Manufacturing Plan
The following manufacturing plan is based on the supplies and equipment available at the Nairobi branch of the Association for the Physically Disabled of Kenya.  It can be found in its original form on page 139 of the laboratory notebook, which can be downloaded here.

Summary
    1.    Assembly of Bottom Hub
    2.    Assembly of top BB-Shell/Cranks
    3.    Chain Routing
    4.    Fork Mounting

Materials
    2     x 6.5” Unity Rear Hub (any rear hubs that have pressed-on flanges will do)
    2-3  x Bicycle chains
    1     x Fully assembled BB shell with axle labeled “32-68-45” and “Special” (this axle is sure
              to work, other axles will need to be tested to make sure the crank and pedals fit on)
    1     x Right hand threaded BB cup.
    1     x Set of spokes, rim, tire, and liner
    3     x Freewheels (APDK: Unity freewheels, preferable 18 teeth)
    1     x Pedal/cog set, geared to user preference
    1     x Fork, with a distance between axis of rotation and axis of drivetrain that is sufficient
              to keep the chain inside of the distance.  More on this later.

Tools Needed
    -    Bender
    -    Grinder
    -    Vice
    -    Hammer
    -    Screwdriver (Flathead) or tool specifically designed to reassemble hubs
    -    14-15 mm Spanner (Wrench)

Definitions
    -    O-side:      The chain on the rider’s right hand side during normal riding in the forwards                    
                            direction.  This is the side of the top bracket that has the large crank.  It 
                            utilizes the standard side of the bottom hub.  It is the only side present on
                            a tricycle with a standard drivetrain.  The chain is in an oval.
    -    8-side:       The chain on the rider’s left during normal riding in the forwards direction.
                            There is a freewheel on the top bracket.  The chain is in a figure-eight.


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1.    Assembly of Bottom Hub

        The goal is to press apart two bottom hubs and reassemble them such that you end up 
        with one hub that has threaded flanges on both sides and one hub with non-threaded 
        flanges.  There are 2 Methods to accomplish this.  Method A is slower but ensures that     
        no damage occurs to the ball bearings.  Method B is significantly faster, but there is a
        chance that the bearings may be damaged.  However, no damage has been found to
        the ball bearings after using Method B.

        Method 1A:  Conservative and Slow
            1A.1    Unscrew the bolts and outer races on the axle.  Remove the axle from the hub
                        and remove and collect the ball bearings for later reuse.
            1A.2    Pop off outer race of non-threaded side using the flat-headed screwdriver.  Be
                        careful not to main the race or distort its shape.

                            
                        
                            

            1A.3    Clamp the shaft of the hub in the vice such that the hub is vertical and the non-
                        threaded side is on the bottom.

                            (please ignore the threading in this photo)

            1A.4    Pop out the inner race of the smooth non-threaded side by pushing screwdriver 
                        through the hub and hitting the race downwards using the screwdriver and a
                        hammer.

                            

                        

            1A.5    Flip the hub over in the vice, this time not clamping the shaft, but allowing the 
                        flange to sit on the lips of the vice.  The vice should be loose enough such that
                        the hub can slide back and forth in the vice.  Be sure not to clamp it tightly.

                        

            1A.6    Place removed inner race upside down over the non-threaded side.  It will be 
                        convex, like a dome over the top of the hub.
                        
                            

            1A.7    Hammer this race down to remove the outer flange from the hub shaft.  A
                        screwdriver can be used to remove the race from the shaft if necessary.

                            

                            

            1A.8    Now repeat steps 1A.1 - 1A.7 but with the objective of removing the threaded
                        flange from the other hub.
            1A.9    Using one of the outer races and the threaded flange, press the outer race 
                        (correctly oriented) part of the way into the flange.  Make sure it is in straight. 
                        Place the flange assembly on the table to make sure the bearing race is level.

                        

            1A.10   Using the vice, press the inner race back into the 6.5” hub (the hub with the 
                         threaded flange).  Make sure that it is in level and flush with the surface.

                                

                        

            1A.11   Press the flange assembly onto the hub all of the way using the vice.  The vice 
                         will get significantly harder to tighten when the flange is on all of the way.

                            
                    
                            

            1A.12   Replace the ball bearings and the axle in the dual-threaded hub. 
            1A.13   Save the remaining ball bearings for use on the top bracket, or if extra ball 
                         bearings are available. replace them to use the other thread-less hub for the 
                         rear wheels.
            1A.14   Submit the hub for spoking.
            1A.15    Attach the freewheels to the hub.  A spot weld will have to be placed on the
                         freewheel that will be on the 8-side, since when torque is applied to it it will
                         unscrew.  The spot weld is to be placed between the freewheel and the
                         spokes.  It is easiest to do this if one or two threads of the flange are exposed.
                         Do not weld to the outer bearing race, as this piece is merely pressed in and
                         is easily removed.
                           
                        


        Method 1B:  Fast and Daring
            1B.1    Place the hub in the vice such that the flange of the non-threaded side is
                        resting on the lips of the vice.  As in step 1A.5, do not clamp the vice.  
            1B.2    Hammer down on the axle to remove the non-threaded flange.
                        
                            

            1B.3    Repeat 1B.1 - 1B.2 with the intent of removing the threaded flange from the 
                        other hub.  
            1B.4    Place hub with the threaded flange into the vice vertically such that the flange 
                       is at the bottom.  Clamp the vice around the shaft or around the axle bolt.
            1B.5    Using a hollow tool to account for the ale, hammer the other threaded flange
                       onto the hub.
            1B.6    Save the remaining bearings as in step 1A.13.
            1B.7    Submit the hub for spoking.
            1B.8    See step 1A.15.



