Shaft decoupler

A decoupling mechanism comprising:

• a first decoupler shaft having a first bore longitudinally disposed therethrough and comprising a first clutch jaw;
• a second decoupler shaft having a second bore longitudinally disposed therethrough and comprising a second clutch jaw, said first clutch jaw engageable with said second clutch jaw to transmit torque in a first angular direction;
• a unitary shear pin comprising a first portion and a second portion, said first portion being disposed substantially within said first bore, said second portion being disposed substantially within said second bore, said unitary shear pin being shearable in response to a predetermined angular displacement between said first decoupler shaft and said second decoupler shaft into said first and second portions;
• and
• a splined washer disposed within said second decoupler shaft, said splined washer comprising a plurality of splines engaging complimentary splines in said second decoupler.

A decoupling apparatus for a drive shaft comprising:

• a first rotatable decoupler shaft having a first clutch jaw;
• a second rotatable decoupler shaft mounted coaxially with respect to said first decoupler shaft, said second decoupler shaft having a second clutch jaw, said first and second decoupler shafts being axially displaceable relative to one another from a first position in which said first and second clutch jaws cooperate to transmit torque between said first and second decoupler shafts to a second position in which said first and second clutch jaws are disengaged one from another;
• a resilient member;
• and
• a torsional shear pin, said torsional shear pin comprising a unitary shaft having first and second ends, the first end operatively engaging said resilient member and the second end operatively attached to said first decoupler shaft, said resilient member and said torsional shear pin cooperating to exert an axially compressive force between said first and second decoupler shafts thereby urging said first and second decoupler shafts axially into the first position, said torsional shear pin being frangible in response to angular movement of said first decoupler shaft relative to said second decoupler shaft to release the axially compressive force, thereby permitting said first and second decoupler shafts to move into the second position and allowing said first and second clutch jaws to disengage.