Kubota U35
Frequently Asked Questions about Kubota U35 Excavator
Answer:
The Kubota U35 is a 3.5-3.7 ton class mini excavator known for its zero-tail swing design and powerful Kubota diesel engine. Below are the detailed specifications for the U35-4 model, the most common variant in production since 2019 .
Complete Specifications Table:
| Parameter | Value |
|---|---|
| Model | U35 / U35-4 / U35-3 |
| Operating Weight | 3,687 – 3,991 kg (8,129 – 8,800 lbs) |
| Engine Model | Kubota D1703M-DI-E4 / D1803M-E3BH |
| Engine Type | 4-cylinder, water-cooled diesel |
| Rated Power | 23.3 HP (17.4 kW) – 25 HP (18.5 kW) |
| Displacement | 1.647 L (100.5 cu in) |
| Fuel Tank Capacity | 46.9 L (12.4 gal) |
| Bucket Capacity | 0.058 – 0.10 m³ |
| Max Digging Depth | 2,970 – 3,010 mm (9 ft 9 in) |
| Max Digging Height | 4,844 mm (15 ft 11 in) |
| Max Dumping Height | 3,370 mm (11 ft 1 in) |
| Max Digging Radius | 5,272 mm (17 ft 4 in) |
| Bucket Breakout Force | 3,594 kgf (7,924 lbs) |
| Arm Breakout Force | 2,019 kgf (4,451 lbs) |
| Tail Swing Type | Zero Tail Swing / Tight Tail Swing |
| Travel Speed (Low/High) | 3.0 km/h / 4.6 km/h (1.9/2.9 mph) |
| Transport Length | 4,749 mm (15 ft 7 in) |
| Transport Width | 1,700 mm (5 ft 7 in) |
| Transport Height | 2,470 mm (8 ft 1 in) |
| Track Width | 300 mm |
| Ground Pressure | 0.34 – 0.38 kgf/cm² (rubber tracks) |
| Hydraulic Pump Capacity | 39.6 L/min x 2 + 20.9 L/min x 1 |
| Auxiliary Hydraulics Flow | 60 L/min (15.8 GPM) |
Key Dimensions (Working Range):
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Max vertical digging depth: 2,013 mm
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Min turning radius (without swing): 2,250 mm
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Tail swing radius: only 48 mm (1.9 inches) beyond track width on U35-4
Answer:
Zero-tail swing (ZTS) means the excavator’s rear end (counterweight and engine hood) never protrudes beyond the track width during 360° rotation. The Kubota U35-4 takes this further with a tight tail swing design where the counterweight extends merely 1.9 inches (48 mm) beyond the track width, while the engine hood is recessed 5 inches inside the counterweight edge for maximum protection .
Key Benefits and Data:
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Worksite Safety – Eliminates risk of rear-end collisions with walls, traffic, or workers. The operator no longer has to worry about damage to the excavator or job site structures, even in tight spaces .
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Space Efficiency – Can work in spaces just wide enough for the machine itself, right up against a wall or fence, and dig a 9-10 foot trench with ease .
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Protected Components – The engine hood is recessed inside the counterweight so that side panels and engine components are extremely well protected from impact damage .
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Market Leadership – Kubota has been the world’s #1 selling compact excavator for 20 consecutive years (according to 2024 data), largely due to pioneering zero-tail swing technology .
Design Advantages:
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The U35 combines zero tail swing with independent boom swing and 360° house rotation
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Maintains stability of conventional tail swing machines through compact track width and specially designed counterweight for superb weight distribution
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The 30° angle of the upper track frame helps prevent dirt accumulation and makes cleanup easier
nswer:
With proper maintenance, the Kubota U35’s undercarriage components can achieve extended service life. Below is the comprehensive maintenance schedule based on Kubota recommendations and industry best practices .
Recommended Maintenance Schedule:
| Component | Interval | Maintenance Action |
|---|---|---|
| Daily (Every 8-10 hours) | ||
| Visual Inspection | Every start | Check for leaks, damage, loose bolts |
| Engine Oil/Coolant | Daily | Check levels, top up as needed |
| Hydraulic Oil | Daily | Check sight glass levels |
| Tracks | Daily | Inspect for wear, foreign objects, proper tension |
| Greasing | Daily | Lubricate all pivot points (boom, arm, bucket linkage) |
| Weekly / Every 50 hours | ||
| Air Pre-cleaner | 50 hours | Clean/inspect, check radiator fins |
| Battery | 50 hours | Check terminals and charge |
| Track Tension | Weekly | Adjust to manufacturer sag specification |
| Every 250 hours | ||
| Engine Oil & Filter | 250 hours | Replace with Kubota approved oil |
| Hydraulic Filter | 250 hours | Replace as recommended |
| Fuel Filters | 250 hours | Replace both main and inline filters |
| Every 500 hours | ||
| Hydraulic Oil | 500-1000 hours | Sample and analyze; replace if contaminated |
| Swing Bearing | 500 hours | Grease and inspect for wear |
| Annually | ||
| Full Hydraulic Analysis | Annual | Perform fluid analysis for heavy-duty usage |
| Pin & Bushing Inspection | Annual | Check all pivot points for wear |
| Pump & Valve Check | Annual | Schedule if performance loss noticed |
Undercarriage Life Expectancy:
| Component | Expected Life | Key Factors |
|---|---|---|
| Rubber Tracks | 1,500 – 2,500 hours | Ground conditions, tension maintenance |
| Track Rollers | 2,000 – 3,000 hours | Regular cleaning, debris removal |
| Sprockets | 2,500 – 3,500 hours | Replace in matched sets with tracks |
| Pins & Bushings | 3,000 – 5,000 hours | Regular greasing is critical |
Longevity Tips:
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Proper track tension adjustment can extend rubber track life by 50%
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Daily cleaning of undercarriage extends service life by up to 30%
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The undercarriage accounts for approximately 40-50% of lifetime repair costs
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Kubota’s X-frame substructure improves track frame rigidity for demanding high-cycle applications
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The crawler tension spring absorbs shock loads that affect rubber track service life
Answer:
Based on operator feedback, dealer experiences, and equipment forums, here are the most common issues reported for the Kubota U35 series along with diagnostic and repair guidance .
