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Kubota U25S, U20-3a, U25-3a Workshop Repair Manual

Kubota U25S, U20-3a, U25-3a Workshop Repair Manual

$32.00

🚜 Equipment
Brand	Kubota
Type	Excavator
Model	U25S, U20-3a, U25-3a
📄 Documents
Type	Repair Manual
Publication	97899-61500
Language	English
Format	PDF
No of Pages	478

The Kubota U25S, U20-3a, and U25-3a Mini Excavators are versatile zero-tail swing machines designed for efficient operation in confined spaces while maintaining strong digging capacity and operator comfort. Powered by reliable Kubota diesel engines and equipped with advanced hydraulics, these models provide contractors and operators with dependable performance for construction, utility, and landscaping applications.

The U25S is a compact yet powerful excavator with an operating weight of approximately 2.55 tonnes and a 20.9 hp engine, delivering a digging depth of 2.81 m. With a fixed width of 1,500 mm, it provides stability and productivity in small to mid-size excavation projects. The U20-3a, at 2.18–2.38 tonnes depending on canopy or cab, uses a 19 PS (13.5 kW) engine and offers a digging depth of 2.54 m. It features an adjustable track width (1,300–1,500 mm), providing flexibility to access narrow areas without compromising balance. The U25-3a, weighing around 2.54–2.55 tonnes, is powered by a 15.5 kW engine and achieves a digging depth of 2.82 m, with a standard 1,500 mm transport width for robust yet compact operation.

The workshop repair manual provides full technical documentation, including safety guidelines, engine servicing, hydraulic circuits, swing and travel motor maintenance, control valve adjustments, electrical system troubleshooting, and cab/canopy installations. It also features detailed wiring and hydraulic schematics, torque specifications, lubrication intervals, troubleshooting charts, and step-by-step disassembly and reassembly procedures. Specialized content covers undercarriage servicing, variable track mechanisms (for the U20-3a), and the Kubota Intelligent Control System (KICS), ensuring precise maintenance and extended machine life.

Key Highlights

Kubota U25S: ~2.55 t operating weight, 20.9 hp engine, 2.81 m digging depth, 1,500 mm width
Kubota U20-3a: 2.18–2.38 t operating weight, 19 PS (13.5 kW) engine, 2.54 m digging depth, adjustable width 1,300–1,500 mm
Kubota U25-3a: ~2.54–2.55 t operating weight, 15.5 kW engine, 2.82 m digging depth, 1,500 mm width
Zero-tail swing design for enhanced safety and maneuverability in confined areas
Auxiliary hydraulic circuits for versatile attachment use
ROPS/TOPS canopy or cab options with ergonomic operator layout
Workshop manual covers engine, hydraulics, electrics, swing/travel motors, and undercarriage
Includes hydraulic and electrical schematics, torque values, lubrication charts, and troubleshooting guides
Variable track system (U20-3a) for flexible stability and narrow site access
KICS (Kubota Intelligent Control System) coverage for efficient diagnostics and performance monitoring

