The M109 family is the most common Western indirect-fire support weapon of armored and mechanized infantry divisions. The M109 was first introduced in the early 1960s and has been upgraded a number of times.The Belgian M109A2/A3 were upgraded in 2008 to M109A4 BE standard through the “MLU M109 program” (Mid-life Update).

Most important upgrades were:

  • Semi-automatic loader (SAL)with Breech Activating Device (BAD) and Temperature Measurment System (TMS)
  • Installation of 1,2 Kw diesel generator (APU)
  • New stowage racks
  • Improved hydraulic system (MHS) for traversing mechanism
  • Improved NBC/RAM kits with airfilter
  • Generator 180 amp
  • Improved Ballistic Turret (IBC)
Play Video
Play Video


Land of origin:

  • United States


  • Length: 9.12 m
  • Width: 3.15 m
  • Height: 3.28 m
  • Ground clearance: 0.45 m
  • Weight: 23.586 kg (empty) / 24.948 kg (combat loaded)


  • 6 persons (2 loaders, 1 gunner, 1 assistant gunner, 1 commander, 1 driver)

 Main armament (Howitzer M185, 155mm with gun mount M178):

  • Caliber: 155mm L – 39 caliber
  • Max Range: 18,50 to 23,50 km
  • Max fire rate: 3 rounds first 20 seconds, 6 rounds first minute (SAL)
  • Elevation: -5° to 75°
  • Travers: 360°

Secondary armament:

  • Machine gun: caliber .50 (M2 Heavy Barrel)
  • Panoramic telescope M117


  • Engine: Detroit Diesel 8V-71Turbo
  • Transmission: Allison XTG411-series
  • Speed: 64 km/h
  • Range: 349 km
  • Fuel content: 133 gallons – 502,74 liters
  • Tracks: Diehl (model 109.2)



  • The installation of “Nuclear, Biological, and Chemical/Reliability, Availability, and Maintainability” product improvement kits.
  • Air purifier and heaters are mounted in the cab for thecrew.

Hydraulic traversing mechanism

  • The traversing mechanism is operated with a hydraulic clutch instead of an electric.
  • A clutch valve with override valve provides for power traversing in the event of an electrical failure to the clutch valve solenoid.

Electrical improvements

  • A combat override switch allows emergency starting.
  • The 100 amp alternator has been replaced by a 180 amp alternator.

Subfloor drains

  • Crew compartment subfloor drains have been added


SAL: Semi Automatic Loader with Breech Activating Device

  • (BAD) and Temperature Measurement System (TMS)
  • The SAL increases the firing rate to 3 rounds within the first 20 seconds and a total of 6 rounds within the first minute.
  • In addition a Breech Activating Device (BAD) makes sure that the breech is closed and opened in any position (elevation) of the canon.
  • A Temperature Measurement Sensor helps the crew to recognize a “cook off” of a propellant charge.

MHS: Metric Hydraulic System

  • The MHS consists of standardized elements with metric measures.
  • All tubes and connections are in Cr-Ni Alloy for better flow and low maintenance.

APU: Auxiliary Power Unit

  • The APU that provides 1.2Kw at 28VDC improves the availability of the M109 and conserves battery power.
  • With the main engine switched off the M109 howitzer is still operational.

SSPC: Stowage System Propellant Charges

  • The SSPC enables the crew to store in a very safe way 38 propellant charges in the howitzer.