Original Year
# of pieces
Cars & Trucks: Dump Trucks
Cars & Trucks: Big Rigs
Other: Universal Sets
Dump Truck
Space Car
Dune Buggy
Robot Walker

8479 Barcode Multi-Set

8479 revolve

The last two sets which could be called Universal Sets came out in 1997, and the greatest of them (and perhaps the greatest Universal Set ever) was the Barcode Multi-Set.  This set is special among the pantheon of Technic in virtually every way.  The first programmable models were the Control Centers, 8094 and 8485, but these were only capable of recording actions and replaying them.  There was no other way to input a program, no output other than motors, and no logic possible within the program.  Enter the Code Pilot, the new computerized brick unique to this set, and the obvious precursor to the first Mindstorms RCX which shares the same form factor.  A program could be entered via a barcode reader, a touch sensor could trigger different actions, and output included not only motor control but also sounds.  Even the sound waveforms had variety and could be played at different pitches.

Apart from the Code Pilot itself, the ways in this set are unique are multitudinous.  It is one of the very few green sets, one of few to use the Flex System (and well), one of the few to include a 9V motor, and the only to ever include a garbage truck.  The set is huge with almost 1300 parts and includes instructions for 4 models which display a huge variety of subjects and techniques.  Nothing like this set had come before, and nothing like it would ever come again unless you include Mindstorms.  The first Mindstorms set came out the following year and took programmable LEGO® in a new direction which diverged somewhat from traditional Technic, so this set is the last time that they were together and it was glorious.  It was the last time a brick could be programmed without a computer.

The Code Pilot is unique to this set, but the set also includes other new parts clearly made to work with it that lived on.  First is the new 9V motor with a more cubic form factor and geared output.  The touch sensor would be used later in Mindstorms.  The clutch gear served to protect the motor and appeared occasionally in future motorized models.

This is a set that rewards the building of all alternate models.  I admit that for years I did not build the 3rd or 4th models because the pictures didn't look that interesting, but I missed out on the fascinating mechanical solutions in those models.  The subjects were clearly chosen not just because they were interesting in their own right, but to display the diversity of effects that could be achieved with the Code Pilot and only a single motor.

This set was near the end of the studded Technic era and the beginning of the studless conversion, yet more than half of the parts are standard plates and bricks.  Within the next few years the studs would disappear almost completely.  This was the last Universal Set.  Never again would a Technic set include full instructions for more than two models.

  Code Pilot
Code Pilot
The Code Pilot is a 12x8x4 stud programmable electric brick that houses 6 AA batteries.  It has a single 9V output port for a motor (colored black) and a single input port for a switch (colored yellow).  It is intended to work with the new 9V motor and the new touch sensor (both shown in the computer image).  The motor has internal gearing and turns at a much lower rate with higher torque than the previous motor.  The touch sensor is nothing more than a momentary contact switch that, when depressed, creates continuity between its two contacts.

The key to programming the Code Pilot is the barcode reader at lower left.  When the "record" button is pushed, the sensor can accept barcodes from the included code card.  Each code is nothing more than a 3 digit number.  There are a total of 44 different codes:
  • 2 - sensor depressed or not
  • 3 - motor clockwise, counterclockwise, or off
  • 6 - sound waveforms: truck, helicopter, robot, gears, air, or off
  • 1 - ampersand to combine sound with motor movement
  • 12 - timer: numbers 0-9 in seconds, random, and decimal point
  • 4 - sound waveform pitch variations for use with the timing wheel
  • 12 - sounds representing the 12 notes of an octave of the chromatic scale
  • 4 - preset programs for each of the 4 main models

Using these codes, a wide variety of programs can be written.  4 preexisting programs are available, one for each model.  These showcase only a small portion of the capability of the Code Pilot.  Besides controlling the motor, the system can also be programmed to play music.

The barcode reader is not only used for programming.  A special timing wheel (shown in white) can be placed in front of the reader within the model.  When the wheel rotates, the reader senses the motion and can vary the pitch of any of the sound waveforms or the speed of the motor.

The programming language is never explained in detail.  The syntax is mostly inferred by observing the effect of the preexisting programs on the models and comparing that to the example list of barcodes used to achieve those programs.

code pilot    code pilot

code pilot
1st Model:  Dump Truck
The garbage or refuse truck is clearly the flagship model of the set, and exceeds the complexity of the others by a large margin.  The enormous model includes only a single motor, yet manages a plethora of interesting features.  The 6 wheeled vehicle uses the additional two tires of the set as cargo.

