Workshop service for the Z122R-AU and Z122RKW-AU runs through this OEM manual (#9Y111-13423): 153 pages built around one machine, your Kubota utility vehicle, from engine to mower deck. It carries exploded-view diagrams for the transaxle, front axle, and lift system, wiring diagrams that trace the start system, OPC safety switches, PTO clutch, and charging circuit, plus hydraulic circuit schematics for the transaxle. Seven troubleshooting charts and 50 step-by-step procedures cover each disassembly, inspection, and reassembly sequence the factory laid out. Fill the transaxle case to exactly 1.66 L, torque your M10 fasteners to 36-44 N·m, and stop guessing at forum numbers. Every idle hour costs money. Bookmarked by system and keyword-searchable, the procedure you need comes up on your tablet in seconds.
What's Inside This Kubota Z122R-AU, Z122RKW-AU Manual
| System | Pages | Key Topics |
|---|---|---|
| Record of Revisions | 3 | - |
| Information | 4-16 | - |
| General | 17-50 | Identification (Serial Number), Handling Precautions for Electrical Parts and Wiring, Battery, Fuse, Connector, Handling of Circuit Tester, Color of Wiring, Lubricants and Fuel |
| Engine | 51-67 | Fuel System, Fuel Line, Lubrication System |
| Transaxle | 68-91 | Hydraulic Circuit, External Components, Inner Components, Parking Brake |
| Front Axle | 92-98 | Separating Front Wheel and Wheel Bracket, Front Wheels Wander to Right or Left, Tightening Torques of Screws, Bolts and Nuts, Remove Wheel Bracket |
| Lift System | 99-105 | Removing Link Shafts, Mower Does Not Lift, Mower Does Not Lower, Tightening Torques of Screws, Bolts and Nuts, Removing the Mower, Removing Front Link Shaft, Removing Cam |
| Electrical System | 106-135 | Wiring Diagram, Start System and Opc, Safety Switches, Relay, Charging System, Hour Meter, Head Light and PTO Clutch, Troubleshooting |
| Mower | 136-153 | Power Transmission, Dismounting the Mower Deck, Disassembling the Mower, Blade Does Not Turn, Blade Speed Is Slow, Mower Is Not Lifted, Mower Belt Slipping, Discharge Chute Plugged |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Fuel tank capacity | 12.2 L (3.22 U.S. gals, 2.68 Imp.gals) | p. 26 |
| Engine crankcase oil capacity | 2.1 L (2.2 U.S.qts, 1.8 Imp.qts) | p. 26 |
| Max engine power | 15.0 kW (21.5 HP) | p. 14 |
| Fuel tank capacity | 12.2 L (3.23 U.S. gals, 2.68 Imp. gals) | p. 14 |
| Engine crankcase capacity | 2.1 L (2.2 U.S. qts, 1.8 Imp. qts) | p. 14 |
| Transaxle oil capacity | 1.66 L (1.75 U.S. qts, 1.46 Imp. qts) | p. 14 |
| Front tire pressure | 170 kPa (24.7 psi) | p. 34 |
| Rear tire pressure | 83 kPa (12.0 psi) | p. 34 |
| Battery nominal voltage | 12V | p. 42 |
| Battery cold cranking amps | 300 A | p. 42 |
| Engine oil change interval | every 50 hours | p. 30 |
| Spark plug check interval | every 100 hours | p. 30 |
Kubota Z122R-AU, Z122RKW-AU Common Problems This Manual Covers
Kubota Z122R-AU engine cranks but won't start or starts hard in cold weather p. 58
Confirm the fuel shutoff valve is open and the tank isn't empty (capacity 12.2 L). Inspect the spark plugs; the service schedule calls for a check every 100 hours. Pull the air cleaner and look for a clogged element, due for replacement every 200 hours. If the battery cranks slowly, test it against the 300 A cold cranking amp spec and make sure the terminals are clean and tight. Work through the full start-fault sequence on pages 58-59.
Manual Section: Engine TroubleshootingEngine loses power under load, runs rough, or produces black exhaust smoke p. 58
Start with the air cleaner element: a restricted element is the fastest path to black smoke and lost power. Check the spark plugs for fouling or wrong gap, since service falls every 100 hours. Verify the fuel filter isn't past its annual replacement. If rough running continues, look at valve clearance, which is set every 300 hours. The diagnostic table on pages 58-59 separates fuel, ignition, and mechanical causes.
