Original Year
# of pieces
Cars and Trucks:  4x4s
Steering, V-8 engine,
5 speed synchronized transmission
with reverse, suspension,
4 wheel drive, gull-wing doors
Other Views

8466 4x4 Off-Roader

iso revolve
Click the image to download the LDraw file of this model.
Model by Orion Pobursky

The 8466 truck could be considered part of the supercar category given its host of functions and scale, but it is sufficiently different in topic to belong in 4x4s.   It still has a V-8 engine, a 3 differentials for 4 wheel drive (or more accurately all wheel drive), a 5-speed gearbox with reverse, 4-wheel independent suspension, working steering, and a damping system that is used for gull wing doors.  A rear pneumatic crane could also be added with a supplemental set.

This model introduced several new parts including wheel hubs, CV joints,  panels in metallic green, and the marvelous liftarm frames (5x5L, 4x4, and 4x6).  The combination of a studded and studless construction give this model the sturdiest and most rigid chassis of any large Technic vehicle.  The model also uses a large number of ribbed hoses and flexible axles to suggest a curved external shape, while in actuality it is mostly empty space.


Similarity to 8448
Although superficially much different, this model shares much with the 8448 Super Street Sensation from 1999.  They both have the same 5 speed plus reverse transmission, 4 wheel independent suspension, and damped gull-wing doors.  The primary difference is that this model adds 3 differentials for 4 wheel drive.
complex1    complex1
The front wheels are steerable with a rack and pinion system.  An overhead "Hand of God" wheel serves as input and then drives through a set of bevel gears.  The rack is guided by a lateral axle and held down by a pair of other pinion gears.  The rack is connected to tie rods going out to the steering knuckles.

Note that these steering new hubs do NOT include Ackerman correction.  This is a bit surprising given the otherwise complex model and the fact that there is plenty of room inside the deep wheels.

A 4th pinion gears pulls power from the rack to backdrive the steering wheel through a universal joint.  Alternatively, the steering wheel can be used as input.  Is turns about 180° lock to lock.
steering    steering
Click for an animation of the steering in motion.
This set features a front mounted V-8 engine.  The engine is made from clear cylindrical engine elements and is driven by the all 4 wheels.
The crankshaft is offset 1/2 stud from center, giving the pistons a stroke of 1 stud.  The crank has 4 crank pins at 180 degree angles.  Most V-8s have crossplane cranks with the pins at 90 degrees.  While many racing V-8s do indeed have flatplane cranks like this LEGO version, they are always 0-180-180-0 instead of 0-180-0-180.

The engine also uses a Bionicle part as an intake manifold or supercharger ram.
engine    engine
Click for an animation of the engine in motion.
The transmission is located between the seats.  As a synchronized unit, this one does not need to be aligned to shift and can even be shifted while rotating.

The photograph shows the shift lever and gate with the 6 positions.  As the lever is moved through the H-shaped gate, one of the three driving rings is forced into position.  Note that only one driving ring can be engaged at a time.  Passing through the center of the H returns the opposite ring to center.

The driving ring is the key to everything.  It slides over the ridged axle joiner which we first saw in 1993.  Small tabs on the driving ring allow it to lock along these ridges, but still slide with some extra force.  The driving ring grips the longitudinal grooves on the axle joiner causing them to rotate together.  A circumferential groove in the middle of the ring allows it to be pushed along the axle joiner in either direction.  A set of 4 driving dogs on either end then mate with a 16 tooth idler gear allowing the idler's rotation to be either synched with the axle or allowed to spin freely.

The animation shows how the driving rings work to engage and disengage the clutch/idler gears.  The driving ring is shown in red.  The lower axles are joined with the gray axle joiner.  The driving ring rotates with the axles.  At first, the driving ring is disengaged so both the dark gray and green gears are not driven and slip on the axle.  The driving ring then engages the green gear and thus drives the blue gear.  Because the driving ring does not use gear teeth but rather uses four tapered driving dogs, there is considerable backlash between the driving ring and the gear.  The allows the driving ring to be engaged even while it and the mating idler gear are turning at different speeds.

The computer images are coded to show the different gears paths for each of the 6 gears.  The red parts go to the engine.  The yellow 16 tooth gear is the output to the center differential ring gear.  You can see that the red axles interface with  the other gears in two places: blue and green.  This means that the red, blue, and green axles are always turning at different rates.  The front orange row of 16 tooth idler gears mates with a 16 tooth yellow output, while the rear orange row of idlers mates with the yellow 24 tooth gear.  This results in a total of 6 combinations depending on which driving ring is engaged, with the driving ring extension producing reverse.
transmission    xmsn

 xmsn animation

xmsn    xmsn
Click for an animation of the transmission shifting.
All 4 wheels have independent suspension. 

The front and rear suspension are nearly identical standard double wishbone type.  Because it is a four bar linkage, the wheel stays perpendicular to the ground throughout its travel.  A set of large shock absorbers provide huge ground clearance and travel.

The front suspension adds steering, while the tie rods on the rear hubs are simply grounded to structure.

All four wheels are also driven via constant velocity (CV) joints connected to the inside of the hubs.

The suspension on this model is quite soft.  The front suspension depresses about half way under the weight of the model, which is exactly as it should be.  This means the shocks can both extend or compress from neutral.
suspension    front susp
Click for an animation of the suspension in motion.
This set 3 open differential gears: front, rear, and center.   Each incorporates a built in 16 and 24 tooth ring gear, either of which work as a spur.  In this case the smaller 16 tooth is used on the center diff which is driven by the transmission.  Each differential is made to house 3 of the 12 tooth bevel gears.  One is on each axle, and one planet gear in the middle allows the axles to turn at different rates.

There are no locking differentials here, although the differential part does include a slot for adding this feature.
diff   diff
Click for an animation of a differential in motion.
Gull Wing Doors
The gull-wing doors use a fascinating damped mechanism, and is coupled to a extensible running board for ease of entry into this high vehicle.  A bushing on top serves as a trigger. Pushing the ball down turns a vertical crank which pushes a slider into the damper, forcing it over center.  At this point, the spring slowly lifts the door and the linkage that lowers the stop.  The red axles in the computer image are rotation points fixed to structure.  Make sure to watch the animation because it is quite mesmerizing.

doors1    top
Click for an animation of the doors opening.
Wheels and Tires
This model uses a set of the huge Power Puller tires from 8457, the only other model to ever include them.  Unlike the tires from that model, these are not marked.  These huge balloon tires are very soft and "grippy" and deform significantly under torque like real power puller tires. This creates a lot of rolling resistance, but it sure looks good!

Other Views

Front View
front view
Back View
back view

Top View
top view
Side View
side view
Computer Render

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