Human Electric Trike Thesis

Design of an electrically assisted human powered trike

Assembly nears completion

Posted by Bob Dold on Sunday, November 12, 2006 8:27 PM

Spent yesterday doing final assembly of the trike it is now just about ready to test under electric power. I bent up new handlebars out of .875 diameter 6061 tube using a conduit bender, these put the controls within easy reach while sitting in the seat. The left handlebar has the motor throttle from the X1000 scooter and the left brake handle, the right bar has the deraillleur twist grip shifter and the right brake handle. Both handlebars have rear view mirrors on top to aid in rear visibility as it is very difficult to see behind while reclined in the seat.

I also installed the three Odyssey batteries to make up the 36 Volt battery pack, the batteries were wired in series by connecting the positive and negative leads of the batteries using copper strips. The controller power was then taken from the first battery’s negative terminal and the third battery’s positive terminal. The batteries were secured bay riveting aluminum angle the the battery support tray to keep the batteries from sliding fore and aft. The frame rails restrain the batteries from moving side to side.

I also put new front tires on the wheels and put new brake and derailleur cables in order to prepare for the first test ride. The first test ride was under pedal power only since I am waiting on the freewheel adaptor for the motor to be completed – this part which should have been simple has been one of the most difficult to fabricate – it took three machinists and four different lathes to get the LH metric thread correct to fit up with the LH freewheel. Problems uncovered during this first ride include the following:

1. Can’t shift more than two or three gears on the rear cogs due to the sharp chain angle from the mid drive cogs to the rear wheel – two possible solutions, either shift the larger sprockets to the right and give up a few gears to allow a reduced chain angle or switch out the rear cogs and derailler for an internally geared hub. I will shift the cogs for now to allow testing to continue and order an 8 speed hub which will eliminate the problem.

2. The chain running from the mid drive up to the pedals rubs on the underside of the frame, to fix this I will use the idler pulley from my Sun tadpole to run space the chain out from the frame. I will have to make up a bracket to attach the idler to the rear swingarm.

3. When the trike rolls backwards the chain backdrives causing problems with the chain jamming and coming off the sprockets. I am not sure why this is happening, the rear freewheel pawls should disengage when rolling backwards but for some reason they are not – hopefully changing to a internally geared hub will fix this.

4. Trike leans severely when cornering, I need to check if this is due to springs that are too soft on the front, or incorrect suspension geometry.

Remaining items to be completed are down to the motor adaptor and the idler bracket, both should be completed tomorrow by Pete in the shop.


One Response to “Assembly nears completion”

  1. punjehl said

    i have two questions
    first does your bike suspension have an anti roll spring
    study of formula 1 motor cars front suspension as to the place ment of anti roll spring as your suspension design is very simmilar to an f1

    also you may like the motor speed controllers from castle creations they make rc motor control gear for helicopters
    the controllers have programable soft start and regen braking and govenor functions
    also the electric motors used in rc helicopters to 1/3 kg for 4000 wats

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