A drill bit is provided that includes a bit body having one or more blades extending therefrom, a plurality of cutters secured to the one or more blades, and a rolling element assembly positioned within a cavity defined on the bit body. The rolling element assembly includes a rolling element rotatable within the cavity about a rotational axis, and a compliant retainer extendable within a retainer slot defined in the cavity to secure the rolling element within the cavity. The compliant retainer and the cavity cooperatively encircle more than 180° but less than 360° of a circumference of the rolling element while leaving a full axial width of the rolling element exposed. The compliant retainer is compressible responsive to forces from the rolling element to absorb vibrations and/or automatically adjust depth of cut.

An earth-boring tool may include at least one blade including a shoulder region and a face. A plurality of cutting elements may be arranged on the face of the blade and at least one cutting element may be positioned in the shoulder region such that a cutting face of the at least one cutting element is spaced a distance behind the face of the blade. A recessed portion of the blade may extend under at least one of the plurality of cutting elements arranged on the face of the blade and extending to the at least one cutting element positioned in the shoulder region.

An earth-boring tool may include at least one blade including a shoulder region and a face. A plurality of cutting elements may be arranged on the face of the blade and at least one cutting element may be positioned in the shoulder region such that a cutting face of the at least one cutting element is spaced a distance behind the face of the blade. A recessed portion of the blade may extend under at least one of the plurality of cutting elements arranged on the face of the blade and extending to the at least one cutting element positioned in the shoulder region.

An isolated lubrication system for a drill bit is disclosed. The system comprises a body having a cutting arm with a journal and a rotary cutter mounted on the journal. The system also comprises a reservoir in a body to contain a fluid lubricant that isolated from communication outside the body. The system also comprises multiple conduits in communication with the reservoir and with respect to each other. The multiple conduits facilitate lubrication between the journal and the rotary cutter, including the bearings, by means of a gravitational force and/or a centrifugal force acting of the fluid lubricant. Further, the system comprises a sealing system. The sealing system includes a sealing cap provided to the reservoir, a seal provided between the journal and the rotary cutter, and a stepped passageway provided in a clearance between the rotary cutter and a cutting arm of the body.

An isolated lubrication system for a drill bit is disclosed. The system comprises a body having a cutting arm with a journal and a rotary cutter mounted on the journal. The system also comprises a reservoir in a body to contain a fluid lubricant that isolated from communication outside the body. The system also comprises multiple conduits in communication with the reservoir and with respect to each other. The multiple conduits facilitate lubrication between the journal and the rotary cutter, including the bearings, by means of a gravitational force and/or a centrifugal force acting of the fluid lubricant. Further, the system comprises a sealing system. The sealing system includes a sealing cap provided to the reservoir, a seal provided between the journal and the rotary cutter, and a stepped passageway provided in a clearance between the rotary cutter and a cutting arm of the body.

A hybrid bit includes fixed blades and wheel support structures. The wheel support structure includes a wheel inserted into a slot between a leading support and a trailing support. One or more shims fill a gap between a flange and the leading supports. An elongated seal between the wheel and the supports is provided to seal the wheel support.

A hybrid bit includes fixed blades and wheel support structures. The wheel support structure includes a wheel inserted into a slot between a leading support and a trailing support. One or more shims fill a gap between a flange and the leading supports. An elongated seal between the wheel and the supports is provided to seal the wheel support.

A hybrid bit includes a fixed cutting structure and a rolling cutting structure. The fixed cutting structure includes a plurality of fixed cutting elements. The rolling cutting structure is coupled to the fixed cutting structure and includes a journal bore extending through the rolling cutting structure from a leading face to a trailing face, and a radially outer surface. The rolling cutting structure also includes a plurality of cutting elements extending from the radially outer surface of the rolling cutting structure.

A hybrid bit includes a fixed cutting structure and a rolling cutting structure. The fixed cutting structure includes a plurality of fixed cutting elements. The rolling cutting structure is coupled to the fixed cutting structure and includes a journal bore extending through the rolling cutting structure from a leading face to a trailing face, and a radially outer surface. The rolling cutting structure also includes a plurality of cutting elements extending from the radially outer surface of the rolling cutting structure.

A drill bit can include a bit body having an upper portion, a central bore, and an adjustable inner gauge. The central bore can define a bore surface, and the bit body can include a plurality of fixed cutters formed on the upper portion. The adjustable inner gauge may be movably positioned within the bit body central bore to increase or decrease an exposed area of the bore surface for adjusting stability or steerability of the drill bit while forming the wellbore.