Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Starting of Vehicles

  1. Feb 20, 2013 #1
    certain vehicles can be started by keeping the gears engaged while certain others cannot.........how ????????
  2. jcsd
  3. Feb 20, 2013 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Specify which types of vehicle can be started with gears engaged.
  4. Feb 20, 2013 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Are you referring to what is known as a "push start"? This is where you push the car to get it rolling and then engage the gears to crank the engine.

    If so, this generally only works if you have a manual transmission. Automatic transmissions usually have a pump that is run off the engine. If the engine isn't already running, the transmission won't engage the gears and the car effectively stays in neutral.

    Another reason that you might not be able to push start a car is if it has a electronic ignition system. If the battery is completely or nearly complete dead, it won't have enough juice to run the system and at the low speed the engine turns during a push start, the alternator won't either.
  5. Mar 4, 2013 #4
    On automatic transmissions, you will have to have a "rear pump" driven by the output shaft.

    Some GM transmission of the early 60s had what is called "grade retard" which was found in the dynaflow and turboglide.

    Some versions had a rear pump.
  6. Mar 4, 2013 #5
    I have a manual transmission. I have been able to move the unresponsive car by engaging lowest gear and operating the ignition and starter motor. Sometimes it then jumps to life, and one can carry on as if nothing had happened!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook