Wedge brakes are designed to be
- self sealing.
- self adjusting. ✓
- self isolating.
- self lubricating.
Answer: B. self adjusting.
Wedge brakes are designed to be self adjusting, because most have internal automatic adjusters.
Why this is the answer
The handbook says most wedge brakes have internal automatic adjusters. When the brakes are applied, air pressure pushes the wedge-shaped pushrod between two rollers, forcing the linings against the drum. The automatic adjusters are meant to keep the lining movement within the stated limit. If either lining moves more than 1/16 inch, or both move more than 1/8 inch total, the handbook says the automatic adjusters have failed. That is why the design is described as self adjusting.
Why the other answers are wrong
- A. self sealing. — The passages describe wedge brakes as using a wedge pushrod and automatic adjusters, and they say nothing about the brakes being self sealing.
- C. self isolating. — Self isolating is not a property the handbook gives for wedge brakes; it discusses their wedge pushrod and adjusters instead.
- D. self lubricating. — The handbook does not describe wedge brakes as self lubricating; it mentions internal automatic adjusters, not lubrication.
Remember it
Picture the wedge pushrod with automatic adjusters inside: the brake is set up to adjust itself.