Armored Combat Earthmover M91-5
M9: General
Date of first acceptance 1986 Total acceptances 620
M9: Manufacturer BMY Combat Systems Crew 1 man
M9: Dimensions
Travel weight 37,000lbs
17,000kg		 Height above cupola 118.00"
299.72cm
Length 245.50"
622.30cm		 Width 110.00"
279.40cm
Tread 88.00"
223.5cm		 Ground clearance 13.00"
33.02cm
Ground pressure, zero penetration 9.5psi
.67kg/cm²
M9: Armament
None
M9: Armor
Assembly
Welding and bolting
Operator's station
Aluminum armor, steel and aramid laminate plates
M9: Automotive
Engine Cummins V903C; eight cylinder, vee diesel
Horsepower 295@2600rpm Fuel capacity 134gal
507L
Transmission Clark 13.5 HR 3610-2, 6 speeds forward, 2 reverse
Steering Geared steer and clutch-brake
M9: Suspension
Type Road wheels Track return rollers
Hydropneumatic 4 individually sprung dual/track Flat track
Drive sprockets Idlers Shock absorbers
Rear drive Front road wheels act as idlers None
M9: Track
Single pin, rubber padded steel
Width 18"
46cm		 Ground contact length 105"
267cm
M9: Performance
Max level road speed 30mph
50kph		 Max water speed 3mph
5kph
Max trench 62"
160cm		 Max sideslope with 18,000lbs (8200kg) in bowl 89%
Max grade with 18,000lbs (8200kg) in bowl 133% Max vertical obstacle 18"
46cm
Min turning diameter Pivot Max fording depth 36"
91cm
Cruising range ~200mi, roads
~320km, roads


The US Army's search for an armored combat earthmover, or universal engineering tractor, spanned thirty years, and finally produced the M9. The M9 ACE features a front-mounted dozer blade behind which is an 8.7 cubic yard (6.7m3) scraper bowl. For jobs requiring a heavier machine, the blade could be raised and the bowl could be filled with dirt, bringing the vehicle's weight up to 55,000lbs (25,000kg). A 25,000lb (11,000kg) winch was mounted in the lower rear hull, beneath the engine and transmission. The dozer blade was positioned by adjusting the hydropneumatic suspension. The operator is stationed at the rear of the vehicle and is provided with a cupola containing eight vision blocks. After the vehicle had entered service, modifications were performed that increased the vehicle's weight to the point that swimming was no longer feasible. The amphibious requirement was therefore dropped.

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References

  1. Hunnicutt, R.P. Sheridan: A History of American Light Tank, volume 2. Navato, CA: Presidio Press, 1995.
    Reprinted with permission from Sheridan, R.P. Hunnicutt ©1995, available from Presidio Press, 505B San Martin Drive, Suite 160, Navato, CA 94945.

  2. Crismon, Fred W. U.S. Military Tracked Vehicles. Osceola, WI: Motorbooks International, 1992.

  3. Federation of American Scientists. "Armored Combat Earthmover - (M9 ACE)." DOD 101. 19 Feb 2000. 7 Nov 2001 <http://www.fas.org/man/dod-101/sys/land/m9-ace.htm>. DOD 101

  4. US Army TACOM. "M9 ACE - Description and Mission." 7 Nov 2001 <http://www.tacom.army.mil/dsa/pmtaws/cbt_spt/m9ace/descrip.htm>.

  5. Reyes, Larry. "ACE." Email to the author. 16 May 2006.



Last updated 5 Feb 2007.

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