Description

Aichi SR18AJ, SR21AJ, SR18A, SR21A, ISR60J Service Manual

If you are working on one of these Aichi crawler lifts and you don’t have the factory service specs, you are guessing. That gets people hurt. I have seen more than a few boom failures from guys using aftermarket torque charts for the engine or the bolts on the swivel joint. The Aichi SR18AJ, SR21AJ, SR18A, SR21A, ISR60J Service Manual is what Aichi wrote for their own technicians. It is 221 pages of procedures, torque specs, wiring diagrams, and inspection data. If you are a shop owner or a tech who touches these machines, this is what you need.

What the 221-Page Manual Covers

Page 3 shows the full index. You get General Information with separate specs and dimensions for SR18A, SR18AJ, SR21A, SR21AJ – including working range diagrams and safety devices. The Mechanical section walks through the Isuzu 4LE2 diesel engine, hydraulic pump and oil cooler installations, rotation bearing, boom rotation gearbox, and the fly-jib. Boom structure, hose arrangements, wire rope inspection and adjustment are all there. The Hydraulic section dives into each component: oil reservoir, filter, emergency pump, main control valve, all cylinders, holding valves, pilot check valves, the platform leveling system. The Electrical section covers Main CPU box (M2D) Master and Slave, upper and lower control boxes, joystick controllers, foot switch, engine control box (EGR cut, safety relay, charge relay), boom sensors, tilt sensors, and the alternator. Then Electric circuit for individual systems gives you dedicated diagrams for start/stop, boom elevation, telescope, rotation, traveling, H/V control, platform rotation, fly-jib articulation, level adjust, work range limit, overload sensing, accelerator, emergency pump, horn, work light, generator. Inspection and adjustment includes engine rpm measurement and relief valve pre-set pressure adjustment procedures. Appendix has the hydraulic circuit diagram and electrical diagram.

Diesel Engine and Hydraulic Systems: The Heart of the Machine

This manual devotes serious space to the diesel engine – it lists the Isuzu 4LE2 with EPA Interim Tier 4 / EU Stage 3-A emission controls. You get the EGR cut controller, timer relay, safety relay, charge relay, and the fuel pump for automatic air bleeding. Page 2 warns: “Do not make any modifications to the machine without obtaining the manufacturer’s approval.” That is a liability warning you ignore at your own risk. The hydraulic section shows you exactly how to test and adjust the main control valve, boom telescope cylinder, and the double holding valves. If you need to set the overload relief valve, the manual gives the procedure with required tool lists – no guessing.

Aichi SR18AJ, SR21AJ, SR18A, SR21A, ISR60J Service Manual: Real-World Use

Whether you are a DIY mechanic who owns a farm or a small construction outfit, or a technician in a rental shop, this manual pays for itself the first time you avoid a misdiagnosis. The step-by-step procedures tell you what tools are needed – for example, you need a torque wrench that reads in ft-lbs, a pressure gauge for the relief valve adjustments, and a multimeter for the error code troubleshooting. The inspection data sheets in Section 6 for each model let you verify the work radius and safety limits. If you have the ISR60J or SR18A, the data is in there. Page 3 lists the four inspection data sheets: SR18A, SR18AJ, SR21A, SR21AJ. Use those sheets during annual inspections and you will catch issues before they become failures.

Error Codes and Countermeasures: What the Electrical Section Tells You

The Main CPU box (M2D) Master section has input/output characteristics for both duplicated and non‑duplicated sensor configurations, plus error codes and countermeasures. That saves you hours of diag time when the tilt warning goes off. You get the pin‑out data for the upper control box with double or single joystick controllers, the joystick controllers for boom and travel, foot switch, and the lower control box relays. Without this, you are pulling your hair out with a meter and a guess. The manual also covers the boom length sensors (R/H and L/H), boom angle sensors, tilt sensors, and the 5‑degree tilt angle sensor. All the electrical specs are factory‑verified.

Inspection and Adjustment: The Difference Between a Safe Lift and a Failure

Four inspection data sheets are included: SR18A, SR18AJ, SR21A, SR21AJ. They cover work radius checks. You also get engine rpm measurement procedures and relief valve pre‑set pressure adjustment procedures. If you skip these steps or use aftermarket pressure specs, the overload system will be off. That can cause a platform to drop or a boom to collapse under load. The manual shows the exact order of operations – no short cuts. Page 3 points you to the right section. Do not rely on a third‑party printout for this kind of safety data.

Related Manuals

• Aichi SR18AJ/SR21AJ Operation Manual
• Aichi SR18AJ/SR21AJ Technical Manual for Aerial Lift
• AICHI SR18A/SR18AJ/SR21A/SR21AJ Parts List
• Manual Transmission
• Manual Transmission

Can I use this manual for the ISR60 model?

Yes, the ISR60 is covered under the SR18A/ISR60 naming in the manual.

Does the manual include wiring diagrams for the entire electrical system?

The manual includes detailed schematics for each system: engine start/stop, boom elevation, telescope, rotation, traveling, H/V control, platform rotation, fly-jib articulation, platform level adjust, work range limit, overload sensing, accelerator, emergency pump, horn/work light/hydraulic generator. Each system has its own circuit diagram in the electric circuit section, plus an overall hydraulic circuit diagram in the appendix. However, there is no separate wiring diagram booklet; it is integrated into the electrical and electric circuit sections. If you need a dedicated wiring harness layout, you might want the Aichi SR18AJ/SR21AJ Operation Manual as well.

Access the Factory Manual and put it on your bench. It will outlast any PDF you find on a forum. This is the same document Aichi ships to their dealer network. Get it now.