Vehicle and method of controlling a vehicle

A method of releasably coupling a second group of wheels of a motor vehicle to prime mover means by means of a driveline such that a first group of wheels and the second group of wheels may be driven by the prime mover means, the method comprising the steps of:

• coupling an auxiliary driveshaft comprised in the driveline to side shafts arranged to provide torque to respective different wheels of the second group of wheels by drive means comprised in the driveline and having a ring gear, a pair of multi-plate wet clutches comprising respective inputs and outputs, and a pair of interference-type clutches comprising respective inputs and outputs, the ring gear being arranged to be driven by the auxiliary driveshaft and to drive the respective inputs of the pair of multi-plate wet clutches, the respective outputs of the pair of interference-type clutches being arranged to provide torque to respective side shafts of the vehicle;
• causing respective actuators to operate each of the pair of multi-plate wet clutches to provide slip between the respective inputs and respective outputs of each of the pair of multi-plate wet clutches to thereby facilitate differential rates of rotation between the side shafts and to cause each of the pair of multi-plate wet clutches to accelerate the respective inputs of the pair of interference-type clutches towards a speed of rotation of the respective outputs of the pair of interference-type clutches rotating with the respective side shafts;
• and
• subsequently causing each of the pair of interference-type clutches to transition from a first condition in which its input is isolated from its output to a second condition in which its input and output are directly coupled such that torque applied to its input is transmitted directly to its output to thereby facilitate driving of the side shafts by the prime mover means.

A controller for controlling a driveline of a vehicle to transition between first and second modes of operation, wherein a first group of wheels is driven by a prime mover means when the driveline is in the first mode of operation and a second group of wheels is additionally driven by the prime mover means via an auxiliary driveshaft comprised in the driveline when the driveline is in the second mode of operation,

• the controller being configured to operate a drive means comprised in the driveline to connect and disconnect side shafts arranged to provide torque to respective different wheels of the second group of wheels to and from the auxiliary driveshaft when the driveline transitions between the first mode and the second mode,
• the drive means comprising a ring gear, a pair of multi-plate wet clutches, and a pair of interference-type clutches, wherein the ring gear is arranged to be driven by the auxiliary driveshaft and to drive respective inputs of the pair of multi-plate wet clutches which are arranged to facilitate differential rates of rotation between the side shafts by means of slip across the respective multi-plate wet clutches, respective outputs of the pair of multi-plate wet clutches being arranged to drive respective inputs of the pair of interference-type clutches, each interference-type clutch operable between a first condition in which its input is isolated from its output and a second condition in which its input and output are directly coupled such that torque applied to its input is transmitted directly to its output, the respective outputs of the pair of interference-type clutches being arranged to drive respective side shafts,
• wherein operating the drive means to connect the side shafts to the auxiliary driveshaft comprises:
• causing respective actuators to operate each of the pair of multi-plate wet clutches to accelerate respective inputs of the pair of interference-type clutches towards a speed of rotation of the respective outputs of the pair of interference-type clutches rotating with the respective side shafts, and
• subsequently causing each of the pair of interference-type clutches to transition from the first condition to the second condition to thereby facilitate driving of the side shafts by the prime mover means.