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RPM to Pulley Question Please Help Thanks

  1. Feb 23, 2012 #1
    RPM to Pulley Question Please Help Thanks!!

    I have a log splitter that uses a gas engine 3600 RPM the drive pulley is 1.5"OD diameter and the driven pulley is 18.25" diameter (Super Splitter is the brand name) So from what i calculated was the driven pulley weighs in at 75lbs and spins at about 295 RPM's.

    Now to my question: They sell these splitters with an electric motor, So my grandfather gave me a 1 hp electric motor that rotates at 1740 RPM. If i put on a drive pulley with a 3"OD will i have basically the same outcome? Im calculation 286 RPM.

    This splitter uses the weight of the flywheel to throw the ram forward. And i would like to convert to Electric because it is alot quiter for my neighbors, they already have to hear my chainsaws screaming! Thanks Everyone!!!!
  2. jcsd
  3. Feb 23, 2012 #2
    Re: RPM to Pulley Question Please Help Thanks!!

    We need to know the power rating of the gasoline engine you are replacing.
    After a quick Google, all the electrically powered splitters I looked at have 1.75 HP motors, and the smallest gasoline powered models run about 3.5 HP.
    You will probably need to change the drive ratio quite a bit to get sufficient torque from your 1 HP motor. The splitter will operate much slower, and almost certainly at reduced capacity (smaller logs).
  4. Feb 23, 2012 #3
    Re: RPM to Pulley Question Please Help Thanks!!

    The splitter that i have has ZERO hydraulics once again the brand name is Super Splitter ZERO hydraulics it uses to flywheels. They sell this SUPER SPLITTER with a 1 hp and a 1.5hp motor the cycle time is 3 seconds its not your everyday log splitter the engine it has right now is 5.5 hp but thats not the issue i am talking about the RPM's. All i need to know is will the big flywheels still be spinning the same from what i calculated.
  5. Feb 23, 2012 #4


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    Re: RPM to Pulley Question Please Help Thanks!!

    Your calculation is in the right ball park (I have not check the numbers with my calculator). The product N*r is proportional the belt speed coming off the engine or motor pulley in either case. So 3600*1.5 is not too different from 1740*3.0; we double one factor and halve the other.

    As mentioned above, the cycle time may be unsatisfactorily slow; it may take a long time to recover flywheel speed, but it should recover to almost the same level and hence same kinetic energy content.
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