Print Reading and Schematics Flashcards

On an engineering drawing, what does the title block typically contain?

Answer: Part name, drawing number, revision level, scale, material, and tolerances

The title block (lower right corner of a drawing) contains essential information: part name, part/drawing number, revision level, scale, material specification, tolerances, company name, and approvals.

What do hidden lines (dashed lines) represent in an engineering drawing?

Answer: Features that exist behind or inside the part and cannot be seen from the current view

Hidden lines are drawn as short dashes and show edges, holes, or features that are obscured from view in that particular projection. They help visualize internal features without requiring a sectional view.

In a first-angle (European) projection, where is the front view placed relative to the right-side view?

Answer: The right-side view is placed to the LEFT of the front view

In first-angle (European) projection, views are projected away from the viewer onto the far plane. The right side view appears to the LEFT of the front view — opposite of third-angle (US/ASME) projection.

What does the symbol ⌀ on a drawing dimension indicate?

Answer: The dimension refers to a diameter

The ⌀ (phi) symbol precedes diameter dimensions on engineering drawings. 'R' precedes radius dimensions. This is per ASME Y14.5 dimensioning standards.

On a hydraulic schematic, what does a rectangle with a diagonal arrow through it represent?

Answer: A variable flow control valve or variable component

In ISO hydraulic symbols, a diagonal arrow through a component symbol indicates it is variable or adjustable. This applies to pumps, motors, valves, and other components.

What does GD&T (Geometric Dimensioning and Tolerancing) specify that conventional +/- tolerancing cannot?

Answer: The form, orientation, location, and profile of features relative to datums, with cylindrical tolerance zones

GD&T (ASME Y14.5) defines tolerances for form (flatness, circularity), orientation (perpendicularity, angularity), location (position, concentricity), and profile. It uses datum references and allows cylindrical tolerance zones that are more functional than square +/- zones.

On an electrical schematic, what does a zigzag line symbol represent?

Answer: A resistor

In North American electrical schematics (IEEE/ANSI), a zigzag line represents a resistor. Internationally (IEC), a rectangle is used for resistors. The zigzag depicts electrical resistance.

What does a 'section view' in an engineering drawing show?

Answer: The interior features of a part as if it were cut along a specified cutting plane

Section views reveal internal features by showing the part as if sliced along a cutting plane line. Section lines (hatching) indicate the cut material. They replace multiple hidden lines and clarify complex internal geometry.

In a pneumatic schematic, what does a circle with two triangles pointing inward (toward the center) represent?

Answer: A compressor

In ISO/ANSI fluid power symbols, a compressor is represented by a circle with triangles pointing inward toward the center, indicating it compresses gas. A pump (for liquids) has triangles pointing outward.

What is the purpose of a 'datum' in engineering drawings and GD&T?

Answer: A theoretically exact reference point, line, or plane from which features are measured and located

Datums are perfect reference geometries (points, axes, planes) established from actual part surfaces. All GD&T feature controls reference datums to establish a consistent measurement coordinate system.

On a P&ID (Piping and Instrumentation Diagram), what does a circle with a tag number represent?

Answer: An instrument or measurement point (such as a pressure gauge, temperature sensor, or flow meter)

On P&IDs, circles (or circles with lines through them indicating location) represent instruments. The tag number (e.g., PT-101 = Pressure Transmitter 101) identifies the instrument type and loop number.

What does a surface finish symbol (roughness mark) with the value Ra 1.6 indicate on a drawing?

Answer: The surface must have a maximum roughness average of 1.6 micrometers

Surface finish symbols specify the required surface texture. Ra 1.6 µm is a moderately smooth machined surface, comparable to a 63 µin finish. Lower values indicate smoother surfaces.

In a ladder logic diagram, what does the horizontal line with two vertical lines (resembling a coil in parentheses) represent?

Answer: An output coil (relay, solenoid, or other output device)

In ladder logic, the coil symbol ( ) represents an output element (relay coil, solenoid, motor output). When the logic conditions on the rung are true (the rung is 'powered'), the output coil energizes.

What does the abbreviation 'TYP' on an engineering drawing mean?

Answer: The dimension or feature applies to all similar features on the drawing (typical)

'TYP' means the noted dimension or specification applies typically — to all identical features on the drawing unless otherwise specified. For example, '4x ⌀6 TYP' means all four holes have 6mm diameter.

On a hydraulic circuit diagram, what does a spring-loaded check valve symbol represent functionally?

Answer: It allows flow in one direction only, and requires a minimum cracking pressure to open

A spring-loaded check valve permits flow in only one direction. The spring sets a cracking pressure — a minimum upstream pressure required to open the valve. Back pressure keeps it closed against reverse flow.

What is the difference between a 'detail drawing' and an 'assembly drawing'?

Answer: A detail drawing shows one part completely dimensioned; an assembly drawing shows how multiple parts fit together

Detail drawings provide full manufacturing information (dimensions, tolerances, material, finish) for a single part. Assembly drawings show the relationship and arrangement of multiple parts, usually without detailed manufacturing dimensions.

In welding symbols on an engineering drawing, what does an arrow with a horizontal reference line and a triangle symbol below the line indicate?

Answer: A fillet weld on the arrow side of the joint

In AWS welding symbols, the triangle (fillet) symbol below the reference line indicates a fillet weld on the arrow side (the side where the arrow points). Above the line means the other side.

What does a 'revision cloud' on an engineering drawing signify?

Answer: An area of the drawing that has been changed since the previous revision

Revision clouds (arcs drawn around a changed area) highlight modifications made in the latest revision. They help users quickly identify what changed between drawing revisions, along with the revision letter in the revision block.

On an electrical one-line (single-line) diagram, what does a circle with an 'M' inside represent?

Answer: An electric motor

In one-line diagrams, a circle with 'M' represents an electric motor. A circle with 'G' is a generator, 'T' refers to a transformer in some contexts. One-line diagrams show the simplified power distribution system.

What is the purpose of 'break lines' on an engineering drawing?

Answer: To indicate that a long, uniform feature has been shortened for clarity on the drawing

Break lines are used to shorten long objects that have a uniform cross-section (shafts, pipes, structural members) so they fit on the drawing sheet. The actual part length is still shown in the dimension.