BENDIX TCH-008-044 Dépliant

Bulletin

Bulletin No: 

         Effective Date: 

     Cancels: 

Page:  1 of 

Subject:

DRAFT

There are many myths and much misinformation when it comes to minimizing the impact of contamination 

in the air braking system. Bendix Commercial Vehicle Systems LLC (Bendix) has found that the majority of 

the procedures available today do not reflect current recommended practices for air treatment and storage 

systems.  Chief among our concerns are the concepts that air system antifreeze or alcohol is often considered 

acceptable, along with the practice of draining air system reservoirs daily. 
Refer to Bendix Technical Bulletin TCH-008-042 which strongly discourages the use of alcohol in the air 

braking system. 

Recommended Reservoir Draining & Dryer Service Intervals 
Bendix discourages draining air system reservoirs daily when powered vehicles are equipped with a properly 

functioning desiccant type air dryer. Why?  Because daily draining tends to saturate an air system (with a 

properly functioning air treatment system) on initial charge, and because it also causes the system’s air 

compressor to work unnecessarily, thus reducing its durability. 
Refer to the chart below for recommended reservoir draining and air dryer service intervals for powered 

vehicles:

* If more than just a trace of moisture is found in any of the reservoirs if may be necessary to replace the desiccant cartridge.

 

 

  

Completely draining reservoirs can reduce the life expectancy of all of the components in the air braking 

system by flushing internal lubrication. Air dryers operate most efficiently when the reservoir pressures are 

between governor cut-in and cut-out.

System Design Limitations 
Total air system demand must be considered for proper sizing of the charging, treatment, and storage system 

on a powered vehicle. It is very important to take into account the number of axles   — and all auxiliary features 

for the entire vehicle combination   — as this will minimize the possibility of system freeze-up on combination 

including any trailers.  Air system leakage can cause contamination in the system by challenging the charging 

and air treatment system capacity. Please refer to Bendix Application Guidelines BW2600 for air dryers 

and BW2625 for air compressors. For acceptable air leakage recommendations refer to video BW2327.
 

TCH-008-044

1-9-2015

N/A

2

Standard

Line haul, city delivery

5 or less

900

25,000

3 months Every 3 years

Medium

Double trailer trains, light 

transit, light off-highway

8 or less

450

12,000

2 months Every 2 years

High

Multiple trailer trains, city 

transit, school bus, heavy 

duty off-road

11 or less

300

6,000

1 month

Every year