• 87,100 lbs Operating Weight
  • 354 @1950 rpm Horsepower
  • 12.3 - 15.6 yd³ Blade Capacity


The D155AX-7 is a dozer that bridges the gap between contractor site prep dozers and large contractor production/mining dozers. The Tier 4 interim D155AX-7 has the precise and responsive hydraulic control and smooth turning of hydrostatic steering of smaller dozers for grading and big dozer features like a lock-up torque converter, Unique, high production Sigma dozer blade and K-bogie oscillating undercarriage.

D155AX-7 Walkaround  >


Automatic/Manual Shift Selectable Mode

Automatic or manual shift modes can be selected with ease to suit the work at hand by simply pressing the switch on the multi-monitor (selection at neutral).

Automatic shift mode

Select for all general dozing. When a load is applied, the transmission automatically shifts down, and when the load is off, it automatically shifts up to a set maximum gear speed. This mode economizes both fuel and production further when the torque converter lockup mechanism is actuated according to load, providing a one-to-one drive.

Manual shift mode

Select for dozing and ripping rough ground. When loaded, the transmission automatically shifts down, but does not shift up when the load is off.

Automatic Transmission with Lockup Torque Converter

A significant reduction in fuel consumption and greater power train efficiency are achieved by the new automatic transmission and lockup torque converter. The automatic transmission selects the optimal gear range depending on the working conditions and load placed on the machine. This means the machine is always operating at maximum efficiency.

The lockup mechanism of the torque converter is automatically actuated to transfer engine power directly to the transmission in travelling and usual dozing speed ranges. Locking up the torque converter results in 10% improved drive train efficiency. Because the electronically controlled Tier 4 Interim engine is extremely efficient, the same low fuel consumption as the D155AX-6 is realized while also maintaining the same machine power.

Hydrostatic Steering System (HSS)—Smooth, Powerful Turning

The engine power is transmitted to both tracks without power interruption on the inside track for smooth, powerful turns. Counter-rotation is available in neutral for minimum turning radius, enhancing maneuverability.

Palm Command Control System (PCCS) Travel Joystick

Palm command travel joystick provides the operator with a relaxed posture and superb fine control. Transmission shifting is simplified with thumb push buttons.

Palm Command Proportional Pressure Control (PPC) Blade Control Joystick

Blade control joystick uses the PPC valve and joystick, similar to the travel control joystick. PPC control combined with the highly reliable Komatsu hydraulic system enables superb fine control.

Rear View Monitoring System

On the large LCD color monitor, the operator can view, through one camera, areas directly behind the machine. This camera can be synchronized with reverse operation.

SIGMADOZER The Next Generation Blade

Based on a completely new digging theory, SIGMADOZER dramatically improves dozing performance and increases productivity. A new frontal design concept adopted for digging and rolling material up at the center of the blade increases soil holding capacity while simultaneously reducing side spillage. It also reduces digging resistance, producing a smoother flow of earth, enabling the dozing of larger quantities of soil with less power.



Model Komatsu SAA6D140E-6*
Type 4-cycle, water-cooled, direct injection
Aspiration Komatsu variable geometry turbocharged, air-to-air aftercooled, cooled EGR
Number of cylinders 6
Bore x stroke 5.51" x 6.50" 140 mm x 165 mm
Piston displacement 930 in³ 15.24 ltr
Governor All-speed and mid-range, electronic
Horsepower :
SAE J1995 - Gross 360 HP 268 kW
ISO 9249 / SAE J1349 - Net 354 HP 264 kW
Rated rpm 1900 rpm
Fan drive type Hydraulic
Lubrication system :
Method Gear pump, force lubrication
Filter Full-flow
*EPA Tier 4 Interim and EU stage 3B 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 ltr/min 85.9 U.S. gal/min for steering and 180 ltr/min 47.6 U.S. gal/min for implemented 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
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 4.33" 110 mm
Blade Tilt (Dual tilt) / 2 6.30" 160 mm
Blade Tilt (Single Tilt) / 1 6.30" 160 mm
Ripper Lift 7.09" 180 mm
Ripper Tilt / 1 7.87" 200 mm
Hydraulic oil capacity (refill):
SIGMADOZER 22.5 U.S. gal 85 ltr
Semi-U dozer 22.5 U.S. gal 85 ltr
Full-U dozer 22.5 U.S. gal 85 ltr
Ripper equipment (additional volume):
Multi-shank ripper 9.8 U.S. gal 37 ltr
Giant ripper 9.8 U.S. gal 37 ltr

Operating Weight

Tractor weight
Including rated capacity of lubricant, coolant, full fuel tank, operator and standard equipment.