2.        Assembly of Top BB-Shell/Cranks

        The goal is to assemble the top bracket with the freewheel, which ratchets under
        normal forwards pedaling, on the long part of the pin on what will be the driver’s left,
        and the crank (using a modified cotter pin) on the short side of the pin.

        2.1    Take the freewheel and screw it onto the bb cup such that when the bb cup is
                 facing left, the freewheel will ratchet when the cup rotates as if being pedaled
                 forwards.  When the assembly is placed flat on a table with the BB cup’s opening
                 (the race) facing upwards, the freewheel should ratchet when the BB-cup is rotated 
                 anti-clockwise (counterclockwise).
        2.2    Ensure that the BB pin is labeled “SPECIAL” and “32-68-45”.  Other pins will work, 
                  but will need to be tested to make sure that the freewheel and crank both fit 
                  appropriately.  Please see the Documents section for more information on the
                  pin dimensions and countermeasures.
        2.3    Punch a hole in one face of the freewheel box and place that face over the pin on
                 the pin’s long side.  This is an important spacer to maintain distance between the 
                 freewheel and the outer side of the bearing race.
        2.4    Place the freewheel/BB-cup assembly over the long pin such that the outside of the 
                 race is against the cardboard and the concave inside of the race is facing 
                 outwards.  This is the top freewheel on the 8-side.
        2.5    Fill the BB cup with extra bearings from the hub.  The bearings keep the freewheel
                 arrangement centered on the shaft.
        2.6    Weld the bearings, BB cup, and pin together.  Make sure freewheel is 
                 perpendicular to the shaft.  Do not weld to the freewheel itself.  Just weld to the
                 pin, bearings, and BB cup.

                       

        2.7    Pace two small spot welds on the freewheel on the outside of the arrangement to 
                 secure it to the BB cup.
        2.8    Attach pedal arm to the 8-side with the cotter pin.  If the pedal does not fit, try (in
                 order of trial): grind the weld face, grind the inside of the pedal face, grind the 
                 cotter pin, grind the inside of the pedal face, grind the pin, grind the BB pin.
                    
                        

        2.9    Attach the crank to the short side.  The cotter pin will need to be ground down in 
                 order to get the crank to fit.  Make sure the cotter pins are opposite each other (in 
                 order for the pedals to be parallel with each other).  Make sure that the pedals do 
                 not wobble or rotate with respect to each other.  Also make sure that the pin 
                 rotates freely.  If necessary, in order of trials, to make the pin rotate freely, grind
                 the cotter pin further, grind the notch on the bb pin, grind the inner face of the 
                 crank (after reinforcing the outer face of the crank with welds).

                        



3.        Chain Routing

        Depending on the size of the crank used, the distance between the fork shaft and the
        axis of rotation must be varied.  This is to keep the chain inside of the centerlines of both
        of these axes.

        The distance can be modified by the lengthening of the plates attaching the fork to the
        axis of rotation.  For a 36 tooth crank to an 18 tooth freewheel, the nominal distance
        between the centerlines was found to be approximately 82 mm.  Thicker plates should
        be used for this span to maintain rigidity.

        The goal is to mount the top bracket in a position that maintains chain tension of the 
        O-side.  The chain tension on the 8-side is to be adjusted with the chain routing tube,
        though it should be pretty close when the O-side is properly tensioned.  Chain tension
        is very important.  Too loose and the chain will de-rail, too tight and one looses 
        proper freewheeling and excessive grinding may occur in the chain routing tube.

        3.1    Place the wheel with the modified hub and freewheels on the bottom of the fork
                 and all the way up the dropouts.  Tighten bolts.
        3.2    Place the top bracket onto the top of the fork.  
        3.3    Place chain on the O-side and approximate the chain tension with a preference to 
                 loose.
        3.4    Lift the top bracket to tighten chain and spot weld bracket, minding the crank and
                 chain alignments.  
        3.5    Measure and bend a piece of approximately 5/8” tube such that it spans from about 
                 5 cm below the top of the 8-side freewheel to the top of the fork curve, and bends
                 around the tensioned 8-side chain.  
        3.6    Place chain into the tube and route it on the 8-side such that the tube is on the
                 inside, containing the chain that is not under tension, and the tensioned chain
                 passes on the outside.

                        

                        

        3.7    Rotate the tube to ensure chain enters the top of the tube in the center with no
                 grinding and exits the tube approximately straight with a tensioned 8-side chain
                 tension such as to allow an approximately 4 cm lateral chain deflection in the
                 the middle of the chain’s span.  Weld the tube securely with braces where
                 necessary.  Parts of the fork may need to be flattened to allow tensioned 8-side
                 chain to be perfectly straight.



4.        Fork Mounting

        The fork must be mounted to the frame in order to allow it to be swung around to allow
        one to both freewheel and propel oneself in reverse.  

                    

        The following schematic and dimensions allow for this:
            (put picture here)

            Distance from top center of BB cup to seat back in the forwards position = 85 cm.
            Distance from wheel contact point in front to rear wheel contact point in forward
                position = 126 cm.

        A diagonal crossbar should be added from the fork axis of rotation (so that the two 
        attachments to the fork axis are as far as possible from one another) to the point on the 
        vertical frame member where the stiffening reinforcement has been added.


Streamlining and Waste Reduction

    -    Use the 2 non-threaded flanges to make a hub for the rear wheel.  This would require
         you to use other bearings for the centering of the 8-side top freewheel.
    -    Bend frame mount from a single piece.
    -    A fork mounting jig would save a significant amount of time, since the fork mounting is
          the only part of the process that is not cut and dry.Notebook.htmlDocuments.htmlshapeimage_2_link_0shapeimage_2_link_1