Abstract: A device to be connected between the engine and power train of a construction vehicle or the like for damping the fluctuations of the engine output torque. The damper comprises a drive plate and a retaining plate coaxially connected to each other for simultaneous rotation, and a driven plate coaxially mounted between the drive and retaining plates for angular displacement within limits. Mounted between the retaining plate and the driven plate are a friction plate and a disc spring, with the friction plate being biased by the disc spring into frictional contact with the driven plate. The friction plate has a conical contact surface which, under the bias of the disc spring, makes frictional contact with the driven plate under even pressure. Two other friction plates lie between the drive and driven plates and make frictional contact with the driven plate and with an intermediate plate in positive engagement with the driven plate.

Abstract: A turbodrill of the type having an annular floating piston between a tubular housing and a bit drive shaft for bounding the top of a lubricant chamber and the bottom of a drilling fluid chamber. The lubricant chamber contains oil for lubricating a bearing supporting the drive shaft in the adjacency of its bottom end. The drilling fluid chamber receives a fraction of drilling fluid (i.e. mud) from a turbine located higher in the housing. For making the mud pressure in the drilling fluid chamber approximately equal to the mud pressure in the drill hole (annulus) around the turbodrill, a seal is provided which restricts the influx of the mud from turbine to drilling fluid chamber. Further a passageway is formed through the housing for placing the drilling fluid chamber in constant fluid communication with the annulus.

Abstract: A device to be connected between the engine and power train of a construction vehicle or the like for damping the fluctuations of the engine output torque. The damper comprises a housing having a drive plate, and a driven plate coaxially mounted in the housing for angular displacement within limits. Mounted between the housing and the driven plate are two friction drive mechanisms for frictionally transmitting the rotation of the housing to the driven plate. A plurality of torsional or compression springs are mounted to the driven plate so as to laterally project out of windows in the housing, so that when a slip occurs in the friction drive mechanisms, the housing acts endwise on the springs to cause their compression. Variable spacings are provided between the ends of the springs and the opposed edges of the housing bounding the windows.