All 178 pages of this Yanmar Crawler Backhoe Parts Catalog (OEM #000Y00K2103) cover the 1986 YB121U and YB151U family: the -2 revisions, Canopy, Cabin, and 3TNA72L-UBVM engine variants. Inside: exploded-view diagrams for every assembly from hydraulic oil piping and control valves to boom, bucket, turning motor, and travel motor, with part numbers cross-referenced across both previous-spec and new-type component revisions. Bucket attachments from 250 to 450mm, standard and wide, are each called out with individual part numbers, pins, shims, and teeth. Electrical assemblies list fuse ratings by position (5A, 10A, and 15A), so you order the right component, not the closest guess. No more hunting through a worn-out parts fiche. Bookmarked by section and keyword-searchable, this PDF puts the correct part number in your hand before you even pick up the phone.
What's Inside This Yanmar YB121U / YB151U Series Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Preface | 1-2 | Parts Catalog Coverage, Engine Numbers, Old Parts Catalog Discard Notice, Mounted Engine Model, Paint Color (Old), Paint Color (New), Model Type |
| Specifications | 3 | Model, Engine, Type, Dimensions, Boom Swing Angle, Digging Force, Travel Speed, Gradability |
| Wiring Diagram | 5-11 | Label Assy, Certificate Label, Greasing Label, Oil/water Label, Grease Label, Model Label, Stripe Label, Sub-Tank Label |
| Tool | 12-13 | Tool Assy, Filter Wrench, Wrench 8X10, Bar Wrench, Grease Gun, Grease Hose, Tool Bag, Plier |
| Tool (Crawler, Rubber Spec.) | 14-15 | Throttle Cable, Throttle Lever Assy, Bush 14X15, Lever Fulcrum, Cable Joint, Side Clutch Spring, Lever Knob, Spring |
| Inlet House & Exhaust Pipe | 18-19 | Left Engine Bed, Right Engine Bed, Shock Absorber, Cushion, Radiator Mount, Sub-Tank Stay, Bracket, Sub-Tank Assy |
| Battery (Previous) | 26-27 | Battery Cord, Battery NS60, Battery Mount, Battery Clamp Rod, Grommet |
| Battery (New Type) | 28-29 | Battery Cord, Dry Battery NS60, Battery Mount, Battery Clamp Rod, Grommet |
| Electric Part (Canopy Spec.) | 30-33 | Wire Harness, Fusible Link, Lead Wire, Earth Wire, Fuse Box Assy, Fuse Box Cover, Fuse 5A, Cartridge Fuse |
| Electric Part (Cabin Spec.) | 34-35 | Wiper Blade, Wiper Arm, Wiper Switch, Wiper Moter a, Collar, Resistor, Band, Grommet 40X13 |
| Control Equipment (Lever) (Previous) | 44-47 | Lever, Trabel Lever W/ Bush, Bush 14X15, Travel Lever W/ Bush, Blade Lever, Lever Rubber Boot, Boot Band, Blade Arm |
| Control Equipment (Lever) (New Type) | 48-51 | Spring, Grommet 17X19, Lock Arm Assy, Block, Blade Lever Shaft, Arm Link W/ Bush, Bush 14X15, Turning Link W/ Bush |
| Control Equipment (Link & Rod) (Previous) | 52-56 | Liner 17X30X1, Arm Link Assy, Bush 14X15, Turning Link Assy, Blade Boss W/ Bush, Link Stay, Lever Link, Link Boss W/ Bush |
| Control Equipment (Link & Rod) (New Type) | 57-58 | Turning Frame Assy, Grommet, Grommet 40X13, Pad, Seal |
| Turning Frame (YB121U) | 59-60 | Turning Frame, Grommet, Grommet 40X13, Pad, Counter Weight |
| Turning Frame (YB151U) | 61-62 | Revolve Bearing, Upper Seal, Lower Seal, Pin |
