236,4 549,8 424,1 876,5 640,9

156,9

245,2

134,8

210,6

94,6

147,8

144,5

225,8

260,1

406,4

219,9

343,6

169,6

265,1

255,1

398,6

400,9

626,4

350,6

547,8

256,4

400,6

539,1

842,3

378,2 879,6 678,6 1.402,4 1.025,4

591,0 1.374,4 1.060,3 2.191,3 1.602,2

p=100 bar

p=160 bar

p=250 bar

Pull force[kN]

180 320

Bore [mm]

A1 Pushing area [cm2] 4,9

4,9

25 32 40

8,0 12,6

50 63 80 100 125 140 160 180 200 250 320 400

19,6 31,2 50,3 78,5 122,7 153,9 201,1 254,5 314,2 490,9 804,2 1.256,6

8,0 12,6 19,6 31,2 50,3 78,5 122,7 153,9 201,1 254,5 314,2 490,9 804,2 1.256,6

7,9

12,3

12,9

20,1

20,1

31,4

31,4

49,1

49,9

77,9

80,4

125,7

125,7

196,3

196,3

306,8

246,3

384,8

321,7

502,7

407,2

636,2

502,7

785,4

785,4 1.286,8 2.010,6

1.227,2 2.010,6 3.141,6

p=100 bar

p=160 bar

p=250 bar

Push force[kN]

PUSH FORCE [kN]

PULL FORCE [kN]

125

Main SWC features:• 2D cylinder with overall dimensions in DXF format• 3D cylinder visualization & file export in IGES, SAT and STEP formats• Cylinder’s sizing module to check the buckling load, the cushioning effects and the cylinder expected working life• Specific technical documentation and spare parts tables• Trolley function for offer requests, orders, bill of materials, etc

cVmax = ––––––––– [mm/s]

ttot - tmin

2.2 Dynamic limits due to oil elasticityThe calculation of the pulsing value wo of the cylinder-mass system allows to define the minimumaccleration/deceleration time tmin, the max. speed Vmax and the min. acceleration/decelerationspace Smin to not affect the functional stability of the system. Calculate wo, tmin, Vmax and Smin withthe below formulas. Flexible piping or long distances between the directional valve and the cylindermay affect the stiffness of the system, thus the calculated values may not be reliable.

Note: for mineral oil consider E = 1,4•107 kg/cm·s2

35 tmin = ––––– [s]

wo

Vmax • tminSmin = ––––––––– [mm]

2

rads

Quantity Unit Symbol

ForcePressureSectionBore sizeRod diameterCylinder strokeFlow rateSpeedAccelerationLoad massOil modulus of elasticity Total time at disposal

Nbarcm2

mmmmmml/minm/sm/s2

kgkg/cm·s2

s

Fp

pADdcQVamEt tot

Vmax

amax

Spee

d

tmin tmin

t tot

Time

P1

P2 A2 A1

V1

D

V2

m

h2 h1d

Symbols

Fp ³ m.a + Ff + m.g

Cylinder speed

Pushing area

Pulling area

Hydraulic force

Fp = p1•A1–p2•A2 •10 [N]

www.atos.com

100

1.000

10.000

1 10 100 1.000

iidide

idea

idea

lid

eal

idea

l lid

eal l

eid

eal l

enid

eal l

eng

idea

l len

gt

idea

l len

gth

idea

l len

gth

id

eal l

eng

th [

idea

l len

gth

[m

idea

l len

gth

[m

mid

eal l

eng

th [

mm

]id

eal l

eng

th [

mm

] id

eal l

eng

th [

mm

] --

llolog

log

lo

g s

log

sc

log

sca

log

sca

llo

g s

cale

log

sca

le

PPuPusPushPush Push fPush foPush forPush forcPush forcePush force Push force [Push force [kPush force [kNPush force [kN]Push force [kN] Push force [kN] -- llologlog log slog sclog scalog scallog scalelog scale

