In a tripod type constant velocity universal joint 1, when D1 represents a large inner diameter being a diameter of a circle connecting radially outer end portions of roller guide surfaces 7 and D2 represents a small inner diameter being a diameter of a circle connecting radially inner end portions of the roller guide surfaces 7, a ratio D2/D1 between the small inner diameter D2 and the large inner diameter D1 is set within a range of from 0.73 to 0.80. Further, when d represents a large diameter of a spline formed in a trunnion hub 8 of a tripod member 3 and PCD represents a pitch circle diameter of the roller guide surfaces 7, a ratio d/PCD between the large diameter d and the pitch circle diameter PCD is set to 0.60 or more.

The present invention is an apparatus, system and method for use of a mud motor having a bearing assembly, a transmission having torque and thrust transfer couplings with a catch pin interface, a power section, a rotor catch assembly, and a cross over sub-valve.

A cup member has a cylindrical portion, a bottom portion, and a short shaft portion having a solid shaft shape and including a joining end surface at an end portion thereof. A shaft member has a solid shaft shape and includes a joining end surface at one end thereof. The joining end surfaces of the cup and shaft members are brought into abutment against each other and welded from a radially outer side to form a welded portion. At this time, center segregation is prevented from interfering with the welded portion. The cup member is formed by forging including upsetting a billet having a columnar shape successively in a plurality of stages, extruding the cylindrical portion and the short shaft portion, and ironing the cylindrical portion. In the course of the upsetting, a region of the billet corresponding to a bottom side of the cup member is narrowed.

Provided is a method of manufacturing an outer joint member of a constant velocity universal joint, which is constructed by forming a cup section having track grooves, and a shaft section, and by welding a cup member and a shaft member, the method including: forming the cup member and the shaft member of medium carbon steel; preparing a cup member having a cylindrical portion and a bottom portion integrally formed by forging, and a joining end surface in a machining step; preparing a shaft member having a joining end surface formed in a machining step; bringing the joining end surface of the cup member and the joining end surface of the shaft member into abutment against each other; welding the cup member and the shaft member by radiating a beam; and performing, after the welding, an ultrasonic flaw detection-inspection step.

A tripod type constant velocity universal joint includes an outer joint member having track grooves formed at trisected positions thereon in a circumferential direction to extend in an axial direction of the tripod type constant velocity universal joint, a tripod member having a trunnion barrel spline-fitted to a shaft and trunnion journals radially projecting from trisected positions on the trunnion barrel in the circumferential direction, and rollers fitted to the trunnion journals, respectively, that are received in the track grooves, respectively. Each of the rollers is guided by roller guide surfaces formed on both side walls of each of the track grooves. The tripod member has quench-hardened layers formed by carburizing, quenching, and tempering, and a depth of a quench-hardened layer of a radially outer surface of the trunnion journal is larger than a depth of a quench-hardened layer of a root portion of the trunnion journal.

A drive shaft includes a first shaft member made of metal, a tubular member made of CFRP, and a first exterior sleeve. The first shaft member is capable of being attached on one end side thereof to a first constant velocity joint, and has a first serrated part on which serrations are formed on another end side thereof. The tubular member is formed with a first fitting part fitted externally over the first serrated part. The first exterior sleeve covers the first fitting part by being disposed to extend over outer circumferential surfaces of the first shaft member and the tubular member. A film provided with a bonding assistance region and an adhesive are interposed between the outer circumferential surface of the tubular member and the inner circumferential surface of the first exterior sleeve.

A rotational driving force transmission mechanism includes a cylindrical shaft made of fiber reinforced plastic, and a first constant velocity joint. The shaft is joined to the first constant velocity joint via a metallic intervening member which is attached to one end of the shaft in the axial direction. The intervening member includes a shaft portion and a main body portion. The shaft portion is inserted into the one end of the shaft from a distal end side thereof. The main body portion is of a bottomed tubular shape made up from a bottom part joined to a proximal end side of the shaft portion, and a tubular portion fitted over the one end of the shaft. The first constant velocity joint includes an inner ring fitted externally over the tubular portion of the intervening member.

A tripod-type constant velocity joint includes an intermediate member, and first and second tripod members connected to the respective ends of the intermediate member. The intermediate member includes first and second outer rings. The first tripod member is formed with three protrusions, and the second tripod member is formed with three protrusions. The first outer ring is formed in its inner periphery with three axially extending first track grooves which are open at its axial end surface. The second outer ring is formed in its inner periphery with three axially extending second track grooves which are open at its axial end surface. The protrusions of the first tripod member are axially slidably received in the respective first track grooves. The protrusions of the second tripod member are axially slidably received in the respective second track grooves.

A tripod type constant velocity universal joint includes an outer joint member that includes track grooves, a tripod member that includes three leg shafts protruding in a radial direction, a roller that is inserted into the track groove, and an inner ring that is fitted onto the leg shaft, and rotatably supports the roller. A hardened layer is formed on a surface of each leg shaft by carburizing, hardening, and tempering. The tripod member is formed a steel material having a carbon content of 0.23% to 0.44%. An effective hardened layer depth of the hardened layer by using, as a Ts torque, 0.3 times a minimum static torsional torque at which a shaft coupled to the tripod member causes torsional fracture and 600HV as limit hardness is equal to or greater than a maximum shear stress depth Z when the Ts torque is applied.

A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members using medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed, and a joining end surface formed on an outer surface of the bottom portion, preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member, and bringing the joining end surfaces of the cup and shaft members into abutment against each other. The method also includes welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member under a state in which a hollow cavity portion is formed inside the abutment portion.