First and second throttle levers are coupled to normally move conjointly with each other by a scissor spring biasing the levers in opposite directions on a throttle shaft carrying a carburetor throttle valve. The first throttle lever is fixed to the throttle shaft, and the second throttle lever comprises a part of the vehicle throttle pedal linkage for normally controlling the position of the throttle valve. The first throttle lever is loosely connected to a vacuum motor to permit normal movement of the throttle pedal linkage and is pivoted in a throttle velve closing direction when the vacuum motor is actuated with engine vacuum communicated when a vehicle brake pedal opens a vacuum valve. Should the second throttle lever be prevented from moving in the closing direction with the first, actuation of the vacuum motor overcomes the bias of the scissor spring and assures the return of the throttle valve to its idle position.

An optical digitizer or tablet employing a linear image sensor behind a microlouver strip and extending along a coordinate axis of a coordinate axes plane. In one embodiment, a non-directional light source floods the plane, and a cursor is provided with a reflector that reflects incident light. In another embodiment, the light source is on the reflector, and the sensor-microlouver combination is located along each tablet edge.

A technique for automatically centering a lightguide fiber (7) in a transparent plastic coating (6) having a refractive index lower than that of the fiber. The fiber (7) is passed through an applicator (14) having the coating material (6) therein to coat the fiber. Orthogonal laser beams (50 or 52) are directed at the coated fiber (5) resulting in first and second forward scattered light patterns (51 or 53) impinging on first and second screens (36 and 37). The patterns are monitored with a pair of CCTV cameras (38 and 39) and the video output signals therefrom are processed to determine the period (P.sub.1 and P.sub.2) of outboard interference fringes (61 and 62) of each pattern. The period of the interference fringes are compared to determine the difference therebetween which is proportional to the eccentricity of the fiber (7) within the coating. The position of the applicator (14) is then adjusted to center the lightguide fiber (7) in the coating (6).

A glass tube extrusion apparatus (50) is comprised of a chamber (52) having a crucible (72) therein mounted within and spaced from an inductive heating coil (77). As a glass tube (170) is extruded from an annular opening (74) in the bottom of the crucible (72) the tube is monitored for bending. When a bend starts to occur an X-Y motion apparatus (54) is activated to move the crucible (72) laterally within the coil (77) in a direction opposite to the bend to straighten the tube (170).

The present method and apparatus provide a possibility to remove components from a magazine, from a storage bin or the like, to transport these components to a workpiece and to put these components onto the workpiece or into it precisely at a preselected position. The component which has been picked-up by and is retained by the transportation member will usually not be in a exactly preselected position with regard to the gripping means of the transportation device, but will be more or less shifted and/or tilted with regard to a theoretical, nominal positioning axis. In order to determine the actual position of the component retained by the gripping means, the component is brought to a position scanning station during its transportation from the magazine or storage bin to the workpiece. The scanning station measures and records the actual position of the component, e.g. by scanning the shape of the component by means of laser beam scanning according to the reflection or shadowing technique, calculates any deviation and generates one or more correction signals. The latter ones are further processed in order to influence the transportation path of the component transportation device, the position of the workpiece or both of them, so that the component finally may be placed onto or into the workpiece exactly at the desired position.