Komatsubulldozersmall ( - d39)

Komatsu DRT031_2H(S/N 41001-UP (D31S/Q/SM-20))

Maintenance schedule, common problems & OEM parts breakdown

Search live DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) parts

The Komatsu DRT031_2H parts book covers the D31S-20, D31Q-20, and D31SM-20 trims for S/N 41001-and-up, a roughly 6.8 to 7.1 tonne (14,900 to 15,700 lb) class small crawler tractor from the D31 -20 series generation, produced in the early-to-mid 1990s. Rather than a conventional dozer blade, this build carries a front loading bucket of about 0.84 m3 (1.1 yd3) heaped capacity on a lift arm driven by dedicated lift and tilt cylinders, making it a dozer-shovel/crawler-loader configuration rather than a blade dozer. Power comes from Komatsu's naturally aspirated 6D95L-1 inline-six diesel through a powershift transmission and bevel-gear steering clutches to final drives on each side. The S and Q trims share the same chassis and engine but differ in track gauge and shoe width, narrow-gauge/higher-ground-pressure for the S trim versus wide-gauge/lower-ground-pressure for the Q trim, while the SM variant shares the same 41001-up serial block without a separately published spec sheet. This generation followed the earlier D31-18 series dozer-shovels and was itself succeeded by the D31EX-21/D31PX-21 generation as Komatsu updated the D31 platform's engine and controls.

Komatsu shared one factory manual set across this bucket-equipped S/Q/SM dozer-shovel line and the blade-equipped D31E/P/PL/PLL straight- and angle-blade dozers built on the same chassis and engine, so undercarriage, engine, and transmission parts cross reference across siblings even though bucket and blade work equipment do not. In the used and parts market today this dozer-shovel variant is valued as a compact, loader-style machine for confined-site grading, backfilling, and light material handling where a full-size wheel loader or blade dozer will not fit, and its shared drivetrain with the wider D31 family keeps common wear parts such as final drives, track components, and engine internals reasonably available despite the machine's age. Buyers sourcing engine or fuel-system parts should confirm the exact engine fitted by serial plate rather than assume it from the model name alone, since documentation across the broader D31-20 serial range shows some windows with a later production changeover to a turbocharged four-cylinder engine that is not interchangeable with this naturally aspirated six.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Komatsu DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) specifications

Engine

Engine model	Komatsu 6D95L-1, naturally aspirated inline-six diesel, for the base of this serial block (confirmed via parts cross-reference and shop-manual grouping with the sibling D37E-5/D37P-5A). Some general spec listings for this D31-20 range instead show a turbocharged four-cylinder engine — that reflects a later running change within the 41001-UP block, not the base engine. Confirm which engine is fitted by the serial plate before ordering engine or fuel-system parts.
Net power / displacement (as commonly listed)	52 kW / 69.8 HP at 2,350 rpm, 3.92 L (239.3 cu in) — this figure is published under a mismatched engine name in some sources, so treat it as unconfirmed for the 6D95L-1 specifically and verify against your dealer or the factory shop manual.
Emissions tier	Pre-emissions-regulation era mechanical diesel; no EPA/EU tier documented for this range.

Weights

Operating weight — D31S-20 trim	6,780 kg (14,947 lb)
Operating weight — D31Q-20 trim	7,120 kg (15,697 lb)
Operating weight — D31SM-20 trim	Not separately published; shares chassis/engine family with S and Q trims, so falls in the same general class — verify with your dealer
Static tipping load — D31S-20	4,260 kg (9,392 lb)
Static tipping load — D31Q-20	4,430 kg (9,767 lb)

