All 130 pages of this Yanmar B50 Parts Catalog cover one job: finding the right part for your B50, B50-P(R), or B50-O(R) Crawler Backhoe the first time. You get exploded-view diagrams and factory part numbers for every major system: engine mounts, radiator and oil cooler, all five hydraulic cylinders (boom, arm, bucket, swing, and blade), control valve assemblies, swivel joint, travel motor, and the complete oil piping layout. Wiring diagrams and hydraulic schematics add visual routing reference from the battery to the pilot valve. Pull seal dimensions directly from the page; the boom cylinder cross-references a 64x78x25 mm piston seal against tube and rod assemblies by OEM number. Your machine is down. Match the exploded view, grab the part number, skip the forum guessing. Bookmarks let you jump to any system by section; search by keyword on any device.
What's Inside This Yanmar B50 P(R) / O(R) (Crawler Backhoe) Parts Manual
| System | Pages | Key Topics |
|---|---|---|
| Inlet Hose & Exhaust Pipe | 10-11 | Pipe, Exhaust, Flange, Muffler, Gasket, Silencer, HOSE(A), Suction |
| Accelerator | 12-13 | Lever W/BUSH, Accel, Wire, Bracket, Joint, Cable, KNOB(D), Lever |
| Engine Mount | 14-15 | Mount, Stay, RADIATOR(L), HOSE(A), Pipe, Radiator, Bracket |
| Radiator & Oil Cooler | 16-17 | Radiator, Cap, Sub-Tank Assy, Cooler Assy, Oil, STAY(L), Cooler |
| Fuel Tank & Fuel Line | 18-19 | Fuel Tank Assy, Gauge, Fuel Oil, Cap, Fuel Tank, Strainer, Fuel Inlet, Hose |
| Battery | 20-21 | Cord(+), CORD(-), Retainer, ROD(B), Fix |
| Electric Part | 22-26 | Canopy Specification |
| Work Lamp | 27-28 | Lamp, Work, Bulb 12V-60W, Stay, Boom Light, Washer 12, Spring, Bolt M12X 25 Plated |
| Heater | 29-30 | Assy, Valve, Miniature, Hose, Tube, Base, Switch |
| Track Roller & Carrier Roller | 31-32 | Idler Assy, Bush, Shaft, Idler Seal, Adjust Cylinder, Valve Assy Nipple |
| Track Frame & Idler | 33-34 | Pin Master, Crawler Assy, Link Assy, Pin Track, Bolt Shoe, Crawler Rubber |
| Crawler | 35-36 | Bush, Support Link, Plate Link, Cushion, Circlip, Nipple Grease |
| Link Stand | 37-38 | Grommet, Lever, Knob, Link Bucket, Shaft Link, Rod-End |
| Control Equipment | 39-46 | Control EQUIP.(BOOM & Bucket), Control Equip.( |
| Operation Lever Stopper | 47-48 | - |
| Turning Frame | 49-50 | - |
| Turning Driving Gears | 51-52 | - |
| Bonnet | 53-54 | Wing Bolt, Step, Seat, Adjuster, Cover, Grill |
| Seat & Step | 55-59 | Seat, Step, Cushion, Adjuster, Mount, Nut |
| Cabin | 60-62 | Assy, Glass, Door, Latch, Trim, Seal |
| Boom Cylinder | 63-68 | Cylinder, Tube Assy, Rod Assy, Piston, Seal Set, Bush |
| Arm Cylinder | 69-70 | Cylinder, Tube Assy, Rod Assy, Piston, Seal Set, Bush |
| Bucket Cylinder | 71-72 | Cylinder, Tube Assy, Rod Assy, Piston, Seal Set, Bush |
| Swing Cylinder | 73-74 | Cylinder, Tube Assy, Rod Assy, Piston, Seal Set, Bush |
| Blade Cylinder | 75-78 | Cylinder, Tube Assy, Rod Assy, Piston, Seal Set, Bush |
| Hyd. Oil Pump & Joint | 79-80 | Motor, Rotary Set, Piston, Case Set, Parallel Pin, Spring Washer |
| Turning Motor | 81-82 | Valve Brake, Valve Check, Spring, Plug, Valve Relief, Seal Set |
| Brake Valve | 83-84 | Valve Check, Spring, Plug, Seal Kit, Valve Assy Control, Piston Free |
| Travel Motor | 85-86 | Joint Assy Swivel, Shaft, Hub Swivel, Spacer Swivel, Seal Assy, O-Ring |
| Swivel Joint | 87-88 | Valve, Section Assy Inlet, Spring, O-Ring, Valve Relief, Tie-Rod |
| Control Valve | 89-98 | Section Assy Spool, Spring Control Valve, Poppet, Plate Seal, Head Bolt Socket, Valve Relief |
| Pilot Valve | 99-100 | Element W/Valve, Valve By-Pass, Spring Strainer, Plug Oil Feed, O-Ring |
| Hyd. Oil Tank | 101-102 | Hyd Oil Tank Assy, Bar Filter Support, Strainer Suction, Element W/Valve, Breather Air, Gauge Oil Level |
| Greasing | 103-104 | Connector, Elbow, Nipple, Joint, O-Ring, Hose |
| Hyd. Oil Piping | 105-118 | Tank-Valve |
| 3rd Valve Control | 119-122 | Adaptor, Connector, Elbow, O-Ring, Joint, Hose |
| 3rd Valve (Valve) | 123-125 | Pin, Arm, Bush, Spacer, O-Ring, Seal |
| Boom & Bucket | 126-127 | Shim, Blade, Bush, Pin, Plate, Cotter Pin |