For cylinders working with push loads, thebuckling load’s checking has to be conside-red before choosing the rod size. This checkis performed considering the fully extendedcylinder as a bar having the same diameterof the cylinder rod (safety criteria):

1. determine the stroke factor “Fc” depen-ding to the mounting style and to the rod endconnection, see table at side

2. calculate the “ideal lenght” from the equa-tion:

ideal length = Fc x stroke [mm]

If a spacer has been selected, the spacer’slength must be added to the stroke

3. calculate the Fp push force as indicated insection or using the formulae indicated insection

4. obtain the point of intersection betweenthe push force and the ideal length using therod selection chart 5.2

5. obtain the minimum rod diameter from thecurved line above the point of intersection

3

2

Pivoted andrigidly guided

A, E, K, N,T, W, Y, Z

5.2 Rod selection chart

Type of mountingStyle Rod end connection Fc

B, P, V

G

B, P, V, L

A, E, K, N,T, W, Y, Z

B, P, V

C, D,H, S

C, D,H, S

Fixed andrigidly guided

A, E, K, N,T, W, Y, Z

Fixed andrigidly guided



Supported butnot rigidly guided




0,5

0,7

1,0

1,0

1,5

2,0

2,0

4,0

4,0

5 CHECK OF THE BUCKLING LOAD

- Nominal pressure 16 MPa (160 bar) - max. 25 MPa (250 bar)- Bore sizes from 250 to 400 mm- Rod diameters from 140 to 220 mm

4 CHOICE OF THE CYLINDER SERIES




SERIES CK/CH - tab. B137 - B140 to ISO 6020-2 SERIES CH BIG BORE SIZE - tab. B160 to ISO 6020-3

SERIES CN - tab. B180 to ISO 6020-1 SERIES CC - tab. B241 to ISO 6022

5.1 Calculation of the ideal lenght

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

100.000 1.000.000 10.000.000 100.000.000

WWo

Wor

Wor

kW

orki

Wor

kin

Wor

king

Wor

king

W

orki

ng p

Wor

king

pr

Wor

king

pre

Wor

king

pre

sW

orki

ng p

ress

Wor

king

pre

ssu

Wor

king

pre

ssur

Wor

king

pre

ssur

eW

orki

ng p

ress

ure

Wor

king

pre

ssur

e [

Wor

king

pre

ssur

e [b

Wor

king

pre

ssur

e [b

aW

orki

ng p

ress

ure

[bar

Wor

king

pre

ssur

e [b

ar]

Wor

king

pre

ssur

e [b

ar]

CCyCycCyclCycleCyclesCycles Cycles -- llologlog log slog sclog scalog scallog scalelog scale

BBoBorBoreBore Bore sBore siBore sizBore sizeBore sizesBore sizes Bore sizes fBore sizes frBore sizes froBore sizes fromBore sizes from Bore sizes from 2Bore sizes from 25Bore sizes from 25 Bore sizes from 25 tBore sizes from 25 toBore sizes from 25 to Bore sizes from 25 to 1Bore sizes from 25 to 10Bore sizes from 25 to 100Bore sizes from 25 to 100 Bore sizes from 25 to 100

25/1222525/25/125/12

32/1433232/32/132/14

44040/40/140/1840/18 40/18 &40/18 & 40/18 & 840/18 & 8040/18 & 80/40/18 & 80/340/18 & 80/3640/18 & 80/36 40/18 & 80/36

66363/63/263/2863/28 63/28 &63/28 & 63/28 & 163/28 & 1063/28 & 10063/28 & 100/63/28 & 100/463/28 & 100/4563/28 & 100/4550/2255050/50/250/22

40/2244040/40/240/22

55050/50/350/3650/36 50/36 H50/36 H 50/36 H &50/36 H &150/36 H &1050/36 H &10050/36 H &100/50/36 H &100/750/36 H &100/7050/36 H &100/70 HH80/5688080/80/580/56 HH

