Abstract: Fill-level indicating device includes an array of optical detectors attached to a mount, vertically spaced apart relative to one another and distributed within the tank over the height of the latter, with each detector including a light source and a receiver, and means for feeding electric power to the light sources of the various detectors, for processing the signals arriving at the various receivers and for transmitting these to a liquefied-gas fill-level display gauge. The mount and the detectors on it are encapsulated in a synthetic resin that is highly transparent to the light beam emitted by the light sources and the surface of the resin facing the detectors is such that the beam emitted by the corresponding light source is reflected toward the associated receiver.

Abstract: This device includes the following:

Abstract: A disengageable linear stepper motor is provided comprising a multipolar stator with a threaded bore, a threaded rotor rolling cycloidally inside said bore under the action of stator forces, and a drive rod fast axially with said rotor. The rod is immobilized radially in the center of said bore by bearings and resilient return means are provided for centering said rotor on said rod in the absence of stator forces, thus providing clean disengagement of the rotor, which reduces wear and noise.

Abstract: A disengageable linear stepper electric motor is provided comprising a multipole stator in the bore of which a rotor of smaller diameter revolves cycloidally, and sealing means for isolating the stator environment and so the environment outside the motor from the rotor environment.