MTD program

[BobS]

The MTD (Modern Technology Demonstrator) program was a single unit experimental vehicle built by GM/MVO in response to TAACOM's request for enhancements prior to the M939A2 program definition.

This vehicle had to improve on the M939 and M939A1 mobility by 25% minimum (we scored 38% improvement), reduced load to the H-point of the driver to a maximum of 15 watts (we scored 12.73 watts), decreased fuel consumption (no spec, but we scored a 13.8% improvement), demonstration of the new STE/ICE system for tactical trucks (this was far before it was incorporated) and most importantly (to me, at any rate), integration of the Eaton 18speed CEEMAT automated mechanical transmission (this was the first truck that was not built by Eaton, to have this transmission) with single speed, AWD transfer case, along with a 20 minute hot engine removal.

I was particularly proud of the 20 min spec completion. We used an M939 wrecker, 2 army techs with 2 hours of training, and were able to do a hot R&R, including ground hop of a replacement powerpack, in 15 minutes and 20 seconds, using only the M939 tool kit.

Best regards,

Bob

 

[cranetruck]

The MTD.... , decreased fuel consumption (no spec, but we scored a 13.8% improvement), demonstration of the new STE/IC.....

Bob

As you may have noticed, the mpg numbers posted on this site for the deuce in particular, varies from about 6 to 12 or so, depending how the truck is driven, my question is, how do you come up with a number and since you can compare it to a different mfg's vehicle, what kind of standardized method is used?
There are so many variables, fuel, ambient temp, tires, tire pressures, all the road conditions, truck loading not to mention the driver habits etc.

Thanks

 

[BobS]

The MTD.... , decreased fuel consumption (no spec, but we scored a 13.8% improvement), demonstration of the new STE/IC.....

Bob

As you may have noticed, the mpg numbers posted on this site for the deuce in particular, varies from about 6 to 12 or so, depending how the truck is driven, my question is, how do you come up with a number and since you can compare it to a different mfg's vehicle, what kind of standardized method is used?
There are so many variables, fuel, ambient temp, tires, tire pressures, all the road conditions, truck loading not to mention the driver habits etc.

Thanks

A single test for "fuel economy" does not exist. The process goes:

1. Determination of the BSFC of the engine (Brake Specific Fuel Consumption), which is NOT the overall fuel consumption of the vehicle-it is simply the basic amount of fuel the engine consumes per horsepower hour and is independent of the vehicle. The test standards are sometimes more extreme than the SAE specifications (available online for a price-and they are copyrighted, which is why I will not post them. Just search the SAE website for the term "fuel consumption test")...

2. Determination of the frictional resistance of all the components in the driveline (generally supplied by the manufacturer of the parts-but we double checked these claims by actual testing on a dyno for each piece. This involves building the "truck" on the dyno and driving it with a known rotational resistance electric motor).

3. Assembling the truck and measuring the fuel flow rates with transducers to determine (in the case of electric or mechanical non-engine driven fuel pumps) that actual maximum capability of fuel flow to the engine. These transducers are then used to measure the actual totalized fuel flow on a road test.

4. In our tests, we used the Euclid (that was self powered) to determine drawbar pull or, in simpler terms, provide a maximum static load rate on the vehicle, regardless of attitude or grade of the road. Tis was accomplished by a primative computer in the cab of the Euc that has a driver controlled set point that the various sensors on the Euc would use to measure the actual drawbar strain on the towing vehicle.

5. Drive the heck out of the combination....LOL....actually, drive the vehicle at the required (by the contract specs) loading-in our case, it was a contract requirement to put a load that was required to develop 0.7 tractive effort, of 70% the total capability of the truck in compound low range (first gear of an 18speed RoadRanger, in essence, since the CEEMAT was based on that trans and had OE gear ratios) that was able to be delivered to the road surface without tire slippage. In our case, the MTD could actually exceed 0.7...it could go much higher with the CEEMAT Rockwell axle, and Michelin tire combination on concrete///up to 105,000 drawbar pull, as I remember.

Under these conditions, the engine was revving at the torque peak in 1st gear, all axles locked up and the differential in the transfer case locked up, all ensuring equal traction and equal RPM to all the tires.

As you can see in that pic, this truck was tested in January in Michigan...not exactly SAE standardized 70 degree F ambiet. SAE has calculation formulas to normalize or correct the measured temps to SAE standards. Driver variance is not material, because the recording sensors on the vehicles (both the Euc and the MTD) record over 700 various parameteres for just this reason, throughout the test cycle. Any variance is immediately shown up and corrected. The road surface is fixed-to eliminate that variable, as is most other variables. The only variable that is uncorrected is the attitude of the test engineer supervising the tests....

Hope this helps explain what is done...

Best regards,

Bob

 

[cranetruck]

RE: Re: MTD program

Much appreciated Bob! Good to have an educated input.