Abstract: A rope hook with an off-the-hook limiting lever connected to a lever support of a body to be able to pivot in a front to rear direction and to shift laterally within a predetermined range. The lever is urged frontward (in a closed direction) and leftward (in a locked direction) by a complex spring. In the locked condition, the lever is prevented from pivoting rearward (in an opened direction) by a stopper edge of the arm engaging with a stopper surface of the body. In this connection, when it is intended to release the locked condition, it is necessary to push the lever rightward to disengage the stopper edge with the stopper surface and then push the lever rearward to pivot it in the opened position. In other words, the lever remains unopened unless two forces perpendicular to each other are applied sequentially to the lever.

Abstract: A speed meter measures low range speeds such as feed speeds on a machining devices. Ultrasonic waves are radiated against a mobile object performing a linear displacement with respect to a detection head, and ultrasonic waves reflected by the mobile object are used for controlling the state of a pair of signal gating elements. Clock pulses passed to the elements are gated over different periods phased from each other by an operation interval which can be adjusted depending on the process conditions. Distances between the detection head and the mobile object in the different periods are specified by count values obtained from the results of respective gating, and the average speed of the linear displacement of the mobile object is calculated on the basis of these count values. Digital mode processing of the signals simplifies the construction and lowers the production cost.