Dimensions

Overall length (bucket on ground) — D31S-20	4.11 m (13.5 ft)
Overall length (bucket on ground) — D31Q-20	3.99 m (13.1 ft)
Width across tracks — D31S-20	1.80 m (5.9 ft)
Width across tracks — D31Q-20	2.26 m (7.4 ft)
Height to top of cab — D31S-20	2.65 m (8.7 ft)
Height to top of cab — D31Q-20	2.71 m (8.9 ft)
Track gauge — D31S-20	1,450 mm (57.1 in)
Track gauge — D31Q-20	1,650 mm (65.0 in)
Track shoe width — D31S-20	330 mm (13.0 in)
Track shoe width — D31Q-20	600 mm (23.6 in)
Track length on ground (both trims)	1.89 m (6.2 ft)
Reach at dump height — D31S-20	0.82 m (2.7 ft)
Reach at dump height — D31Q-20	0.75 m (2.47 ft)
Clearance at full height/dump — D31Q-20	2.65 m (8.7 ft)
Track rollers per side (both trims)	Five per side

Performance

Maximum travel speed (both trims)	6.6 km/h (4.1 mph); forward/reverse gear breakdown not published for this range
Ground pressure — D31S-20 (narrow-gauge trim)	53 kPa (7.7 psi)
Ground pressure — D31Q-20 (wide-gauge trim)	30.4 kPa (4.4 psi)
Breakout force — D31S-20	62.7 kN (14,100 lb)
Breakout force — D31Q-20	66.8 kN (15,000 lb)
Drawbar pull	Not documented in available sources for this exact serial range — verify with your dealer or the factory shop manual
Gradeability	Not documented in available sources for this exact serial range — verify with your dealer or the factory shop manual

Blades / Work Equipment

Configuration	This DRT031_2H (S/N 41001-UP, D31S/Q/SM-20) build is a dozer-shovel configuration fitted with a front loader bucket, not a discrete dozer blade. No S/SU/A/VPAT blade width or capacity options are published for this serial range.
Bucket capacity, heaped (both S and Q trims)	0.84 m³ (1.1 yd³)

Service Capacities

Fuel tank (both trims)	115 L (30.4 gal)
Engine oil, hydraulic oil, coolant capacities	Not consistently documented across independent public sources for this exact serial range — check the Komatsu shop manual for this machine or ask your dealer for the factory lubrication chart

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase (w/ filter)	14 L (3.7 US gal)	Komatsu genuine diesel engine oil (EO series). Select SAE grade by ambient temperature per the Komatsu viscosity chart for this era — roughly SAE 10W in cold conditions, SAE 30 in warm conditions, or a 10W-30/15W-40 multigrade across the mid-range. Confirm exact break points against the OMM chart for this serial range before topping off.
Cooling system	22 L (5.8 US gal)	Komatsu genuine antifreeze/coolant (ethylene-glycol based, corrosion-inhibited), mixed to the ratio specified for expected ambient low temperature. Use soft/clean water if premix concentrate is used.
Fuel tank	115 L (30.4 US gal)	ASTM D975 No. 2-D diesel fuel (No. 1-D or a winter blend in cold climates to prevent waxing/gelling).
Transmission (powershift)	13 L (3.4 US gal)	Komatsu genuine powertrain oil (TO series).
Bevel gear case / steering clutch compartment	About 47 L (12.4 US gal) per factory refill-capacity data; some owner references cite a smaller figure (roughly 20 L / 5.3 US gal) for this compartment. Treat as approximate and confirm against the dipstick/fill-plug level rather than topping strictly to a fixed volume.	Komatsu genuine powertrain oil (TO series), shared with the steering clutch and brake assemblies in this compartment.
Final drive (each side)	9.5 L (2.5 US gal) per side on the narrower (1450 mm) track-gauge configuration; 12 L (3.2 US gal) per side on the wider (1650 mm) track-gauge configuration	Komatsu genuine powertrain/axle gear oil (TO or AXO series, per final-drive gear spec).
Damper case	1.5 L (0.4 US gal)	Komatsu genuine engine oil (EO series), same grade as the crankcase fill.
Hydraulic system / tank	Not separately documented for this chassis in the sources reviewed.	On this generation of small dozer the blade-control hydraulic circuit draws from the transmission/steering-clutch oil rather than a standalone hydraulic reservoir; if a dedicated hydraulic tank exists on this configuration, service it with Komatsu genuine hydraulic oil (HO series) and verify capacity with your dealer or the OMM refill-capacity table.
Pivot shaft	Not listed as a separate fluid reservoir in the sources reviewed.	Serviced via grease fitting with the machine's standard chassis grease; no separate oil fill documented.
Grease (all fittings — track/idler/equalizer, blade linkage, pivot points, etc.)	Per-point application, no bulk reservoir	Komatsu genuine multipurpose grease, G2-LI type, at all lubrication points per the OMM grease schedule.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Komatsu DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) maintenance schedule

