Abstract: The multiple small pitch helical drives in linear and rotary actuators uses a plurality of small pitch helical screws in place of a single large pitch lead screw to provide increased power or force in a linear actuator or increased torque in a rotary actuator. The multiple small pitch helical drive includes a plurality of screws disposed between a base panel and a rear panel in a rigid skeleton, the screws having a single degree of freedom, i.e., they are free to rotate, but cannot move axially. A piston head having spaced disks includes floating nuts disposed in sockets on the disks for each of the screws, the piston head being free to travel on the screws between the base panel and the rear panel as the screws are rotated. The helical pitch reduction provided results in increased force output and increased torque for linear and rotary actuators.

Abstract: Push-pull controls utilizing linear and rotational inputs to create linear output are disclosed. One control includes an elongate push rod and a roller pin. The rod has an outer surface, a generally circular cross-section perimeter, a center axis, a proximal end with a user input, and a distal end configured to directly or indirectly interact with an apparatus to be controlled. The rod is rotatable and slidable along the rod axis. The roller pin has a center axis and an outer surface that contacts the push rod outer surface. The roller pin center axis is angularly offset from and non-intersecting with the push rod center axis. The amount of angular offset is greater than zero degrees.

Abstract: The invention relates to helical gearing having a spindle and a counterpart, which engages on a thread of the spindle. The counterpart is, for example, tube-shaped, encloses the spindle concentrically, and has rollers on the inside of the counterpart which roll on thread flanks of the thread. By rotation of the spindle, the counterpart is driven like the nut of a spindle drive. The thread of the helical gearing according to the invention is provided with a changing pitch and thus a changing gear ratio.

Abstract: A downhole tractor is provided that includes a motor, at least one rotatable screw powered by the motor, and a chain engageable with the at least one rotatable screw, whereby rotation of the at least one rotatable screw moves the chain.