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Technical Data

Cushion Formulas andFactorsCushions are recommendedwhen piston speed is inexcess of 20-25 feet per minute. Cushions deceleratethe piston and rod assemblyat the end of the stroke, less-ening the noise and shockand increasing cylinder life.Heavy loads attached to thepiston and rod assembly should be stopped by exter-nal means, such as shockabsorbers, springs, decelerat-ing valves, etc.Use the information below,along with the examples onpage 25 to determine if stan- dard cushioning is sufficientfor your application.

FORCE FACTOR TERMINOLOGYTERM FORCE FACTOR CHART USEDEXPLANATIONUNITS Force Factors (a = v2 x .001294)(continued) WWeight of the loadpounds
PISTONVELOCITY PISTONVELOCITY AbBore areasquare inches
ipsa ipsa AhAb less rod areasquare inches 1.00129 26.875 AccAb less cap plunger cross-sectional areasquare inches 2.00518 27.944 AhcAb less head plunger cross-sectional areasquare inches 3.0117 281.02 aForce factor– 4.0208 291.09 sAcceleration or deceleration distanceinchesuCoefficient of friction of load’s motionHorizontal = .15; 5.0324 301.16 6.0466 311.24 Vertical = 0vVelocityinches per 7.0635 321.33 second (ips) 8.0829 331.41 FaccForce needed to accelerate a weightpounds 9.105 341.50 FdecForce needed to decelerate a weightpounds 10.129 351.59 FfFriction force due to load motionpounds 11.157 361.68 FpDriving pressure forcepounds 12.186 371.77 FtTotal cushioning forcepounds PpPump pressurepounds per 13.219 381.87 14.254 391.97

Acceleration andDeceleration Forces

square inch (psi)PcContained cushioning pressurepounds per 15.291 402.07 16.332 412.18 square inch (psi) 17.374 422.28 18.420 432.39 19.467 442.51 20.518 452.62

•The a force factors shownare used to determine theforces required to acceler- ate or decelerate a weightthrough a given distance,

21.571 462.74 22.627 472.86
Facc

or

Fdec

= (

W

x

a/s

) –

W

.•Friction due to load motionaffects

23.685 482.98 24.746 493.11
s Ft

. Add

Ff

to

Ft

if theload is accelerating.Subtract

25.809 503.24

(Refer to

Force Factor Chart

).•If the motion of the load ishorizontal, use the generalformula

Ff

from

Ft

if theload is decelerating.•Cylinder friction is negligible.Note The contained cushioningpressure must not exceed5000 psi. If the standard cushion results in a too highpressure, then a longer cush-ion spud must be specified.

GENERAL FORMULAS Facc Fdec W a/s Horizontal motion
Facc or
Fdec =
W x
a /s

or = x .•If the motion of the load isvertical and is being decel-erated downward or accel-erated upward, use thegeneral formula

Vertical motion, decelerating downward or accelerating upward
Facc or
Fdec = (
W x
a /s ) +
W Vertical motion, decelerating upward or accelerating downward
Facc or
Fdec = (
W x
a /s ) –
W Frictional force
Ff =
u x
W Facc

or

Fdec

= (

W

x

a/s

) +

W

.•If the motion of the load isvertical and is being decel-erated upward or acceler- ated downward, use thegeneral formula

Total cushioning force
Ft =
Facc or
Fdec +
Fp ±
Ff (+
Ff if load accelerating, —
Ff if load decelerating) Contained pressure
Pc =
Ft/Acc or
Ft/Ahc 24 EATON Hydro-Line Industrial Tie Rod Cylinders N5/AN5/LAN5 H-CYIG-TM002-E September 2003