Most Common Issues and Solutions:
| Issue Category | Specific Problem | Diagnosis & Solution |
|---|---|---|
| Electrical / Display | Screen error “Tab 514” flashing intermittently | Caused by water intrusion into the electronic throttle module. The hidden button above auto-idle gets activated. Solution: Replace throttle module ($500 OEM) or try aftermarket ($82) |
| Hydraulic System | Slow or weak hydraulics | Check hydraulic fluid level first. If low, inspect for leaks. Contaminated fluid or clogged filters are common. Perform hydraulic pressure test if level is normal |
| Overheating | Engine or hydraulic overheating | Dirty radiator fins and blocked airflow are primary causes. Clean cooling package thoroughly, verify fan operation, and check coolant concentration |
| Track & Undercarriage | Premature track wear | Caused by abrasive ground conditions or incorrect tension. Inspect regularly, maintain proper sag, and replace worn components in matched sets |
| Fuel System | Power loss when hot / hard starting | Check all fuel filters including inline and banjo union filters. Contaminated fuel or blocked injectors are common on D1703 engines |
| Attachment Issues | Undersized hydraulic supply | Installing high-flow attachments without proper pump configuration causes sluggish operation. Confirm auxiliary flow requirements (max 60 L/min) |
| Cold Start | Difficulty starting in cold weather | Check battery condition and glow plug operation. Ensure clean fuel system with winter-grade diesel |
Diagnostic Tips from Experienced Technicians:
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The U35-4 features an intelligent fault diagnosis system on the LCD display that shows error codes and maintenance alerts
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If the machine runs rough and loses power when hot, suspect fuel starvation – check filters first before assuming pump failure
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Kubota had three different groups build the U35 control units, so ensure you have the correct schematic and manual for your specific serial number
Cost-Saving Tip:
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The two-piece configuration of boom and dozer cylinder hoses reduces hose replacement time by up to 60% and lowers replacement cost
Answer:
The Kubota U35 features a robust hydraulic system with proportional flow control that allows programming of up to five different oil flow rates for specific attachments directly from the digital control panel – no tools or manual adjustment required .
Compatible Attachments and Specifications:
| Attachment Type | Flow Requirement | Best Applications | Performance Notes |
|---|---|---|---|
| Standard Bucket | 0-60 L/min | Trenching, grading, general excavation | 0.058-0.10 m³ capacity; multiple widths available |
| Hydraulic Breaker | 40-60 L/min | Light demolition, concrete cutting, rock breaking | Matches U35’s 3.5-4 ton class; use proportional rocker switch |
| Auger | 30-50 L/min | Fence posts, signposts, planting, small foundations | Bi-directional rocker switch enables easy operation |
| Hydraulic Thumb | 20-40 L/min | Material handling, loading cycles | Mechanical or hydraulic options available |
| Tilt Coupler | 30-50 L/min | Angled grading, complex terrain work | Quick change-out of tools |
| Grapple | 40-60 L/min | Demolition, scrap handling, forestry cleanup | Requires one-way or two-way flow configuration |
Key Attachment Features of U35:
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Proportional Auxiliary Flow Control – A convenient bi-directional rocker switch on the right-hand control lever enables easy operation of hydraulic thumbs, breakers, augers, and other attachments
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Third-Line Hydraulic Return – Standard system allows oil recirculation directly to the tank without passing through control valves when operating one-way attachments, decreasing back pressure and increasing oil flow efficiency
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Auxiliary Diverter Valve – Standard feature allows a second hydraulic attachment to be connected with oil flow switched between attachments without disconnecting the primary tool
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Maximum Auxiliary Flow – 60 L/min (15.8 GPM) at system pressure
Performance Tips:
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Always confirm attachment flow requirements match the U35’s auxiliary output (max 60 L/min)
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Using undersized or oversized attachments can cause sluggish operation or hydraulic overheating
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The float function on the dozer blade (standard feature) enables quick ground finishing without adjusting blade height
Productivity Data:
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The U35 can dig a 9-10 foot trench with ease when working against walls or fences
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With the optional hydraulic angle blade, operators can angle the blade right or left using a thumb-operated rocker switch, eliminating repetitive repositioning when backfilling trenches
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The two-speed travel system (3.0/4.6 km/h) combined with auto down-shift ensures smooth operation when dozing and turning
