XM757 design features

[cranetruck]

The M656 series 5-ton trucks may be few and far between, but it is interesting to note some of the design features of these vehicles. They were designed to mil spec from the ground up.
I'll list features as I go along and "discover" them on the XM757.

Here is one such feature, there is a separate belt with tensioner for the fan so that it will slip when the truck is fording/swimming without effecting the compressor and alternator functions.

 

[doghead]

That's military for you! The simplest "clutch" fan = dedicated fan belt, tension correct (loose), drive underwater (or at least to up your engine air intake), and your fan automatically slips! cool!

 

[cranetruck]

Another little feature is a "low air" buzzer defeat button.

The frame was designed for rigidity with tubular cross members to
allow the suspension to handle off-road irregularities without twisting the frame.

 

[cranetruck]

Another feature of this vehicle is the watertight cab. The image shows the Canon type connectors used to feed wires through the aluminum floorboards from the dash area.

 

[jh1990]

Very cool Bjorn.

 

[cranetruck]

The tire/wheel design is also unique to this vehicle.
The tubeless radial tires are low profile with a 12 inch wide rim. It's spec'ed to run at only 30 psi on the highway. Tires are marked 16-20 (or 16R20 on the one Uniroyal tire that blew out). They also have a FSN number molded into the side wall.
The wheel is just a ring with 8 lug nuts around the periferi. Parts are aluminum, which makes a tire/wheel assembly easy to handle for two people and no crane needed to handle the spare, which is strapped in place behind the driver.

 

[cranetruck]

Weighed the wheel and tire assembly this morning and it may not be that easy for two average guys to handle. It weighs 220 lb on a bathroom scale.
Checking with a magnet, the only part that's aluminum is the back plate on the brake drum that holds the eight studs, all other parts turns out to be steel.

I got a false impression handling the blown tire, which must have left a lot of rubber along interstate I-81....