Original Year
# of pieces
Other:  Other
(robot form)
Steering, transformation
Other Views

8852 Robot

iso    iso revolve
Click the image to download the LDraw file of this model.
Model by Jerome Boulanger

Set 8852 was released in 1987 and was the only set available that year.  This set is a truck which features rack and pinion steering.  When a crank in the rear is turned, the upper chassis rotates upwards and the wheelbase shortens, transforming the vehicle into a robot.  This is the only Technic set ever made with this theme and was almost certainly influenced by the popularity of the Hasbro Transformer series of toys in the same time period.  The mechanism itself is very clever, but the robot is not very interesting once transformed.

This set features almost  no traditional studded construction, a sign of things to come.  This set is also an excellent source of regular and toothed connectors.


The front wheels can be steered using a "hand of god" wheel.  The wheel drives an axle connected to an 8 tooth pinion gear through a set of 14 tooth bevel gears.  The pinion drives a rack.  The steering mechanism itself uses control arms and toothed links.

The overhead control is carefully placed so that it fits through a gap in the chassis when in truck form and does not interfere with the torso during transformation.

Click for an animation of the steering in motion.
The transformation from truck to robot is controlled by a crank in the rear of the vehicle.  First the arms must be disengaged from the axle pins which hold them in place.  The arms pivot via connectors and pins at the shoulder.  Then the crank is turned.  The crank drives a worm gear which mates with a 24 tooth spur gear.  Beside the spur gear are two pulley wheels with 1/2 pins attached to adjacent beams which form the torso of the robot.  As the pulleys rotate, the torso pivots upward.  The torso and the head form a 4 bar linkage, so the head stays parallel to the ground as it rises.

The same 24 tooth gear which drives the torso also drives an 8 tooth pinion in parallel.  This axle has another pinion (16 tooth) on each end which mates with gear racks on either side of the chassis.  As the racks translate, the entire wheelbase constricts and shortens.

A second set of pinion gears mates with the racks but is not driven.  The function of this second set is to keep the racks level.

Once the robot is upright, the shoulder connector joints can be rotated into place.  The elbows are hinges, and the hands are claw pieces.

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 robot to be supported in transit so that it does not fall under its own weight.
robot    robot

robot    robot
Click for an animation of the transformation in motion.
Wheels and Tires
This set has 4 of the 13x24 Model Team wheels.

Other Views

Side View
side view
Front View
front view
Side View
side view
Front View
front view
Computer Render

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