Original Year	1986
# of pieces	191
Categories	Other: Universal Sets
Dimensions	various
Models	Car with Conveyor Compactor Crane Centrifugal Force Machine Electric Gate Car

8055 Motorized Universal Building Set

The small set 8050 was released in 1986 as a Universal Building Set, and the second Technic set to ever include a motor. (Note that this does not include the earlier supplemental sets, some of which had motors.) It includes full instructions for 6 models as well as photographs of several other possibilities. There a number of parts left over when any of the models are built.

This is the second set to include a motor, which is 4.5V and runs on 3 C-cell batteries (more about the motor on the 1982 page). The motor is used in each of the models to drive a variety of functions, except for the gate. In each case, the motor is coupled to the model via a belt (rubber band) to prevent stalling the motor.

The models in this universal set cover a wide variety of subjects and complexity levels. The first car features rack and pinion steering and a trailer with a motorized conveyor system. The second model is a mystery vibrating tool which could be a tamper, a floor sander, or a concrete smoother. The mobile crane slews 360° and has a motorized winch. The fourth model is very unique and demonstrates the concept of centrifugal force. The electric gate is, ironically, not electric but driven by a worm gear. Finally, a Jeep has rack and pinion steering and a motorized rear axle.

This set uses the new worm gear, but only for one model.

I find the 5^th model the most interesting, and it is the model I chose to keep assembled for my display of this set.

1^st Model: Car with Conveyor
This little car seems to be pulling some mining equipment for some reason. The front wheels can be steered using a wheel in the cabin. The wheel drives an 16 tooth pinion gear at an angle. The pinion drives the steering rack. The steering mechanism itself uses control arms and toothed links. The trailer uses the motor to drive a pulley. This pulley, in turn, uses a belt to reduce the speed and drive another pulley. This final pulley drives a series of 4 long rubber belts which act as a conveyor to haul pieces along the length of the trailer. Why? Who knows, but it is the only set with these long rubber bands.	Click for an animation of the steering in motion. Click for an animation of the conveyor in motion.
2^nd Model: Compactor
What is this thing? Good question. I don't know the answer. It is a bit like an oscillating floor sander, or like a heavy tool used to vibrate and smooth concrete. It is most likely a tamper or compactor for site preparation. It might also be used to drive away vermin! The motor drives a belt which is not geared down so it rotates at very high speed. The output pulley has a 2L Technic brick attached to it which causes it to be imbalanced. This results in a high speed vibration of the whole model. The vibration in the animation is fake. Actual motion is far too fast to capture with stop motion, and even full motion video would have trouble. This is more of a "buzz" than an oscillation.	Click for an animation of the compactor in motion.
3^rd Model: Crane
This small mobile crane slews the boom and retracts the cable. The motor drives a cable drum through a belt and a set of 8 and 24 tooth gears. The cable moves quite quickly. The cabin can slew using a crank and a set of 8 and 24 tooth gears. There is no turntable here, the whole thing simply rotates on an axle. The boom is at a fixed angle.	Click for an animation of the boom slewing. Click for an animation of the cable lifting.
4^th Model: Centrifugal Force Machine
Now here is something really unusual, a bit of a science experiment. A rotor supports two masses on pivoting arms. The faster the rotational velocity of the rotor, the higher the angle of the masses due to centrifugal force (slow speed on the left, high speed on the right). No doubt some of you will complain that there is technically no such thing as centrifugal force but actually a centripetal acceleration. You'd be right, but that is beyond the scope of this web page. A simple transmission is used to change speeds. A motor drives the first axle through a belt and pulley. This axle drives another at the same speed via a pair of 8 tooth spur gears. This second axle rotates at a fixed speed, but it can drive the third axle at two different speeds based on its position. If moved to the left, an 8 tooth gear drives a 24 tooth gear. If moved to the right, a 16 tooth gear drives another 16 tooth gear. So there is a 3X difference between these two positions. A final set of 8 and 24 tooth gears drive the rotor. The stop motion animation is not fast enough to show the rotation, but frames were taken at a constant interval as the machine slowed down. You can see the "arms" relaxing as the speed decreases.	Click for an animation of the machine at different speeds.
5^th Model: Electric Gate
This electric gate is the only model which does not use the motor, and also the only model to use the new worm gear. A crank drives the worm gear which rotates a 24 tooth spur gear, lifting the gate, and resulting in 24:1 gear reduction in one stage. The use of a worm gear results in a system which cannot be backdriven (because the axial friction is higher than the backdriving torque due to the screw pitch angle) which allows the gate to be supported so that it does not fall under its own weight.	Click for an animation of the gate in motion.
6^th Model: Car
This small car, which looks like a Jeep or Land Rover, has steering and a motorized rear axle. The front wheels can be steered using a wheel in the cabin. The wheel drives an 8 tooth pinion gear. The pinion drives the steering rack. The steering mechanism itself uses control arms and toothed links. A motor mounted on the rear drives a pullley via a belt. A set of 8 and 24 tooth gears transfer the torque to the rear axle. This model could use a bit more gear reduction. The vehicle tries to go faster than the motor can really handle.	Click to download the LDraw file of this model. Model by Eric Albrecht Click for an animation of the steering in motion. Click for an animation of the car in motion.

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