7.3.11:
fin/mobi`brakes
overview
7.4.22:
. rear`brakes went through several
months of evolution
. front`brakes are part the dahon` module
. law also requires parking | emergency brakes,
and in some places tire chains
. this design is based on a slow-moving
vehicle model,
where regen (battery-regenerating) brakes might not save much energy,
but in a hilly place they may be worth it .
motivation
6.11.5:
mobi#culti.sawyer pivot is too weak for front-only braking
. a dahon-trailer`boom connection would be acceptably strong
only if
quick braking is done by the rear wheels
7.2.10: front`brake-only is short on traction
. when something is that much heavier than a bike
it needs more braking traction than what a single bike tire can provide,
atleast in the winter .
7.3.3:
mobi#culti.sawyer risks jack.knifing when front-braking
. suppose the driver is not concentrating
and then the brakes are applied hard to the front wheel
it's easy to jackknife that wheel;
because, the weight of trike is pushing against the wheel`s resistance
with great force,
and since the steering pivot is slightly behind the wheel,
that pivot will tend to rotate while giving in to that force
. direct drive is ok, but not for deceleration;
use only for maintaining speed down hills
7.3.4:
. likewise for any other front-only braking:
if going down a hill, you have to be going slow eno' to stop immediately
rather than be going fast eno' to travel some distance during the
deceleration
. very slow .
. also, pot.holes are causing a loss of steering control by forcing a
sharp turn
that results in a jackknife at sufficient speed
. so remain very slow too if the pot.holes are hidden by darkness or
snow .
7.6.1:
. even if pot.holes are plainly visible, there can be psychological
blindness at any time;
so an easily jack-knife'd design should always be driven slowly
-- as should any design with a slow-moving vehicle sign .
7.3.4: substitutes
. rear`brakes would be missed because without them speed has to be
reduced to a crawl
in any situations where the pot.holes can't be seen
. if rear`braking is unavailable or for any other reason jack.knifing
becomes a problem,
then either
use geared
steering, where chainwheels transfer handlebar rotation to trike`pivot
rotation,
or
anchor the seat`post,
thereby restricting it to only safe angles,
and then take tight angles by releasing the anchor
7.3.10: legal
imperative
. to really feel safe with police,
you'd need to spend on a lawyer to
confirm mobi`s legal status
. I intend to follow codes that apply to an animal-driven vehicle
( rear has 2reflectors, a light, and a slow<20mph emblem )
. however, I may also have to follow the laws of a bike
which means being able to make all tires skid on dry pavement .
7.4.9:
. looking at the sum of laws for slow-moving vehicles and bicycles
(which include human-powered trikes)
you could argue that slow-moving vehicles don't need quick-stopping
brakes
because wearing the slow-moving vehicle emblem is your
promise to keep speeds under 25mph;
but if you wanted to avoid an argument,
you might try assuming a liberal interpretation of the law:
. a reasonable expectation of brakes on any machine that shares public
space -- not just bicycles --
is that all wheels should be able to skid to a stop .
fence`gate hinge and
fender reuse
6.11.5: pad#
tire`tread
. with hinges, the fenders can be reused as rear.brakes
7.2.13: hinged fenders
. the heavy fenders that
came with the trailer can be fitted with the rubber from old shoes,
and then hinged to the trailer`frame instead of bolted .
7.3.9: hinge# y-axis
rotation
. fence`gate hinge would have it`s long.plate bolted to the side of
trailer`frame,
and then the wide.plate would be bolted to something that would
have on one side a brake pad applied to the tire tread;
and on the other side, a cable anchor .
. the hinge is placed the same as in the fencing it's designed
for;
and, the main stress vector would be alligned with the axis of the
hinge`pivot .
7.4.9:
hinged-fender`construction
. fence`hinge is normally used for hanging a long gate on a ranch fence,
. the gate is wide eno' to allow farm equipment to pass;
it has a normal-sized plate connected to a fence post,
and then a very long plate for getting a grip on the gate
(the extra length is needed because gate`wood is thin,
and connectors near the edges would rip the wood apart )
. mobi`s brake design reuses a fence`hinge;
because,
the forces in a fence`gate are similar to the forces involved in
braking
as you can see when translating like so:
the trailer`frame`s side becomes the gate,
and the vertical brake`pad becomes the fence`post .