40/2844040/40/240/28 HH

32/2233232/32/232/22 HH

66363/63/463/4563/45 63/45 H63/45 H

6 PREDICTION OF THE EXPECTED CYLINDER’S MECHANICAL WORKING LIFE

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

100.000 1.000.000 10.000.000 100.000.000

PPr

Pre

Pre

sP

ress

Pre

ssu

Pre

ssur

Pre

ssur

eP

ress

ure

Pre

ssur

e [

Pre

ssur

e [b

Pre

ssur

e [b

aP

ress

ure

[bar

Pre

ssur

e [b

ar]

Pre

ssur

e [b

ar]

CCyCycCyclCycleCyclesCycles Cycles -- llologlog log slog sclog scalog scallog scalelog scale

BBoBorBoreBore Bore sBore siBore sizBore sizeBore size Bore size fBore size frBore size froBore size fromBore size from Bore size from 1Bore size from 12Bore size from 125Bore size from 125 Bore size from 125 tBore size from 125 toBore size from 125 to Bore size from 125 to 4Bore size from 125 to 40Bore size from 125 to 400Bore size from 125 to 400

200/140220200200/200/1200/14200/140160/110 116160160/160/1160/11160/110160/110 &160/110 & 160/110 & 250/180160/110 & 2160/110 & 25160/110 & 250160/110 & 250/160/110 & 250/1160/110 & 250/18160/110 & 250/180

116160160/160/9160/90160/90

112125125/125/9125/90125/90 125/90 H125/90 H200/110, 220200200/200/1200/11200/110200/110,200/110, 250/140 200/110, 2200/110, 25200/110, 250200/110, 250/200/110, 250/1200/110, 250/14200/110, 250/140200/110, 250/140 &200/110, 250/140 & 200/110, 250/140 & 200/110, 250/140 &

200/140 220200200/200/1200/14200/140200/140 H200/140 H

160/110 116160160/160/1160/11160/110160/110 H160/110 H

320/180332320320/320/1320/18320/180

320/220332320320/320/2320/22320/220

125/70112125125/125/7125/70

125/56112125125/125/5125/56

160/70116160160/160/7160/70

220200200/200/9200/90200/90

160

100

250

160

100

250

B015

Rod life cycles - log scale

Working

press

ure [bar]

Rods fatigue life for bore sizes from 25 to 100 mm


Working

pressure [bar]


The rod thread is the cylinder’s max critical part, thus the expected cylinder’s working life can be evaluated by the prediction of the expected rod thread fatiguelife. The fatigue rod fractures take place suddenly and without any warning, thus it is always recommended to check if the rod is subject to fatigue stress (notnecessary if the cylinder works with push loads) and thus if the expected rod threads fatigue life may become an issue in relation to the required cylinderworking life. The charts below do not include the rods which are fatigue-free for working pressures over 250 bar. The curves are referred to ideal working condi-tions and do not take into account misalignments and transversal loads that could decrease the predicted life cycles. The charts are intended valids for all thecylinders and servocylinders series with standard materials and sizes (section 6.2) or option K “Nickel and chrome plating” rods (section 6.3). For the evaluationof the expected fatigue life of stainless steel rods (CNX series), contact our technical office. For double rod executions the mechanical working life calculationdoes not apply to secondary rods since the thread is weaker than the primary rods.

6.1 Mechanical working life calculation procedure1. Identify the curve of proper rods fatigue life graph according to the selected bore/rod size and rod treatment. Fatigue-free bore/rod couplings are notincluded in the graphs.

2. Intersect the working pressure with the curve corresponding to the rod under investigation and determine the expected rod life cycles. If the calculatedrod fatigue life is lower than 500.000 cycles a careful analysis of our technical office is suggested.

