| So they can be inspected | |
| To verify they meet pressure requirements | |
| To check for leaks | |
| To release oil and water buildup |
| Cannot be used | |
| Can still be used several times | |
| Can be used indefinitely | |
| Immediately fail |
| Two control systems that each have their own set of breaks | |
| Two brake systems use the same set of brake controls | |
| Two brake systems that each have their own set of controls | |
| Two sets of brake controls operate a single brake system |