12
HOW TO USE
THE STATIC DATA CHART
We also refer to this chart as the load/deflection
(L/D) curve for an air spring. The force [1] is given
on the right hand axis vs. the air spring height [2]
as shown along the bottom axis; thus, load vs.
deflection. The internal volume [3] is also given
along the left hand axis, again vs. height [2]. It is
called static data because the air spring is in a
static, or non-moving, constant pressure condi-
tion. In almost all cases the static curves were run
using a two ply bellows; however,
where a four
ply bellows is available, use the two ply chart for it
also.
AIRSTROKE ACTUATION
The important considerations are minimum
height [4] (3.0 inches) and maximum recom-
mended height [5] (10.1 inches). Subtracting one
from the other gives the stroke potential for this
part (10.1 – 3.0 = 7.1 inches). As an actuator, the
entire stroke may be used,
or any potion thereof.
Ignore recommended airmount design height [6]
and the corresponding darkened line [7]. This
height is important in using the air spring as an
isolator (AIRMOUNT). It has nothing to do with
the concern here of actuation. To determine the
force at any given height, simply move up the
height line to where it intersects any of the static
pressure curves. Then move to the right and
read from the force scale [1].
EXAMPLE: At 80 psig, what is the force using a
#22 from 4.0 to 9.0 inches, or 9.0 – 4.0 = 5.0 inch
stroke? See [8] for force at 4.0 inches (7,180 #)
and [9] for force at 9.0 inches (4,670 #). This
example illustrates the primary difference
between Firestone Airstrokes and conventional
air cylinders. Air cylinders have a constant area
for the pressure to work against, or constant
effective area.
the effective area and force of an
air spring changes as the height changes.(There
is one exception: notice the plateau section of
reversible sleeve 1T type curves.)
Bumper Contact
(4.2 IN.)
MAX. HT.
11
10
9
8
7
6
5
4
3
2
1
11
10
9
8
7
6
5
4
3
2
1
12 11 10
9 8 7 6 5 4 3
MIN. HT.
[16]
[5]
[2]
HEIGHT IN.
V
OLUME (WITHOUT B
UMPER) CU IN.
x 100
[3]
FORCE LBS x 1000
[1]
Static Data
1227
[6]
Recommended
Airmount
Design Height
9.5 Inches
Do not use Airstroke in
shaded area without
consulting Firestone
[13]
752
120
100
80
60
40
20 Psig
Volume
100 Psig
[12]
349
[11]
4,280
4,670
[14]
[15]
[9]
7,180
[10]
[4]
[7]
[8]
