Abstract: In a turbo-refrigerator apparatus provided with a compressor in the form of a turbocompressor, a speed increasing gear system capable of switching from one speed increase ratio to another at least in two stages is located between the turbocompressor and an electric motor, so that a speed increase ratio suitable for the conditions of outdoor air can be selected to operate the apparatus with high efficiency. Housings of the turbocompressor, electric motor and speed increasing gear system are connected together in such a manner that a shaft supporting an impeller of the turbocompressor, an output shaft of the electric motor and shafts of the speed increasing gear system are located within the respective housings to render the apparatus hermetic to avoid extension of the rotary shafts through the housings, thereby avoiding leak of the working fluid of the turborefrigerator apparatus to outside.

Abstract: An apparatus for controlling the operation of a fluid pressure raising system having a motor and a centrifugal fluid machine adapted to be driven by the motor. The apparatus has an overdrive gear disposed between the motor, which is typically an electric motor suited for the commercially available electric power, and the centrifugal fluid machine. The overdrive gear consists of two gear trains or pairs having different overdrive ratios, each consisting of a gear and a pinion meshing with the gear, and a clutch adapted to selectively switch over the gear pair taking part in the torque transmission between the output shaft of the motor and the impeller shaft of the centrifugal fluid machine, from one gear pair to the other gear pair and vice versa. Thus, the overdrive gear can transmit the power of the motor to the impeller at two different overdrive ratios.

Abstract: In a multistage speed change gear system including a plurality of gears selectively interconnecting an input shaft and an output shaft located parallel to one another, the gears disposed concentric with the input shaft are supported by ball-and-roller bearings supported by at least one stationary member which is an entity separate from the input shaft. By this arrangement, relative movements occur between inner and outer races of the ball-and-roller bearings when a rotational force is transmitted from the input shaft to the output shaft, thereby preventing or reducing the development of fretting corrosion in the ball-and-roller bearings.

Abstract: A plate type heat exchanger having heat exchange plates wherein in order to increase the support strength of the packing groove periphery to prevent flexure while providing reliable sealing, the lateral wall defining the peripheral edge of a packing groove is shaped in such a manner that its upper surface is capable of abutting against the bottom surfaces of distributing grooves while in a double seal region the width of a liquid passage groove in a plate having no packing mounted therein is smaller than that of a packing groove in a plate having a packing mounted therein, so that the bottom surface of the liquid passage groove and the upper surface of the lateral wall abut against the upper surface of the packing and bottom surface of the packing groove.