| Bonnet (Previous) | 65-67 | Cover, Motor Cover, Rubber, Support, Tool Box Assy, Lock Lever Knob, Under Cover, Undar Cover |
| Bonnet (New Type) | 68-69 | Operator Seat, Seat Bracket, Center Step, Side Step, Angle Bar, Rear Step |
| Seat & Step (Previous) | 70-71 | Safty Work, Cushion Rubber, Operator Seat, Seat, Seat Bracket, Center Step, Cross Bar Assy, Rear Step |
| Seat & Step (New Type) | 72-73 | Canopy Assy, ROPS Assy, Hood, Rope a, Rope B, Canopy Roof, Pole L Assy, Pole R Assy |
| Canopy | 74-76 | Cabin Assy, Cabin Comp, Grommet, Spring 2X12X25, Floor Mat, Mark, Gromet, Cap Assy |
| Cabin (Previous) | 77-80 | Cabin Assy, Cabin Comp, Grommet, Spring 2X12X25, Floor Mat, Mark, Cap Assy, Cover |
| Cabin (New Type) | 81-82 | Cabin Assy, Cabin Comp, Door Assy, Window Assy, Floor Mat, Mark, Gromet, Seal |
| Hyd. Oil Piping (Valve-Swivel) (Previous) | 87-89 | Adaptor, Elbow PF1, Connector PF1, Male/male Adapter, Joint, Elbow PT1, Elbow, Connector |
| Hyd. Oil Piping (Tank-Valve-Motor) (New Type) | 90-91 | Adaptor, Nipple, Connector PF1, Suction Joint, Connector, Busing, Elbow 45SS, Back-Up Ring P14 |
| Hyd. Oil Piping (Tank-Valve-Motor) (Previous) | 92-96 | Adaptor, Nipple, Connector PF1, Suction Joint, Connector, Busing, Elbow, Back-Up Ring P14 |
| Hyd. Oil Piping (Travel) | 97-98 | Elbow PF1, Connector PF1, Connector PF1/ - S, Elbow PT1, Nipple, Plate, Arm Tube L Assy, Arm Tube R Assy |
| Hyd. Oil Piping (Work Equipmnt) (Previous) | 99-100 | Elbow PT1, Plate, Arm Pipe, Bucket Pipe, Hose P204BK088, Hose, Nipple, Joint RGI1 |
| Hyd. Oil Piping (Work Equipmnt) (New Type) | 101-102 | Hydraulic Reservoir Assy, Hydraulic Oil Tank Assy, Cover Assy, Reservoir Cover, Oil Level Gauge, Gasket, Pipe 8X, Air Breather |
| Hyd. Oil Tank | 103-105 | Arm Assy, Grease Nipple B, Bucket Link W/ Bush, Bucket Link, Bucket Arm, Bucket Arm L Assy, Bucket Arm R Assy, Grease Nipple PT1 |
| Boom & Bucket (YB121U) | 106-108 | Arm Assy, Grease Nipple B, Bucket Link W/ Bush, Bucket Link, Bucket Arm, Bucket Arm L Assy, Bucket Arm R Assy, Grease Nipple PT1 |
| Boom & Bucket (YB151U) | 109-110 | Blade Assy, Grease Nipple PT1, Grease Nipple B, Pin |
| Control Valve (Blade) | 113-114 | Control Valve, Valve Section Assy, P1 Assy Section, Relief Valve Assy, Section P2 Assy, Center Plate, Rod M 8X294, Rod 8X294 |
| Control Valve (P1, P2) | 115-116 | Valve Section Assy, Swing Section Assy, Return Spring, Oil Seal, Seal Plate, Spring Seat, Spacer, Cap |
| Control Valve (Swing) | 117-118 | Valve Section Assy, Boom Section Assy, Oil Seal, Seal Plate, Spring Seat, Spacer, Cap, Check Valve |
| Control Valve (Boom) | 119-120 | Valve Section Assy, Bucket Section Assy, Oil Seal, Seal Plate, Spring Seat, Spacer, Cap, Check Valve |
| Control Valve (Bucket) | 121-122 | Drive Section Assy, Oil Seal, Seal Plate, Spring Seat, Spacer, Cap, Return Spring |
| Control Valve (Travel) | 123-124 | Valve Section Assy, Arm Assy Section, Check Valve, Valve Guide, Valve Spring, Oil Seal, Seal Plate, Spring Seat |
| Control Valve (Arm) | 125-126 | Boom Cylinder Assy, Grease Nipple B, Boom Tube W/ Bush, Boom Tube Assy, Boom Rod W/ Bush, Head Seal Set, Cushion Plunger, Cushion Collar |
