HEMTT / LVS truck.

The HEMTT (Heavy Expanded Mobility Tactical Truck)is a tactical truck used by the US military. There are many different versions of this truck. It is all-wheel drive, features differential locks on all axles, central tire inflation system, and winch. Payload capacity depends on the version. For more information on this truck, go to http://www.army-technology.com/contractors/vehicles/oshkosh/index.html#oshkosh1

The version I built is the LVS (Logistic Vehicle System), which is an articulated steering variant of the HEMTT. For more information on the LVS, go to http://206.144.165.49/htm/defense/lvs.cfm

This model was built beginning-2001. It features all-wheel drive with locking or limited-slip differentials, suspension on all axles, working winch and on-board compressor.

This model is powered by four motors; the two pairs of motors are each an input to a differential, allowing low/high speed by powering one or two pair(s). The motors in a pair a connected in serie. Steering is done by a geared-down motor. The model has an on-board compressor powered by a regular motor, and a winch powered by a geared-down motor. 

Before we get going, since this is a big model and I have lots of pictures, I broke this down in three pages. They are rather large, so be patient while they load.

Construction phase

Loading procedure

My model in action

	Starting at the back: the input from the motor. A u-joint connects the drive shaft to the axle. On the other side of the differential (in the front), you can see a series of cog wheels for each wheel axle; the last wheel in the front is on a sliding gearshift (correct name?) part, to manually by-pass the differential and locking the wheels relative to each other.
	This is the tandem layout. The axles are attached to the chassis in the middle, and at each end via the shock absorbers. Due to lack of parts, the second axle has a limited-slip system (red rubber bands) instead of locking differential.
	The front part of the truck chassis. The turntable at the top is for the articulated steering. The dark grey differential in the middle will take the output of the motors. It is connected to the axles via worm gear. You can also see a drive shaft going to the turntable to drive the wheels on the other half of the truck.
	The geared-down motor at the bottom powers the turntable. You can see the string spool of the winch in front of the middle differential. The spool is turned by the geared-down motor on the left.
	The 2 regular motors next to each other on the right drive the wheels. Two more will go on the other side. The last motor on the left powers the air compressor.
	View of the cab. Two simple seats and a (very) low detail level. Notice the wire bundle on the left side.
	The compressor is there, along with the last two driving motors. The cog wheel in the turntable will connect to the driveshaft of the other half of the truck.
	The front half is finished; see the air tanks and the spare tire. The rear-half has three axles, also driven and suspended.
	The rear half features a hook lift mechanism (more details on the next page) to load/unload containers onto the truck.
	This is the trailer pulled by the truck. Three solid axles, with suspension.
	View of the other side of the trailer.
	The lifting arm goes up to vertical, then bends at 90 degree about half way along.The truck backs up, hooks the palette, and reverses the procedure to load.