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MBS-1P Installation
Plumbing Instructions
Install the MBS-1P as follows:
NOTE: Because of volume considerations discussed later, the spring
brake valve may be supplied from either the "upstream" (glad-hand side)
or the "downstream" (relay side) of the MBS-1P. Wabash recommends
that it be supplied from the downstream side to help purge contaminates
from the anti-compounding supply line.
routed to the relay valve first, and from there, to the trailer emergency
valve (TEV). Circumstances where the TEV is supplied downstream of
the MBS-1P then 1/4" airline must be used from the R-12 to the TEV.
Wabash requires the following pneumatic plumbing:
equal the volume of between three and five feet of 3/8" tubing. The
volume of 1/4" tubing is about 40% that of 3/8" tubing of equal length.
Calculate tubing equivalents using the following formula:
Leq = equivalent length of the combined 3/8" and 1/4" tubes
L3/8 = actual length of 3/8" tubing
L1/4 = actual length of 1/4" tubing
Then:
Leq = L3/8 + (0.4 x L1/4)
The air volume in the tubing after the MBS-1P is a significant performance
factor. Leq must be between three and five feet.
18
1. Select a suitable mounting location near the front of the bogie.
2. Install the MBS-1P in the blue service line (see Figure 12).
3. Connect the port marked "SUP" to the glad-hand side.
4. Connect the port marked "DEL" to the relay valve side.
IMPORTANT: When the Trailer Emergency Valve (TEV) is supplied
downstream of the MBS-1P, the line from the MBS-1P must be
1. From "DEL" of MBS-1P, route 3/8" tubing to a tee at the relay valve.
2. From the tee at the top of the relay valve, route 1/4" tubing to the spring
brake valve anti-compounding port.
IMPORTANT: The line lengths are significant. The combined
volume in the two lines mentioned in steps 1 and 2 above must
Example:
3 feet of 3/8"
2.5 feet of 1/4"
Leq= 3 + 0.4 (2.5)= 4.0
®
322UX041
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