Re: RE: Crane
Jones said:
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MV frames are designed for a certain amount of flex over rough terrain but that's using the axles as fulcrum points and allowing it to 'wind-up' one direction or the other. A crane behind the cab shortens the twist area by about half and the wind-up is in two reverse directions at once.
Granted, two tons isn't much compared to some of the loads I've seen deuces and 5 tons carrying; but those load's were distributed correctly, mostly over the rear axles, not piled tight against the headboard.
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You will have a certain amount of frame twist no matter where the crane is mounted but it doesn't cause any permanent damage. Driving off road on "frame twister " terrain also doesn't cause permanent damage, like you said, it's designed to move a little.
A 2-ton load carried almost 3 ft behind the rear axle is also not a correct way to load cargo. The weight of the crane must be used 100% when considering the load on the rear axle(s), while only a portion of the midvehicle mounted crane need to be considered.
My K-boom is mounted exactly midway between the front axle and the forward rear axle. In the figure 4 config it can serve as a headboard and ROP even, but mostly the boom is carried over the bed for good load distribution.
Many commercial K-booms are installed at the end of the bed, so it's not only the HEMTT or FMTVs, it does limit the use of the bed though and a dumper version is not possible.
IMHO a Grove crane from a HEMTT is not very practical on a deuce and certainly not on a bobbed one. The K-booms come in many sizes, some very suitiable for smaller vehicles like the Unimogs, however, they are more expensive, for sure, so that may also be a consideration.
