Slack Adjusters

[Montana Dan]

Hello Everyone- Since I stated doing my own maintenance, can someone help me with the proper way to adjust the slack adjusters and how often this should be done. Although they should self adjust, my old maintenance shop always stated that they need periodic adjustment. Thanks for your help

[-Gramps-]

What's a slack adjuster?

[walt2137]

Dan this is a past from another site.

Walt

TESTING YOUR AIR BRAKES AND SLACK ADJUSTERS

Auto slack adjusters are used to maintain proper brake chamber
stroke
and lining to drum clearance during normal operation. The entire
slack
adjuster operates as a unit rotating with the brake camshaft as
brakes
are applied or released. THE MOST EFFICIENT BRAKING OCCURS WHEN PUSH
ROD TRAVEL IS HELD TO A MINIMUM.
Auto Slack Adjusters adjust themselves automatically during full
brake
applications to accommodate brake lining and drum wear. The key
words
here are FULL BRAKE APPLICATIONS. Have you ever engaged your brakes
full.... pedal to the floor... probably not many have. But there is
way to do this properly to ensure you get your auto adjusters to
work
for you. If you have never fully depressed this pedal it is likely
that your auto adjust system has not been fully activating its full
adjustment potential. DO NOT RUN OUT AND DO IT NOW....DO THE
FOLLOWING
PROCEDURE TO ENSURE THE SAFETY OF YOUR BRAKING SYSTEM AND THAT YOU
DO
NOT DAMAGE IT.
Following is a procedure that should be done every day before you
start your drive. Certainly, it should be done if your unit has been
sitting for a time without use. This will tell you if your air brake
system is functioning satisfactorily and will also adjust your slack
adjusters.
1.Start engine and let air pressure build up.
2.Block wheels (use chocks that can be purchased from an RV supply
store and chock
the outside dual on each side. Be sure to insert a chock in front
and
behind the tire to
ensure no vehicle movement. Parking on level ground when you do this
is a big help.
After this is done and you are sure your Discovery can not move
RELEASE YOUR PARK BRAKE.
3.Your brake pressure should be at max. Now fan your brakes to
85psi.
NOW ENGAGE YOUR PARK BRAKE AGAIN. Compressor should cut in and watch
to ensure a return to full pressure.
4.When you have reached max pressure and the compressor has cut out
RELEASE YOUR PARK BRAKE AGAIN AND SHUT OFF THE ENGINE.
5.MAKE FULL BRAKE APPLICATION (BE SURE you have released your park
brake before you do this or you will damage the system.) Hold the
pedal all the way to the bottom for one minute. Watch your air
gauges
as they should not move (allowable loss in this mode for 60 seconds
is
3 psi). Listen for audible leaks as you wait for the 60 seconds to
expire. After 60 seconds release the pedal. (YOUR AUTO SLACK
ADJUSTERS
WILL SET UP AUTOMATICALLY DURING THIS PROCEDURE.)
6.Turn on key... fan brakes to 20 psi. LOW AIR WARNING SHOULD START,
continue to fan down to 20psi.. by now your park brake will have
engaged automatically although you will not have any indication of
this. Start engine and run at 1000 rpm using your cruise setting.
Time
3 minuets. In this time your air pressure should be up to between 50
and 90psi. This will tell you your Compressor is functioning
properly.
8. Apply park brake.

End of Test

[rvguru]

Quote:

Originally posted by Montana Dan: Hello Everyone- Since I stated doing my own maintenance, can someone help me with the proper way to adjust the slack adjusters and how often this should be done. Although they should self adjust, my old maintenance shop always stated that they need periodic adjustment. Thanks for your help

Inch forward then slam on the brakes. It's old school but it is the best way to adjust automatic slack adjusters.

Gramps, its a brake component.

[moisheh]

Now I know why every Canadian province requires DP drivers to obtain an air brake endorsement. Any one who does not know how to adjust the slacks or does not even understand the brake system should NOT be allowed to drive a DP. The complete air brake manuals that are provided by the Canadian provinces are online for your perusal.

[elgarc]

I was able to find an excerpt here http://www.angelfire.com/biz/s...busses/airbrakes.htm
but was not able to find the "complete air brake manual" Moisheh refers to. Got a reference?

Thanx

[SacsTC]

Here ya go.

[Montana Dan]

Thanks to all for your help--Montanadan