Bendix E-12-E-15 BRAKE VALVE User Manual
®
Bendix® E-12™ & E-15™ Dual Brake Valve
TREADLE
SD-03-826
UPPER
BODY
ASSEMBLY
PRIMARY
DELIVERY
DEL-1
( )
21
SECONDARY
DELIVERY
DEL-2
( )
22
LOWER
BODY
ASSEMBLY
FIGURE 1 - E-12™ AND E-15™ DUAL BRAKE VALVES
EXHAUST
MOUNTING
PLATE
PRIMARY
SUPPLY
SUP-1
( )
PRIMARY
SUPPLY
SUP-2
( )
DESCRIPTION
The E-12™ and E-15™ dual brake valves are floor mounted,
treadle operated type brake valves with two separate supply
and delivery circuits for service and secondary braking. The
separation of circuits provides the driver with a graduated
control for applying and releasing the vehicle brakes.
The E-12™ and E-15™ brake valves are similar in design with
the exception of the rubber spring (9) and spring retainer (7)
located in the upper body . The rubber spring which is used
in the E-12™ brake valve alters the performance of the valve
such that the primary circuit delivers full reservoir pressure
to the spring brakes with less treadle travel than that of the
E-15™ brake valve. See Figure 2 for delivery pressure versus
treadle travel diagram. The greater treadle travel of the E-15
brake valve yields a more gradual delivery of air to the spring
brakes resulting in a less sensitive “feel” to the driver when a
brake application is made. This characteristic makes the
E-15™ brake valve more adaptable to transit vehicle applications where smooth brake applications contribute to
passenger comfort.
11
SECONDARY
DELIVERY
12
The E-12™ and E-15™ valves are designed such that the
treadle does not sit in an upright position until the air system is built up to full reservoir pressure. The supply pressure
moves the primary piston upward transmitting a mechanical
force to the spring retainer and plunger of the treadle
assembly , causing the treadle to move upright.
E-12™ DUAL
BRAKE VALVE
™
(PSI)
↑↑
↑
PRIMARY DELIVERY
FIGURE 2 - TREADLE TRAVEL VERSUS DELIVERY
PRESSURE
↑↑
TREADLE TRAVEL
PRIMARY DELIVERY
E-15™ DUAL
BRAKE VALVE
(PSI)
↑↑
↑
↑↑
TREADLE TRAVEL
PRIMARY
DELIVERY
DEL-1
( )
21
DEL-2
( )
22
1
26
30
27
28
29
7
6
8
9
15
14
13
12
11
10
17
12
13
14
FIGURE 3 - E-12™ DUAL BRAKE VALVE CROSS
SECTIONAL VIEW
15
25
24
21
23
22
4
5
20
UPPER BODY
18
19
LOWER BODY
10
11
The circuits in the E-12™/E-15™ valves are identified as
follows: The no. 1 or primary circuit is that portion of the
valve between the primary piston (2) and the secondary
piston (18); the no. 2 or secondary circuit portion consists
of the area between the secondary piston and the exhaust
cavity .
™
/E-15
™
31
32
The supply , delivery and exhaust ports of the E-12
brake valves are identified by designations cast into the valve
body adjacent to their associated port. (See Figure 1). The
primary supply and delivery ports are located in the upper
body portion while the secondary supply and delivery ports
are located in the lower body portion of the valve.
The primary circuit of the valve is similar in operation to a
1
2
3
4
standard single-circuit air brake valve and under normal
operating conditions the secondary circuit is similar in
operation to a relay valve.
Both the primary and secondary circuits of the brake valve
use a common exhaust protected by an exhaust diaphragm.
OPERATION
APPLYING: NORMAL OPERATION-PRIMARY
CIRCUIT PORTION
When the brake treadle (26) is depressed, the plunger (27)
exerts a force on the spring retainer (7), graduation spring
(8) and primary piston (2). The primary piston, which contains the exhaust valve seat closes the primary circuit
exhaust valve. As the exhaust valve closes the inlet valve for
the primary circuit moves off of its seat allowing the air from
the supply port of the primary circuit to flow out the delivery
port of the same circuit.
TRAILER
CONTROL
VALVE
BRAKE
SLACK
ADJUSTER
FIGURE 4 - TYPICAL PIPING SCHEMATIC
CHAMBER
DUAL BRAKE
VALVE
AIR DRYER
COMPRESSOR
™
MV-3
MODULE
SUPPLY
RESERVOIR
#1 SERVICE
RESERVOIR
™
TRACTOR
TP-5
PROTECTION
DOUBLE
CHECK
VALVE
#2 SERVICE
RESERVOIR
SLACK
ADJUSTER
SPRING
BRAKES
QUICK
RELEASE
VALVE
™
BP-R1
BOBTAIL
PROPORTIONING
VALVE
2
SUP-1
PLUNGER
FORCE
2
7
8
SUP-1
PLUNGER
FORCE
2
DEL-1
18
SUP-2
EXHAUST
FIGURE 5 - APPLYING - NORMAL OPERATION FIGURE 6 - APPLYING - FAILURE IN THE PRIMARY
APPLYING: NORMAL OPERATIONSECONDARY CIRCUIT PORTION
The relay piston moves down with the primary piston and
closes the secondary circuit exhaust. When the inlet valve
in the primary portion of the valve is moved off its seat, air
passes through the bleed passage in the lower portion of
the upper body and enters the relay piston cavity. The air
DEL-2
SUP-2
EXHAUST
CIRCUIT
BALANCED: PRIMARY CIRCUIT PORTION
When the primary delivery pressure acting upon the primary
piston (2), equals the resultant mechanical force of the brake
treadle application, the primary piston will close preventing
further air flow from the supply to the delivery port of the
brake valve. The exhaust valve remains closed preventing
the escape of air through the exhaust port.
moves the relay piston (18) downward and opens the secondary inlet valve, allowing the air from the secondary supply
to flow out the delivery port of the same circuit.
PLUNGER
FORCE
2
7
APPLYING: LOSS OF AIR IN THE PRIMARY
CIRCUIT
DEL-1
DEL-2
If air is lost in the primary circuit, the valve will function as
follows: As the brake pedal is depressed and no air pressure is present in the primary circuit, the primary piston (2)
will mechanically move the relay piston closing the secondary exhaust and opening the inlet valve of the same circuit
allowing air flow from the secondary supply to its associated delivery port.
APPLYING: LOSS OF AIR IN THE SECONDARY
CIRCUIT
If the air is lost in the secondary circuit, the primary circuit
will function as described above under Normal Operation:
Primary circuit portion.
8
SUP-1
DEL-1
18
SUP-2
EXHAUST
FIGURE 7 - APPLYING - FAILURE IN THE SECONDARY
CIRCUIT
DEL-2
3
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