Abstract: A toy vehicle comprises a chassis having a front end, a rear end and first and second lateral sides extending between the ends. Two wheel trains are disposed on separate lateral sides of the chassis. Each train includes first, second, third and fourth wheels, a first pair of the wheels being mounted on separate axles fixed with respect to the chassis and a second pair of the wheels being mounted on separate axles movable along the first lateral side of the chassis. A separate continuous track extends about each wheel train so that the track engages over at least the first wheel and another other wheel. A separate linkage connects each second pair of wheels with the chassis and is configured to displace the second pair of wheels between a first wheel arrangement in which the wheels of the train are generally disposed in a single row, and a second wheel arrangement in which the wheels of the train are generally disposed in two rows and all the wheels engage the track.

Abstract: A mobile marker board unit has a wheeled base which mounts a pair of upright and vertically enlarged marker boards. The marker boards, as they project upwardly, are rearwardly sloped to define a triangular storage space between the marker boards. This storage space is accessible from at least one end of the unit, and is preferably provided with structure which permits storage therein. A slidable tray arrangement is mounted adjacent the lower edge of each marker board and can be moved between open and closed positions. Each tray arrangement includes an outer tray disposed directly adjacent the lower edge of the marker board and positioned for support of articles thereon. This outer tray is fixedly joined to an enlarged inner tray which is normally stored in a closed position between the marker boards, with the tray assembly being slidable into an outer position wherein the inner tray projects outwardly from the marker board adjacent the lower edge thereof.

Abstract: A model kit for creating replicas of animals comprises a mold into which a casting material is placed to generate the chosen animal-like form. Components simulating internal organs of the creature are assembled and placed within the mold prior to casting, whereby they are embedded in the casting material. One or more of the components may simulate selected soft tissue organs or groups of organs, and may be of a bladder-like construction, allowing it to be filled with a liquid. The casting material sets to a thick gel-like consistency, allowing the material to be excised from about the internal organ components, whereby the user can "dissect" the creature.

Abstract: A double pendulum device displaying regular and chaotic behavior simultaneously when the pendulums are in motion, comprising: a beam (55) mounted symmetrically to a vertical surface about a pivot point consisting of a friction reducing insert (56) with a fastener (57) passing through it for attachment of the beam to said vertical surface and allowing free rotation of the beam (55) about its horizontal axis; a long pendulum (44) attached near one end of the beam (55) with a fastener (46) passing through a friction reducing insert (45) installed in and near one end of the long pendulum and a spacer (47), said long pendulum (44) being free to rotate about a horizontal axis; an arm (66) fixed at the opposite end of beam (55) from long pendulum (44) in such a manner as to become a ninety degree extension of beam (55) directionally equal to the long pendulum (44) when the pendulum device is static; a short pendulum (77) attached near the opposite end of the arm (66) from said arm's attachment to the beam (55) with

Abstract: A toy vehicle comprises a chassis having a front end, a rear end and first and second lateral sides extending between the ends. Two wheel trains are disposed on separate lateral sides of the chassis. Each train includes first, second, third and fourth wheels, a first pair of the wheels being mounted on separate axles fixed with respect to the chassis and a second pair of the wheels being mounted on separate axles movable along the first lateral side of the chassis. A separate continuous track extends about each wheel train so that the track engages over at least the first wheel and another other wheel. A separate linkage connects each second pair of wheels with the chassis and is configured to displace the second pair of wheels between a first wheel arrangement in which the wheels of the train are generally disposed in a single row, and a second wheel arrangement in which the wheels of the train are generally disposed in two rows and all the wheels engage the track.

Abstract: A radio controlled toy vehicle has a central chassis, a front end mounting a pair of front wheels which is rotatably coupled to the front of the chassis and a rear end mounting a pair of rear wheels. An electric motor is provided in the chassis to selectively rotate the front end with the front wheels about a generally longitudinal axis through a partial rotation for steering or through as many complete rotations as desired for stunts. In one embodiment, the front end includes a yoke pivotally supporting a pivot body mounting the front wheels. The rear end contains a propulsion drive coupled to the rear wheels and is pivotally coupled with the chassis so that both rear wheels remain grounded as the chassis pivots in reaction to rotation of the front end for steering. In another embodiment, a stop is provided to limit the rotation of the front end. The stop releasably engages a collar around a shaft rotating the front end and is disengaged by providing more torque to the shaft.

Abstract: In one aspect, the present invention is directed to a kit for constructing a biomechanical model of a lever system selected from a first class lever system, a second class lever system, and a third class lever system, comprising a base, a support structure attachable to the base, at least one lever assembly attachable to the support structure, and at least one cord assembly attachable to the lever assembly. The present invention is also directed to first, second and third class lever system models useful for teaching and demonstration purposes.