Table of Content

📙 Table of Contents

U20-3A

U20-3a
- CONTENTS
  - I General
    - A.Body and engine identification marks
    - B.Safety precautions for servicing, disassembly and
    - C.IMPORTANT SAFETY PROCESS AND CRITICAL
    - D.IMPORTANT INSPECTION ITEMS AFTER
    - E.SERVICING FUNDAMENTALS
    - F. Maintenance intervals
      - a. Maintenance intervals chart : EU-version
      - b.Maintenance intervals chart : PP-version
      - c.Water and oil quantity
      - d.Recommended oil
      - e Hydraulic Oil Check for machines with Hydraulic Breakers
      - f. Periodic replacement of important parts
  - II Machine Body
    - A.Specifications
      - a. Machine weight
      - b. Machine specifications
      - c. Lever stroke and operating force
      - d. Dimensions of parts
        [1] Front pins
        [2] Bucket
        [3] Rubber crawler
        [4] Iron crawler
        [5] Track roller, idler, and sprockett
        [6] Dozerr
        [7] Parts weight
        [8] Water and oil quantity
    - B.Front attachment
      - a. Parts designation
      - b. Exchange of bucket (Kubota
      - c. Exchange of bucket teeth and
      - d. Installing of dust seal and thrust
      - e. Installation of pin and bush
        [1] Pin bush
        [2] Pin, bush-(2)
        [3] Front bucket mounting instruction (PP-version)
      - f. Front hose
        [1] Front hose assembly (U20-3α)
        [2]Front hose assembly (U25-3α, U25S)
        [3] Hose clamp
        [4] Front hose control valve side
    - C.Upper structure
      - a. Lever and pedal
        [1] Travel lever
        [2] Acceleration lever
        [3] Blade lever
        [4] Swing pedal
        [5]Service port pedal
        [6] Limit switch
      - b Counterweight
    - D.Cab / canopy installation
      - a. Installing the cabin or canopy
        [1] Installing the cabin
        [2] Canopy installation
        [3]Floor Mat
        [4] Heater setup
        [5]Defroster setup
        [6] Thermal insulation and sound
        [7] Seat and seat belt
        FYI (For your information)
        [8] Boom cylinder for cab type
        [9] Outlook of covers
    - E. Under carriage
      - a Swivel bearing
      - b Grease tube
      - c Track tension device
      - d Upper roller and track roller
      - e. Crawler replacement and tension adjustment procedure
    - F. Variable track (U20-3α)
      - a. Dimensional view
      - b.Service data
      - c. Track frame
      - d. Blade
      - e. Track cylinder
      - f. Blade cylinder
      - g. Hydraulic hose
      - h. Control valve
      - i. Swivel joint
      - j. Track control lever
      - k. Counterweight
    - G. Label
  - III Engine
    - III-1 Engine specifications for construction machinery
    - III-2 Engine mount on the construction machinery
      - A. Engine bracket
      - B. Radiator
        [1] Detaching the radiator
        [2] Reassembling the radiator
      - C. Muffler
        [1] Reassembling procedure
      - D. Fan belt
      - E. Air cleaner
      - F. Fuel tank and hose
    - III-3. 05-M Series Engine WSM-General
    - III-4. Engine WSM (Mechanism section)
      - A.Feature
      - B.Engine body
        [1]Cylinder block
        [2]Cylinder head
        [3]Crankshaft
        [4]Piston and piston rings
        [5]Connecting rod
        [6]Rocker arm
        [7]Camshaft
        [8]Fuel camshaft
        [9]Flywheel
      - C.Lubricating system
        [1]General
        [2]Oil pump
        [3]Relief valve
        [4]Oil filter cartridge
        [5]Oil pressure switch
      - D.Cooling system
        [1]General
        [2]Water pump
        [3]Thermostat
        [4]Radiator (not included in the basic engine)
        [5]Radiator cap
      - E.Intake / exhaust system
        [1]Air cleaner (not included in the basic engine)
        [2]Muffler (not included in the basic engine)
      - F. Fuel system
        [1]General
        [2] Injection pump
        [3] Injection nozzle
        [4]Fuel filter (not included in the basic model)
        [5]Governor
      - G.Electrical system
        [1]Charging system
    - III-5. Engine WSM (Service section)
      - A.Engine mount on the machine
      - B.General
        [1]Engine identification
        [2]General precaution
        [3]Tightening torques
        [4]Troubleshooting
        [5]Servicing specifications
        [6]Maintenance check list
        [7]Check and maintenance
      - C.Engine body
        CHECKING AND ADJUSTING
        DISASSEMBLING AND ASSEMBLING
        [1]Draining water and oil
        [2]External components
        [3]Cylinder head and valves
        [4]Gear case
        [5]Piston and connecting rod
        [6]Flywheel and crankshaft
        SERVICING
        [1]Cylinder head
        [2]Timing gear and camshaft
        [3]Piston and connecting rod
        [4]Crankshaft
        [5]Cylinder
      - D.Lubricating system
        CHECKING
        SERVICING
        [1]Oil pump
      - E.Cooling system
        CHECKING
        [1]Fan belt
        [2]Radiator
        DISASSEMBLING AND ASSEMBLING
      - F. Fuel system
        CHECKING AND ADJUSTING
        [1] Injection pump
        [2] Injection nozzle
        DISASSEMBLING AND ASSEMBLING
        [1] Injection pump
        [2] Injection nozzle
      - G.Electrical system
        CHECKING
        [1]Starter
        [2]Glow plug
        DISASSEMBLING AND ASSEMBLING
        [1]Starter
        [2]Alternator
        SERVICING
        [1]Starter
        [2]Alternator
      - H.Turbo charger system
        CHECKING
        DISASSEMBLING AND ASSEMBLING
  - IV.Hydraulic system (Service section)
    - A.Troubleshooting
      - a. Common Circuit
      - b. Hydraulic system and front attachment
      - c. Pump
      - d. Motor
      - e. Swivel performance
      - f. Traveling performance
    - B.Specifications
      - a. Pump
        [1] Specifications
        [2] Piston pump P-Q performance curve (Theoretical)
      - b. Relief valve
        [1] Location
        [2]Main relief valve (bench data)
        [3]Main relief valve (at the measurement port on the machine)
        [4]Pilot system pressure
        [5]Overload relief valve (bench data)
        [6]Overload relief valve (at the measurement port on the machine)
      - c.Swivel performance
      - d.Traveling performance
      - e. Cylinder
        [1] Specifications and dimensions listt
        [2] Speed
        [3] Natural fall
        [4] Cylinder list
    - C.Testing
      - a. Pump flow
      - b. Pressure measurement
        [1] Pilot pressure
        [2] Main relief valve pressure
        [3] Overload relief pressure
        [4] Swivel brake pressure
        [5] Swivel brake release valve
        [6] Travel two-speed selector pressure
      - c. Drain measurement
        [1] Travel motor
        [2] Swivel motor
      - d. Measurement of block performance
        [1] Swivel
        [2] Travel
      - e. Operating speed
        [1] Checking procedure of each speed
      - f. Straight travel performance
      - g. Control and traveling lever operating force
      - h. Control and traveling lever stroke
      - i. Cylinder natural fall amount
    - D.Disassembling and Assembling
      - a. Pump
        [1] Pump coupling
        [2] Mounting and dismounting the pump
        [3]Component parts of pump
        [4]Disassembling and reassembling the pump.
        [5]Troubleshooting of pump
      - b. Control valve
        [1]Mounting and dismounting the valve
        [2] Disassembling and reassembling
        [3] Component parts of sections
      - C. Pilot valve
        [1] Mounting and dismounting the pilot
        [2] Disassembling and reassembling the pilot valve
      - d. Swivel motor
        [1] Mounting and dismounting the swivel motor
        [2] Swivel motor mounting/dismounting component parts
        [3] Disassembling and reassembling
      - e. Rotary joint (Swivel joint)
      - f. Traveling motor
        [1] Mounting and dismounting the wheel motor
        [2] List of adapter hoses
        [3] Component parts of wheel motor (Kayaba-make)
        [4] Disassembling and reassembling the wheel motor
      - g.Cylinder
      - h. Hydraulic hose
        [1] Delivery hose
        [2] Delivery hose routing
        [3] Blade / travel hose
        [4] Pilot hose
      - i. Other hydraulic valve
        [1] Selector valve
        [2] Pilot filter
        [3] TPSS valve, PP-version
        [4] Accumulator
        [5] Third line valve
  - V.Electrical system (Service section)
    - A.Specifications
    - B Troubleshooting
      - a Engine
      - b Meter panel
      - c Others
      - d Check instructions
        [1] Fuse
        [2] Battery voltage
        [3] Automatic release relay
        [5] Starter motor
        [6] Key switch
        [7] Fuel pump coupler
        [8] Engine stop solenoid
        [9] Glow relay
        [10] Charge and engine oil lamp
        [11] Water temperature gauge
        [12]Fuel sensor
        [13]Solenoid valve
        [14]Horn
        [15]working light
    - C Wireharness installation
      - a Front wireharness
      - b Wireharness around engine
      - C Swivel frame wireharness
      - d. Wireharness around battery
      - e Wireharness around seat
  - Conversion Tables

