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Class 3 sample questions with answers and explanations

The six items below follow the Class 3 format: a Japanese question, four options and exactly one right answer. ViMai wrote them for this page; they are not JASPA questions and are not taken from the app's papers.

Last updated: 2026-10-19

Questions

Read the Japanese first and look at the translation only when you need it. Tap "Show answer" to see the explanation.

  1. 4サイクル・ガソリン・エンジンの行程こうていに関かんする記述きじゅつとして、適切てきせつなものは次つぎのうちどれか。

    Which statement about the strokes of a four-stroke petrol engine is correct?

    • 1. 吸入きゅうにゅう行程こうていでは、排気はいきバルブが開ひらいている。 The exhaust valve is open on the intake stroke.
    • 2. 圧縮あっしゅく行程こうていでは、吸入きゅうにゅうバルブと排気はいきバルブがともに閉とじている。 Both the intake and exhaust valves are closed on the compression stroke.
    • 3. 燃焼ねんしょう・膨張ぼうちょう行程こうていでは、ピストンは上死点じょうしてんに向むかって上あがる。 On the power stroke the piston rises towards top dead centre.
    • 4. クランクシャフトが1回転かいてんする間あいだに、4つの行程こうていが完了かんりょうする。 The four strokes are completed in one crankshaft revolution.
    Show answer

    Answer: 2. Answer 2. Compression needs a sealed chamber, so both valves are closed. The intake valve opens on intake, the power stroke pushes the piston down, and four strokes take two crank revolutions.

  2. ブレーキ装置そうちに関かんする記述きじゅつとして、不適切ふてきせつなものは次つぎのうちどれか。

    Which statement about the brake system is incorrect?

    • 1. マスタ・シリンダは、ペダルの踏力とうりょくを油圧ゆあつに変かえる。 The master cylinder turns pedal force into hydraulic pressure.
    • 2. ブレーキ・フルードは吸湿性きゅうしつせいがあるので、定期的ていきてきに交換こうかんする。 Brake fluid absorbs moisture, so it is replaced periodically.
    • 3. ディスク・ブレーキは、ドラム・ブレーキより放熱性ほうねつせいがよい。 Disc brakes shed heat better than drum brakes.
    • 4. ブレーキ・ラインに空気くうきが入はいると、ペダルの踏ふみしろが少すくなくなり硬かたくなる。 Air in the brake line makes the pedal travel shorter and the pedal harder.
    Show answer

    Answer: 4. Answer 4. Air compresses, so the pedal goes soft and spongy with longer travel, not harder. The other three are correct.

  3. ジーゼル・エンジンに関かんする記述きじゅつとして、適切てきせつなものは次つぎのうちどれか。

    Which statement about the diesel engine is correct?

    • 1. 燃料ねんりょうはスパーク・プラグの火花ひばなで着火ちゃっかする。 Fuel is ignited by the spark plug.
    • 2. 圧縮比あっしゅくひは、一般いっぱんにガソリン・エンジンより低ひくい。 The compression ratio is usually lower than in a petrol engine.
    • 3. 圧縮あっしゅくされて高温こうおんになった空気くうきに燃料ねんりょうを噴射ふんしゃして着火ちゃっかさせる。 Fuel is injected into air heated by compression and ignites.
    • 4. グロー・プラグは、走行中そうこうちゅうに燃料ねんりょうを噴射ふんしゃする部品ぶひんである。 The glow plug is the part that injects fuel while driving.
    Show answer

    Answer: 3. Answer 3. A diesel compresses air until it is hot enough to ignite the injected fuel, so its compression ratio is higher than a petrol engine's. The glow plug only heats the chamber for cold starts.

  4. 内径ないけい80mm、行程こうてい90mmの4シリンダ・エンジンの総排気量そうはいきりょうに最もっとも近ちかいものは次つぎのうちどれか。ただし、円周率えんしゅうりつは3.14として計算けいさんする。

    A four-cylinder engine has an 80 mm bore and a 90 mm stroke. Which is closest to its total displacement? (take π as 3.14)

    • 1. 452cm³ 452 cm³
    • 2. 1,357cm³ 1,357 cm³
    • 3. 1,809cm³ 1,809 cm³
    • 4. 2,261cm³ 2,261 cm³
    Show answer

    Answer: 3. Answer 3. One cylinder: 3.14 ÷ 4 × 8² × 9 ≈ 452 cm³ (work in cm). Four cylinders ≈ 1,809 cm³. Option 1 is a single cylinder, a common trap.

  5. 12Vのバッテリに抵抗ていこう4Ωの電球でんきゅうをつないだとき、流ながれる電流でんりゅうとして適切てきせつなものは次つぎのうちどれか。

    A 4 Ω bulb is connected to a 12 V battery. What current flows?

    • 1. 0.33A 0.33 A
    • 2. 3A 3 A
    • 3. 16A 16 A
    • 4. 48A 48 A
    Show answer

    Answer: 2. Answer 2. Ohm's law: I = V ÷ R = 12 ÷ 4 = 3 A. 48 is V × R and 16 is V + R, both wrong operations.

  6. ノギスの使用しように関かんする記述きじゅつとして、不適切ふてきせつなものは次つぎのうちどれか。

    Which statement about using a vernier caliper is incorrect?

    • 1. 外側そとがわ用ようジョウで部品ぶひんの外径がいけいを測はかる。 Use the outside jaws to measure an outside diameter.
    • 2. 内側うちがわ用ようジョウで穴あなの内径ないけいを測はかる。 Use the inside jaws to measure a bore.
    • 3. デプス・バーで穴あなや段差だんさの深ふかさを測はかる。 Use the depth bar to measure the depth of a hole or step.
    • 4. 測定そくてい面めんを強つよく押おし付つけるほど、正確せいかくに測はかれる。 The harder the jaws are pressed on the part, the more accurate the reading.
    Show answer

    Answer: 4. Answer 4. Pressing too hard tilts the jaws or deforms the part and gives a wrong reading. Use light, even pressure.

What these six items teach

See how to read each type in answering four-choice items and the formulas in Class 3 calculations.

VIP unlocks papers 4 to 20 in all three subjects (51 papers), the per-item tips and the detailed explanations for missed items. VIP is bought inside the iOS app with Apple payment, and Apple shows the price. The App Store version is coming soon. You can try the free exams on the web now.

Sources checked on 2026-10-19: the JASPA registration test page and its 2026 (令和8) guide, the JASPA results for the 2025 first session, the JASPA past papers page and the MLIT press release on the new mechanic qualifications. Rules can change, so check the latest version at these sources.

FAQ

Are these real exam questions?

No. They are written by ViMai for the Class 3 textbook scope. JASPA publishes previous papers on its own site.

Does the real test have furigana like this?

No. The furigana here helps you learn the readings. When you practise in the app, turn it off gradually to get used to the real test.

Where can I practise more items like these?

Open Seibishi 3kyu: each subject has three free papers of 30 items, with an explanation for every item.

Take a 30-item mock paper and see right away which items you missed and why.

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