Depending on the manufacturer, the angle between the centre of the slack adjuster arm and the brake chamber pushrod with the brakes applied is 90 degrees,
- plus or minus 10 degrees ✓
- plus or minus 5 degrees
- plus or minus 30 degrees
- plus or minus 20 degrees
Answer: A. plus or minus 10 degrees
The angle between the centre of the slack adjuster arm and the brake chamber pushrod with the brakes applied is 90 degrees, plus or minus 10 degrees depending on the manufacturer.
Why this is the answer
The handbook points out that the 90-degree angle is not a reliable sign of correct brake adjustment, because it mostly depends on how long the chamber pushrod is. It also notes that some manufacturers vary the angle by up to plus or minus 10 degrees so the slack adjuster will not interfere with suspension parts. So the figure to expect is 90 degrees with that 10-degree tolerance either way, which is what the bank answer gives.
Why the other answers are wrong
- B. plus or minus 5 degrees — Plus or minus 5 degrees is a tighter tolerance than the handbook allows; it states the angle can vary by up to 10 degrees.
- C. plus or minus 30 degrees — Plus or minus 30 degrees is far wider than the variation the handbook describes for manufacturer differences.
- D. plus or minus 20 degrees — Plus or minus 20 degrees is twice the variation the passage gives, which is up to 10 degrees either side of 90.
Remember it
Picture the pushrod and slack adjuster meeting near a right angle, and let it lean only a little either way, about ten degrees.