Service interval	Tasks
Every 10 h	Check engine oil level before starting and top off with the correct-viscosity oil for ambient temperature. Check coolant level at the radiator and reserve tank; look for leaks around hoses and the water pump. Drain water and sediment from the fuel tank and check the fuel/water separator. Inspect the air cleaner element, empty the dust cup, and note any restriction warning. Grease the bucket lift-arm and tilt-cylinder pivot pins and inspect the bucket cutting edge for wear. Check track tension and walk the undercarriage for loose bolts, damage, or leaks at the final drives.
Every 250 h	Change engine oil and replace the oil filter cartridge. Check and adjust fan belt and alternator belt tension. Grease all work-equipment pivot points, including bucket linkage and equalizer bar. Check battery electrolyte level and clean terminal connections. Check bevel-gear/steering-clutch compartment oil level and top off as needed. Inspect the PTO winch cable, if fitted, for fraying and lubricate.
Every 500 h	Replace the fuel filter cartridge. Check and top off powershift transmission oil level. Check final drive case oil level on both sides and top off per the track-gauge configuration fitted. Clean radiator fins and inspect hoses and clamps for cracking. Check track shoe bolt torque and re-torque as needed.
Every 1,000 h	Change powershift transmission case oil. Change bevel-gear/steering-clutch compartment oil. Change final drive case oil on both sides. Check and adjust engine valve clearance. Inspect the fuel injection pump and injectors for wear or leakage.
Every 2,000 h	Change engine coolant and flush the cooling system. Change damper case oil. Inspect and repack equalizer-bar/trunnion bushings and check for play. Check alternator output and starter motor condition. Inspect bucket lift-arm bushings and tilt-cylinder pins for wear and replace as needed.
Every 4,000 h	Overhaul the powershift transmission clutch packs and torque converter. Rebuild final drives on both sides, including bearings, seals, and gears. Rebuild or replace track chains, rollers, and idlers as undercarriage wear dictates. Inspect and recondition the fuel injection pump at a certified shop. Recondition the bucket lift arm, tilt cylinder, and pivot bushings as a set.

Servicing the DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) beyond the schedule

Predictive Maintenance & Fluid Analysis

Sample engine, transmission, and final-drive oil every 250 hours on this 6D95L-1-powered dozer-shovel to catch wear-metal trends before they cost a rebuild. Because bucket lift-arm and tilt-cylinder pins carry constant cyclic loading instead of a blade's push loads, track grease-fitting condition and pin play at scheduled greasing intervals. Confirm engine identity by serial plate at each service, since Komatsu's D31-20 family includes serial windows with a later running change to a different engine, and oil/filter specs are not interchangeable between builds.

Corrective & Common Repairs

Common fixes on the DRT031_2H center on bucket lift-arm and tilt-cylinder pin wear from repeated loading cycles, fuel starvation from a neglected water separator, and bevel-gear/steering-clutch compartment oil leaks at the final-drive seals. Track sag traces back to equalizer-bar bushing wear rather than blade-linkage parts, since this trim has none. On the naturally aspirated 6D95L-1, hard starting in cold weather usually points to injector pump wear or glow-system faults rather than any electronic sensor, since this machine carries no ECM.