6.2 Rods fatigue life charts for standard rod

Note: the curves are labelled according to the bore/rod size. The light male thread (option H) is indicated by the “H” after the rodExample: label 125/90 H means bore = 125 mm, rod = 90 mm and rod with option H

& 400/220

7 CHECK OF THE HYDRAULIC CUSHIONING

Stroke-end

RealIdeal

Pmax

Pressure

Stroke

Stroke-end

SoftViolentS

pee

d

Stroke

Pressure in the cushioning chamber

Speed during cushioning

7.1 Functioning features

Hydraulic cushionings act as “dumpers” to dissipate the energy of a mass connected to the rodand directed towards the cylinder stroke-ends, reducing its velocity before the mechanical contact,thus avoiding mechanical shocks that could reduce the average life of the cylinder and of the entiresystem. Cushioning proves to be effective as much as the pressure inside the cushioning chamber getsclose to the ideal profile described in the diagram at side. The diagram compares the ideal profilewith typical cylinders real pressure profile.

7.2 Application featuresThe following guidelines refer to CK, CH, CN and CC cylinders: for CH big bore sizes, contact ourtechnical office. In order to optimize the performances of cushioning in different applications, threedifferent cushioning versions have been developed:

- slow version, with cushioning adjustment, for speed V £ 0,5 • Vmax- fast version, without adjustment, for speed V > 0,5 • Vmax- fast version, with cushioning adjustment, for speed V > 0,5 • Vmax

Adjustable cushionings are provided with needle valve to optimize the cushioning performances.The maximum permitted speed value Vmax depends to the cylinder size, see table below.

ø Bore[mm]

Vmax[m/s]

25 32 40 50 63 80 100 125 160 200

1 1 1 1 0,8 0,8 0,6 0,6 0,5 0,5

7.3 Max energy calculation procedureCheck the max energy that can be absorbed by the selected cushioning as follow:

1. calculate the energy to be dissipated E by the algrebraic sum of the kinetic energy Ec and thepotential energy Ep (for horizontal applications the potential energy is: Ep = 0)

E =Ec +Ep

- Ec (kinetic energy) due to the mass speed

Ec =1/2 • M • V2 [Joule]

- Ep (potential energy) due to the gravity and related to the cylinder inclination angle α as shown at side

For front cushioning: For rear cushioning:

Ep= -Lf • M • g • sen α [Joule] Ep= + Lf • M • g • sen α [Joule] 1000 10002. identify the proper cushionings chart depending to the rod type, the cushioning side (front orrear), and the cylinder series (section 7.4 for CK, CH, CN cylinders or section 7.5 for CC cylinders)

3. intersect the working pressure with the proper bore/rod size curve and extract the correspondingEmax value

4. compare the Emax value with the energy to be dissipated E and verify that:

5. for critical applications with high speed and short cushioning strokes an accurate cushioningevaluation is warmly suggested, contact our technical office

α

p

M

V

E £ Emax

E = energy to be dissipatedEmax = energy max dissipableM = mass V = rod speed Lf = cushioning length (see section of tables B137, B140)g = acceleration of gravityconsider g=9,81 m/s2

a = inclination angle

12

Symbols

[J][J]

[kg][m/s][mm]

[m/s2]

[°]

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

100.000 1.000.000 10.000.000 100.000.000

125/90112125125/125/9125/90

100/70110100100/100/7100/70

88080/80/380/3680/36 80/36 &80/36 & 80/36 & 180/36 & 1080/36 & 10080/36 & 100/80/36 & 100/480/36 & 100/4580/36 & 100/45

116160160/160/7160/70160/70 160/70 &160/70 & 160/70 & 200/90220200200/200/9200/90

50550//22 22222 & && 63663//28228

112125125/125/5125/56125/56 125/56 &125/56 & 125/56 & 1125/56 & 16125/56 & 160125/56 & 160/125/56 & 160/9125/56 & 160/90125/56 & 160/90

88080/80/480/4580/45 80/45 &80/45 & 80/45 & 180/45 & 1680/45 & 16080/45 & 160/80/45 & 160/180/45 & 160/1180/45 & 160/11080/45 & 160/110

66363/63/363/3663/36 63/36 &63/36 & 63/36 & 163/36 & 1063/36 & 10063/36 & 100/63/36 & 100/563/36 & 100/5663/36 & 100/56

40440//22222

112125125/125/7125/70125/70 125/70 &125/70 & 125/70 & 2125/70 & 20125/70 & 200125/70 & 200/125/70 & 200/1125/70 & 200/11125/70 & 200/110125/70 & 200/110

