Abstract: Methods and apparatus are disclosed for coupling components within a downhole motor drivetrain, and particularly to improving the torque carrying characteristics through threaded couplings in the drivetrain that extends between the mud motor and the drill bit. The described downhole motor drivetrain includes one or more threaded couplings, with each coupling configured to define a gap to accept a spacer having a dimension within a range of sizes. The dimension of the selected spacer placed in the threaded coupling facilitates establishing a desired balance of the force loading at each of two contact regions of the coupling. In many examples, the two contact regions of the coupling will be located on opposite sides of the threaded region.

Abstract: A driveshaft transmission assembly may include a coupling mechanism for coupling a radial bearing assembly to a driveshaft. The coupling mechanism may include a bearing cap for creating an interference fit with a downhole portion of the radial bearing assembly. The coupling mechanism may include locking pins and a retention sleeve to retain the locking pins in grooves of the driveshaft and openings in the radial bearing sleeve. The radial bearing assembly may include a catch mechanism for preventing the loss of certain driveshaft transmission assembly components downhole in the event of a failure of the driveshaft transmission. The coupling mechanism may prevent the loss of the driveshaft downhole subsequent to separation of certain driveshaft transmission assembly components.

Abstract: An interference apparatus is provided for a motor shaft transmission assembly. The interference apparatus may include split-ring shells and a retaining device. The interference apparatus may be mounted to an intermediate sleeve of the motor shaft transmission assembly. The interference apparatus is configured to prevent the loss of certain motor shaft transmission assembly components downhole in the event of a failure of the motor transmission due to dynamic loads.

Abstract: Methods and apparatus are disclosed for coupling components within a downhole motor drivetrain, and particularly to improving the torque carrying characteristics through threaded couplings in the drivetrain that extends between the mud motor and the drill bit. The described downhole motor drivetrain includes one or more threaded couplings, with each coupling configured to define a gap to accept a spacer having a dimension within a range of sizes. The dimension of the selected spacer placed in the threaded coupling facilitates establishing a desired balance of the force loading at each of two contact regions of the coupling. In many examples, the two contact regions of the coupling will be located on opposite sides of the threaded region.

Abstract: A driveshaft transmission assembly may include a coupling mechanism for coupling a radial bearing assembly to a driveshaft. The coupling mechanism may include a bearing cap for creating an interference fit with a downhole portion of the radial bearing assembly. The coupling mechanism may include locking pins and a retention sleeve to retain the locking pins in grooves of the driveshaft and openings in the radial bearing sleeve. The radial bearing assembly may include a catch mechanism for preventing the loss of certain driveshaft transmission assembly components downhole in the event of a failure of the driveshaft transmission. The coupling mechanism may prevent the loss of the driveshaft downhole subsequent to separation of certain driveshaft transmission assembly components.

Abstract: An interference apparatus is provided for a motor shaft transmission assembly. The interference apparatus may include split-ring shells and a retaining device. The interference apparatus may be mounted to an intermediate sleeve of the motor shaft transmission assembly. The interference apparatus is configured to prevent the loss of certain motor shaft transmission assembly components downhole in the event of a failure of the motor transmission due to dynamic loads.