BENDIX TCH-003-030 User Manual

Technical Bulletin

Bulletin No.: PRO-03-30 Effective Date: 1/1/91 Page: 1 of 3

Subject: E-1 Single Circuit Brake Valve Obsolescence And

Changeover

When our current stock of E-1 brake valves is depleted, this valve will no longer be
available for service replacement, either as new or remanufactured exchange. Because
of this obsolescence, those vehicles currently using the E-1 single circuit brake valve will
be required to changeover to a currently produced brake valve.

Background

The E-1 brake valve is of single circuit design and was primarily used on pre-1975 transit
and parlor coaches because of its generous graduating range. The larger graduating
range of the E-1 requires greater treadle movement per pound of air pressure delivered.
This fact results in the driver being able to more easily control small increases or
decreases in braking pressure which is sometimes desirable in coach operation.

Changeover Options

While several changeover options are possible the most appropriate are:

1. The E-1 can be replaced with the E-3 single circuit brake valve.

2. The E-1 can also be replaced with the E-10 dual circuit brake valve.

Each changeover option has some positive and negative aspects to be considered
before a choice is made.

E-1 to E-3 Changeover
Advantages

This changeover is the most easily accomplished since the existing vehicle air lines,
along with the treadle and mounting plate may be reused. The E-3, like the E-1, is a
single circuit brake valve. It is substantially shorter than the E-1 and is no larger in
diameter and therefore should present little or no physical fit problems. The E-3 is
equipped with four ½” PT delivery ports and two ½” PT and two ¼” PT supply ports. The
E-1 is equipped with a single ½” PT supply and four ½” PT delivery ports.
Refer to Figures 1 & 3. Reference catalog pages 03-C-2 & 3 for the E-1 and 03-E-1 to 4
for the E-3.

Disadvantages

The E-3 has a smaller graduating range than the E-1 and is therefore somewhat more
“sensitive” to treadle movement and hence delivery pressure increases and decreases.
The driver may perceive the E-3 brake valve as more sensitive or “touchier”.

E-1 to E-10 Changeover
Advantages

The E-10 dual circuit brake valve may be used to replace single circuit E-1 without
converting the entire coach to a dual brake system. The E-10 is the current standard on
many coaches today and more closely approximates the brake “feel” provided by the
E-1. The existing treadle and mounting plate can be reused on the E-10. Refer to
Figures 2 & 3. Reference catalog pages 03-C-2 & 3 for the E-1 and 03-J-1 & 2 for the
E-10.