During its year of introduction this set was priced 62.50 guilders.
Set 856 was released under the "Technical Set" series in 1979 in Europe and in the USA as 951, an "Expert Builder"set. This bulldozer features a bucket which raises and dumps via rack and pinion systems, and rides atop large tracks wound around 40 tooth gears. The body uses mostly traditional studded construction, with the exception of the linkage which makes the bucket functional. A large number of connectors are used to form tie rods.
This bulldozer has one of my favorite mechanisms of any Technic set. Rather than using the expected rotational controls to move the bucket, this model uses two ingenious, interconnected rack systems which translate within the structure. As if that wasn't enough, this model also introduces tracks, a variation on the new chain link parts included in 857. There are 106 tracks in this set and, for a long time, this was the only set in which you could get them. Only two other sets would ever be released which sit atop tracks, and they would be spaced out 10 years. This model also uses a specialized piece for the side of the bucket. This was unusual for 1979 since most parts still had many possible uses and were not highly specialized like this one.
Main model
Features |
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Raising Bucket |
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The bucket can be lifted from ground level (and slightly below) to almost straight up using a crank at the right rear of the vehicle. This crank drives a set of 8 and 24 tooth gears, as can be seen in the computer image. After another set of 8 and 24 tooth gears, the system drives a translating rack in the bottom of the vehicle. When moved forward, this rack pushes a connecting rod (circled in red on the right of the picture) attached to the bucket linkage. The bucket linkage looks like a series of two four bar linkages, but is so much more. The system begins by pivoting around an axle (circled in red in the center of the image). At this point, the bucket rotates and lifts at the same time, tipping upward as it raises. Just at the point that the bucket becomes level, the linkage bottoms out on the structure, and subsequent motion raises the bucket without tipping it! This is easy to see in the animation. The motion is simply amazing to watch. A pair of rubber bands right behind the bucket keep it from falling freely. |
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Dumping Bucket |
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When raised, the bucket can dump by rotating down about 90 degrees. This is driven by a crank at the left rear of the vehicle. As can be seen in the computer image, torque is driven through a set of 8 and 24 tooth gears into another 24 tooth gear, then into a pair of pinions on the same axle. These pinions drive a translating rack system in the top of the vehicle. When moved aft, this rack pulls a connecting rod attached to the bucket linkage. The bucket linkage, when raised, is a pair of 4 bar linkages. The beams which make up the linkages rotate and stay parallel, tipping the bucket, and stretching the rubber bands. |
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Bucket |
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The bucket is constructed of plates and a specialized part used in only 2 Technic sets. |
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Wheels and Tires |
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This set contains 106 Track elements and Gears:
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By Technicopedia