Push trailer build for my disabled friend.

Discussion in 'Push Trailers' started by ibuiltmine, Jul 16, 2012.

  1. ibuiltmine

    ibuiltmine New Member

    This thing is going to have some complicated parts, but Im going to try and keep it as simple as possible, but im scientifically minded, and engineer and I have built tons and tons of different stuff. I like stuff to be strong, not break down and work well. I dont like wasting my time on junk that I will just throw away when I am done. With that said......

    My buddy has a nice new TREK bicycle. so I can not put a motor in or on it.

    I do not want to visibly have a motor on this bike. I want it concealed in the trailer.

    The trailer is going to be actually pretty big, I want to be able to have all the cloths, tent, sleeping bag, supplies, spare parts, gas, etc on the trailer.

    I want it single rear wheel (not sure if I have decided what size wheel yet) I might want it a BMX size wheel just to keep things compact, but if I decide to use a full size mountain bike size wheel it will have the ability to carry less supplies in case of break down. When everything is the same you dont have to carry 3 different size parts for 3 different size wheels. Plus a taller tire will have more contact patch and more rubber to wear letting the tire wear less then a smaller tire.

    I want to be able to reasonably change gearing from a low gear hill country gear that will cruise about 20mph to a flat country tall gear capable of sprinting at say 40mph. I have built a simple change gear system that will only take a few min to change the gear, readjust the chain tension and off you go! not something you would do very often, but still have the ability and therefore save undue wear on your clutch.

    I do not want any belts or anything that will wear and faster then a chain will

    i want it to attach and push as close to the rear axle as possible

    I want it to have a semi-quick disconnect, but a very solid hitch at the same time

    I want the frame to be aluminum if I can find the materials at the scrap yard. If not ill cannibalize a few chromoly department store bicycles I have collected to build it out of chromoly.

    Most importantly it has to be ultra reliable. I have a brand new Briggs 3.5hp flat head motor I got for $20 bucks at a scratch and dent sale. Plus I have a heavy duty centrifugal clutch that I have taken apart and put in the lathe and stripped all the motorcycle size gears off of it and I will fit the proper size sprocket on it when I figure out the right gear ratio.
    I have also done the same thing to a regular BMX freewheel in order to put a larger sprocket onto it. Ill machine it for a good fit then tig weld a carrier on it that is keyed and bolted that allows me to change gears by taking a couple bolts off, swapping to the other sprocket setting the tension with a chain tensioner and then good to go!

    The important thing about using a freewheel on the drive wheel is that if there ever was a failure in the motor there would not be all the parasitic drag of turning the whole chain and drive system. you wouldn't have to stop and unhook anything if you were in traffic and if you topped a large hill you could kill the motor and let it cool down while you coasted down the other side.

    Thing I need to find out:
    What do other push trailers weight?
    What is the gear ratio that pushes a 100lb trailer and a 230lb guy up a hill without over stressing the motor?
    What gear ratio will push the same load at 45mph?
    Does the rear wheel usually stay planted or do people find that it tends to bounce?

    More to come soon!

    This is the part that I am starting with!

  2. ibuiltmine

    ibuiltmine New Member

    I have been reading up on a LOT of info on here, and my design is already changing. This is a very good site and there is a LOT of experience here! I don't want anything experimental. I want something that works flawlessly and s as reliable as my Toyota!
  3. BigBlue

    BigBlue Active Member

  4. ibuiltmine

    ibuiltmine New Member

    I forgot to mention this had to cost less then 100 bucks when all said and done. Hopefully less. I found a 1 gallon riding mower gas tank this morning. That will make the range of the motor further then that of a persons behind! Plus I got a big super quiet generator muffler to.

    As potter my gear ratios i'm going to gear it for 30 mph with a 20 inch wheel that has a 24 inch diameter at 2800rpm. So it will have a 52 tooth on the wheel and an 8 tooth on the clutch. I think I am going to use go kart size chain to get the ratio right with a bigger sprocket. I don't know yet. We will see what I can make out of bicycle parts first.
  5. ibuiltmine

    ibuiltmine New Member

    So plans changed on this. He came up with soem money, so its going to be a clone 6.5 motor and its going to be two wheels.
    then with the new 3.5hp I have we are making a little one for times we need no load.
    waiting for the mail man to bring us parts! more to come soon!
  6. ibuiltmine

    ibuiltmine New Member

    Plan is coming along! We have purchased a new 6.5 clone, and we found a belt clutch at the scrap yard. Got me to thinking... I think we are going to direct drive the beast with belt drive, no centrifugal clutch. We are going to put a manual clutch on it similar to a riding mower set up to tension the belt. This is just a though..... But tomorow is teh day we are getting together to start working on frame design.
  7. ibuiltmine

    ibuiltmine New Member

    While at the scrap yard getting metal for this push trailer, someone dropped off a three wheel mobility scooter. I seized the opportunity to take that home and we built it into a gas powered machine! Still want to build a push trailer someday, but for now this project has been canceled.
  8. Jammit

    Jammit New Member

    A big motor is good... BUT if it all goes badly, given the power to weight ratio, you may find your own trailer running you over with the wheels leaving skid marks across your head as you admire the underside of the trailer.

    I'd go for a big motor, but with a very small carburettor, or to lock the throttle so it will never run much above a quicker idle.