Description

Aichi SP18AJ, SP21AJ, SP18A, SP21A, SP25B Parts Catalog – 398 Pages of Factory Part Numbers

I’ve watched too many guys order a seal kit for an SP18AJ and get a part that belongs on an SP25B because they trusted some aftermarket list. That’s money burned and a machine down. This Aichi SP18AJ, SP21AJ, SP18A, SP21A, SP25B Parts Catalog is the original OEM document – 398 pages of factory nomenclature, part numbers, and exploded-view illustrations. No translations, no guesswork. You get the same pages the Aichi dealer uses.

What You Get in This 398-Page OEM Parts Catalog

Every group in the machine is broken down into lists: CHASSIS, TURNTABLE, BOOM, BASKET, hydraulic valves, cylinders, wiring components, decals. The Table of Contents alone runs fifteen ILLUSTRATIONS INDEX sections plus dedicated weight and tubing lists. You’ll find the exact part number for an oscillation axle cylinder, a flow divider valve, a rotary actuator assembly, or a CPU box. The manual uses a LEVEL column to tell you if a part is a parent assembly (1), a sub-assembly component (2), or a piece of that component (3). That matters when you’re ordering a repair kit – you don’t want to buy the whole valve block if you only need the solenoid.

Each list gives you the quantity per machine, the serial number range it applies to, and the CLASS code – A for mandatory-replace-on-disassembly repair kit, B for matched set parts, C for single-service parts, D for non-service items. That CLASS column saved me more than once on a SP21AJ elevation cylinder rebuild.

Chassis and Tubing Listings – Where Most Guys Mess Up

The chassis section covers three main groups plus three separate tubing sub-sections. If you’re replacing a hydraulic line on an SP18A, you need the tubing list that matches your serial number. Aftermarket catalogs often bundle all SP18 variants together – this catalog separates SP18A from SP18AJ tubing because the routing and fittings differ. Same for SP21A vs SP21AJ. The oscillation axle cylinder, steering cylinder, flow divider valve, double pilot check valve, and shuttle valve each get their own list. You’ll also find weight blocks for chassis and turntable – those aren’t just lumps of metal; they have specific part numbers and mounting hardware.

Page references aren’t printed in the PDF bookmarks, but the structure is logical. You go from chassis to turntable to boom to basket. Follow the group numbers and you’ll land on the right list.

Decoding the Level and Class System

Open page 2 of the PDF – that’s the Japanese foreword with the explanation. Page 3 has the English version. The LEVEL column is critical: a part marked “1” is the complete assembly you order if you want everything in that group. “2” means it’s a component of that assembly. “3” means it’s a sub-component of that component. For example, the VALVE BLOCK (EXTENSION) has multiple lists – the assembly itself is LEVEL 1, the individual valves inside are LEVEL 2, and the seals within those valves are LEVEL 3. If you order a LEVEL 2 part without checking the CLASS column, you might get a matched set (Class B) that can’t be separated. Pay attention.

CLASS codes are printed in a column. Class A parts (generally seals, gaskets, crush washers) must be replaced every time you break the joint – no exceptions. Class B parts come as a set – you don’t order just one half of a pilot check valve. Class C are loose parts you can order individually. Class D means the part is not sold as service – you buy the bigger assembly. This system is standard across Aichi Equipment.

Turntable, Boom, and Valve Block Coverage

The turntable section runs eight different list sets – each with 4 to 6 sub-lists. You get breakdowns for the rotation gearbox, flow priority valve, angle sensor, swivel joints, covers, and the entire turntable tubing with four separate routing lists. The boom section covers all five models: SP18A, SP18AJ, SP21A, SP21AJ, SP25B. Each boom has six list groups plus two tubing lists per boom. The extension cylinder, leveling cylinders (upper and lower), boom length sensors, and boom sweepers are listed separately. If you’re working on a SP25B fly jib, there’s a dedicated fly jib list and cylinder section.

Valve blocks are covered in detail: extension, elevation, rotation. The proportional control valves, solenoid valves, relay box, and CPU boxes are all there. The control boxes for upper and lower controls each have multiple lists. Even the foot switch and decals get their own pages. 398 pages means nothing is left out.

Why This Aichi Parts Catalog Beats Aftermarket Copies

Aftermarket parts catalogs re-draw the illustrations and often combine models that Aichi intentionally keeps separate. I’ve seen a SP21AJ list that showed a boom length sensor bracket that didn’t fit any actual machine because the catalog house merged SP21A and SP21AJ. This PDF is scanned from the original Aichi Corporation publication – part number PA00107A. The abbreviations list (page 4) uses standard JIS and ISO terms: ASSY, BRG, BKT, CYL, S/K, R/K. The foreword explicitly states that due to product improvements, parts may change without notice, and you must provide the model and serial number when ordering. That’s the kind of warning you don’t get from a $5 aftermarket CD.

For reference on the broader context of construction equipment maintenance, you can check the Automotive Industry Overview for general background, but for specific Aichi part numbers, this catalog is the only source you should trust. Also see the Automotive Industry Overview – though that article covers automotive, the same principles of verifying OEM documentation apply to aerial work platforms.

Frequently Asked Questions

Does this catalog cover every serial number range for all five models?

Yes. Each list includes the applicable serial number range (last four digits) per the Aichi specification. For example, the SP18AJ lists specify applied specification EFO, FFO. If your machine falls outside the range shown, you’ll need to contact Aichi with your full serial number. But for the vast majority of production SP18A, SP18AJ, SP21A, SP21AJ, and SP25B units, this catalog covers them.

Can I use this to order parts for an SP18A if I only have a SP21AJ manual?

No. The BOOM and TURNTABLE sections are model-specific. Ordering SP21AJ parts for an SP18A will get you the wrong cylinder lengths and valve block configurations. You need the exact model catalog.

Bottom line: if you maintain any of these five Aichi boom lifts – SP18A, SP18AJ, SP21A, SP21AJ, SP25B – you need this OEM parts catalog on your bench. 398 pages of factory part numbers, level codes, class codes, and illustrations that match the real machine. Stop relying on aftermarket lists that mix models. Access the Factory Manual now and get the right part the first time.

Related manuals you might need: AICHI SP18AJ/SP21AJ Operation Manual”>AICHI SP18AJ/SP21AJ Operation Manual, AICHI SP18A/SP21A/SP21AJ/SP25B Parts List”>AICHI SP18A/SP21A/SP21AJ/SP25B Parts List, Aichi SR18AJ SR21AJ SR18A SR21A Parts Catalog – 300pp OEM”>Aichi SR18AJ SR21AJ SR18A SR21A Parts Catalog – 300pp OEM.