You'd definitely need a parking brake here.

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It may seem like a simple thing to lock the transmission and keep it from spinning; but there are actually some complex requirements for this mechanism:

  • You have to be able to disengage it when the car is on a hill (the weight of the car is resting on the mechanism).
  • You have to be able to engage the mechanism even if the lever does not line up with the gear.
  • Once engaged, something has to prevent the lever from popping up and disengaging.

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­The mechanism that does all this is pretty neat. Check out the next page for photos and explanations of how all those parts work together to keep you from rolling away.