AirSpring. - Firestone

TRAILING ARM SUSPENSION
CALCULAT|ONS
The trailing arm design is a common truck and
trailer air suspension. The air spring does not carry
the same load that is applied at the wheel (axle). The
formulas developed in Section 6 are used.
One method of obtaining a trial suspension
design follows for a 20,000 lb axle, using a 1T15M-6
reversible sleeve air spring at 13 inch height.
Determine the necessary trailing arm ratio needed
to support the axle design load within the air spring
maximum allowed static pressure of 100 psig which
creates a lifting force of 7,045 lb at a 13 inch height.
See Product Data Sheet (W01-358-9082).
Assume an unsprung weight of 800 lb
Load at wheel Lw (20,000- 800) + 2 9600 lb.
LAR
Lw 9600
Ls 7045
1.36 using the M-6 at 100 psig
For this example a 90 psig operating pressure will be used.
LAR
Lw 9600
---1.52 using the M-6 at 90 psig
Ls 6340
FRAME
/
( WHEEL
Note, the 6340 lb at 90 psig is calculated by multiplying the pressure ratio
times the load at 100 psig, or:
90
--x 7045- 6340 lb
100
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