Abstract: A rotary throttle assembly is disclosed for operating a power unit such as an engine or a motor in either a first power setting or a second power setting. The rotary throttle assembly may be used in a concrete vibrator to operate the vibrator in either an idle power setting or a desired power setting. The throttle assembly includes a rotatable throttle handle, a linkage mechanism contained in a casing, and means for urging the throttle assembly selectively to adopt a first position or a second position.

Abstract: A start-up coupling engages progressively in two stages. During the first stage drive is transmitted from an input shaft (3) along respective paths (8,7,9,12,11,10,25 and 26; and, 19,20,19 and 32) to helically-toothed rollers (27,30) which mesh but are designed to be incapable of transmitting drive between them, or of doing so very inefficiently. The rollers (27,30) are mounted in an oil-filled chamber (18) in a casing (1) integral with an output shaft (2). During the first hydraulic stage of engagement, oil pockets between their oppositely-moving teeth (28,31) prevent them from engaging as the phase of one roller (27) is progressively changed by a centrifugal adjustment (4) against the bias of a torque cell (19). However, increasing frictional resistance in the oil pockets causes the rollers (27,30) to exert an increasing rotational torque on the casing (1).

Abstract: A centrifugal spark-advance controlling device has a weight being subjected to centrifugal force caused by the revolution of a driving shaft to be opened against the elastic force of a spring member to thereby advance an advancing sleeve with respect to the driving shaft. There are base plate fixed to the driving shaft, the base plate being provided with an elongated groove for guiding which serves as a guide for the weight to be moved in the direction of opening and an advancing plate fixed to the advancing sleeve, the advancing plate being provided with an elongated groove for advancing which determines a relative advance angle of the advancing sleeve with respect to the driving shaft in association with the elongated groove for guiding.

Abstract: Ignition timing of an internal combustion engine is caused to advance in stepped increments as the engine speed increases in a uniform manner. Centrifugal weights of different sizes move a timing control element by angular increments against the action of a spring. The movement is with respect to a rotary member turning in timed relation with the crankshaft of the engine.