Overhaul & Rebuild Points

Major overhaul work falls on the final drives, track rollers and idlers, and powershift transmission clutch packs at high hours, plus the bevel-gear steering-clutch compartment shared by both sides. Bucket lift-arm bushings and tilt-cylinder pins wear from constant cycling and typically need line-boring or bushing replacement at rebuild. Because track gauge and final-drive oil capacity differ between the narrow S-trim and wide Q-trim configurations, confirm which trim is being rebuilt before ordering final-drive parts or setting fill volumes.

Seasonal & Environment Servicing

Cold climates call for correct-viscosity engine oil and verified coolant freeze protection before winter, plus more frequent water-separator draining to keep ice out of the fuel system feeding the 6D95L-1. In hot, dusty sites, service the air cleaner and clean radiator fins more often to protect the naturally aspirated engine from overheating and dust ingestion. Wash mud from the equalizer bar, track frame, and bucket lift-arm pivots regularly on this loader-style machine, since packed debris accelerates bushing and pin wear faster than on a blade dozer.

DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) common service parts

Part number	Part	Notes
113-60-43321	Cartridge,Hydraulic Oil Filter (D31s)	Hydraulic service	Check fitment →
07002-03334	O-Ring, At Transmission Filter	Scheduled service item	Check fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) attachments & work tools

Blades

This serial range (D31S-20, D31Q-20, D31SM-20, S/N 41001-UP) is cataloged as a shovel-dozer/crawler-loader configuration, factory-fitted with a front loading bucket (about 0.8 m3 / 1.1 yd3 heaped) in place of a dozer blade. Straight (S), semi-U (SU), and angling (A) blade options belong to the sibling D31A/D31E/D31P straight- and angle-blade dozers on the same chassis, not to this bucket-equipped variant; no factory blade fitment is documented for this exact serial range. VPAT-style blades are a different manufacturer's feature and do not apply to this Komatsu class.

Rippers

The D31 dozer/loader class accepts a rear-mounted multi-shank parallelogram ripper (twin lift/tilt cylinders, three shank pockets), running roughly 700-750 kg complete with shanks and hoses. A dedicated single-shank giant-tip ripper is also common in this dozer class for harder digging, though factory documentation specific to this bucket-equipped serial range does not confirm exact ripper part fitment - verify shank count and cylinder count with your dealer.

Winches

The Allied W3C PTO-driven winch is the documented fit for the D31/D37/D39 dozer family, rated in the roughly 13-14 t (about 30,000 lb) line-pull class with single-lever control. PTO-driven cable winches were standard-fit hardware across small Komatsu dozers of this era before hydraulic winch options became common industry-wide in the mid-2000s.

Drawbars/Counterweights

No drawbar or counterweight specifications are documented for this exact D31S/Q/SM-20 serial range in available factory or aggregator data - verify with your dealer or the shop manual for this range if a drawbar hitch or added counterweight is required for towing or shovel-balance work.

Cab/ROPS guarding

Certified aftermarket ROPS canopy and enclosed ROPS cab structures are available for the D31 platform and are required fitment on all machines in this class. Forestry-specific brush/window guarding or screen kits for this exact serial range are not documented in available sources - treat as a dealer/aftermarket fitment question rather than a confirmed factory option.

Hydraulic arrangement

Front hydraulics on this shovel-dozer configuration drive bucket lift and tilt/dump cylinders rather than a blade circuit, consistent with its loader-bucket front end. Rear implement power (winch) is PTO-driven off the transmission rather than hydraulic on this era of small Komatsu dozer, so winch and any rear ripper cylinders draw from separate circuits rather than a shared rear hydraulic valve bank.

All DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) assemblies by section

Every catalogued assembly group for the Komatsu DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)). Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Guard

Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch And Ripper) (For 2-Pillar Type Canopy)

01***25	Bolt,Without Revolution Sensor	3
01***20	Bolt,(For Quick Shift) (Mitsubishi)	20
01***25	Bolt,(For Canvas Canopy?Head Guard)	2
01***40	Bolt,R.H. Outside And L.H. Inside, Bolt	4

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Guard : Rear Cover And Hydraulic Tank (For 3-Point Hitch And Ripper) (For 4-Piller Type Canopy)

01***25	Bolt,Without Revolution Sensor	3
01***20	Bolt,(For Quick Shift) (Mitsubishi)	20
01***25	Bolt,(For Canvas Canopy?Head Guard)	2
01***40	Bolt,R.H. Outside And L.H. Inside, Bolt	4

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Guard : Rear Cover And Hydraulic Tank (With Rops Cab) (For 3-Point Hitch And P.T.O? Ripper)

01***25	Bolt,Without Revolution Sensor	3
01***20	Bolt,(For Quick Shift) (Mitsubishi)	20
01***40	Bolt,R.H. Outside And L.H. Inside, Bolt	4
01***45	Bolt, Mount Center Hinge Retainer (Upper)	4

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Hydraulic System

Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Hydraulic System : Hydraulic Piping (Ripper And 3-Point Hitch Cylinder Line) (Chassis Side)

01***20	Bolt, Wiring Harness Mounting Bracket	3
01***09	Nut,(With Body Positioner)	4
01***25	Washer,Spring?For Additional Rear Lam	1
01***23	Washer, Wiring Harness Mounting Bracket	7

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Hydraulic System : Hydraulic Piping (Tank To Pump To Valve) (For 3-Point Hitch Or Ripper) (For Multi Purpose Bucket)(#41001-41183)

01***40	Bolt,(With Air Conditioner)	4
01***20	Bolt,(For Quick Shift) (Mitsubishi)	1
01***25	Bolt,(For Canvas Canopy?Head Guard)	4
01***35	Bolt,(For Quick Shift) (Mitsubishi)	4

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Hydraulic System : Hydraulic Tank And Filter (For 3-Point Hitch Or Ripper)

01***25	Bolt,(For Canvas Canopy?Head Guard)	6
01***35	Bolt,(F4320-52a0 -5 )	5
01***16	Bolt - Starting Motor Ground Cable	2
01***20	Bolt, Hose Clamps (Inlet And Return Line Hoses)	1

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Operator'S Compartment And Control System

Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Operator'S Compartment And Control System : Work Equipment Control Lever (1/2) (For 3-Point Hitch Or Ripper)

01***16	Bolt - Seat And Tether Belt Mounting	4
01***25	Bolt,(Rear Attachment Less)	1
01***30	Bolt - M8 X 30lg	3
01***25	Bolt	2

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Operator'S Compartment And Control System : Work Equipment Control Lever (1/2) (For Ripper And Front Attachment)

01***16	Bolt - Seat And Tether Belt Mounting	4
01***25	Bolt,(Rear Attachment Less)	1
01***30	Bolt - M8 X 30lg	3
01***25	Bolt	2

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Operator'S Compartment And Control System : Work Equipment Control Lever (2/2) (For 3-Point Hitch Or Ripper)

Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Operator'S Compartment And Control System : Work Equipment Control Lever (2/2) (For Ripper And Front Attachment)

01***25	Bolt,(Rear Attachment Less)	6
01***05	Nut,L.H. (For Trimming Dozer)	2
01***06	Nut,(With Back-Up Alarm) (Op), Nut; Was 01580-10806	2
01***25	Washer,Spring?For Additional Rear Lam	6

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Service Kit And Component Parts

Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Service Kit And Component Parts : Control Valve (3-Spool) (1/2) (For 3-Point Hitch Or Ripper)

01***20	Bolt (Itl)	4
01***25	Bolt, Seal Cover Mounting	2
01***30	Bolt	6
01***30	Bolt (Itl)	1

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Service Kit And Component Parts : Control Valve (3-Spool) (2/2) (For 3-Point Hitch Or Ripper)

07***34	O-Ring, O-Ring, Oil Level And Fill Plug	3
07***34	O-Ring, At Transmission Filter	1
07***34	O-Ring,(F2310-59a0 -4 )	2
70***61	O-Ring,(Pc100ss)	1

