• 89,300 lbs Operating Weight
  • 354 @1900 rpm Horsepower
  • 12.3 - 15.6 yd³ Blade Capacity


The new Tier 4 Final D155AX-8 dozer incorporates well proven Komatsu engine emissions technology that does not interfere with daily operation. Class leading engine horsepower, large capacity Sigmadozer blade and automatic lockup torque converter efficiently move massive amounts of material while using less fuel than prior model. The operator cab is loaded with features to help maintain operator comfort during the work day.

D155AX-8 Walkaround  >


Auto-pitch Mode*

To reduce operator effort and increase operating efficiency the new auto blade pitch mode sets blade pitch position between digging and dump positions while dozing. By pressing the autopitch switch it will toggle the pitch position from digging to dump position with no additional lever movements. The blade pitch control can be set through the monitor to automatically return to the digging position when reverse is selected.

* Requires dual tilt dozer

Heavy-duty aftertreatment system

This new system combines a Komatsu Diesel Particulate Filter (KDPF) and Selective Catalytic Reduction (SCR). The SCR NOx reduction system injects the correct amount of DEF at the proper rate, thereby decomposing NOx into non-toxic water (H2O) and nitrogen gas (N2).

Komatsu Auto Idle Shutdown

Komatsu auto idle shutdown automatically shuts the engine down after idling for a set period of time to reduce unnecessary fuel consumption and exhaust emissions. The amount of time before the engine is shutdown can be easily programmed from 5 to 60 minutes.

New Fuel Efficient Bulldozer

New D155AX-8 has achieved both high levels of productivity and fuel economy through usage of SIGMADOZER and automatic transmission with lockup torque converter.

New Tier 4 Final Engine

The Komatsu SAA6D140E-7 engine is EPA Tier 4 Final emissions certified and provides exceptional performance while reducing fuel consumption. Based on Komatsu proprietary technologies developed over many years, this new diesel engine reduces nitrogen oxides (NOx) by more than 80% when compared to Tier 4 interim levels. Through the in-house development and production of engines, electronics, and hydraulic components, Komatsu has achieved great advancements in technology, providing high levels of performance and efficiency in virtually all applications.

Ripper Auto-return

The ripper control lever is new, ergonomic and incorporates an auto-return function that will automatically raise the ripper so the operator is less fatigued at the end of the day. The function starts when travel lever is moved to reverse position.



Komatsu SAA6D140E-7**
4-cycle, water-cooled, direct injection
Komatsu Variable Geometry Turbocharged, air-to-air aftercooled, cooled EGR
Number of cylinders
Bore x stroke 140 mm x 165 mm 5.51" x 6.50"
Piston displacement 15.24 ltr 930 in³
Mid-range, electronic

SAE J1995 - Gross 268 kW 360 HP
ISO 9249 / SAE J1349* - Net 264 kW 354 HP
Rated rpm
1900 rpm
Fan drive type
Lubrication system:

Gear pump, force lubrication
*Net horsepower at the maximum speed of radiator cooling fan: 239 kW 320 HP

**EPA Tier 4 Final emissions certified    

Final Drive

Double-reduction, spur and planetary final drives increase tractive effort. Segmented sprockets are bolt-on for easy in-the-field replacement.

Hydraulic System

Closed-center load sensing system (CLSS) designed for precise and responsive control, and for efficient simultaneous operation.

Hydraulic control unit:
All spool control valves externally mounted beside the hydraulic tank.

Variable piston pump with capacity (discharge flow) of 325 L/min 85.9 U.S. gal for steering and 180 L/min 47.6 U.S. gal for implement at rated engine rpm.

Relief valve setting
. . . for implement 27.5 MPa 280 kg/cm² 3,980 psi
. . . for steering 38.2 MPa 390 kg/cm² 5,550 psi
Control valves:

Spool control valve for SIGMADOZER, Semi-U tilt dozer and Full-U tilt dozer.

Positions: Blade lift Raise, hold, lower, and float

Blade tilt Right, hold, and left
Additional control valve required for variable digging angle multi-shank ripper and giant ripper.

