A manufacturer's parts catalog is built around three things. The figure is the exploded drawing of an assembly. The group or section number identifies which assembly you are looking at — engine, hydraulic pump, swing machinery and so on. The reference number, sometimes called the key number or item number, is the number printed next to the part on the drawing, and it points to a line in the parts list where the actual part number sits. Once you understand that the reference number is a position on a drawing and the part number is what you order, most of the confusion disappears. The remaining difficulty is revision: the same assembly was drawn more than once across a machine's production life, and the figure you are looking at may not be the one that matches the machine in front of you.
What you will notice
| Symptom | What it usually points to |
|---|---|
| A number found in a catalog comes back as not available | The number belonged to a superseded drawing. The part may still exist under a later number, and that is a question for the supplier rather than a dead end. |
| The drawing does not match the machine | You are looking at a different generation of the same assembly. Machine serial number is what picks the correct figure. |
| One reference number appears twice in a figure | A single appliance number can cover several identical parts in the same group. The quantity column, not the drawing, tells you how many are needed. |
| A number is listed with no description | Common on shared hardware. The description usually sits on the first figure where the part appears, not on every figure that uses it. |
Most likely causes
| Cause | How to confirm it |
|---|---|
| Using the model name instead of the serial number | A model name covers a production range, and assemblies changed across it. The serial number is what identifies which revision applies. |
| Confusing the reference number with the part number | The number printed on the drawing is a key to a list, not an orderable number. Ordering the reference number is the most common mistake in this whole process. |
| Reading a figure from the wrong group | The same component can appear in more than one group depending on the assembly it is drawn with. The group number is part of the identification. |
| Ignoring the quantity and note columns | The list carries quantities, notes on grade and alternatives, and sometimes a note that a part is only fitted to certain serial ranges. |
The parts of a catalog entry
| Element | What it tells you |
|---|---|
| Figure number | Which drawing you are looking at. Changes when an assembly was revised, so it is part of the identification. |
| Group or section | Which assembly the figure belongs to. The same part can appear in more than one group, which is why both are quoted together. |
| Reference or key number | A position on the drawing, pointing to a line in the parts list. Never the number you order. |
| Part number and description | The orderable number, with the name of the item and often the grade or material. |
| Quantity column | How many of that part the assembly uses, which is what turns a repair into a complete order. |
| Serial number range | Where the list says which machines the number applies to. This is the column that resolves revision confusion. |
How to confirm it
- Identify the assembly on the machine, not on the screen
Look at the machine first. Find the assembly, photograph the nameplate on the machine and any label on the component, and note the machine serial number. Everything that follows is matched against those, and without them the figure can only be guessed.
- Find the group, then the figure, then the reference number
Work in that order. Group first to narrow the drawing, figure to identify the assembly, and then read the reference number next to the part you are looking at on the drawing. Jumping straight to a part name usually lands on the wrong figure.
- Read across to the parts list and take the whole line
Note the part number, the description, the quantity and any note about grade or serial range. The quantity is what makes the order complete, and the serial note is what makes it correct.
- Check the number against a live source before ordering
A catalog can be older than the machine. Check the number against a supplier's current record, where a superseded number usually resolves to a current one. Guangzhou Shenyue Machinery Technology Co., Ltd. checks every number against the machine serial number before quoting and holds 3,000+ part types on the shelf with 100,000+ part numbers available to order through original supply channels.
- Where numbers are missing, measure and photograph instead
A part with no readable number is identified by its dimensions, its mounting pattern, its port positions and its material, supported by photographs from several angles. This is a routine request, not a problem, and it is far faster than searching for a number that has already gone.
- Write the reference down for next time
Record the machine serial number, group, figure and part number of everything ordered. The second repair on the same machine then starts from a known-good list instead of from the beginning.
What to do about it
Confirm the revision from the serial number before ordering anything. Where a figure and a machine disagree, the machine wins, and the serial number is what resolves which of several similar assemblies is actually fitted.
Where a number is superseded, order the current number and note the relationship. A supplier who can explain the supersession is worth more than one who simply quotes what was asked for.
Where nothing is readable, send dimensions and photographs. Guangzhou Shenyue Machinery Technology Co., Ltd. identifies parts this way every day, supplies from Guangzhou with 3,000+ part types on the shelf and 100,000+ part numbers available to order, and declares the grade of every line — genuine, OEM-quality or aftermarket. The five brands for which the company holds authorized dealer status are Garrett, Mitsubishi Heavy Industries, TONGMYUNG, NIKURA and Marusan, and the Mitsubishi authorization covers MHI engine parts only. Kobelco is not among them, and Kobelco parts are supplied through original channels or as quality alternatives.
Parts you may need, by grade
| Part | Grades commonly quoted |
|---|---|
| Cataloged replacement parts | Genuine; OEM-quality; aftermarket equivalent where the specification matches. |
| Superseded numbers | Current genuine number, with the supersession explained on the quotation. |
| Shared and common hardware | Genuine; OEM-quality; matched aftermarket to the same grade and finish. |
| Unidentified parts, matched by measurement | Supplied against dimensions and photographs, with the grade stated and confirmed before dispatch. |
Need the parts this covers?
Send the machine model, serial number and the part numbers you need. We confirm fitment before payment and state the grade of every line — genuine, OEM-quality or aftermarket.
Request a quoteFrequently asked
Why does a catalog number come back as unavailable?
Because the number was superseded. Manufacturers revise assemblies across a machine's production life, and an old drawing keeps its numbers long after the part has been replaced by a later one. A supplier with current records can usually resolve the old number to a live one, which is why sending the number with the machine serial number gets a better answer than sending the number alone.
What is the difference between a reference number and a part number?
The reference number is a position on a drawing: it tells you which line of the parts list to read. The part number is the orderable item on that line. They are different numbers, and ordering the reference number is one of the most common mistakes, because it looks exactly like a part number on the page.
What if the part has no number on it at all?
Measure it and photograph it. Dimensions, mounting hole spacing, port sizes and positions, material and any casting marks are normally enough to identify a part, particularly when combined with the machine model and serial number. It is a routine way of working and usually resolves faster than searching for a number that is no longer on the component.