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Service Kit And Component Parts : Ripper Cylinder

01***20	Bolt,(For Quick Shift) (Mitsubishi)	1
01***24	Nut,Bearing	1
01***32	Washer,(With Auto Emergency Steering)	1
07***95	O-Ring,(Y1620-11a0a-12)	1

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Work Equipment

Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Work Equipment : Hydraulic Piping (Ripper Cylinder Line)

07***06	Hose,(D21s) (Tbg Spec.)	2
07***15	Nut,(For Shipping And Storage)	2
07***12	Plug,(For Shipping And Storage)	2
(1***1)	Cylinder Ass'Y,(See Fig.7511)	1

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Komatsu : Drt031_2h(S/N 41001-Up (D31s/Q/Sm-20)) : Work Equipment : Ripper

01***20	Bolt,(For Quick Shift) (Mitsubishi)	2
01***25	Bolt,(For Canvas Canopy?Head Guard)	3
01***30	Bolt,(Not Used With Emergency Str.)	4
01***60	Bolt, Mount Pole	10

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DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) serial number reference

On this generation of D31 crawler loader/dozer-shovel, the PIN/serial plate is a riveted metal tag on the main frame near the operator's platform (right-hand side, front of the tractor case on most units of this era). The stamped number is the whole serial (e.g. 41184), not a separate alpha prefix — this D31S/Q/SM-20 family is identified as a block by the 41001-and-up starting point itself rather than a 3-letter code. Cross check the stamped digits against the parts book cover, which lists the model and "S/N 41001-UP" together.

Prefix	Identifies	Notes
41001-UP	D31S-20 dozer shovel / crawler loader	Base configuration of this PIN block. Runs the 6D95L-1 diesel. Komatsu factory parts book groups it with D31Q-20 and D31SM-20 under the same serial range.
41001-UP	D31Q-20 dozer shovel / crawler loader	Shares the D31S/Q/SM-20 41001-UP PIN block. Same 6D95L-1 engine. Exact mechanical distinction from D31S-20 (bucket/steering trim) is not spelled out in the sources checked.
41001-UP	D31SM-20 dozer shovel / crawler loader	Shares the D31S/Q/SM-20 41001-UP PIN block. One factory transmission-case listing tags a D31SM-20 41001-UP unit as a forestry-spec build — single source, confirm with dealer before relying on it.

Frequently asked questions

What engine powers the Komatsu DRT031_2H (D31S/Q/SM-20, S/N 41001-up)?

This serial range runs Komatsu's naturally aspirated 6D95L-1 inline-six diesel, shared with the sibling D37E-5/D37P-5A models on the same factory manual set. Some general spec listings for related D31-20 trims show a turbocharged four-cylinder engine instead; confirm the exact engine on your unit by its serial plate before ordering engine or fuel-system parts, since the two builds are not interchangeable.

What is the operating weight of this machine?

Operating weight varies by trim: about 6,780 kg (14,947 lb) for the D31S-20 narrow-gauge configuration and about 7,120 kg (15,697 lb) for the D31Q-20 wide-gauge configuration. The D31SM-20 shares the same chassis and serial block but has no separately published weight figure, so confirm against your machine's own nameplate.

What replaced the Komatsu DRT031_2H (D31S/Q/SM-20)?

Komatsu carried this small dozer-shovel/crawler-loader class forward into the D31EX-21/D31PX-21 generation once the -20 series ended production, with later dash-22 and dash-23 updates continuing the line with revised engines and controls.

What DRT031_2H(S/N 41001-UP (D31S/Q/SM-20)) owners discuss

What should I expect from the powershift transmission and steering controls on this dozer-shovel?