Positions: Ripper lift Raise, hold, and lower

Ripper tilt Increase, hold, and decrease
Hydraulic cylinders
Double-acting, piston
Number of cylinders Bore Bore
Blade Lift / 2 110 mm 4.33"
Blade Tilt (Dual tilt) / 2 160 mm 6.30"
Blade Tilt (Single Tilt) / 1 160 mm 6.30"
Ripper Lift 180 mm 7.09"
Ripper Tilt / 1 200 mm 7.87"
Hydraulic oil capacity (refill):

SIGMADOZER 95 ltr 25.1 U.S. gal
Semi-U dozer 95 ltr 25.1 U.S. gal
Full-U dozer 95 ltr 25.1 U.S. gal
Ripper equipment (additional volume):

Multi-shank ripper 37 ltr 9.8 U.S. gal
Giant ripper 37 ltr 9.8 U.S. gal

Operating Weight

Tractor weight
Including rated capacity of lubricant, coolant, full fuel tank, operator, and standard equipment (including ROPS cab).
632700 kg 72,100 lb
Operating weight
Including strengthened SIGMADOZER, giant ripper, ROPS cab, operator, standard equipment, rated capacity of lubricant, coolant, and full fuel tank.
40500 kg 89,300 lb
Ground pressure 99.5 kPa / 1.01 kg/cm² 14.4 psi

Service Refill Capacities

Fuel tank 625 ltr  165 U.S. gal
Coolant 104 ltr 27.5 U.S. gal
Engine oil 37 ltr 9.8 U.S. gal
Damper 1.5 ltr 0.4 U.S. gal
Transmission, bevel gear, and steering system 90 ltr
23.8 U.S. gal
Final drive (each side) 31 ltr
8.2 U.S. gal
DEF tank 39 ltr 10.3 U.S. gal
Hydraulic oil capacity
95 ltr 25.1 U.S. gal

Steering System

PCCS lever controls for all directional movements. Pushing the PCCS lever forward results in forward machine travel, while pulling it rearward reverses the machine. Simply tilt the PCCS lever to the left to make a left turn. Tilt it to the right for a right turn.

Hydrostatic steering system (HSS) is powered by steering planetary units and an independent hydraulic pump and motor. Counter-rotation turns are also available. Wet, multiple-disc, pedal-controlled service brakes are spring-actuated and hydraulically released. Gearshift lock lever also applies parking brakes.

Minimum turning radius 2.14 m 7'0"

TORQFLOW Transmission

Komatsu's automatic TORQFLOW transmission consists of a water-cooled, 3-element, 1-stage, 1-phase, torque converter with lockup clutch, and a planetary gear, multipledisc clutch transmission which is hydraulically actuated and force-lubricated for optimum heat dissipation. Equipped with gearshift lock lever and neutral safety switch.
Travel speed:
1st Gear forward 3.8 km/h  2.4 mph
1st Gear reverse 4.6 km/h  2.9 mph
2nd Gear forward 5.6 km/h  3.5 mph
2nd Gear reverse 6.8 km/h  4.2 mph
3rd L Gear forward 7.5 km/h  4.7 mph
3rd L Gear reverse 9.2 km/h  5.7 mph
3rd Gear forward 11.6 km/h  7.2 mph
3rd Gear reverse 14.0 km/h  8.7 mph


Suspension: Oscillation-type with equalizer bar and forward mounted pivot shafts

Track roller frame: Monocoque, high-tensilestrength steel construction

K-Bogie undercarriage
Lubricated track rollers are resiliently mounted the track frame with a bogie suspension system whose oscillating motion is cushioned by rubber pads.