Manual Section: Engine TroubleshootingMachine pulls left or right, won't track straight, or drives in one direction only p. 74
Check the transaxle oil level before anything else. Both rear tires must sit at an equal 83 kPa (12.0 psi); uneven pressure on its own will pull the machine off-line. Look over the linkage for bent or disconnected rods. If it drives one direction only, suspect a hydrostatic control fault, whose full fault tree is on page 74. Make sure the oil isn't contaminated or foamy, which points to internal seal trouble.
Manual Section: Transaxle TroubleshootingMower deck blades won't engage or disengage slowly when PTO switch is activated p. 123
Measure PTO clutch clearance; adjustment comes due every 100 hours. Inspect the PTO belt for wear, glazing, or slip, with replacement at 300 hours. Make sure the PTO switch and its connector seat fully (see the wiring notes on page 106). A blade that turns but spins up slowly often means a loose belt rather than a worn one. Work through the PTO clutch fault sequence on page 123 to split electrical from mechanical causes.
Manual Section: Electrical System Troubleshooting (PTO Clutch)Uneven cut: grass streaking, scalping on high spots, or strips of uncut grass left behind p. 141
Set the machine on level ground and measure blade height; the spec is 76 mm (3.0 in.) at the flat surface. Confirm all four deck hangers sit at equal height and that no lift linkage is bent or worn. Check the blades for dullness, nicks, or imbalance, since a dull blade tears instead of cuts and leaves a ragged stripe. Torque the blade bolts to 103 to 118 N·m after any removal. The full cut-quality fault list runs on pages 141-142.
Manual Section: Mower TroubleshootingMower deck won't lift or lower when operator raises the lift lever p. 103
Inspect the lift linkage for bent rods, a worn cam, or a detached spring. Verify the cam flange nut is torqued to 48 to 55 N·m; a loose cam lets the mechanism slip without moving the deck. Rule out the safety interlock (operator presence switch) by running the OPC switch checks in the Electrical System section on page 106. The full mower lift fault procedure is on page 103.
Manual Section: Lift System TroubleshootingFrequently Asked Questions
What are the recommended service intervals?
The manual lays out a maintenance schedule with checks and services tied to operating-hour intervals. Engine oil, for instance, changes every 50 hours. The air cleaner element gets a check every 50 hours and a full replacement every 200 hours. The spark plug is due for a check every 100 hours.
What fluids and capacities does this machine require?
Fuel capacity is 12.2 L (3.22 U.S. gals, 2.68 Imp.gals). The engine crankcase takes 2.1 L (2.2 U.S.qts, 1.8 Imp.qts) of API Service Classification SF, SG, SH, SJ or SL SAE40 oil. For the transaxle case, use 1.66 L (1.75 U.S.qts, 1.46 Imp.qts) of API Service Classification SL SAE20W-50 oil.
How to troubleshoot engine won't start?
When the engine won't start, make sure the operator is on the seat, the parking brake lever sits in the proper position, and the PTO switch is disengaged. Verify the main switch is in the "ON" position and that there's fuel. If all of that checks out, move on to the fuse, air cleaner, spark plug, and fuel hose/filter.
What are the hydraulic system specifications?
Maximum input speed for the transaxle hydraulics is 3800 min⁻¹ (rpm), with a minimum of 1800 min⁻¹ (rpm). Overall transaxle reduction works out to 19.2:1, and the variable displacement pump tops out at 10 cc/rev.
Is this Kubota Z122R-AU, Z122RKW-AU Workshop Manual a digital download?
It's a 153-page searchable PDF, available to download the moment you check out. Open it on a laptop, tablet, or phone and take it straight to the shop floor.
Can I print specific sections of this Kubota Z122R-AU, Z122RKW-AU manual?
Yes. Print as many copies as you like; there are no restrictions. Plenty of mechanics run off just the section they need and keep it at the bench.
Does this Kubota Z122R-AU, Z122RKW-AU manual include hydraulic schematics?
Yes. The manual includes hydraulic circuit diagrams, system schematics, and component specifications with pressure ratings.
Document Quality
This document is a high-quality scanned PDF, featuring an OCR layer that allows you to search and copy the full text content. The text is consistently crisp and very easy to read across all pages. Diagrams and illustrations are clear raster images, and their labels are generally legible, though some fine details might soften slightly upon extreme zoom. The pages are clean, free from significant scan artifacts, stains, or skewed content, maintaining a professional appearance. Please note there are several blank pages interspersed throughout, typically used to delineate new sections.
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