Steering on the 20-series machines is by a single lever (joystick-style) rather than the twin steering levers used on the earlier 18-series D31. Operators commonly note a brief pause of a second or two when shifting between forward and reverse under load, followed by a noticeable clunk into gear as the clutch pack takes up; on a well-maintained machine this is normal mechanical powershift behavior, not a fault. A winding or whining noise from the transmission housing, or loss of drive to one side only, points to worn steering clutch or brake components rather than routine wear and should be checked before the machine strands itself in the field. Have your dealer verify steering clutch and brake condition before returning the machine to work.

What undercarriage wear pattern is typical on a machine like this?

As with any small crawler dozer-shovel of this era, the undercarriage — track links, bushings, rollers, idlers, sprockets — drives a large share of total operating cost, and wear rate depends heavily on ground conditions and operator habits. Owners commonly report that the steering clutch drums and final-drive components wear alongside the track chain on high-hour units, so a thorough undercarriage check should cover the drive components, not just track sag and pad wear. Keeping track tension adjusted correctly and clearing debris from the rollers noticeably slows wear compared to neglected machines.

Are there known quirks with the 6D95L-1 engine used in this machine?

The 6D95L-1 is a naturally aspirated, fully mechanical diesel with no electronic controls, and owners generally describe it as a durable, low-drama engine as long as oil changes and fuel filtration stay current. Most reported failures trace to maintenance lapses rather than a design flaw: running the engine low on oil leads to spun rod or main bearings, which then damage piston rings and cylinder walls. Idle oil pressure on a healthy engine reads modest by modern standards and should rise clearly at operating rpm; pressure that stays low at speed after a bearing or oil pump job points to a bearing clearance or pump installation problem worth investigating. Loss of power, higher fuel burn, or overheating usually traces to a clogged air filter, worn injectors, or a failing fuel delivery component rather than the engine's core mechanicals.

Does this dozer-shovel have electronic sensors or an ECM that can fail?

No. This is a fully mechanical machine — mechanical fuel injection, mechanical powershift transmission, and no engine control module or electronic sensors of any kind. What owners actually run into on machines this age is old-fashioned wiring degradation: brittle insulation, corroded connectors, and in some reported cases rodent damage to the harness feeding gauges and lighting. Treat any gauge or warning-light complaint as a wiring or connection issue first, since there is no electronic sensor network in the drivetrain to diagnose.

What hydraulic issues come up with the loading shovel/bucket linkage?

The bucket lift and tilt cylinders are the parts most likely to show age-related wear, and worn cylinder seals are the most commonly reported cause of cylinder drift or leak-down under a held load. Slow or weak bucket response can also come from a worn hydraulic pump or a sticking control valve spool rather than the cylinders themselves, so diagnosis should check fluid condition, pump output, and valve operation before condemning a cylinder for reseal or rebuild.

Does the shovel/loader configuration create different wear habits than a blade dozer of the same size?

Because this configuration carries a front loading bucket rather than a dozer blade, most of the working load goes through the bucket linkage and lift arms instead of a straight push blade, so operators watch bucket pin and bushing wear and lift-arm cylinder condition more closely than blade edge wear. Using the bucket for repeated impact loading or as a makeshift ripper accelerates wear on the linkage pins and cylinder rod seals faster than normal loading and carrying duty.

What should I check before buying a used DRT031_2H (D31S/Q/SM-20) dozer-shovel?

Start with an undercarriage inspection — track link, bushing, roller and sprocket wear is the single biggest driver of near-term repair cost on a machine this age, and a dedicated undercarriage measurement is worth the modest inspection fee before committing to a purchase. Confirm the transmission shifts cleanly between forward and reverse and through gears without excessive delay, clunking, or loss of drive to one side, since that points to worn steering clutch or brake packs. Check engine oil pressure cold and at operating rpm, look for metal contamination in the transmission fluid, and watch the bucket cylinders for drift under a raised, held load. Walk the machine for abuse signs — bent or gouged bucket edges, damaged guarding, missing bolts — and verify the serial number and hour meter against the paperwork before finalizing a price. Have your dealer verify transmission, steering clutch condition, and remaining undercarriage life before purchase.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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