When the program is run, an idling diesel sound is heard.  The vehicle can be pushed and steered manually.  While the vehicle is rolling, the timing wheel turns and is seen by the Code Pilot resulting in engine sounds which increase in pitch with speed.  When the sensor at the front of the arm hits a tire, a blast of air is heard and the engine idles up simulating powering the hydraulic system.  The arm then lifts the tire over the cab and drops it in the bed.  With a flip of the switch on the transmission, the single motor instead powers the bed and raises it to dump the tires.

The computer image shows the tremendous number of gears and the way in which the mechanisms are routed together.  Blue is the arm mechanism, red the steering, yellow the drive train, orange the transmission, and green the dumping bed.  Click the image for a larger version to study the detail.

The model is capable of using a second motor on the other side to power the wheels.  This motor was available separately as a Supplemental Set.

The model is roughly to scale with Technic figures and has the right size seats, but no room for their legs.
1    Render

guts    guts
Click to download the LDraw file of this model.
Model by Eric Albrecht

The electrical system of the garbage truck uses everything the set has to offer: the Code Pilot, a motor, and two touch sensors.

Since the Code Pilot has only a single sensor port, both switches trigger the same action.  That action is running the motor for 11 seconds, then reversing for 11 seconds.  The position of the transmission controls whether the arm or the bed moves.  The mechanisms had to be geared in such a way that both take about the same amount of time to reach their full travel.  That helps explain the huge gear train in the bed system.
electrical schematic
The single motor is capable of driving either the arm or the bed depending on the position of the transmission.  The transmission selection levers on the sides of the vehicle serve a dual purpose.  Not only do they mechanically slide the drive ring, they also rotate a cam which pushes a touch sensor buried deep inside the vehicle.  Activating this touch sensor is the trigger which tells the Code Pilot to dump the bed.  When in arm mode, nothing touches the sensor and the sensor on the arm is used instead.  A short Flex System cable connects the two levers to the central switching mechanism.

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.
xmsn    xmsn

xmsn animation
Click for an animation of the transmission in motion.
Loading Arm
The loading arm is the best and most clever part of the model.  First of all, it looks completely convincing made from the new angle connectors and loaded with Flex System tubes that look like hydraulic lines and wiring as well.  The touch sensor at the mouth of the jaw triggers the system when it hits a tire.

The gear system driving the arm powers only a single rotating axle, yet the motion occurs in two stages.  Study the computer image to see why.  Rotation of the input axle drives a pair of 3L liftarms used as cranks with ball joints at the end.  Pulling on the ball joints retracts the Flex Cables which are connected to the jaws at the end of the arm.  When the jaws close on something and cannot move any farther, the torque instead serves to lift the entire arm.  After the arm passes the balance point straight above the cab, it drops its load into the bed.  Reversal of the motor returns the arm to the beginning of the cycle, ready to accept another tire.  Watch the animation to see the sequence.

The color coded computer image should the multi stage gear reduction from the motor to the arm.  There are 3 sets of 3:1 reduction resulting in a total of 27:1.  This provides just enough torque to lift the heavy arm.  Note the clutch gear shown in yellow.  This part is needed to prevent the motor from stalling in case 11 seconds is enough to load the system into the stops.  With 27:1 reduction, there is enough torque to destroy the Flex Cables.  By putting the clutch at the right stage in the gear system, there is still enough torque to lift the arm but not enough to damage anything.

This mechanism was only possible with the Flex System and remains the best use of the System with the possible exception of the 8485 Dinosaur.

arm    arm
Click for an animation of the loading arm in motion.
Dumping Bed
The motorized dumping bed uses a custom made mechanical linear actuation system.  3 stages of 3:1 reduction result in a total reduction of 27:1, the same as the arm.  The output is a gear rack used as a linear actuator inside a housing made from Technic triangles.  Like the arm, this mechanism takes about 11 seconds to reach its full travel.  Also like the arm, it requires a clutch gear to keep the motor from stalling.  The bed raises to just over 45 degrees, enough to usually dump the tires although they sometimes become trapped by the lumpy base of the bed.
bed    bed
Click for an animation of the bed dumping.
Drive Train
The middle of 3 axles is the only drive axle.  This axle includes simulated disc brakes, although a real heavy truck is likely to have drums.  A differential sits between the half shafts to allow rotation of the tires at different speeds.  A series of gears transmit the rotation to the white timing wheel which is seen by the barcode reader of the Code Pilot.  Movement of the timing wheel causes the pitch of the engine to change in 4 stages.  The gear ratio is important to allow the engine to respond to reasonable vehicle speeds.

A second motor (or the same motor) can be placed on the right side of the vehicle to power the wheels with a 9:1 ratio.  The motor struggles with this load.