160

100

250


Working

pressure [bar]


Note: the curves are labelled according to the bore/rod size

6.3 Rods fatigue life charts for Nickel and Chrome plating rod (option K)

B015

1

10

100

1.000

10.000

100.000

0 20 40 60 80 100 120 140 160

EEm

Em

aE

max

Em

ax

Em

ax [

Em

ax [

JE

max

[J]

Em

ax [

J]

Em

ax [

J] --

llolog

log

lo

g s

log

sc

log

sca

log

sca

llo

g s

cale

log

sca

le

WWoWorWorkWorkiWorkinWorkingWorking Working pWorking prWorking preWorking presWorking pressWorking pressuWorking pressurWorking pressureWorking pressure Working pressure [Working pressure [bWorking pressure [baWorking pressure [barWorking pressure [bar]Working pressure [bar]

FFrFroFronFrontFront Front cFront cuFront cusFront cushFront cushiFront cushioFront cushionFront cushioniFront cushioninFront cushioningFront cushioning Front cushioning -- sststastanstandstandastandarstandardstandard standard rstandard rostandard rodstandard rod standard rod

1

10

100

1.000

10.000

100.000

0 20 40 60 80 100 120 140 160

EEm

Em

aE

max

Em

ax

Em

ax [

Em

ax [

JE

max

[J]

Em

ax [

J]

Em

ax [

J] --

llolog

log

lo

g s

log

sc

log

sca

log

sca

llo

g s

cale

log

sca

le


FFrFroFronFrontFront Front cFront cuFront cusFront cushFront cushiFront cushioFront cushionFront cushioniFront cushioninFront cushioningFront cushioning Front cushioning -- iinintinteinterintermintermeintermedintermediintermediaintermediatintermediateintermediate intermediate aintermediate anintermediate andintermediate and intermediate and dintermediate and diintermediate and difintermediate and diffintermediate and diffeintermediate and differintermediate and differeintermediate and differenintermediate and differentintermediate and differentiintermediate and differentiaintermediate and differentialintermediate and differential intermediate and differential rintermediate and differential rointermediate and differential rodintermediate and differential rod intermediate and differential rod

1

10

100

1.000

10.000

100.000

0 20 40 60 80 100 120 140 160

EEmm

am

axm

ax

max

[[J[J]

[J]

[J]

--llolo

glo

g

log

slo

g s

clo

g s

calo

g s

cal

log

sca

lelo

g s

cale


RReReaRearRear Rear cRear cuRear cusRear cushRear cushiRear cushioRear cushionRear cushioniRear cushioninRear cushioningRear cushioning

25

7.4 Cushionings charts for CK - CH - CN cylinders

Notes:- the front cushionings graphs are labelled according to the bore/rod size, the rear cushionings graph is labelled according to the bore size- the curves are intended valid for mineral oil ISO 46 and a fluid temperature of 40-50 °C: the use of water or water-based fluids and higher/lower tempe-ratures can affect the cushioning performance because of high viscosity variations respect to standard mineral oil

- for adjustable versions the Emax value is referred to cushioning cartridge fully closed, the max energy to be dissipated may be increased opening thecushioning cartridge, thus reducing the max pressure reached in the cushioning chamber

- the cushionings charts have been determined with 250 bar maximum pressure admitted in the cushioning chamber

Front cushionings - standard rods

Front cushionings - intermediate & differential rods

Rear cushionings

Working pressure [bar]



Emax

[J] - lo

g sca

leEmax

[J] - lo

g sca

leEmax

[J] - lo

g sca

le

320/220 250/180 200/140

160/110 180/110

140/90

125/90

100/70

80/56 63/45

50/36

10

100

1.000

10.000

100.000

0 20 40 60 80 100 120 140 160

50

80

100

140

160 180 200 250 320

63

125

10

100

1.000

10.000

100.000

0 20 40 60 80 100 120 140 160

7.5 Cushionings charts for CC cylinders

Notes:- the front cushionings graphs are labelled according to the bore/rod size, the rear cushionings graph is labelled according to the bore size- the curves are intended valid for mineral oil ISO 46 and a fluid temperature of 40-50 °C: the use of water or water-based fluids and higher/lower tempe-ratures can affect the cushioning performance because of high viscosity variations respect to standard mineral oil