. the fenders can be combined synergistically with this brake foundation
because
the trailer`s fenders need a new anchor point
since the trailer kit they belong to got modified;
and, the fence`hinge alone cannot do the braking,
as it needs somthing heavy-duty -- like the fender`s metal --
on which to attach the brake`pad and the control cable;
so,
the fender is being attached between the {hinge`plate, brake`pad},
and then the brake`control cable will be attached to the fender in such
a way
as to prevent sway in the fender while mounted on the fence`hinge
. now when the fender`front is pulled inward,
the fender`back pivots on the hinge, and is pushed onto the wheel .
. when making revisions to this design,
keep in mind that
if the outer part of the fender is used for anchoring brake`pad
then the forces can become unlike a fence`gate;
because,
if the outer part of the pad is getting more bite than the part closest
to the hinge,
then
-- back to fence analogy --
it's as if there is a rotational force twisting the gate
just as if the gate`s top and bottom were being pulled in opp'directions
. the primary forces should be straight downward,
like when someone stops to sit on the gate
. also,
if the joint of the hinge is resting on the fence`post,
then the twisting forces on the fence`post`plate will be negligable .
. therefore, if the pad is designed to be applied across as much tire
as possible,
then there must be added some side structures
to prevent twisting of the hinge`s gate.plate (the long plate attached
to the trailer`frame) .
fender`placement/z-axis
. the hinge is easier to drill than the trailer`frame,
so, the hinge should be redrilled to match existing holes on the
trailer`frame if possible
. when redesigning fender placement,
ensure that the fender will not be touching the ground even when the
tire is flat .
7.5.5:
. give the fender`s placement careful consideration,
because changing
the location means
either there must be a bolting mechanism that can
slide along the trailer`frame`s side.beam when loosened,
or the holes must be redrilled for each change .
7.6.1:
. nearly all the forces would be vertical, ie, tangent to wheel at
brake`pad` contact.point;
so most of the holding power
could be done adjustably without bolts
by mounting the hinge on a u-beam that wrapped around the
trailer`side.beam .
. a less ambitious application of that idea
would use angle.iron on the underside,
so that side.bolting would not only have more plate to grab,
but would also spread shear.stress from the bolt to the angle.iron .
. having the angle.iron lapping over the hinge`plate
would also reduce bending in the plate .
fender`placement/x-axis
. on both sides of each fender an inch of the sides is bent down to a
right angle,
so they are vert's (vertical surfaces)
. in the trailer.kit`s design, that vert' is flat against the
trailer`frame,
. if that were so in mobi`s brake design,
then during the brake activation, pivoting on the hinge would not be
possible,
because part of the fender`s vert' would be pushed into the
trailer`frame .
7.6.1:
. a part of the side could be pushed in to accommodate the limited
range of pivoting needed for braking;
however, the fender can still be well onto the joint (so that bending
of hinge is minimized)
even when the vert' over the trailer`frame is not bent .
hinge`joint
reinforcement
. when the brakes are causing a rapid deceleration,
they will tend to bend the hinge`joint`s top inward (x-axis`zero)
and bend the joint`bottom outward;
so to prevent that, there should be something strong obstructing the
path of bending .
. the joint`top could be stopped by bolting something solid beside it
(it can't be attached directly to the hinge`joint because that is
rotating relative to the trailer)
. the hinge`joint`bottom can be stopped by side some cabling anchored
at the
point (x=0, z= brake`joint)
-- hence both brakes could share the same side cable .
7.6.1:
. the only reason for being concerned about bending of the hinge,
is that bending of hinge`plate will cause metal fatigue
. having the hinge`joint u-bolted to the trailer`frame
will likely minimize hinge`plate bending without need of a support
cable .
. suppose the hinge`s metal was too soft for this job,
and would uncurl from around the joint`s axle, ...
7.4.10:
. in that case, u-bolts can be placed around the joint and through
the trailer`frame
( a hole has to be drilled through the other plate too, before the
u-bolt will fit ) .
hinge`u-bolt`locknut
by epoxy
7.4.23:
. there are u-bolts for reinforcing the hinge;
they don't have lock nuts, but they can be epoxied in place;
because, the trailer will still be portable if it includes the hinge,
and even the fenders
(tho' getting it through elevators will be easier without the fenders) .
pad` construction
7.3.15:
. make the backing long enough so that when wood is screwed onto the
metal backing by either end,
the ends will never reach the rubber even if the middle is worn through
. put the lips so they help contain the brake pad .
. the motorcycle brake control can be reused for the back brakes .
7.3.17:
. on bikes with caliper brakes,
one part has rubber while the other part is metal,
and since tire provides the rubber part,
the brake`hinge doesn't need anything added
. the hinge`s brake foot can be straight metal,
textured by roughing the metal
or adding a plate of slotted angle iron,
by addition of slotted iron so it acts like a dull grater .