Track shoes
Lubricated tracks. Unique dust seals for preventing entry of foreign abrasives into pin-to-bushing clearance for extended service. Track tension easily adjusted with grease gun.
Number of shoes (each side) 42  
Grouser height 80 mm 3.1"
Shoe width (standard/maximum) 24" / 28" 610 mm / 710 mm
Ground contact area 39955 cm² 6,193 in²
Ground pressure (tractor only) 80.3 kPa / 0.82 kg/cm² 11.6 psi
Number of track rollers (each side) 7  
Number of carrier rollers (each side) 2  


  • Air cleaner, double element with dust indicator
  • Alternator, 140 ampere/24V
  • Backup alarm
  • Batteries, 200 Ah/2 x 12V
  • Battery disconnect switch
  • Blade lift cylinders with double dust seal
  • Color monitor, LCD
  • Decelerator pedal
  • Engine hood
  • Engine idle auto shutdown with adjustable timer
  • Engine intake centrifugal precleaner
  • Engine, gull-wing side covers
  • Engine shutdown secondary switch
  • Exhaust pipe with raincap
  • Fast fuel provision
  • Fenders
  • Front pull hook
  • Fuel pre-filter and primary filter
  • Grid heater starting aid in cold weather
  • High mount foot rests
  • Horn, warning
  • Hydraulic driven radiator cooling fan with manual reverse clean mode
  • Hydraulics for dual tilt and pitch dozer
  • Hydraulics for ripper VGR/MSR
  • KOMTRAX® Level 5
  • K-bogie undercarriage
  • Komatsu Diesel Particulate Filter (KDPF)
  • Komatsu Variable Geometry Turbocharger (KVGT)
  • Komatsu Selective Catalytic Reduction (SCR)
  • Locks, filler caps and covers
  • Oil pressure check ports for power train
  • PM service connector
  • Radiator mask, double door, heavy-duty, hinged, perforated
  • Radiator reserve tank
  • Rear cover
  • ROPS cab (1420 kg, 3,131 lb)**
  • Air conditioner/heater/defroster

    --Condenser remote mounted
  • Cab accessories
  • Work lights
    --2 front, hood mounted

    --2 front, cab mounted

    --2 rear, fender mounter

    2 rear, cab mounted
    --1 rear, for ripper point
  • Seat, air suspension, fabric, heated, low back, rotates 12.5° to right, headrest
  • Seat belt, 76 mm 3", retractable
  • Seat belt indicator
  • Sealed electrical connectors
  • Starting motor, 11.0 kW/24V
  • Steering system: Hydrostatic Steering System (HSS)
  • Torque converter with auto lock-up
  • Track roller guards, end sections
  • Track shoe assembly
  • Sealed and lubricated
  • 610 mm 24" extreme service shoes
  • Transmission with auto/manual shift modes
  • Underguards, heavy duty
  • Hinged belly pans
  • Water separator, fuel
  • Wide core cooling package, 6 fins per inch spacing


Shoes (optional) - Additional weight:

  • 660 mm 26" extreme service shoes: +240 kg +530 lb
  • 710 mm 28" single-grouser shoes: No additional

Shoes (optional) - Ground contact area:

  • 660 mm 26" extreme service shoes: 43230 cm2 6,700 in2
  • 710 mm 28" single-grouser shoes: 46505 cm2 7,208 in2

Variable Multi-Shank Ripper:

  • Additional weight (including hydraulic control unit): 3760 kg 8,290 lb
  • Beam length: 2320 mm 7'7"
  • Hydraulically-controlled parallelogram-type ripper with three shanks. Digging angle infinitely adjustable. Standard digging angle: 49°
  • Maximum digging depth: 900 mm 2'11"
  • Maximum lift above ground: 950 mm 3'1"

Variable Giant Ripper:

  • Additional weight (including hydraulic control unit): 2440 kg 5,380 lb
  • Beam length: 1400 mm 4'7"
  • Hydraulically-controlled parallelogram-type ripper with one shank. Digging angle infinitely adjustable. Standard digging angle: 49°
  • Maximum digging depth: 1240 mm 4'1"
  • Maximum lift above ground: 950 mm 3'1"


  • HD Counterweight 9-plate with rigid drawbar, 3568 kg 7,860 lb
  • Sigma push group (bladeless) for Allied blade

Dozer Equipment:

  • Full-U
  • Semi-U