Manual Slack Adjuster Adjustment Procedure
Checking and Adjusting S–Cam Brakes–Manual Slack Adjusters. Number of makes and models of air disc brakes, each with a different adjustment procedure. Adjustment and setup of slack adjustors used in combination with drum brakes. The Technical Advisory Procedure is a guide only, and its use is entirely. There are a range of suppliers of both manual and automatic slack adjusters, all with.
BRAKE SETTING PROCEDURES There is one Brake setting procedure that is easy and can be used no matter which type of slack adjuster you have. Once you have found a brake that is out of adjustment, simply take your wrench and turn the adjusting nut ¼ of a turn less or more depending how far the brakes are out of adjustment. Then take the TRUCK IRON and check the free travel. If you have a ½ to ¾ inch free travel, you are done. But if not, then simply adjust another part turn and re-check the free travel until you have the desired ½' to ¾' free travel. Once you have the desired free travel, you can use the hammerhead of the TRUCK IRON to tap the brake drum to check for a clear ringing sound indicating the brake pad is not too tight to the brake drum.
If you are adjusting a manual slack adjuster, make sure the locking collar is back in locked position. This procedure works whether manual or automatic slack adjuster. This prevents the operator from tightening the adjustment completely tight and risking ovetightening and having to back the adjustment off, which can be difficult with some automatic clack adjusters. This procedure is easily accomplished with the TRUCK IRON. AUTOMATIC SLACK ADJUSTERS HALDEX The Haldex has an 11mm adjusting nut. Turning clockwise tightens up the adjustment counter clockwise backs the brakes off.
You can back off adjustments by simply turning the adjusting nut counter clockwise. You will hear and feel a clicking.
This will not harm anything. The Haldex has a range indicator. The point must line up with the notch on the side of the slack adjuster.
To line up the points properly, there is an 11/16' nut that you loosen. You then line up the pointer to the notch. This ensures that it will adjust in the proper range. GUNITE The gunite has an 11mm adjusting nut.
Clockwise to tighten up the brakes, counter clockwise to back them off. When backing off the brakes, you will feel and hear a clicking. This is normal and no harm will occur. You have no other adjustments to make with this slack adjuster. ROCKWELL The Rockwell has a 5/16' square shaft for adjusting the brakes.
This slack adjuster is backwards to others, clockwise backs the brakes off, and counter clockwise tightens the brakes up. Also, if you have to back the brakes off, you must pull the pawl out about 1/8' or a bit more in order to turn the adjusting shaft. If you dont, damage to the adjuster will occur. Pulling the pawl out is easily done with the TRUCK IRON. Simply use the bevel on the tip of one claw to slide behind the collar of the pawl. Pulling back on the pawl you simply stick a key or something of sufficient thickness to hold the pawl out.
You then take the TRUCK IRON, back off the brake to where you want it set, then remove the key or whatever you have used to hold the pawl out and it will snap back into place. As mentioned before, if you adjust a brake up a little at a time and re-check, you very seldom need to back the automatics off. FONT=Verdana, Arial, Helvetica, sans-serif Automatic Slack Adjusters/FONT FONT=Verdana, Arial, Helvetica, sans-serif October 1994 FMVSS 105 and 121 required that all new air-braked vehicles with S-Cam style brakes shall be equipped with automatic slack adjusters. /FONT FONT=Verdana, Arial, Helvetica, sans-serif Well-known manufacturers of automatic slack adjusters: Bendix, Gunite, Crewson-Brunner, Haldex (SAB), and Meritor (Rockwell)./FONT FONT=Verdana, Arial, Helvetica, sans-serif Adjustment: Bendix, Gunite, Crewson & Brunner and Haldex all can be adjusted in a similar manner. Turning the adjusting nut clockwise shortens the stroke (tightens up the brake).
Turning the adjusting nut counter-clockwise adds stroke (loosens up the brake). You will find it will take about 20 to 25-ft.
Of torque to back off the adjusting hex. On the other hand, if it backs off too easily, the auto slack needs replacement. Meritor automatic slack adjusters are slightly different. They require you to remove a pawl assembly to back them off on the earlier auto slacks, and the current units just require you to pry up a button on the pawl's cap to release the pawl./FONT. FONT=Verdana, Arial, Helvetica, sans-serif Click photo for larger image./FONTFONT=Verdana, Arial, Helvetica, sans-serif Lubrication Yes, automatic slack adjusters need to be greased. But, you can over do it.
Manual Slack Adjuster Adjustment Procedures
Use a grease gun to lubricate automatic slack adjusters. Apply grease until the grease starts to purge out from around the camshaft or some type of grease relief. Be sure and inspect the seals and dust boots for damage after lubrication. Using the recommended lubricant is critical so you don't damage the internal clutch mechanism. Too heavy of grease can cause the automatic slack adjuster to back off on its own.
Rockwell Automatic Slack Adjuster Adjustment
/FONT FONT=Verdana, Arial, Helvetica, sans-serif Replacement You must use the same brand of automatic slack adjuster on both sides of the axle and it is recommended to keep the same brand on the entire truck. Each brand has subtle differences and should not be mixed on an axle.