Maintenance, Safety Practices and Engineering Drawing Basics
This section covers Maintenance, Safety Practices and Engineering Drawing Basics. The exam tests maintenance types, safe workshop behaviour, and basic drawing conventions such as projections, line types, scales and dimensions.
Core concepts
- Maintenance types: breakdown maintenance after failure; preventive maintenance on a schedule; predictive maintenance based on condition monitoring such as vibration or oil analysis. Lubrication, cleaning and inspection reduce failures.
- Safety includes PPE, machine guards, proper housekeeping, safe lifting and lockout/tagout before repair. The fire triangle needs fuel, oxygen and heat; remove one to stop combustion. Never bypass an interlock.
- Drawing lines have meanings: continuous thick for visible outlines, dashed for hidden edges, chain thin for centre lines, and thin continuous for dimension and projection lines.
- In first-angle projection, the object is between observer and plane; the top view is placed below the front view and the left-side view to the right of the front view. Third-angle projection places the top view above the front view. Dimensions should be clear, not duplicated, and should not rely on scaling the drawing.
Worked example
A drawing is made to scale 1:20. A measured line on the paper is 35 mm. Actual length = 35 × 20 = 700 mm, or 0.70 m. The reasoning is that a scale of 1:20 means one drawing unit represents 20 real units. Never measure a dimensioned drawing with a rule when a written dimension exists.
Traps that cost marks
Do not mix first-angle and third-angle view positions. Do not treat hidden edges as visible outlines. Do not work on a machine without isolation and tags. Predictive maintenance is not the same as breakdown maintenance.