The problem with a 3 axle vehicle which powers only the middle axle is that the middle wheels can easily come off the ground when going over a dip in the road.  The model solves that problem by having the rear axle on a swing arm.  The rear axle can therefore not support and weight so the middle axle is always on the ground.
drive train    drive train
Click for an animation of the drive train in motion.
The front wheels can be steered with a marvelous rack and pinion system.  The rack uses Ackerman correction.  You can see in the images that the tie rod attachments are not directly behind the kingpins, but are one stud inboard.  The result of this is that the wheel on the inside of the turn is rotated more sharply than the wheel on the outside, which is exactly what is required for a turning in a proper circle without skidding.

The steering is controlled via an overhead "Hand of God" input, but also turns the steering wheel in the cabin.  The cabin wheel even tilts to different angles.  The cabin itself is pretty well detailed with seats, a shift lever, and an instrument panel.
steering    steering
Click for an animation of the steering in motion.
2nd Model:  Space Car
The second model is a planetary exploration vehicle of some sort, complete with towed radar or communication station.  It includes 4 wheel steering (shown in blue), speed based sound driven through a differential (shown in orange), a motorized tow arm which raises and lowers the trailer tongue (shown in red), and a rotating antenna.

When the program is run, the Code Pilot makes the sound of an idling diesel engine.  The trailer has a ratchet on the axle to prevent it from rolling backward when disconnected.  When the vehicle is backed against the trailer, the tow arm contacts the rear sensor.  A rushing air sound is heard and then the engine sound races up to a higher pitch and the tow arm lifts the trailer tongue.  This runs for a preset period of time and then the engine returns to idle.  Touching the sensor on the front causes the same routine to put the trailer back down.

When driving forward or backward, the timing wheel causes the pitch of the engine to change.  The motor can be moved to the back of the vehicle to power the wheels instead of the arm, but this is not controlled by the program.
2    Render

guts    guts
Click to download the LDraw file of this model.
Model by D3K
The electrical system of this model includes both switches, the motor, and Code Pilot.  One switch is on the back of the vehicle and is actuated by contact with the tow arm.  The other switch is operated manually and is above the driver's cabin.

Although this model has two switches, both switches go to the same port so there is no way for the Code Pilot to distinguish between them.  The sequence alternates between driving the tow arm up and driving the tow arm down.  If it were to ever get out of sequence, the motor would run against the stop and slip the clutch gear.  This model demonstrates the principle of programming the unit to alternate different actions based on the same input.
electrical schematic
The 4 wheel rack and pinion steering is manually controlled by an overhead "Hand of God" wheel, but also rotates a steering wheel at the driver's position.  As can be seen in the computer image, this gear system uses an unusual gear pair of back-to-back bevel gears against a spur gear.

The front and rear steering racks use a different gear ratio and therefore turn at different rates to different lock angles.
steering    steering
Click for an animation of the steering in motion.
Drive Train
A differential between the rear wheels allows them to turn at different rates.  A spur gear connected to the differential ring gear runs torque up to the timing wheel to allow the Code Pilot to vary the engine pitch with speed.  The bevel gears at the back of the computer image are unused in normal operation, but connect to the motor if is is optionally placed in the rear of the vehicle.
drive train    drive train
Click for an animation of the drive train in motion.
Towing Arm
The towing arm is motorized and geared down 243:1 via 5 stages of 3:1 reduction (3^5 = 243).

The black connector with half pin seen at the lower left of the towing arm in the photograph contacts the touch sensor on the rear bumper when the vehicle is backed into the trailer.  This triggers the arm to lift the trailer tongue.   Touching the sensor again (or the other sensor) reverses the process.

The clutch gear in this system is designed to allow the arm to run into the stops without stalling the motor.  Since it is located 2 reduction stages from the load, a lot of force can still be put into the stop.  In fact, you can hear plastic creaking and groaning if the system hits the stops.  It would be better for the gear to be one stage further down.
boom    boom
Click for an animation of the towing arm in motion.
Communications Trailer
The interstellar communications dish is towed on a trailer.  It rotates with the rear wheels at a 3:1 ratio.

The tongue of the trailer implements a clever ratchet system.  When the tongue is down, it connects to a pawl via a 4-bar linkage which blocks the axle from turning.  This allows the vehicle to back into the trailer with enough force to actuate the touch sensor.  Once the tongue is lifted, the pawl pulls away from the ratchet and the axle turns freely.

