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)
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°
- 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)
STANDARD UPGRADES M109A2/A3 to M109A4
- 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.
- A combat override switch allows emergency starting.
- The 100 amp alternator has been replaced by a 180 amp alternator.
- Crew compartment subfloor drains have been added
SPECIFIC BELGIAN UPGRADES
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.