Searching for a factory part number on your Yanmar YB401 crawler-backhoe? This 188-page parts catalog covers the YB401, with exploded assembly views across every major system. Open it to full hydraulic piping breakdowns, wiring harness diagrams, control valve spool section IDs, and complete boom, arm, and bucket assembly drawings, plus dedicated sections for optional equipment: heater/defroster, radio, windshield washer, and B-type control kit. The traveling motor entry breaks down to the piston motor, individual seal set, turning brake valve, and planetary gear, each tagged with its own OEM part number. Chasing a part while the dealer clock runs? Pull up the PDF on your phone, read the exact OEM number off the exploded view, and order the right piece the first time. Bookmarked by system; jump straight to hydraulics, drivetrain, or cab without scrolling.
What's Inside This Yanmar YB401 / YB401-2 Series Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Labels | 6-13 | Label Set, Label, Specification, Grease, Stripe |
| Tools | 14-15 | Tool Assy, Driver, Screw, Wrench, Bar Wrench, Box Wrench, Gun 800, Grease |
| Tools Box | 16-17 | Cover, Tool Case, Clamp, Spring Washer, Bolt W/WASHER, Nut |
| Engine Control | 18-19 | Lever Assy, Throttle, Cable, Pivot, Accel, Knob, Washer, Bolt W/WASHER |
| Eng. Mount | 20-21 | Support, Engine, Bracket |
| Radiator & Mount | 22-23 | - |
| Fuel Tank & Fuel Line | 24-25 | - |
| Battery & Clamp | 26-27 | - |
| Wiring | 28-33 | Harness, Lead Wire, Fuse Box, Battery, Switch, Clamp |
| Electric Parts | 34-37 | Lamp Assy, Fuse Box, Switch Assy, Meter, Controller, Wiper |
| Seat | 38-39 | Mat, Floor, Operator, Slider, Cushion |
| Bonnet | 40-41 | Rubber, Cushion, Assy, Pin, Spring, Cover |
| Idler & Crawler Adjuster | 42-43 | Idler Assy, Coller, Seal, Shaft, Adjust Cylinder, Valve Assy, Nipple |
| Canopy | 44-47 | Assy, Column, Prop, Hood Assy, Roof Assy, Glass |
| Link Stand | 48-49 | Lever, Rubber Boot, Knob, Link, Arm, Shaft |
| Cabin | 50-51 | Assy, Window, Door, Glass, Seal, Trim |
| Front Open Cabin | 52-53 | - |
| Front Flat Cabin | 54-55 | - |
| Cylinder Protector | 56-57 | - |
| Bucket Cylinder | 58-59 | - |
| Blade Cylinder | 60-61 | - |
| Arm Cylinder | 62-63 | - |
| Swing Cylinder | 64-67 | - |
| Boom Cylinder | 68-69 | - |
| Track Frame & Track Guard | 70-71 | Counter Weight, Spacer, Washer, Bolt, Turning Frame, Panel |
| Hydraulic Oil Pump & Coupling | 72-73 | Motor Assy, Drive, Seal Case, Bearing, Planetry Gear, Shaft |
| Traveling Motor | 74-75 | Motor Assy, Turning, Valve, Turning Brake, Piston Motor, Seal Set |
| Cover & Interior | 76-77 | Floor Float, Step, Guard, Pedal, Pad, Rubber, Shim |
| Step & Turning Lock | 78-79 | Mat, Floor, Seat, Operator, Slider, Cushion, Arm Rest |
| Control Valve | 80-83 | Outlet Section, Spool Section, Valve, Load Check, O-Ring |
| Hydraulic Oil Tank | 84-85 | Flange, Pump Inlet, Connector, Nipple, O-Ring, Discharge |
| Hyd. Oil Piping | 86-99 | Adaptor, Connector, O-Ring, Elbow, Nipple, Hose |
| Greasing | 100-101 | Nipple B, Grease, Pin Bush, Shim, Cotter Pin, Boom Assy, Arm |
| Boom & Arm | 102-103 | Boom Assy, Arm, Bracket, Boom, Pin Bush, Shim, Bolt |
| Bucket | 104-105 | Shim, Blade Assy, Bush, Pin, Blade, Circlip, Nipple C, Grease |
| Blade | 106-119 | - |
| Btype Control Equipment (Option) | 120-121 | - |
| Lift Pin (Option) | 122-123 | - |
| Windshield Washer (Option) | 124-125 | - |
| Electric Parts (Option) | 126-127 | - |
| Radio (FFCabin) (Option) | 128-129 | Lamp Assy, Work, Lead Wire, Bulb, Clamp, Bolt |
| Work Lamp (Option) | 130-131 | Heater Assy, Lead Wire, Valve, Miniature, Base, Heater |
| Heater & Defroster (Option) | 132-135 | Heater Assy, Lead Wire, Valve, Hose, Switch, Defroster Assy |
| Seat (Option) | 136-188 | Operator, Mount, Spring Washer, Bolt, Nut |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Yanmar YB401 Crawler Backhoe (YB401, YB401-2, YB401-UC, YB401-UZP) | ||
| Parts Catalog | ||
| 188 | ||
| Y00K2040 | ||
| Hydraulic Filter Strainer (172112-74801), Boom Cylinder Seal (p.68), Hydraulic Oil Piping (p.86) |
Yanmar YB401 / YB401-2 Series Common Problems This Manual Covers
Yanmar YB401 boom cylinder seals leaking, need correct seal kit part numbers to order p. 68
Open the Boom Cylinder exploded view on page 68. Each seal and O-ring position carries its own part number and listed quantity in the parts table. Cross-reference your serial number range before ordering, since YB401 variants may use different cylinder bore configurations. Order by position number to avoid mixing inner and outer seal sets.
