Which tires lock up on a 4WD, Front Wheel Drive, or Rear Wheel Drive when I pull emergency brake?
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Type_R
ANSWERS: 3
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Handbrakes are almost universally attached to the rear wheels only.
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While they may exist, I don't think I have never read about a parking or emergency brake on the front wheels. This may have to do with the complexity of routing a cable to the pivoting part of the steering mechanism... I did read about a sports car with high performance disk brakes that had a special inboard drum (not out at the wheel) for the parking brake. If you do have a 4WD without front to rear differential (with 4WD engaged), setting the parking brake (securing the rear wheels) will prevent the front wheels from turning the same direction - they will still be able to turn opposite directions through the front differential. The front wheels will be connected through the transfer case and drive shafts to the rear wheels which are secured by the brake, so there will be some range of movement from tolerances in the drive train but the two fronts will not rotate freely in the same direction.
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Some 4WD's have the handbrake located on the rear drive shaft just as it comes out of the transfer case. This is known as a transmission handbrake. When all four wheels are in contact with the ground, it will have an effect on either the rear wheels (if 4WD is disengaged, or the centre diff lock is disengaged). If the car is in 4WD, or has the centre diff locked, the trans-brake will lock all four wheels - only if all four wheels have grip on the ground. If you lift either two diagonally opposite wheels off the ground, and the vehicle has open differentials, then the differentials will let the wheels turn. I've seen this happen - scared the crap out of the driver.
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