Mack Military – The Mack Trucks Mobile Dynamometers of the U.S. Army

[kscarbel2 4,732]

The U.S. Army has for decades purchased mobile dynamometers. By generating tractive rolling resistance (power absorption), the dynamometer is able to test the tractive effort of both wheeled and tracked vehicles.

Delivered to the Ordinance Department of the U.S. Army at Aberdeen Proving Ground in September 1940, the Mack Trucks M5 was based on a model FKSW 6x4 chassis powered by a 707 cu.in. 178 horsepower Mack model EY gasoline engine. The truck’s special retardation ability was accomplished by utilizing two Hale model MCT-8S 750GPM positive displacement pressure pumps. The Mack M5 weighed 50,000 pounds and could develop a retardation capability of 20,000 pounds.

Pleased with Mack’s engineering, the U.S. Army ordered an additional 6x4 dynamometer from Mack Trucks within one year of the M5. The Mack M6 was based on a model LPSW 6x4 chassis, and featured an upgraded version of Mack’s proven 707 cu.in. model EY gasoline engine now rated at 195 horsepower. Like the M5, the Mack M6 weighed 50,000 pounds and had a retardation capability of 20,000 pounds.

Both the Mack M5 and M6 were paired with Mack-designed and built power absorption (retardation) trailers which could add an additional 15,000 pounds of retardation.

During the 1960s, the U.S. Army had Mack Trucks create a dynamometer based on the Mack M125 tactical cargo chassis. Little is publicly known about it. This picture was taken at Fort Belvoir in 1983. While standard M125s had an open-type tactical cab, this unit was custom-fitted with an enclosed cab to meet the Army’s requirement.

Today, the Aberdeen Test Center continues to operate two mobile dynamometers, the M16 and M18 produced by Barnes and Reinecke.

The 1978 vintage “heavy” M16 dynamometer’s power package utilizes a GM-EMD (General Motors – Electro-Motive Diesel) model EMD8-645E4 turbocharged diesel engine rated at 1,650 horsepower coupled to a GM-EMD model AR5 3-phase AC current generator. The power developed drives two GM-EMD model D79-F series wound four-pole direct current traction motors.

The late eighties vintage “medium“ M18 dynamometer’s power package utilizes a Cummins model KTA-19P600 turbocharged diesel engine rated at 600 horsepower coupled to a General Electric model 603 3-phase AC current generator. The power developed drives one General Electric model 5GE773DS2 series wound four-pole direct current traction motor.

(For those interested, this 2012 year PDF elaborates on the U.S. Army's Aberdeen, Maryland and Yuma, Arizona vehicle test facilities - http://www.dtic.mil/dtic/tr/fulltext/u2/a557002.pdf. The M16 and M18 are shown on page 18.)

In addition, the U.S. Army’s Tank, Automotive, Research, Development and Engineering Center (TARDEC) has built a one-of-a-kind Power and Energy Vehicle and Environmental Lab (PEVEL) at the Detroit Arsenal which has 12 dynamometers paired with an environmental chamber that can generate up to 95 percent relative humidity, create wind speeds up to 60-mph, and simulate temperatures from -60°F up to 160°F.

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Edited October 29, 2013 by kscarbel2

[TacticalTruck 5]

I own the M124 pictured.

 

https://www.facebook.com/SledgehammerMfg/photos/pcb.3335726239823570/3335724446490416/

Edited June 15, 2020 by TacticalTruck

[75T 37]

Great save! Excellent story line.

[terry 506]

Quite the beast!!    terry

[TacticalTruck 5]

 The truck is a 1957 XM124. When the 10 tons were being designed, there was to be a tractor, cargo, dump and long wheelbase cab and chassis. Only the tractor and cargo trucks were produced. I believe this is the only XM124 (long wheelbase) built. It is serial number M124-1001. It's powered by a 844ci V-8 gas LeRoi. The truck was used by the Engineer Research & Development Laboratories (ERDL) at FT Belvior, Virginia where I bought it surplus.  I believe the cab was built at Ft Belvior. I have some more photos of it in service. I have since met an engineer that used the truck in the sixties and seventies who gave me the photos.

[mp8_macky 10]

great story! thank you!

[james j neiweem 765]

I hear those LeRoi gassers were great sounding engines. I will try looking them up on you tube.

[1958 F.W.D. 3,711]

Used to see the Barnes and Reinecke dynos all the time out on the road courses when I was a Firefighter at Aberdeen Proving Ground.