| Blade | 128-130 | Bush, Pin, Bolt, Cotter Pin, O-Ring, Washer |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| SEAL 64 78 25 | 64x78x25 mm | p. 32 |
| SEAL WSF30X62X20 | 30x62x20 mm | p. 54 |
| Boom Swing Angle | Left 50 - Right 90 degree | p. 2 |
| Travel Speed (high-low) | 4.3(4.5)/2.2(2.3) km/h | p. 2 |
Yanmar B50 P(R) / O(R) (Crawler Backhoe) Common Problems This Manual Covers
Yanmar B50 crawler backhoe front idler leaking grease and failing to hold track tension p. 34
Review the Track Frame & Idler drivetrain parts diagram on page 34. Identify the exact replacement idler seal, which measures 66x86x28 mm. Order the required seal part number alongside the corresponding idler bush and shaft components to complete the rebuild.
Manual Section: Track Frame & IdlerTracks barely move and the machine struggles to reach its normal travel speeds p. 85
Check the Travel Motor parts breakdown on page 85. Identify the swivel joint assembly and O-rings required to restore the factory high travel speed of 4.3(4.5) km/h. Order the correct replacement hub and spacer components to stop internal hydraulic bypass leaks.
Manual Section: Travel MotorLoud grinding noise and heavy fluid leakage from the swing motor during rotation p. 51
Inspect the Turning Driving Gears components on page 51. Locate the exact replacement lower shaft oil seal measuring 62x80x12 mm detailed on page 52. Verify the specific bearings, collars, and mounting hardware part numbers required to properly rebuild the turning mechanism.
Manual Section: Turning Driving GearsFrequently Asked Questions
What are the replacement specifications for hydraulic hoses?
The manual provides specific part numbers for various hydraulic hoses, which serve as their replacement specifications. For example, in the "Hyd. Oil Piping (Tank Return)" section on page 112, a hose with the specification "HOSE G706BB140W" is listed under part number 172124-78321.
What are the replacement specifications for hydraulic seals?
The manual lists specific part numbers for various hydraulic seals and seal kits, which are the replacement specifications. For instance, in the "Boom Cylinder" section on page 64, replacement specifications include "SEAL SET, HEAD" (part number 172151-71810) and "SEAL SET, PISTON" (part number 172151-71800).
How do you fix yanmar B50 crawler backhoe front idler leaking grease and failing to hold track tension?
Review the Track Frame & Idler drivetrain parts diagram on page 34. Identify the exact replacement idler seal, which measures 66x86x28 mm. Order the required seal part number alongside the corresponding idler bush and shaft components to complete the rebuild.
How do you fix tracks barely move and the machine struggles to reach its normal travel speeds?
Check the Travel Motor parts breakdown on page 85. Identify the swivel joint assembly and O-rings required to restore the factory high travel speed of 4.3(4.5) km/h. Order the correct replacement hub and spacer components to stop internal hydraulic bypass leaks.
Is this Yanmar B50-P(R) & variants Parts Catalog a digital download?
Instant PDF download. You get the full 130-page searchable Parts Catalog immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Can I print specific sections of this Yanmar B50-P(R) & variants Parts Catalog?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Does this Yanmar B50-P(R) & variants Parts Catalog cover the hydraulic system?
A hydraulic system diagram for the Yanmar B50-P(R) & variants is included.
Document Quality
This document is a scanned PDF, but it includes an OCR layer, so you can search and copy text from all pages. The text on both the scanned pages and the OCR-generated pages is crisp and easy to read. All diagrams and illustrations are scanned images, but they are clear with sharp lines and readable labels, even at higher zoom levels. The pages are clean with no noticeable scan artifacts, marks, or skewed content, though many pages consist solely of OCR-generated text corresponding to the preceding diagram.
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