This is the official Kubota B21 parts catalog, a 365-page PDF you can download and keep on any device. It covers the B21 compact tractor, with exploded diagrams and Kubota part numbers for every major system: the diesel engine, fuel and cooling systems, clutch, transmission, HST, rear and front axles, brakes, steering, hydraulics, and the full electrical system.Each section pairs a numbered illustration with a parts table listing the reference number, Kubota part number, description, quantity, and the serial number range a part fits. That serial number column matters on an aging B21, where components changed mid-production, so you order the version that actually bolts to your machine.Use it to identify worn or broken parts, cross-check numbers before buying, and plan a repair or restoration without guessing.
What's Inside This Kubota B21 Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Clutch & Transmission | Clutch, Clutch Rod, Clutch Pedal, Clutch Housing, Transmission Case, Clutch Shaft, HST, 2Nd Shaft/3Rd Shaft/4Th Shaft, Range Gear Shift Fork, Neutral Holder Link, Range Gear Shift Lever, Range Gear Shift Rod, PTO Gear Shift Lever | |
| Fuel System | Fuel Camshaft and Governor Shaft, Idle Apparatus, Injection Pump, Governor, Speed Control Plate, Nozzle Holder and Glow Plug, Nozzle Holder, Fuel Pump, Air Cleaner, Accelerator Lever, Fuel Tank, Fuel Pipe, Fuel Filter, Stop Solenoid, Speed Control Pedal | |
| Cooling System | Water Flange and Thermostat, Water Pump, Fan, Water Pipe, Radiator | |
| Engine | Crankcase, Oil Pan, Cylinder Head, Gear Case, Head Cover, Oil Filter, Main Bearing Case, Camshaft and Idle Gear Shaft, Piston and Crankshaft, Flywheel, Valve and Rocker Arm, Inlet Manifold, Exhaust Manifold, Muffler, Upper Gasket Kit, Lower Gasket Kit | |
| Electrical System | Alternator, Starter, Battery, Switch, Panel Board, Head Light, Hazard Light, Tail Light, Winker Lamp, Electrical Wiring, Working Light Kit, Wire Harness Kit | |
| PTO | PTO Shaft, PTO Protector | |
| Rear Axle, Differential & Brakes | Rear Axle Case, Rear Differential, Rear Axle, Brake, Parking Brake Lever, Brake Pedal, Differential Lock Pedal, Front Axle Case, Rear Wheel | |
| Front Axle & Steering | Propeller Shaft, Front Wheel Propeller Shaft, Front Wheel Drive Lever, Front Axle Frame, Front Differential, Front Axle, Front Drive Shaft, Drag Link, Tie Rod, Steering Handle, Front Wheel | |
| Hydraulics & 3-Point Hitch | Hydraulic Control Lever, Hydraulic Change Rod, Hydraulic Pump, Hydraulic Oil Line, Flow Divider Valve, Hydraulic Cylinder, Control Valve, Hydraulic Outlet, 3-Point Linkage 2, Hitch/Lower Link, 3-Point Linkage 1 | |
| Body & Operator Station | Center Frame, Oil Tank, Bonnet, Panel Cover/Shutter Plate, Fender LH, Fender RH, Seat, Seat Turn Table, Base Seat Turn Table, Seat Adjuster, Step, ROPS/FOPS, Smv Emblem | |
| Decals & Accessories | Label, Accessories and Service Parts | |
| Other Components | Front Shaft, Main Flame, Drawber Kit |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| FUSE | 50A | p. 142 |
| FUSE AUTO | 5A | p. 142 |
| SHIM INJECTION PUMP Thickness | 0.20mm | p. 41 |
| PISTON Oversize | +0.5mm | p. 30 |
| METAL CRANKPIN Undersize | -0.2mm SET | p. 30 |
| METAL CRANKSHAFT Undersize | -0.4mm | p. 30 |
| ASSY BATTERY | 12V36AH | p. 122 |
| FUSE Rating | 50A | p. 142 |
| FUSE AUTO Rating | 5A | p. 142 |
| BULB LIGHT Power | 27W | p. 133 |
| GEAR CLUTCH SHAFT Tooth Count | 23T | p. 162 |
| GEAR 4WD Tooth Count | 19T | p. 182 |
Kubota B21 Common Problems This Manual Covers
Hard starting or no-start
Owners often trace a crank-but-no-start B21 to a blown fuse, a failed relay, the fuel shutoff solenoid, or a worn key switch. The exploded diagrams here let you identify and order the correct stop solenoid and related electrical parts.
Manual Section: Stop Solenoid p. 110Weak 3-point hitch or loader lift
A B21 that lifts with no load but struggles under weight usually points to hydraulic wear, a clogged filter, or a tiring pump. Use this section to identify the HST and hydraulic drive parts you need.
Manual Section: HST p. 165Overheating under load
Rising temperature on a hard-working B21 is often a dirty radiator, low coolant, or a cooling system restriction. The diagrams show the radiator and its fittings so you order the right replacement.
Manual Section: Radiator [Except [Au]] p. 106Blown fuses and dead accessories
Intermittent gauges, lights, or a dead starting circuit frequently come back to corroded connectors and blown fuses. This section maps the wiring and fuse parts for the B21.
Manual Section: Electrical Wiring p. 141Fuel starvation and rough running
Rough running or stalling on an older B21 often follows a clogged fuel filter or a restricted supply. Identify the filter and related fuel components before ordering.
Manual Section: Fuel Filter [Component Parts] p. 100No charge from the alternator
A battery that keeps going flat points to the alternator or its wiring. The exploded view lists the alternator and its component parts for an exact match.
Manual Section: Alternator p. 113Frequently Asked Questions
Which machine does this catalog cover?
It covers the Kubota B21 compact tractor. The 365-page catalog breaks the machine into system sections, from the engine and HST to the axles, brakes, steering, hydraulics, and electrical parts, each with exploded diagrams and Kubota part numbers.
Is this a repair manual or a parts catalog?
It is a parts catalog. You get exploded illustrations, Kubota part numbers, quantities, and serial number ranges for ordering parts. It does not contain step-by-step repair or torque procedures.
How do I make sure a part fits my serial number?
Each parts table has a serial number (S.No.) column showing the range a part fits. The Instructions for Parts Books page explains how to read it so you pick the correct version for your B21. p. 1
Does it include HST and hydraulic parts?
Yes. The HST section lists the hydrostatic drive and its component parts, and separate sections cover the hydraulic control linkage, all with exploded diagrams. p. 165
What do I get after purchasing this Kubota B21 manual?
You'll receive a 365-page searchable PDF, available for immediate download. It works on any device, so you can pull it up on your phone right at the machine. No shipping, no waiting.
Am I able to print pages from this manual?
No restrictions. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Does this Kubota B21 manual include hydraulic schematics?
Yes, this parts catalog includes detailed exploded diagrams for all hydraulic components: pump, cylinder, and valves. It does not contain hydraulic circuit schematics.
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