Patent ID: 7497311

Claim:
An apparatus for engaging a rotary driving member with an element to be driven, the apparatus including a housing containing: a first rotatable member capable of being axially moved into positive engagement with a second rotatable member, one of the first or the second rotatable members being drivably connected to the rotary driving member and the other of the first or the second rotatable members being drivably connected to the element to be driven such that positive engagement between the first and second rotatable members effects engagement of the rotary driving member with the element to be driven; a piston slidably mounted in the housing, the piston being operably connected with the first rotatable member such that pressure acting on one end of the piston effects axial movement of the piston with respect to the housing, thereby effecting axial movement of the first rotatable member; and a delay device for delaying the establishment of a positive connection between the first and second rotatable members, the delay device having: means for producing a friction drive between the first and second rotatable members to cause rotation of the rotatable member that is drivably connected to the element to be driven prior to engagement of the first and second rotatable members; and a friction drive actuator, the actuator being axially movable to activate the friction drive; wherein the piston has a passageway through it for transmitting pressure acting on the end of the piston through the piston to the friction drive actuator such that the pressure acting on the end of the piston also acts on the friction drive actuator to effect movement of it.