Since the trailer has a solid axle, it does not turn very well.  It is also difficult to back because of the short wheelbase.
trailer    trailer
Click for an animation of the trailer in motion.
3rd Model:  Dune Buggy
The third model is motorized dune buggy.  While it looks quite simple at first glance, this model is actually very clever and uses mechanical techniques that do not appear in any other model.

When the program is run the model drives straight forward until it hits an obstacle.  The impact causes the rear suspension link to compress very slightly striking the touch sensor.  Once the sensor state is switched, the motor's polarity is reversed and the car goes backward.  The really cool part is that the steering turns as the car backs up causing it to change direction.  A timer on this function causes the car to back and turn about 120° before reverting to forward motion and starting the program again.  All of this could be done in a modern Mindstorms set with a program, but in this model it is all handled mechanically.  It demonstrates the capability to control multiple functions even with only a single motor and sensor.

The model moves reasonably quickly and can handle carpet, but not uneven ground.  Surprisingly, it does not make use of the clutch gear so the motor stalls when the model backs into something.

The car makes an annoying robotic beeping sound when moving forward and a differently annoying sound when moving backward.  The only way to avoid the sounds is to encode a custom program.  There is no volume control on the Code Pilot.

This is the only model in the set that uses the 40 tooth gear.  It is extra when the main model is built.
3    Render

Click to download the LDraw file of this model.
Model by D3K
The electrical wiring is very simple with a single switch wire (orange) and a single motor wire (blue).  The Code Pilot is housed on rails right over the rear wheels and is easily removable.  The motor is not removable but is trapped once the model is built.  The timing wheel is not used on this model so the barcode reader does nothing when the program is running.
electrical schematic
Drive Train
The key to this drive train is the differential.  Although differentials are most commonly used to allow the wheels on an axle to turn at different speeds, what they really do at the core is equalize torque.  As seen in the computer image, the motor drives one pinion gear of the differential.  The other pinion gear goes to the steering, and the housing ring gear goes to the left rear wheel (right wheel is not powered).  The steering linkage is built so that it is blocked from turning left and can only turn right.  When power is applied in the forward direction, the steering cannot turn so all motion goes to the drive wheels.  When power is applied in the backward direction, the steering moves into the right turn stop first because that circuit has less resistance than the drive wheels.  Once the stop is encountered, the car starts to back up.  In either case, the steering stop has to react an amount of torque equal to that being applied to the drive wheels.
drive train    drive train
4th Model:  Robot
The 4th model is bi-pedal robot walker with a pistol grip controller.  Unlike previous attempts at making a motorized walking robot with Technic, this one actually works!  It can walk either forward or backward at varying speeds, but no turns are possible.  Rotation of the wheel atop the controller causes the robot to walk forward.  In theory, different rotation rates should result in different walking speeds, but in practice the motor does not have enough power and the lower speeds to move the robot.  Holding the "trigger" switch makes the robot walk backwards.  It does not matter which direction you rotate the wheel, the walking direction of the robot is only related to the state of the switch.

The robot is tethered to the controller with a single wire.  The wire is not very long so the operator must remain quite close to the robot.

The default program for this model uses an annoying beeping sound that sounds like it is from an old Atari game.  Possibly Space Invaders.

This model demonstrates the capability of controlling the speed of the motor using the timing wheel.  It is the only model that does so.
4    Render

Click to download the LDraw file of this model.
Model by D3K

The electrical system is about as simple as is possible for the Code Pilot.  The Code Pilot is housed on the remote along with a single switch used for switching from forward to reverse (connected with blue wire).  Two wires (red and yellow) are connected in series to tether to the  robot.
electrical schematic
The key to the stability of this robot is that fact that either leg by itself is large enough to support the whole thing so no complex balancing is required.  This is possible because the feet pass under the robot's center of gravity.

As shown in the computer image, the walking mechanism is a simple 4-bar parallel linkage driven at the black cranks.  The left and right legs are 180° out of phase.  The motor is geared down 3:1 at a single stage; the other stages are 1:1.  This results in a robot that walks very quickly.  It would actually be preferable if it was geared down further.
robot    robot
Click for an animation of the robot in motion.
The pistol grip controller houses the Code Pilot.  Rotation of the wheel on the top drives the timing wheel as shown in the computer image.  When the barcode reader senses rotation of the timing wheel, it sends power to the motor at a level proportional to the speed of the wheel.  In practice, only max speed with make the robot move since there is insufficient power at lower speeds.  This suggests that the control center regulates speed by simply dropping voltage.  Depression of the trigger switch causes the robot to walk backward (reversed polarity on the motor).

Note that the wheel must be rotated to continually; the robot will not keep walking once started.  This makes it rather cumbersome to control for more than a couple of seconds.
controller    controller

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