- for adjustable versions the Emax value is referred to cushioning cartridge fully closed, the max energy to be dissipated may be increased opening thecushioning cartridge, thus reducing the max pressure reached in the cushioning chamber

- the cushionings charts have been determined with 320 bar maximum pressure admitted in the cushioning chamber

Front cushionings

Rear cushionings



Emax

[J] - lo

g sca

leEmax

[J] - lo

g sca

le

B015

8 SEALING FRICTION AND IN / OUT SPEED RATIO

3. Verify that

If the equation above is not verified contact our technical office

8.2 Static and dynamic sealing friction

Sealing systems may affect the smooth rod motion, thusthe assessment of the sealing friction forces is recommen-ded in several applications like :

• Servoactuators with closed loop control • Servocylinders where high accuracy in rod positioning

is required• Cylinders with low speeds (<0,05 m/s)• Low pressure hydraulic systems ( <10 bar) where sea-

ling friction forces may have significant influence

The following sections allow to calculate both static anddynamic sealing friction according to the sealing systemselected for CK, CH and CK* servocylinders.

8.3 Sealing friction calculation procedure

Calculate the dynamic sealing friction as follow:

1. Intersect the speed with the proper curve depending tothe sealing system from the chart in section 8.4.

2. Extract the corresponding C value

3. Identify the proper diagram according to the sealingsystem (section 8.5)

4. Intersect the working pressure with the curve depen-ding to the Bore size.

5. Extract the corresponding A value

6. Fsf = A . (D + d) + C [N]considering D= Bore size [mm]; d= Rod size [mm]

Calculate the static sealing friction as follow:

1. Extract the C value corresponding to speed V = 0 m/s inthe chart in section 8.4

2. Identify the proper diagram according to the sealingsystem (section 8.5)

3. Intersect the working pressure with the curve depen-ding to the Bore size.

4. Extract the corresponding A value

5. Fsf = A . (D + d) + C [N]considering D= Bore size [mm]; d= Rod size [mm]

G1

G2-G4 G6-G7

G8

0

50

100

150

200

250

300

350

400

450

500

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45 0,5

Speed [m/s]

C

50-63

80

100

125

160

200

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120 140 160

25-32-40

50-63

80

100

125

160

200

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120 140 160

SEALING G1


A

25-32-40

50-63

80

100

125

160

200

0

2

4

6

8

10

12

14

16

0 20 40 60 80 100 120 140 160

SEALING G2 - G4 - G6 - G7


A

SEALING G8


A

8.5 Friction charts - A parameter vs pressure

8.4 Friction charts - C parameter vs speed

0

50

100

150

200

250

0,2 0,4 0,6 0,8 1 1,2

Rmin

Working

pressure [bar]

Total back pumpingNo leakages

Partial back pumpingPossible leakages

Basic sealing performances reported in the cylinders tech-nical tables are not sufficient for a comprehensive evalua-tion of the sealing system, the following sections reportadditional verifications about minimum in/out rod speedratio, static and dynamic sealing friction.

8.1 In / out speed ratio

Applications with low in/out rod speed ratio may involveleakages caused by partial “back pumping” of the oil trap-ped between the rod seals, thus it is recommended tocheck the correct back pumping with the diagram repor-ted below.

1. Determine the in/out speed ratio R of the cylinder

2. Intersect the working pressure with the curve below andextract the corresponding Rmin value admitted

R ³ Rmin

06/17

Documents

Sizing criteria for cylinders and servocylinders - ATOSdb95b641-9889-4ff4-bb91-f3ae691f4a2b/B015.… · SWCis a smart software for fast and efficient design of Atos hydraulic Cylinders