Abstract: A hydraulic control apparatus is employed in a stepless transmission in which an endless belt is stretched between and wrapped around a pair of pulleys and the velocity ratio between input and output shafts is changed by varying the width of a groove defined in each of the pulleys. Hydraulic pressure supplied from a hydraulic pressure supply source is reduced to necessary levels by first and second adjusting apparatus, respectively, and then sent ot respective cylinder chambers of the pulleys. A controller controls the hydraulic pressure supply source on the basis of either one of the hydraulic pressures respectively reduced by the first and second adjusting apparatus which is higher than the other so that the supply source generates a hydraulic pressure which is sufficiently high to supply the higher hydraulic pressure, thus reducing loss of power in the hydraulic pressure supply source.

Abstract: An electronic control circuit calculates the actual revolution speed ratio between the driving and driven pulleys of the transmission, generates a first electric control signal corresponding to the difference between the actual revolution speed ratio and an aimed revolution speed ratio predetermined for both the pulleys in conjunction with the input torque of the input shaft and required torque for the output shaft, and generates a second electric control signal made of the sum of both an electric signal corresponding to the actual revolution speed ratio and an electric signal corresponding to the difference.

Abstract: A low noise level, pressure fluid spouting device includes an inlet for introducing a pressure fluid therein at one end thereof; a nozzle connected to the inlet for jetting or emitting the pressure fluid therefrom, the nozzle having an annular inner wall of a predetermined diameter as a nozzle port thereof with an enlarged portion at the other end thereof for spouting the pressure fluid from the nozzle. The enlarged portion has a predetermined length (1.sub.o) from the entrance to the exit or open end thereof, and comprises an annular inner wall of a predetermined diameter (d.sub.2) larger than that of the nozzle means as an enlarged passage communicating with the nozzle port; and an outer wall which is tapered or gradually decreased in width towards the exit or open end portion of the enlarged portion with a predetermined angle of inclination (.theta.). The wall of the enlarged portion has a predetermined thickness (t) at the exit or open end portion of the enlarged portion.