Operating weight
Including strengthened SIGMADOZER®, giant ripper, ROPS cab, operator, standard equipment, rated capacity of lubricant, coolant, and full fuel tank.

Tractor weight68,350 lb31000 kg
Operating weight87,100 lb39500 kg
Ground pressure15.4 psi106 kPa / 1.08 kg/cm²

Service Refill Capacities

Fuel tank165 U.S. gal625 ltr
Coolant27.3 U.S. gal103.5 ltr
Engine oil9.8 U.S. gal37 ltr
Damper0.4 U.S. gal1.5 ltr
Hydraulic oil24.2 U.S. gal91.5 ltr
Transmission, bevel gear, and steering system23.8 U.S. gal90 ltr
Final drive (each side)8.2 U.S. gal31 ltr

Steering System

Palm Command Control 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 radius7'0"2.14 m

TORQFLOW Transmission

Komatsu TORQFLOW transmission consists of a water-cooled, 3-element, 1-stage, 2-phase, torque converter with lockup clutch, and a planetary gear, multiple-disc clutch transmission which is electronically controlled, hydraulically actuated and force-lubricated for optimum heat dissipation. Shift lock lever and neutral safety switch.

Travel speed:
1st Gear forward 2.4 mph 3.8 km/h
1st Gear reverse 2.9 mph 4.6 km/h
2nd Gear forward 3.5 mph 5.6 km/h
2nd Gear reverse 4.2 mph 6.8 km/h
3rd L Gear forward 4.7 mph 7.5 km/h
3rd L Gear reverse 5.7 mph 9.2 km/h
3rd Gear forward 7.2 mph 11.6 km/h
3rd Gear reverse 8.7 mph 14.0 km/h


K-Bogie undercarriage
Lubricated track rollers are resiliently mounted on 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.

Suspension Oscillation-type with equalizer bar and forward mounted pivot shafts
Track roller frame Monocoque, high-tensilestrength steel construction
Rollers and idlers Lubricated
Number of shoes (each side) 42
Grouser height 3.1" 80 mm
Shoe width (standard/maximum) 610 mm / 710 mm 24" / 28"
Ground contact area 6,193 in² 39955 cm²
Ground pressure (tractor only) 11.9 psi 82.4 kPa / 0.84 kg/cm²
Number of track rollers (each side) 7
Number of carrier rollers (each side) 2


  • Air cleaner, double element with dust indicator
  • Alternator, 90 ampere/24V
  • Backup alarm
  • Batteries, 200 Ah/2 x 12V
  • Battery disconnect switch
  • Blade lift cylinders
  • Color monitor, LCD
  • Decelerator pedal
  • Engine hood
  • Engine intake centrifugal precleaner
  • Engine, gull-wing side covers
  • Engine shutdown secondary switch
  • Exhaust pipe with raincap
  • Fast fuel provision
  • Fenders
  • Front pull hook
  • 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 4
  • K-bogie undercarriage
  • Komatsu Diesel Particulate Filter (KDPF)
  • Komatsu Variable Geometry Turbocharger (KVGT)
  • Locks, filler caps and covers
  • Oil pressure check ports for power train
  • PM service connector
  • Radiator mask, heavy-duty, hinged, perforated
  • Radiator reserve tank
  • Rear cover
  • ROPS cab (700 kg, 1,545 lb)**
  • Air conditioner – Pressurized
  • Cab accessories
    --12V power supply (2 ports)

    --Cup holder

    --Rearview mirror

    AM/FM Radio w/remote AUX plug (3.5 mm)
  • Work lights
    --2 front, hood mounted

    --2 front, cab mounted

    --1 rear, left fender mounted

    2 rear, cab mounted
  • Seat, air suspension, fabric, heated, low back, rotates 15° to right, headrest
  • Seat belt, 76 mm / 3", retractable
  • Seat belt indicator
  • Sealed electrical connectors
  • Secondary engine shutoff switch
  • 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 pan
  • Transmission
  • Water separator, fuel
  • Wide core cooling package

* Dozer assembly and rear mounted equipment are not included in base machine standard equipment
** Cab meets OSHA/MSHA ROPS and FOPS Level 2 standards


Shoes - Additional Weight:

  • 26' / 660 mm extreme service shoes: +2,070 lb / +940 kg
  • 28' / 710 mm single-grouser shoes: +1,370 lb / +620 kg

Shoes - Ground contact area:

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

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"


  • Additional rear light for ripper point
  • Drawbar, long type
  • Drawbar, Dual tilt blade hydraulics
  • Guarding - rear screen
  • HD Counterweight with rigid drawbar, 3148 kg / 6,940 lb
  • Single tilt blade hydraulics
  • Working light for ripper

Dozer Equipment

  • Full-U
  • Semi-U