Chevrolet 30 Series 1967 Service Manual page 278

BRAKES 5-64
HAND CONTROL VALVE
Removal
1. Exhaust air pressure from system.
2. Disconnect air lines from valve.
3. Remove bolts and washers securing valve bracket.
4. If valve is to be replaced with a new unit, remove
lock nut and nd control lever for installation on
2
replacement unit. Remove air line connector fittings
for installation on replacement unit.
Disassembly
1. Remove cover screw, name plate and cover.
2. Loosen nut and remove operating lever.
3. Scribe marks on valve body and cam housing to per­
mit proper reassembly.
4. Unscrew and remove housing collar.
5. Remove cam housing assembly, camshaft and cam.
Separate the individual parts.
. Remove adjusting bearing from cam housing.
6
7. Remove piston spring from body.
. Remove piston and piston cup from body. Remove
8
cup from piston.
9. Remove piston return spring from body.
10. Remove end cap and seal from body. Remove seal
from end cap.
11. Remove nut from inlet and valve spring retainer.
Remove valve disc.
12. Remove valve spring retainer from body.
13. Remove discharge valve spring from body.
Cleaning and Inspection
1. Clean all metal parts in mineral spirits. Make sure
all passages in valve body are open and clean.
2. Inspect internal bores in valve body and external
surfaces of piston which have sliding contact with
To Stop
Light Switch
Valve Guide
Body
Brake
Application
Valve
Delivery Port
To Trailer Brake
Service Line
Fig. 100—Double Check V a lv e
SERVICE OPERATIONS
Gasket
Shuttle Valve
Cover
From Trailer
Brake Hand
Control Valve
each other for evidence o f wear,
corrosion.
3. Inspect all metal parts for wear and deterioration
and replace if necessary. Replace all rubber parts.
Assembly
1. Position discharge valve return spring in body.
2. Install valve spring retainer in body.
3. Compress discharge valve return spring, install
valve disc and secure with nut.
4. Install new seal on end cap and install end cap in
body.
5. Install piston return spring in body.
. Install new piston cup on piston and install piston in
6
valve body.
7. Install piston spring in valve body.
. Install adjusting bearing in cam housing.
8
9. Install cam and camshaft in cam housing and place
assembly in position on valve body. Align scribe
marks made during disassembly. Secure by install­
ing collar.
10. Install operating lever and secure with nut.
11. Install cover and name plate and secure with pan
head screw.
Installation
1. If a new valve assembly is being installed, install
operating lever and shaft which were removed from
old unit. Also, install air line connector fittings in
inlet and outlet ports, using sealing compound on
connector threads. Keep sealing compound off first
two threads of fitting.
2. Position valve and secure with two bolts and lock
washers. Tighten bolts firmly.
3. Connect air lines to valve.
4. Build up air pressure in system and test valve
operation as previously directed under "Serv ice­
ability T ests" .
DOUBLE CHECK VALVE (Fig. 100)
Disassembly
Remove two cap screws and lock washers attaching
valve cover to body. Remove cover and gasket, then
remove shuttle valve and valve guide.
Installation
Wash all parts in a cleaning solution and wipe dry.
Examine all parts for corrosion or deterioration and
replace as necessary. Make sure shuttle valve will slide
freely back and forth in valve guide.
Assembly
Apply a thin coating of Lubriplate or equivalent to in­
side of valve guide. Place valve guide and shuttle valve
in body. Position cover on body, using new gasket. Install
cover cap screws and lock washers, and tighten evenly
and firmly.
scoring, o r
CHEVROLET TRUCK SERVICE M ANUAL