3 Sizes :
A dual function S-Cam Brake Stroke Indicator & Brake Chamber Seal.
Since the early 1980's, truck makers have continued to improve big rig fuel mileage by making what is called a "slippery truck".
Where once the wind helped slow the vehicle due to a large square truck cab, as did the Bias-ply tires, driveline drag, engine brakes etc., we now mainly use the brakes. Many towns have signs suggesting "DO NOT use engine brakes within town limits".
Brake maintenance costs are rising, but they are not excessive unless neglected until it's panic time.
D.O.T. Roadside Inspectors DO NOT check brake adjustment, they check for excessive brake stroke.
Excessive brake stroke can be a simple matter of improper brake adjustment, but more often than not, the problem is from excessive brake component wear.
D.O.T. Roadside inspectors perform what is known in the industry as a "Mark & Measure Test". First, they chock (block) the wheel(s). Release the park brakes, and mark each
pushrod where it leaves the brake chamber . If a BrakChek is installed it becomes your high visibility replacement for that chalk mark.
With dash air gauge's) reading 90-100 PSI the driver is asked to make and hold a FULL brake application, while the inspector return under the vehicle to measure the movement of each chalk mark from brake released to brake applied.
This movement will exceed the 1 1/2 inch caused by a "Park brake" application, due to
much more pressure applied. Driver's often estimate brake adjustment by looking at the position of the stroke indicator with park brakes applied.
Tractor drive or trailer park brake stroke, is always less than the travel measured when a proper "Mark & Measure Test" is done.
A DAILY brake adjustment by mechanics is NOT necessary, but, regular "Mark and Measure tests" will provide the mechanic with insight on extreme brake wear other than drums or lining.
When a full brake application is made and held by one person, while the other person measures the brake strokes it helps identify failures such as;
Worn s-cam bushings
Worn brake spiders
WChamber bracket orn clevis pin bushings
Excessive S-cam rotation (longest s-cams)
Brake drum deflection (badly worn drums)
Worn S-cam splines
Worn worm-gear in brake adjuster
Every trailer axle and truck drive axle has a built in brake stroke reference point for the EZ Chek . The standard 1 ½" brake chamber mounting studs help the driver identify a suitable "Parked" brake stroke as shown here.
Always Check Brake Adjustment.
It's as easy as kneeling along side a truck or trailer wheel, bending over and looking at the position of the EZ Chek stroke indicator.
Brake released EZ Chek is up against the brake chamber.
The chamber mount studs in all Type 24 and Type 30 chambers are 1 1/2 inches long. So with the vehicle "Park Brake" applied the EZ Chek should line up with the tip of the studs. If not, have it checked by maintenance.
Fig. 3 Brakes applied with a full brake application. Excessive brake stroke is indicated.