Manual Section: Boom CylinderHydraulic hoses cracking or leaking, can't identify correct replacement hose part numbers by location p. 86
Go to the Hydraulic Oil Piping section starting on page 86. The diagrams are organized by circuit: tank-to-pump, valve-to-motor, valve-to-swivel, return, track frame, boom, and 3rd valve. Locate your failed hose by routing position, then pull the adaptor, connector, elbow, and nipple part numbers from the corresponding parts list.
Manual Section: Hyd. Oil PipingBattery dead or starter not engaging, need replacement battery clamp and wiring harness part numbers p. 26
Check the Battery and Clamp section on page 26 for clamp assembly and terminal hardware part numbers. For harness connectors, lead wire assemblies, and fuse box components, turn to the Wiring section on page 28. Match the fuse box part number to your cabin or canopy variant before ordering, as wiring assemblies differ by cab configuration.
Manual Section: Battery & ClampTrack idler worn or seized, need part numbers for idler assembly and crawler adjuster components p. 42
Turn to the Idler and Crawler Adjuster section on page 42. The exploded view breaks down the idler assembly, collar, seal, shaft, adjust cylinder, and valve assembly, each with individual part numbers. Identify the seal collar and shaft part numbers from the description column and verify against your model variant before submitting your parts order.
Manual Section: Idler & Crawler AdjusterFuel tank or fuel line leaking, can't match correct tank assembly and fitting part numbers p. 24
Open the Fuel Tank and Fuel Line section on page 24. The exploded diagram shows the complete tank assembly with all fuel line connectors, nipples, and O-rings indexed by position number. Cross-reference each fitting part number against your specific model variant before ordering, as fuel line routing differs between undercarriage configurations.
Manual Section: Fuel Tank & Fuel LinePin and bushing joints worn loose, need correct greasing nipple, shim, and pin part numbers p. 100
Go to the Greasing section on page 100. The diagram maps every grease nipple location across the boom and arm and lists nipple part numbers by joint position. Cross-reference shim and cotter pin part numbers in the same table to complete your hardware order. For pivot pin and bush part numbers at each joint, check the Boom and Arm section on page 102.
Manual Section: GreasingFrequently Asked Questions
What are the replacement specifications for Hydraulic filters?
For hydraulic filters, refer to the 'RESERVOIR TANK ASSY' section (Fig. 59) on page 130. The STRAINER, SUCTION has part number 172112-74801, the ELEMENT W/VALVE has part number 172112-74901, and the ELEMENT has part number 172112-74911. Additionally, the 'HYD. OIL TANK' section (Fig. 60) on page 132 lists a FILTER, HYD. OIL with part number 172130-75110.
What are the replacement specifications for Fuel filters?
For fuel filters, refer to the 'FUEL TANK & FUEL LINE' section (Fig. 10) on page 24. The STRAINER, FUEL INLET has part number 101504-55101. Additionally, the ELEMENT, FUEL has part number 129100-55650.
How do you fix yanmar YB401 boom cylinder seals leaking, need correct seal kit part numbers to order?
Open the Boom Cylinder exploded view on page 68. Each seal and O-ring position carries its own part number and listed quantity in the parts table. Cross-reference your serial number range before ordering, since YB401 variants may use different cylinder bore configurations. Order by position number to avoid mixing inner and outer seal sets.
How do you fix hydraulic hoses cracking or leaking, can't identify correct replacement hose part numbers by location?
Go to the Hydraulic Oil Piping section starting on page 86. The diagrams are organized by circuit: tank-to-pump, valve-to-motor, valve-to-swivel, return, track frame, boom, and 3rd valve. Locate your failed hose by routing position, then pull the adaptor, connector, elbow, and nipple part numbers from the corresponding parts list.
How will I receive this Yanmar YB401 Series Parts Catalog?
You get a 188-page searchable PDF that downloads instantly after checkout. Open it on your laptop, tablet, or phone, and bring it right to the shop floor.
Are there any print restrictions on this manual?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Does this Yanmar YB401 Series manual include wiring diagrams?
Yes, this Yanmar YB401 Series Parts Catalog includes a wiring diagram for the electrical system.
Document Quality
This document is a scanned PDF, not a native digital file. You can search the full text due to an OCR layer, though the text itself is not always crisp and can appear slightly faded. Diagrams and illustrations are raster images, meaning they may pixelate when zoomed in, but labels are generally readable. Pages are mostly clean with minimal scan artifacts or skewed content. There are several blank pages throughout the document.
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