A transmission having an input shaft, piston, dog clutch, sensor sleeve and control system is provided. The dog clutch includes male and female members, where one of the members is coupled to the piston for common movement therewith. The sleeve includes a through channel and a reduced diameter sensor portion terminating at a shoulder. The control system is configured to: command a supply of hydraulic fluid against an engagement side of the piston, determine when a terminal end of the sensor portion contacts a control, and determine that the dog clutch members are in a predetermined partially engaged state less than a fully engaged state of the dog clutch members. A length of the reduced diameter sensor portion directly corresponds to the predetermined partially engaged state of the dog clutch that is less than a fully engaged state of the male and female members of the dog clutch.

A composite clutch (110) is adapted to transmit an operational range of torques (60) from a driving member (118) to a driven member (122). The composite clutch (110) incorporates both of a friction clutch assembly (124) and a dog clutch assembly (126), each assembly adapted to address one of two segments (62, 68) of the operational range of torques (60). The clutch (110) further includes a spring-loaded detent system (180) configured to control transition (66) between the two segments (62, 68) of operational ranges of torques (60). The friction clutch assembly (124) includes first friction clutch elements (128) coupled to the driving member (118) and second friction clutch elements (132) coupled to the driven member (122) for providing torque control within the lower operational range of torques (64). The dog clutch assembly (126) includes a first dog clutch element (136) coupled to the driving member (118) and a second dog clutch element (138) coupled to the driven member (122), in which the first and second dog clutch elements (136, 138) are configured to mechanically lock together during the higher operational range of torques (70).

A composite clutch (110) is adapted to transmit an operational range of torques (60) from a driving member (118) to a driven member (122). The composite clutch (110) incorporates both of a friction clutch assembly (124) and a dog clutch assembly (126), each assembly adapted to address one of two segments (62, 68) of the operational range of torques (60). The clutch (110) further includes a spring-loaded detent system (180) configured to control transition (66) between the two segments (62, 68) of operational ranges of torques (60). The friction clutch assembly (124) includes first friction clutch elements (128) coupled to the driving member (118) and second friction clutch elements (132) coupled to the driven member (122) for providing torque control within the lower operational range of torques (64). The dog clutch assembly (126) includes a first dog clutch element (136) coupled to the driving member (118) and a second dog clutch element (138) coupled to the driven member (122), in which the first and second dog clutch elements (136, 138) are configured to mechanically lock together during the higher operational range of torques (70).

A horizontal directional drilling system. The system has a pilot drill and an exit side drill, with a drill string extending between them. A backreamer is positioned between the drills to enlarge a borehole. The pilot drill pulls and rotates the backreamer. The exit side drill adds segments to the product pipe and pushes the product pipe into the enlarged borehole. The exit side drill is equipped with a rotational disconnect. The disconnect is engaged to allow torque transfer between a motor and a spindle when adding segments to the product pipe. The disconnect is disengaged to prevent torque transfer between the motor and the spindle when pushing the product pipe into the enlarged borehole.

A vehicle clutch control device is provided for switching from a two-wheel drive traveling to a four-wheel drive traveling. The vehicle clutch control device includes a dog clutch that separates a rear wheel drive from a front wheel drive by releasing the dog clutch, an electronically controlled coupling that distributes a driving force of a transverse engine to left and right rear wheels in accordance with a clutch connection capacity, and a four-wheel drive control unit. The four-wheel drive control unit switches the drive mode to one of a disconnect two-wheel drive mode in which the dog clutch and the electronically controlled coupling are released, a connect four-wheel drive mode in which the dog clutch and the electronically controlled coupling are engaged, and a stand-by two-wheel drive mode in which the dog clutch is engaged while the electronically controlled coupling is released.

A vehicle clutch control device is provided for switching from a two-wheel drive traveling to a four-wheel drive traveling. The vehicle clutch control device includes a dog clutch that separates a rear wheel drive from a front wheel drive by releasing the dog clutch, an electronically controlled coupling that distributes a driving force of a transverse engine to left and right rear wheels in accordance with a clutch connection capacity, and a four-wheel drive control unit. The four-wheel drive control unit switches the drive mode to one of a disconnect two-wheel drive mode in which the dog clutch and the electronically controlled coupling are released, a connect four-wheel drive mode in which the dog clutch and the electronically controlled coupling are engaged, and a stand-by two-wheel drive mode in which the dog clutch is engaged while the electronically controlled coupling is released.

A steering system includes: a steering shaft to which a steering member is coupled; a worm wheel attached to the steering shaft so as to be rotatable integrally with the steering shaft; a housing that houses the worm wheel; an output shaft that is coaxial with the steering shaft and rotatable relative to the steering shaft and coupled to a steering operation mechanism; and a clutch mechanism that enables and disables transmission of power between the steering shaft and the output shaft. The clutch mechanism is housed and disposed in an internal space in the housing.

A steering system includes: a steering shaft to which a steering member is coupled; a worm wheel attached to the steering shaft so as to be rotatable integrally with the steering shaft; a housing that houses the worm wheel; an output shaft that is coaxial with the steering shaft and rotatable relative to the steering shaft and coupled to a steering operation mechanism; and a clutch mechanism that enables and disables transmission of power between the steering shaft and the output shaft. The clutch mechanism is housed and disposed in an internal space in the housing.

A clutch control device is provided for a four-wheel drive vehicle for transmitting drive force to the rear wheels. The clutch control device includes a dog clutch and a friction clutch, and a 4WD control unit that controls the engagement and disengagement of the dog clutch and the friction clutch. The 4WD control unit is switchable between a two-wheel drive mode and a four-wheel drive mode. The 4WD control unit is programmed to control engagement of the dog clutch so that the dog clutch is engaged after the friction clutch is engaged and the dog clutch is synchronized. During engagement of the dog clutch, the 4WD control unit is programmed to reduce a transmission torque of the friction clutch when the dog clutch engagement standby state is detected.

A clutch control device is provided for a four-wheel drive vehicle for transmitting drive force to the rear wheels. The clutch control device includes a dog clutch and a friction clutch, and a 4WD control unit that controls the engagement and disengagement of the dog clutch and the friction clutch. The 4WD control unit is switchable between a two-wheel drive mode and a four-wheel drive mode. The 4WD control unit is programmed to control engagement of the dog clutch so that the dog clutch is engaged after the friction clutch is engaged and the dog clutch is synchronized. During engagement of the dog clutch, the 4WD control unit is programmed to reduce a transmission torque of the friction clutch when the dog clutch engagement standby state is detected.