BENDIX TP-3DC TRACTOR PROTECTION VALVE Manuale - Pagina 2

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TRACTOR CONTROL

(PRIMARY)

TRACTOR

CONTROL

(SECONDARY)

STOP LIGHT

SWITCH

PLUNGER

TRACTOR

SUPPLY

AUXILIARY SUPPLY

™

FIGURE 2 - TP-3DC

TRACTOR PROTECTION VALVE WITH

DOUBLE CHECK SECTIONAL VIEW

TRAILER

SUPPLY VALVE

TRAILER

CONTROL VALVE

DOUBLE CHECK VALVE

FIGURE 3 - PARTIAL AIR BRAKE SYSTEM SCHEMATIC WITH TP-3DC

CHECK

DIAPHRAGM

GUIDE

VALVE SPRING

TRAILER

CONTROL

CHECK VALVE

SPRING

TRAILER

SUPPLY

(TO TRACTOR

SPRING BRAKES)

OPERATION

INITIAL CHARGE

As shown in Figure 4, during initial charge air pressure

™

enters the TP-3DC

tractor supply port (TRAC SUP). In

addition to passing through the TP-3DC

the trailer and auxiliary supply lines, supply air moves the

plunger, against valve spring pressure, into contact with

the guide. With approximately 45 psi at the tractor supply

port, the inlet valve opens. The TP-3DC

normal "run" mode, ready to receive and deliver a service

brake application from the foot valve or hand valve.

SERVICE BRAKE APPLICATION

Figure 5 shows a normal service brake application. Supply

air holds the valve open, and the TP-3DC

service air from the primary and secondary service

circuits on the tractor. The greater pressure of the two (the

secondary service circuit double check valve delivers the

greater of foot valve secondary delivery and trailer hand

control valve delivery) will cause the TP-3DC

internal check valve diaphragm to seal the port with the

lower pressure. The higher pressure will then ﬂ ow out the

open inlet to the trailer control line. Figure 5 shows an

application with primary service air as the greater pressure.

Note that service air pressure also activates the stop light

switch, and it ﬂ ows to the single check valve. However, with

supply pressure acting on the opposite side of the single

check valve, the valve remains closed.

TRACT

CONT

TRAC

CONT

STP LT

TRAC

SUP

Embossed I.D.

TRAC SUP

AUX SUP

TRACT CONT

TRAC CONT

STP LT SW

TRLR SUP

TRLR CNTL

™

TRACTOR PROTECTION VALVE WITH DOUBLE

™

valve to and out

™

valve is now in the

™

valve receives

™

TRLR CNTL

TRLR

SUP

AUX

SUP

Thread Size

1/4"-18 NPT

3/8"-18 NPT

1/4"-18 NPT

1/2"-14 NPT

valve's