Look at the cables while someone else pulls the handle.
Notice that the primary cable is left floating...
When you pull the handle, the cable core moves one way and yanks the P side.
The Jacket of that cable also moves the opposite direction and yanks the cable for the drivers side.
This is why you've got to make sure that the primary cable does not bind/drag against things as it moves. You can damage the cable easy if it pulls or rests on something sharp, hot, etc.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave (It's also at the top of every forum page...)