Original Year
Parts and Construction
Alternate Model(s)
Implements, Saw,
Punch Press
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851/952 Additional Information

Parts and Construction

Parts and Instructions
This model contains 315 parts (pictured).  Most are standard plates and a few bricks.  At upper left are the Technic beams and the axles and gears have also been separated.

My instructions from 1977 were printed in poster form.  The main instructions are one big foldout sheet with 25 steps, and the alternate model instructions are another sheet which also shows "blueprints" of the main model.  There are no parts lists for each step like you would expect from Technic.  Later editions of this set would have a conventional instruction booklet with individual step parts lists.  There are also photos of how to motorize both the main and alternate models with the optional 4.5V 870 Motor.

Like all Expert Builder sets, this model also came with a booklet showing many ideas of how to make alternate models by combining the parts of this set with other sets
The following images show the construction at intermediate stages.

The first image shows the steering assembly.  The second image shows the begining of the chassis with the gears for the PTO.
build    build


Alternate Model(s)

Instructions were included for 4 additional implements for the rear of the tractor.  The first 3 do not have any moving parts, while the 4th rotates as the tractor is driven.
alt    alt

alt    alt
This saw reciprocates as the crank is turned.  Not exactly stunning, but a good example of the kinds of simple machines which can be built from these parts with minimal effort.  It uses 3:1 gear reduction and one of the offset holes in the 40 tooth gear.
Click to see an animation of the saw in motion.
Punch Press
I am only guessing that this is a punch press since it is very difficult to tell.  In any case, the fairly complex motion combines the rotation of the punch with the translation of the table and is mesmerizing to watch.  The offset holes in the 40 tooth gear are used with linkages to control the motion.
Click to see an animation of the press in motion.

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