| Bucket Cylinder | 131-133 | Swing Cylinder Assy, Backup Ring, U-Nut M27, Grease Nipple PT1, Head W/ Bush, Head 70X40 W/ Bush, Rod Bush, Head Seal Set |
| Turning Motor | 140-142 | Brake Valve, Seat, Spring, Body, Sleeve, Popet, Choke, Spool |
| Brake Valve | 143-144 | Drive Motor Assy, Motor, Reduction Gear Assy, Seal Set, Spacer, Gear, Bush, Cover Set |
| Travel Motor (Previous) | 145-146 | Drive Motor Assy, Motor Assy, Reduction Gear Assy, Reduction Seal Kit, Spacer, Sun Gear, Bush, Cover |
| Travel Motor (New Type) | 147-148 | Drive Motor Assy, Motor Assy, Reduction Gear Assy, Reduction Seal Kit, Spacer, Gear, Bush, Cover Set |
| Bucket 250 (Attachment) | 149-150 | Bucket Assy, Side Teeth, Teeth Assy, Teete Assy, Teeth Shim Set, Grease Nipple PT1 |
| Bucket 300 (Attachment) | 151-152 | Bucket Assy, Side Teeth, Teeth Assy, Teete Assy, Teeth Shim Set, Grease Nipple PT1 |
| Bucket 350 (Attachment) | 153-154 | Bucket Assy, Side Teeth, Teeth Assy, Teete Assy, Teeth Shim Set, Grease Nipple PT1 |
| Bucket 450 (Attachment) | 155-156 | Bucket 450 Assy, Side Teeth, Teeth Assy, Teeth Shim Set, Grease Nipple PT1 |
| Bucket 250W (Attachment) | 157-158 | Bucket 250W Assy, Side Teeth, Teeth, Grease Nipple PT1 |
| Bucket 300W (Attachment) | 159-160 | Bucket 300W Assy, Side Teeth, Teeth, Grease Nipple PT1 |
| Bucket 350W (Attachment) | 161-162 | Bucket 350W Assy, Side Teeth, Teeth, Grease Nipple PT1 |
| Bucket 450W (Attachment) | 163-164 | Bucket 450W Assy, Side Teeth, Teeth, Grease Nipple PT1 |
| Heater & Defroster (Optional) | 165-166 | Wiper Assy, Lead Wire, Wiper Switch, Washer |
| Wind Washer (Optional) | 167-168 | Third Valve Assy, Selector Valve, Blade Lever, Swing Spool, Spool Link, Lever Knob, 3RD Brackt Assy, Bush 14X15 |
| Control Equipment (3rd Valve) (Optional) (Previous) | 169-170 | Third Valve Kit, Control Valve, Blade Lever Shaft, Swing Spool, Spool Link, 3RD Bracket Assy, 3RD Link a Assy, Bush 14X15 |
| Control Equipment (3rd Valve) (Optional) (New Type) | 171-172 | Nipple, Elbow, Male/male Adapter, 90SS Nipple, Connector, Adapter, Hose G106AC165, 3RD P1 Tube Assy |
| 3rd Valve Piping (Optional) (Previous) | 173-174 | Elbow, Connector, Back-Up Ring P14, Adapter, Rotary Joint, Tube 3RD, 3RD Tube Assy, Pipe P206BC032 |
| 3rd Valve Piping (Optional) (New Type) | 175-176 | Control Valve, Outlet Section, Spool Section, Load Check Valve, Spring Seat, Plunger Spring, Cap, Seal Plate |
| Control Valve (3rd) (Optional) | 177-178 | Section Assy, Valve, Spring, Seal, Oil, O-Ring, Bolt, Spool |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| FUSE | 5A | p. 28 |
Yanmar YB121U / YB151U Series Common Problems This Manual Covers
Yanmar YB121U hydraulic hose part number needed for travel circuit, unsure which fitting type applies p. 97
Check the Hyd. Oil Piping (Travel) exploded view on page 97. Identify your hose by position in the circuit diagram, then match the connector type (elbow, nipple, or tube) against the parts list. Cross-reference your serial number against the Preface on page 1 to confirm Previous vs. New Type spec before ordering.