Specification

Specification	Kubota U25S	Kubota U20-3a / U20-3α	Kubota U25-3a / U25-3α
Operating Weight	≈ 2,550 kg (5,625 lb) :contentReference[oaicite:0]{index=0}	≈ 2,380 kg (cab) / ≈ 2,180 kg (canopy) :contentReference[oaicite:1]{index=1}	≈ 2,540-2,550 kg :contentReference[oaicite:2]{index=2}
Engine Power	20.9 hp / ≈ 15.6 kW :contentReference[oaicite:3]{index=3}	19 PS / 13.5 kW :contentReference[oaicite:4]{index=4}	≈ 15.5 kW :contentReference[oaicite:5]{index=5}
Maximum Digging Depth	≈ 2,810 mm :contentReference[oaicite:6]{index=6}	≈ 2,540 mm :contentReference[oaicite:7]{index=7}	≈ 2,820 mm :contentReference[oaicite:8]{index=8}
Transport / Operating Width	≈ 4 ft 11 in / 1,500 mm :contentReference[oaicite:9]{index=9}	1300-1500 mm (adjustable track width) :contentReference[oaicite:10]{index=10}	≈ 1,500 mm :contentReference[oaicite:11]{index=11}
Length (Transport / Overall)	≈ 13 ft 7 in / 4,150 mm :contentReference[oaicite:12]{index=12}	≈ 3.85 m :contentReference[oaicite:13]{index=13}	≈ 4.1 m :contentReference[oaicite:14]{index=14}
Bucket / Standard Bucket Capacity	Not specified in sources checked :contentReference[oaicite:15]{index=15}	≈ 0.066 m³ :contentReference[oaicite:16]{index=16}	≈ 0.08 m³ :contentReference[oaicite:17]{index=17}
Tear-Out Force / Breakout Force	≈ 5,765 lb / 2,615 kgf :contentReference[oaicite:18]{index=18}	≈ 13.2 kN arm / 18.4 kN bucket force :contentReference[oaicite:19]{index=19}	≈ 22 kN :contentReference[oaicite:20]{index=20}
Travel Speed / Max Speed	≈ 1.6 mph (low) / 2.9 mph (high) :contentReference[oaicite:21]{index=21}	≈ 2.2 / 4.2 km/h :contentReference[oaicite:22]{index=22}	Not clearly specified in sources checked :contentReference[oaicite:23]{index=23}

Buyer Questions & Answers

Frequently Asked Questions❔

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