In a two-wire bidirectional telephone transmission line, a power converter and a directional threshold detector form in combination an impedance transparent bilateral voice-signal controller which can supply stable voice-switched gain to a dominant signal originating from either direction and a simultaneous, equal loss to any signals propagating from the other direction without separating the respective signals.

A power tong includes a frame and a pipe-gripping mechanism associated with a throat at one end of the frame. Power is transmitted to the pipe-gripping mechanism from a power unit through a drive train. The pipe-gripping mechanism cooperates with the throat to receive a pipe section to be rotated and includes a partial ring rotatably mounted within the frame and having an opening which may be aligned with the throat. The ring may be rotated in either direction by the power unit. Mounted on the t...

A power unit having an endless belt immersed in a tank of water and disposed on upper and lower rotatable rollers in parallel alignment tightly enough to frictionally engage and rotate the pullies, there being transversely arranged and longitudinally spaced, relative to the belt, collapsible air buckets or air traps on the outwardly facing side of the belt. When operating, the belt has one part continually moving upwardly and an opposite part moving downwardly. The air buckets open downwardly an...

In power saws of the kind comprising a cutter bar around which travels a motor-driven saw chain, a safety device arranged to ensure automatic release of a safety brake to stop the saw chain. The device comprises a two-arm lever which is pivotally mounted in the body of the saw in such a manner that one arm abuts against the cutter bar so as to transmit jerky movements of said bar to the opposite arm which cooperates with means on a pivotable plate to influence the braking means.

A power monitor including a high power shunt connected in series with an electrical load to develop a signal proportional to current which is then modulated. A second signal proportional to the voltage across the load is developed by a voltage divider network. The two signals are applied as inputs to an electronic multiplier which produces a modulated output signal which is proportional to the power being dissipated by the load. The ouput signal from the multiplier is fed through an isolation tr...

A power transmission usable with a vehicle and having three ranges or speeds of operation in both forward and reverse directions of travel of the vehicle, including a low-speed range, an intermediate-speed work range, and a high-speed range and having a planetary differential with a sun gear drivingly connected to the motor of the hydrostatic transmission, a ring gear drivable either by the power input shaft or the hydrostatic transmission and a third intermediate planetary gear system connected...

The present invention concerns a power diode with a semiconductor body having an inner zone with a given thickness and a given specific resistance, and having on each side of said inner zone at least one outer zone which adjoins the inner zone and has a lower specific resistance in comparison with the inner zone. The diode is characterized in that the specific resistance and the thickness of the inner zone are so adapted to each other that U.sub.B < U.sub..rho.T, wherein U.sub.B is the avalan...

A power tong includes a frame and a pipe-gripping mechanism associated with a throat at one end of the frame. Power is transmitted to the pipe-gripping mechanism from a power unit through a drive train. The pipe-gripping mechanism cooperates with the throat to receive a pipe section to be rotated and includes a partial ring rotatably mounted within the frame and having an opening which may be aligned with the throat. The ring may be rotated in either direction by the power unit. Mounted on the t...

A cartridge type sleeve and plunger hydraulic valve is retained in a blind bore along with a biasing spring by a closure plug. Spaced transverse passages intersecting the bore are either separated or connected depending upon whether the plunger is either shifted by the spring bias or by fluid pressure overcoming the spring bias. An elastomeric seal eliminates leakage when the valve is in closed position. To insure against accidental fall out of any loose parts when the valve is disassembled unde...

A toggle-type power regulator is adapted to shunt or open a power control circuit at opposite limit positions and has infinitely variable power control at all intermediate positions between the limit positions. A potentiometer incorporated in the control circuit comprises a pair of arcuate tracks of resistive and conductive material positioned on opposite faces of the control circuit substrate. Variable voltage output is achieved as the tracks are engaged or wiped by the opposed resilient contac...