Classroom activity Grade 12 Art & Music
Wendrow Street Pump Teardown: An Exploded-View Layout Critique
Grade 12 teams turn a fictional pump's part list into an exploded-view layout for a repair manual page, then trade layouts in a timed studio critique and revise.
Objectives
- Students will simplify mechanical parts into scaled geometric silhouettes suitable for a technical illustration.
- Students will arrange parts in an exploded view along a single axis in assembly order, resolving a real page-size constraint.
- Students will give and use specific critique on another team's layout using a structured studio protocol.
- Students will apply a line-weight hierarchy and numbered callouts so a mechanic can follow the drawing.
Vocabulary
Key words: exploded view, assembly axis, trace line, callout, subassembly, line weight, centerline, studio critique
Teacher overview
Repair manuals for pumps, valves, and blowers rely on exploded views, drawings that pull an assembly apart along its axis so a mechanic can see every part, its order, and where it goes. In this activity teams of three or four act as the illustrators for the fictional Wendrow Street Pump Station's maintenance manual. They draw a simplified end-suction centrifugal pump's parts to scale on cards, lay the cards out along one axis on a manual page, discover that the full assembly will not fit at the required scale, decide how to solve that, and then trade layouts in a timed studio critique before revising. The activity's rules follow the conventions of the drawing itself: every part must stay on the shaft's axis and appear in the order it sits on the pump, so moving along the drawing is the same as moving through the repair. The misconception addressed directly is that an exploded view is a collage of parts spread evenly around a page, often sorted by size; a usable exploded view is a sequence along an axis, and the spacing, grouping, and line weights all serve that sequence.
Activity Directions
- Before class (moderate prep): Print the Student Handout, set out index cards, scissors, rulers, and two sheets of 11 by 17 inch paper per team, and form teams of three or four. On one sheet per team, lightly mark a drawing area 15 inches wide and 8 inches tall, centered on the page, as the handout describes.
- Frame the task (5 min): Read the handout's scenario aloud. Explain that a mechanic replacing a leaking seal will use this page at the pump, often in poor light, and must be able to find each part and put it back in the right order. State the four layout rules on the handout and sketch a three-part example on the board: a disc, a ring, and a shaft pulled apart along a thin centerline.
- Round 1, part cards (15 min): Each team divides the part list among its members. For every part, students draw a side-view silhouette at one-quarter scale on an index card, simplifying the part into basic shapes: a disc seen edge-on becomes a narrow rectangle, a tube becomes a long rectangle with a hollow center shown by hidden lines, and a housing becomes a block. They write the part name and its number from the handout on the back, then cut the silhouettes out.
- Round 2, layout (15 min): Teams draw a thin centerline across the drawing area and place the cards along it in the handout's order. Most teams will find that the parts alone nearly fill the 15-inch width, which leaves almost no room for gaps. Each team must choose and carry out one solution: leave the motor out because it is not removed during a seal repair and mark its position with a ghosted outline; break the axis into two rows with a clear jog line; or draw only the coupling end of the motor, cut off at the page edge with a break line. Teams tape the cards down, add trace lines where a part has moved off the axis, such as the key, and add numbered callout circles in order along the axis.
- Round 3, studio critique (12 min): Teams leave their layouts on the table and rotate clockwise. At each of two layouts, they spend 6 minutes using the handout's critique prompts, writing observations on one color of sticky note and suggestions on the other, and leaving the notes on the page. Teams do not speak with the authors during this round.
- Round 4, revision (10 min): Teams return to their own layouts, read the notes, choose the two changes they agree with most, and make them. They then ink the final layout on the second sheet or over the taped cards, using the heavier fineliner for part outlines and the lighter one for the centerline, trace lines, and callout leaders.
- Debrief (8 min): Pin the layouts in a row. Ask the class the handout's debrief questions 1 through 4 and take two or three answers for each. The activity ends when every team has pinned a revised, inked layout and the debrief questions have been discussed.
Student Handout
Scenario. In our scenario, Pump 2 at the fictional Wendrow Street Pump Station is an end-suction centrifugal pump. Its mechanical seal has started to leak, and the station's maintenance manual needs an exploded view of the parts a mechanic removes to replace it. The manual page is 11 by 17 inches, turned sideways, with a drawing area 15 inches wide and 8 inches tall. The drawing must be at one-quarter scale, so 4 inches on the pump is 1 inch on the page.
