At the outset, it is noted that an alternative carrier vehicle has been designed which has differences from the carrier vehicle that is illustrated along with certain advantages. It is expected that illustrations of the alternative carrier vehicle will be available soon. In the meantime, the differences are explained herein.

In the illustrated vehicle, a main frame (light brown) includes a pair of posts that extend up through a longitudinal slot in a top wall of a tubular guideway and to a pair of pads (yellow). The pads can be securely but detachably locked to connectors of uniform configuration that are provided on the undersides of all platforms, passenger cabins and freight container of the system. Front and rear bogies are directly under the posts and are rotatable about the axes of the posts.

Three phase electrical power is supplied to the vehicle through pairs of shoe structures (blue) on the bogies. Each shoe structure includes three current conducting shoes that are positioned to be slidably engageable with conductors which extend along the insides of both side walls of the tubular guideway. In the alternative vehicle, similar shoe structures are provided, but they are positioned to engage the shoes with conductors that extend along the undersides of top wall portions of the guideway.

The bogies are supported, guided and controlled by a wheel arrangement that produces accurate wheel tracking, reliable movements through Y junctions, high traction forces when needed, safe support of loads and other advantages. Two pairs of lower wheels (green) ride on lower guideway tracks while three pairs of grooved upper wheels (violet) engage upper guideway tracks to limit upward movement of the vehicle. One pair of the lower wheels and one pair of upper wheels are on each bogie. The third pair of upper wheels is on a carriage which is between the bogies and which is shiftable sideways relative to the main frame. Aerodynamic losses are minimized by housings including a housing (light green) of the carriage which has a forward end extending within a front bogie housing and a rearward end receiving the forward end of a rear bogie housing. "Carrier Vehicle Internal Construction" shows the vehicle with such housings removed to show details of construction, a drive train and other features.

In the alternative vehicle, the upper wheels are not grooved but engage in downwardly open slots defined by the upper tracks. Also, the supports for the upper wheels also support the shoe structures of the alternative vehicle that engage the shoes with conductors extending along the underside of the guideway.

Accurate tracking of the wheels is obtained through using a sideways displacement of the carriage from a neutral position to rotate the bogies away from neutral positions and in opposite rotational directions. When the vehicle moves through a curve or turn to the right, for example, the upper wheels on the carriage operate to shift the carriage sideways and to the left relative to the main frame to rotate the front and rear bogies in clockwise and counter-clockwise directions as viewed from above. See "Carrier Vehicle in Turn Condition" .

Preferably, the carriage is coupled to each of the front and rear bogies at a point that in relation to a central point of the axis of the bogie, is about one-fourth the distance to the axis of the other bogie. As a result, the axis of each wheel will always be positioned in a vertical plane that is substantially perpendicular to the portion of the track engaged by the wheel.

The carrier vehicle has a number of additional features, including the following:

• Electrically controllable wheel actuators are provided for control of the forces exerted by upper wheels against upper tracks and for lowering upper wheels on one side or the other to positions out of engagement with an upper track. The actuator may be in the form of an hydraulic cylinder and spring unit that is controlled by an electrically operated servo valve, or it may a screw jack and spring unit controlled by an electric motor. In alternative vehicle previously referred to, the wheel actuators also control upward and downward movements of the shoe assemblies.
• The upper wheels on either side may act alone to control the path of movement of the vehicle. As a result, a redundant control is obtained when wheels on both sides engage the upper tracks and, when control of movement through Y junctions is desired, it can be obtained by lowering the wheels on one side or the other. To move through right portions of Y junctions, the grooved upper wheels on the left are lowered to allow those on the right to control the path of travel; to move through left portions of Y junctions, the grooved upper wheels on the right are lowered. Switching can thereby be controlled through electrical control of the actuators within the vehicle; no mechanical switch mechanisms are required in the guideway.
• Traction is controlled in part by upward forces applied to the upper wheels that increase the forces applied between the lower wheels and lower tracks. Through electrical control of the wheel actuators, traction can be increased when desirable, as during acceleration and braking.
• In inclined or curved portions of a guideway or portions where high accelerations or decelerations may occur, increased traction may be obtained by decreasing the distance between upper and lower tracks to thereby increase the deflection of springs of the wheel actuators.
• With upper wheels on both sides elevated, they act in response to cross-wind and centrifugal forces to limit tilting movements about a longitudinal axis.
• With upper wheels on both front and rear bogies, they limit tilting movements about a transverse axis in response to braking and drive torques applied to lower wheels. No appreciable "dive" or "squat" actions can take place.
• Important advantages result from the actions of the lower and upper wheels which keep the vehicle in the desired path of movement. The actions are unlike the actions of the wheels of conventional railway cars that have cone-shaped portions for engaging tracks and outer flanges. The cone-shaped portions develop transverse forces to oppose movements away from a centered relation to the tracks. However, they inherently produce hunting actions which can become severe and cause derailments if not safely limited by the action of the outer flanges. In the Autran vehicle, the upper grooved wheels control the angles of the bogies to oppose displacement from the desired path through frictional engagement of the lower tracks by the lower wheels which preferably have a cylindrical shape and which may be relatively wide to increase such frictional engagement. The forces applied between the upper wheels and the upper tracks are normally low, the actions being similar to the actions that occur in steering an automobile. However, the flanges of the upper wheels of the illustrated vehicle can insure that high side-wind or centrifugal forces will not cause displacement of the vehicle from the desired path. In the alternative vehicle previously referred to, the engagement of upper wheels in slots defined by upper tracks serve a similar function.

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