There are two ways to tell if the timing belt has been replaced. One is obvious-you are looking at a service receipt showing the replacement.
Swimlane diagrams are used whenever you need to show activities, tasks, or process steps which are being performed by different actors/roles. You can use swimlanes to group activities in an activity diagram or process flow by any category what you need: by role, by system, by department, etc.
Use cross-functional flowcharts to show the relationship between a business process and the functional units (such as departments) responsible for that process. The swimlanes in the flowchart represent functional units, such as departments or positions. Each shape representing a step in the process is placed in the swimlane for the functional unit responsible for that step.