Manual Section: Hyd. Oil Piping (Travel)Need correct seal kit part number for boom cylinder overhaul, multiple model variants in this manual
Locate the Boom Cylinder Repair/Overhaul exploded view on . Identify the seal set by the cylinder bore dimension shown in the diagram. For YB121U boom and bucket pin/bush cross-reference, check page 106; for YB151U, check page 109. Confirm your model suffix (Previous vs. New Type) on page 1 before placing the order.
Manual Section: Boom Cylinder Repair/OverhaulCorrect fuse ratings and part numbers for electrical panel unclear, canopy versus cabin spec differs p. 30
For Canopy Spec machines, pull the fuse box parts list from page 30. For Cabin Spec, use page 34. Verified fuse ratings are 5A, 10A, and 15A , confirm which position uses which rating by matching the fuse box diagram to your harness layout on the wiring diagram starting at page 5. Order by part number shown in the diagram, not just amperage.
Manual Section: Electric Part (Canopy Spec.)Bucket tooth and pin part numbers needed, not sure which bucket width fits the machine p. 149
Find your bucket size in the Attachment section: 250mm on page 149, 300mm on page 151, 350mm on page 153, or 450mm on page 155. Wide-bucket variants (250W, 300W, 350W, 450W) start at page 157. Each exploded view lists teeth part numbers, side teeth, pins, shims, and grease nipples separately. Match bucket assembly number to your attachment before ordering teeth.
Manual Section: Bucket 250 (Attachment)Travel motor seal kit part number uncertain, previous type versus new type units use different kits p. 145
Identify your travel motor generation first: Previous Type parts are listed on page 145 (includes Seal Kit, Gear, Bearing, and Carrier Kit line items); New Type is on page 147. Check the Preface on page 1 for your serial number range to confirm which generation applies. Order the complete seal kit as a set , individual seal dimensions are not listed separately in this catalog.
Manual Section: Travel Motor (Previous)Control valve section assembly part numbers needed after teardown, swing and boom sections look identical p. 117
Each control valve section has its own exploded view. Swing section parts are on page 117; boom section on page 119. Both use an O-Ring 1B G-55.0 and share similar seal and oil plate components, so verify the Section Assy part number from the correct page before ordering. Cross-check against the Control Valve (P1, P2) list on page 115 if the main stack assembly number is needed.
Manual Section: Control Valve (Swing)Frequently Asked Questions
How do I find the correct part number for a hydraulic hose in the travel circuit?
Check the Hyd. Oil Piping (Travel) exploded view on page 97. Identify your hose by position in the circuit diagram, then match the connector type (elbow, nipple, or tube) against the parts list. Cross-reference the part number with the YB121U or YB151U variant column before ordering.
What seal kit do I need for a boom cylinder overhaul on the YB121U?
Locate the Boom Cylinder Repair/Overhaul exploded view on page 106 (YB121U) or page 109 (YB151U). Identify the seal set by the cylinder bore dimension shown in the diagram. Match the head seal set part number to your specific boom and bucket pin/bush cross-reference on that page.
Which fuse ratings are used in the fuse box and where is the parts list?
For Canopy Spec machines, pull the fuse box parts list from page 30 for Canopy Spec or page 34 for Cabin Spec; match the fuse rating (5A/10A/15A) to your harness using the wiring diagram on page 5, then order by part number.
How do I determine whether my YB121U is a Previous Type or New Type to order the correct cabin or control lever parts?
Check the serial number prefix on page 1 of the catalog. Previous Type and New Type sections are listed separately throughout the parts catalog (e.g., Cabin (Previous) vs Cabin (New Type), Battery (Previous) vs Battery (New Type)). Match your machine serial range to the correct section before ordering any cabin, control equipment, or hydraulic piping parts.
Document Quality
This is a scanned document with an OCR layer, allowing you to search and copy the full text. The text is generally readable, though some fine print in diagrams may appear slightly less crisp due to the scanning process. All diagrams and illustrations are raster images with mostly readable labels, and the pages are clean, showing only minor skewing, with one blank page at the end.
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