Variable Regeneration Controls - Part 1
My Kelly KLS7230S controllers are capable of providing variable regeneration. To alter the amount of regeneration the controllers need a 0-5 volt signal. The simplest way to provide that variable signal would be with a common twist or thumb throttle located on the handlebars. But I felt a second twist throttle, or even a thumb throttle would be confusing and sort of counter intuitive. I felt a better solution might be to mount a typical brake lever on left side handlebar and then run its cable to a thumb throttle mechanism located toward the rear of the trike. My thinking is that this will provide the more natural “feel” of a traditional motorcycle hand brake when the regen is activated.
Unfortunately, the “throw” of most brake levers is not quite long enough for the cable to pull the thumb throttle from the zero position to the full throttle position. As a result, the controllers would not receive a signal for maximum regeneration. To remedy this situation I needed a way to “gear up” the cable so the brake lever movement can provide a longer pull.
To do this I am using a freewheel body from an old six speed cassette stack. Note that the freewheel body has two grooves (arrows), one larger than the other. By running the incoming brake lever cable around the smaller diameter groove and the outgoing thumb throttle cable around the larger groove, the pull of the brake lever can be multiplied enough to move the thumb throttle lever from its zero position to its 5 volt (maximum) position. The six speed freewheel body is threaded onto the wheel hub allowing it to freely rotate while still being held in the proper position.
Only the threaded “cassette” side of the wheel hub is needed, so the balance of the hub is cut off leaving the hub disk and threads as a mounting platform for the freewheel body.
The hub disk is ground flat on the back side.
To guide the cable from the brake lever onto the groove of the free wheel, an old brake lever handle is cut apart saving the guide (arrow) and a portion of the lever which is drilled for mounting bolts. A stock brake lever is shown on the right and the cut down portion use for the guide is shown on the left.
With the freewheel body unscrewed and removed we can see the threaded mount of the hub disk. Two 1/4″ holes (arrows) are drilled in the hub disk for mounting.
The components are laid out on 3/16 x 3″ wide flat stock. On the left is the “guide”, in the middle is the freewheel body “gear multiplier” and on the right is the thumb throttle. (Photo 6) When everything appears to be in alignment for smooth operation, the mounting points for each component are marked and the flat stock can be cut to the appropriate length and appropriate holes drilled for mounting the guide and the hub disk. The thumb throttle is mounted on a short length of handlebar tubing which is welded to the 3″ flat stock.
The components attached to the base. The thumb pad of the throttle will have a small hole drilled through the center for inserting the cable.
To secure the end of each cable in the freewheel body groove a “bridge” is welded over the top of each groove. The cable is then inserted into the groove and under the bridge. To insure the weld does not go all the way to the base of the groove, making it impossible to fit the cable under it, a large diameter copper wire is placed in the groove while the bridge is tacked in place. The copper will not bind to the weld and can be pulled out once the weld has cooled. The cable can then be threaded under the bridge, tightened and a stop crimped to the cable. [Note: Variable Regen continued in next post.]