Parts, in order along the shaft from the suction end to the motor end. Sizes are for this simplified pump. "Length" is measured along the shaft.
| No. | Part | Simplified shape | Height (in) | Length along shaft (in) |
|---|---|---|---|---|
| 1 | Volute casing | Block with a round inlet on the left | 16 | 8 |
| 2 | Impeller nut | Short cylinder | 1.5 | 1 |
| 3 | Impeller | Disc | 10 | 2.5 |
| 4 | Impeller key | Small bar that sits in a slot in the shaft | 0.5 | 2 |
| 5 | Casing gasket | Thin ring | 13 | 0.125 |
| 6 | Seal chamber cover | Thick disc with a center hole | 13 | 3 |
| 7 | Mechanical seal | Short ring | 3 | 2 |
| 8 | Shaft sleeve | Tube | 2 | 5 |
| 9 | Bearing frame with shaft | Block with shaft ends showing | 7 | 16 |
| 10 | Coupling half | Short cylinder | 5 | 3 |
| 11 | Motor | Block | 12 | 18 |
The impeller key is not on the centerline. It sits in a slot in the shaft, so it is drawn offset from the axis and joined to its slot with a thin trace line.
Layout rules.
- Every part stays on one centerline, except parts such as the key that sit off the axis, which get a trace line.
- Parts appear in the order in the table, with no part overlapping another.
- Each part gets a numbered callout circle, and the numbers run in order along the axis.
- Part outlines use the heavier line; the centerline, trace lines, and callout leaders use the lighter line.
Critique prompts for Round 3. Write each on a sticky note: "I can follow the order from ___ to ___." "I lost the order at ___." "The spacing between ___ and ___ makes me think they are ___." "What if you ___?"
Debrief questions.
- At one-quarter scale, why did the full assembly, motor included, not fit the 15-inch drawing area with room for gaps?
- Why should the parts stay on one centerline instead of being spread across the page wherever they fit?
- Why is the impeller key drawn off the axis with a trace line?
- Which comment from the critique led to the most useful change on your layout, and why?
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Answer: The parts alone take up nearly the full width.
The ten parts that sit on the axis, every part except the key, have lengths along the shaft that add up to about 58.6 inches. At one-quarter scale that is about 14.7 inches, which leaves only about a third of an inch for all nine gaps in a 15-inch area. Leaving out the motor frees 4.5 inches on the page, which is why a ghosted motor outline is a common solution. Accept any answer that compares the scaled lengths with the drawing area. - Answer: The centerline shows where each part goes and in what order.
A mechanic reads an exploded view as a sequence: moving along the axis is the same as moving through the assembly. Parts placed off the axis lose their position, and the reader can no longer tell what slides onto what. - Answer: The key sits in a slot in the shaft, not on the shaft's center.
Moving it straight along the axis would hide it inside the other parts. Drawing it off to the side and joining it to the slot with a thin trace line shows both what it looks like and where it goes. - Answer: Answers vary.
Accept any answer that names a specific critique comment and describes the change it produced, such as adding a gap between the impeller and gasket so the gasket no longer looked like part of the impeller.
Differentiation
Support
Give teams a partly completed set of cards, such as the casing, impeller, and bearing frame already drawn to scale, so they can focus on the layout decisions in Round 2. Provide a scaled ruler strip marked in quarter-scale inches. During the critique, allow students to use only the first two prompts.
Extension
Ask teams to redraw their final layout as an isometric exploded view, with the axis running at 30 degrees, and to compare which view makes the order of parts easier to follow. Teams may also add a numbered parts list in a table beside the drawing that matches the callouts, laid out so it fits the remaining space on the page.
ELL supports
Pre-teach the part names with the table and a simple labeled sketch of an assembled pump. Pair students so each team has one strong English reader for the handout. Allow critique notes to be written as a sketch with an arrow and a short phrase, and post the frame "I lost the order at ___" at every table.
Extensions
Invite a maintenance mechanic or operator from a local water or wastewater utility to review the class's layouts and describe how they use drawings in a real repair. Students can then revise the strongest layout into a finished manual page with a title, a parts list, and a short caution note about isolating and locking out the pump before any work begins.