7.3.21:
. the wheels and their treads are placed far eno' from the frame
so that having bolt.heads inside the fender (the brake`foot),
will not have the tire rubbing against these bolts even with no pads .
. one way to make brake graters (texturing that rubs the tire more
effectively)
-- and which can also double as pad holders --
is bolting pieces of shelf-hanging U-beams
. the forked end of the u-beams would face the tires,
and hide the bolts that tie the bolt to the brake`foot
7.4.10:
. if it were better to have a rounded pad that fit the tire,
then a cable weave could be suspended from the concavity of the fender;
however,
the brake pad does not need to fit the tire like that;
because, having a point on a compressable gives better leverage;
so,
add only square tubing as brake pad
simply to ensure that the inner tire is getting braked harder than the
outer tire .
control` construction
7.2.24:
. the trigger should move forward so that when braking,
there is a tendency to be thrown into it, which makes braking easier
during an emergency
. the handle for the rear brakes should be to one side,
so that within mobi`s culti-architecture,
(
where the steering is done by holding 2 handles
and rotating a unicycle with a twist of the waist
),
there will still be
both hands pushing forward on things to the side .
7.3.25: push-down
descending vert's
. use a vert' but rotatable rod, pointing down, to reach below
the pulley
and thereby pull on brake cable when lowering the handlebar .
. the handlebars should always be high eno' to take turns,
and then the brakes should be activated by
pulling down on the bar rather than up
. now the control`transmission has to be rerouted:
the bar needs a rising vert,
so when the bar goes down, the vert goes forward
. if this is necessary, it may obviate the need for a pulley system
. there should be cable length adustment mechanism;
this could be provided by a set of double-eye screws .
7.3.17: mis#
pull-up descending vert'
. arrange the control cable so that when the gym`arm is raised up,
then the cable is pulled forward .
. attach a descending vert'al beam to gym`arm,
and then pulley the cable to that
beam .
7.3.25:
. the handlebars must be routinely raisable for taking sharp
turns?
the handlebars`raising is supposed to activate the rear brakes!
. therefore, need push-down descending vert's
7.3.29: mis# rising
vert's
. the cheapest way is to use just 2 pulleys, anchoring the cable at the
top of
vert's rising from the handlebar .
7.3.30: problem:
. that way obstructs the driver entrance from the side .
7.5.17: push-down rod
. little hinges might be useful for getting the control rod attached
between the handlebars and cable;
. the sure way would be to cut a hole in the square tubing on the
underside,
leaving 3 sides and all 4 corners intact;
and use that hole to access an existing horz'ly placed bolt ;
but
that is a lot of tight space to hack on, if trying to not mess a corner
edge
. however,
if the rod were small, then it could fit in through a drill hole
but then it would be too small for the bolt to go through
. if the rod were hollow, then a cable could loop through the hollow
and around the bolt;
tho', a new style of bonding warrants caution .
7.3.7: cable`route
idea#1:
. the cables are not easily conveyed up the middle? bring them up the
side
idea#2:
. bring them up the middle with garage door conveyer pulleys bolted to
the side .
7.3.8: idea#3
. they need independent control to help steering too
for when the ice is bad eno' that the front wheel is short on traction
7.3.21: tangent to
hinge`sweep
. there will be a better leverage and quicker brake action
if the cable is pulled from the side
. the pulleys can be attached to the lockbox walls
because the forces are symmetric and light
. then another pulley near the bottom of the lockbox will provide
a good angle for anchoring to the handlebars
. the handlebar arms should be arranged so that they are
intersecting the plane that the cable is traveling;
and
then the descending vert' will be alligned with the cable, simplifying
the design .
7.3.30:
. the pair of bookshelf vert'rods might be a good size for these vert's
.
cable`housing#
garage-door pulleys
--. using pulleys to contain the cable rather than sheathes .
7.3.23:
. in the supplytek`cat, their pulley's have some interesting forms:
not just the swivel
not just the usual hanging kind, but also {vertical, flush}-mount
. it warns tho', that one reason hangers are preferred
is that others are stiff mounted, so if you change the cable angle
or if the cable is constantly not quite alligned,
than you get a pull-out, where the cable is riding over the groove and
riding against the mounting
. buying local is preferred, and a larger pulley causes less wear
. the largest I've seen is for garage door systems;
7.3.25: trailer bolts fit garage pulley exactly .
7.3.25:
. ways to use pulley:
(1) usu' way:
. cable anchored to rotor; pulley anchored to stator .
(2) new way:
. cable anchored to stator; pulley anchored to rotor .
