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MenaHey there, this is Menachite — I passed Japan’s Mechanical Maintenance Skill Test, Level 1, on my first attempt after just three months of study, all while regularly clocking over 60 hours of overtime a month.
This article covers the questions that show up almost every year on the practical (hands-on) portion of Japan’s Mechanical Maintenance Skill Test (機械保全技能士), a national trade qualification for industrial equipment maintenance technicians — so you can study efficiently and pass on your first try.
The exam is split into a written test and a practical test. This article focuses on the questions that come up every year, or nearly every year, on the practical test.
The practical test for the Skill Test has 8 hands-on questions, and you have 10 minutes per question to solve them.
The passing score is 65 points out of 100.
MenaTen minutes per question feels tight the first time you practice, but once you’ve drilled the recurring questions a few times, the timing stops being the hard part.
Each question is worth 12.5 points, so in theory you pass if you get 6 out of 8 right. That means if you study the questions covered in this article, you have an 80%+ chance of passing.
The 4 questions that are almost guaranteed to appear
You can get past exam papers for the Mechanical Maintenance Skill Test from the official website.
Looking through past exams, there are questions that show up almost every single year, and others that come up very frequently.
If you nail down these questions, you can study efficiently and free up time for other topics.
Bearing damage, gear reducers, shaft dimensions, and sealing devices are the 4 topics that come up almost every single year.
(Based on past exam data from 2016 through 2020.)
Make sure you can solve all 4 of these before you sit the exam.
Bearing damage questions
For bearing questions, you mainly need to know why a bearing failed and how to prevent it.
Causes of bearing damage include rust, temper colors, brinelling (indentation marks), creep, electrical erosion, flaking, fretting, smearing, and cracking — make sure you can explain the cause and the countermeasure for each of these.
Gear reducer / exhaust fan vibration questions
For gear reducer questions, you’re given a diagram of the gear reducer along with a vibration spectrum waveform chart, and you have to identify which part is abnormal from that data.
Level 1 asks about reducers; Level 2 asks about blowers/fans.
Either way, you need to be able to calculate the gear meshing frequency, so make sure you’ve got that down.
Fm (meshing frequency) = Z (number of teeth) × N (shaft rotation speed)
Fo (rotation frequency) = rpm (rotation speed) / 60
You’ll use these formulas repeatedly for meshing-frequency calculations, so make sure you understand how they relate to the actual gear reducer, not just the formulas on paper.
Shaft dimension questions
These questions are about measuring shaft dimensions with a micrometer.
You have to be able to read the scale on a micrometer correctly — that’s the baseline requirement, so make sure you’ve mastered how to use one.
If a shaft dimension falls outside tolerance, the correct response depends on how far out of tolerance it is, so understand what action is required at each level of deviation.
Sealing device questions
Sealing device questions are mainly about gaskets and packing — devices that prevent oil leaks.
You’ll be asked what type of packing should be used in a given housing (the sealing device body) and how, and to what finish the housing itself needs to be machined.
Gaskets are used on static joints and packing on sliding parts, but both come in several types, so you need to know each type’s name and what it’s used for.
O-rings, gaskets, U-packing, V-packing, back-up rings, gland packing, mechanical seals, and oil seals all come up — as long as you understand what each one is and what function it serves, you’ll be fine.
MenaOnce the 4 near-guaranteed questions above are solid, these next ones are what push you comfortably past the passing line instead of scraping by.
Questions that appear more than 80% of the time
These aren’t guaranteed every year, but over the past 5 years they’ve shown up more than 80% of the time.
Make sure you can solve these too. Combined with the 4 questions above, that’s 6 questions worth 75 points total — well past the 65-point passing line.
Fracture surface questions
Fracture surface questions mainly require knowledge of metal fracture mechanics.
Knowledge you’ll need
Two questions come up here: bending fatigue fracture and tensile fracture, both on metal bar-shaped materials.
For tensile fracture:
You need to be able to look at the fracture surface of a metal rod and determine whether it’s a ductile fracture, a brittle fracture, or a fatigue fracture.
Other causes also exist, such as creep rupture, impact fracture, and stress corrosion cracking — make sure you can explain the cause of each of those too.
For bending fatigue fracture:
You’ll be asked to identify, from the pattern on the fracture surface, whether it’s rotating bending fatigue, fully-reversed bending fatigue, or one-sided (repeated) bending fatigue.
MenaThis is the one most people dread, but don’t skip it — it’s worth points, and it’s more learnable than it looks once you connect the symbols to real components.
Hydraulic circuit diagram questions
Hydraulic circuit diagram questions require broad knowledge.
These are by far the hardest of the bunch, but if you nail down the key points you’ll be able to solve them.
The key is understanding how the hydraulic circuit symbols in the diagram map to the actual physical components.
If you understand what each component does and what happens when it fails, you can solve these without any trouble.
5-year exam-frequency summary
Here’s a summary of how often each topic has appeared over the past 5 years of past exams.
Other topics beyond the ones covered above do appear too, so use this data to round out your prep.
| Exam topic | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|
| Lubricating oil | ○ | ○ | ○ | ○ | |
| Bearing damage | ○ | ○ | ○ | ○ | ○ |
| Gear damage | ○ | ○ | ○ | ||
| Gear reducer | ○ | ○ | ○ | ○ | ○ |
| Fracture surface | ○ | ○ | ○ | ○ | |
| Shaft dimensions | ○ | ○ | ○ | ○ | ○ |
| Bearings (general) | ○ | ||||
| Hydraulic circuit diagram | ○ | ○ | ○ | ○ | |
| Pneumatic circuit diagram | ○ | ○ | ○ | ||
| Sealing devices | ○ | ○ | ○ | ○ | ○ |
| Gears (general) | ○ | ○ | |||
| Valves | ○ |
If you prepare using this data, the practical exam for the Mechanical Maintenance Skill Test shouldn’t throw any real curveballs at you, and you should be able to pass consistently.
Study the past exam papers thoroughly, and you’ll be well prepared!
MenaThat’s everything I leaned on to pass Level 1 in one attempt — good luck with your exam.
Featured image: Nottingham Hackspace, CC BY-SA 2.0, via Wikimedia Commons
