Firestone EMDG198 - Manual (Page 16)

16
Angular Capability continued
These measurements must fall within the guide lines for that
particular part. Consider style #22 in the following scissors
arrangement:
Reversible sleeve Type 1T parts may also stroke through an
arc. In this case, care must be taken to prevent the bellows from
rubbing (internally) against itself where it rolls over the piston:
HORIZONTAL MISALIGNMENT
The upper and lower bead plate centers (or mounting plate
centers in the case of a bead ring type attachment) may be out
of line somewhat without injury to the bellows. Our “rule of
thumb” for convoluted type Airstrokes is one inch misalignment
allowed per convolution. So, a single convoluted air spring
may be out of line by as much as 1 inch, a double by 2 inches,
and a triple convoluted air spring by 3 inches.
DESIGN ENVELOPE
Adequate clearance should be provided around the Airstroke
to prevent puncturing or rubbing of the bellows. The maximum
diameter @ 100 psig for each Airstroke (bellows) is located
just above the cross-sectional view of the air spring.
STACKING
It is permissible to stack Airstrokes (one on top of another) to
increase stroke; however, the center plate (or plates) connect-
ing the two or more Airstrokes MUST BE GUIDED.
Please note that the air spring forces are not additive in this
configuration. A method for guiding, which also illustrates one
center ring concept for mounting the two parts together at the
middle, is illustrated below:
FAIL SAFE DEVICES
Some applications require the use of fail safe mechanisms
(such as a mechanical lock-out on a scissors lift) to prevent
damage or injury in the event of an air system failure.
VACUUM
An Airstroke can withstand a small amount of vacuum without
injury to the bellows. The maximum amount of acceptable vacu-
um is dependent upon the bellows’ size, the height in use, and
whether it is a two ply or high strength (fabric) air spring. (A high
strength Airstroke bellows has a “stiffer” wall than a two ply;
therefore, it is less susceptible to dimpling and deformation
inward). It is generally best to use only single convoluted air
springs under vacuum.
An Airstroke Design Parameter Worksheet
can be found on page 103.
Max Ht
(Must be ≤ 10.1)
Bellows must
not rub against
itself here.
Max Ht
(Must be ≥ 3.0)
Calculate
Force Here
Pivot
Point
#22
Center Ring
Customer Must
Supply Button
Head-Socket Head
Cap Screws