. gym pivot cut in half would be good for new cable design
if the pivot cut in half is doable,
7.4.2:
. it would make the cables last longer if the pulleys had a much larger
diameter,
or if simulating the same by structuring groups of pulleys
. towards the back this is not a problem because the angle is not steep,
but in the front`s current design, where a rod pushes the cable below
the pulley,
there should be 2 or 3 pulleys per side (4 or 6 garage`door pulleys) .
7.3.25: house# sheathing
. homemade housing needs a plastic that is shaped to cradle the cable
. the plastic is folded around the cable,
given some slits on the edges to allow bending,
and is the riveted to a board that is in the plane in which the cable
is bending
. that way, the harder the cable is pulled on,
the more snugly the plastic hugs the friction side to maximize surface
area .
7.4.4: pulley`anchor#
angle.iron
. cheaper and sturdier than a u-bolt is angle.iron;
I shouldn't be suprised it fits:
now I vaguely recognize that angle.iron is what they use in some garage
door systems
which where my pulley came from .
7.3.31:
pulley`anchor# ring
. to attach the pully to the lockbox,
get the type of pulley with a ring on one end,
and then use the cable`u-bolt to tie that ring to the sheet metal
. replace the crosspiece with a couple of washers .
7.4.4: pulley`anchor# u-bolts
. use u-bolts through the garage`door`pulleys,
in order to connect them to walls at any angle
. just drill 2 holes in the wall and it takes a cable from anywhere in
space
and can turn it parallel to the wall and hugging it,
so that it can feed the pulley into another pulley
that is single-bolted into the same wall
. this is exactly what the mobi`brakes need,
as their braking arms are moving co.planar with a wall (the side of the
lockbox),
emergency
brake
7.1.4: emergency
brake# driver`s step reuse
. assuming the driver enters from the front by raising the handlebars
a spring loaded stepping stool could serve both as an emergency
brake
and as a step-up for a seat that is slightly higher than accessable
due to currently preferred angle of the seat post .
7.4.22:
. perhaps the gym`pivot could be reused as part of this emergency brake
design
7.6.1:
. this doesn't fit with the plans to use skating boots as toe.clips;
because, there is no quick way to reach the controls in an emergency .
7.2.6: emergency
brake# spare tire on a spring-loaded boom
. have the spare tire on a spring-loaded boom,
and then during emergency stops,
you could put your foot`s weight on the tire and have it grind on the
road
. could rotate the tire occassionally to have it still be useful as a
spare,
but not sure how to do this without it getting in the way of steered
wheel ...
2.7.7:
. with good leveraging, you could also place it behind you,
and then pull up on a lever to push it down
7.2.24: emergency
brake# rear`chocks
. parking brakes that double as emergency brakes
could be trigger-released tire chocks
like a sleeve that comes down with lips that get caught under the wheel
when going in either direction .
parking
brakes
7.2.26: parking
brake# ratchet winch
. the parking brake might be from simply <any ratchet mechanism>
applied to
the brake handle
7.4.22:
. the cable rachet and vice grips could make parking brakes of either
the rear`brakes, or an emergency brake .
7.4.10:
. the ratchet device should be removable for use either as parking
brake hold
or for getting a tow up hills .
-- re: 7.2.26: parking brake#vicegrip:
. the parking brake might be from simply a vicegrip wrench applied to
the brake handle .
7.2.27: parking
brake#front`chocks
. the parking brake might be from tire chocks that are suspended around
the front tire .
7.1.29: parking
brake#front`chocks
. even if not used for braking,
it would be convenient to have a lever that auto'ly lowered tire chocks
into place .
. during hills,
the chocks would constantly be trailing behind,
and preventing movement backwards to make it easy to
rest without stressing the brakes all the time
.
. both front and back chocks are in a frame connected to a plunger rod
that is trapped in a sleeve
. when pulled up off the ground then there vertical fenders
that keep the chock frame from bumping into the tire;
but, when they are lowered, the fenders are no longer containing them,
so when they hit the ground, they can also be sliding under the wheel .
7.2.15: treads with
tire.chains
. this design is complicated if needing tire.chains
7.2.24:
. if the brake pads are angled or large,
then they will work even with stock chains on the trailer wheels .
7.3.11:
. if there are many sets of plastic chains then they will
make a
relatively smooth surface that won't catch on brake pads .
7.6.1:
. if the pad is long in a direction tangent to the wheel,
then a normal set of chains won't catch on brake pads .
log
7.6.1:
. a separate rope can keep the hinged fenders from moving outward when
the brake`cables are slack .
