BENDIX TCH-001-040 产品宣传页

Bulletin

Bulletin No: 

Effective Date: 

Cancels: 

Page:  1 of 

Subject:

© 2011 Bendix Commercial Vehicle Systems LLC, a member of the Knorr-Bremse Group • 10/2011 •  All Rights Reserved.  

The Bendix

® 

ST-4

™

 safety valve is available for installation into the cylinder head of the Bendix

® 

Tu-Flo

®

 550, 

Tu-Flo

®

 750, BA-921

® 

and BA-922

®

 compressors to prevent excessive cylinder head pressure in the event the 

discharge line is blocked.  The excessive pressure typically results in compressor damage and may cause 
subsequent engine damage.  

These safety valves are installed in the unused compressor discharge port. During normal operation the air 
pressure in the compressor exerts a force on the safety valve piston, which is held against its seat by the safety 
valve spring.  When the operating pressure acting upon the safety valve piston exceeds the force of the safety 
valve spring, the safety valve piston opens and vents the pressure to atmosphere.  The safety valve is preset 
to relieve pressures above 250 psi and comes in a variety of thread sizes as shown in the table below.

Because these safety valves are designed specifi cally for this application, a standard safety valve must not be 
used in lieu of the valves shown here.

TCH-001-040

10/25/2011

PRO-01-40 dated 12/1/94 

1

®

131081 

(includes washer)

1/4-18

9/16”

2

250 psi

800154

1/2-14

7/8”

2

800533

3/4-16 7/8”

2

800534

M16

7/8”

2

801116

7/8-14

15/16”

2

ST-4

™

 Safety 

Valve

Hex 

Install In Unused 

Compressor Discharge Port

Hole

Typical Compressor 

Cylinder Head

Thread 

Size