Note: Descriptions are shown in the official language in which they were submitted.
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MOTORCYCLE CONVERSION KIT AND ASSOCIATED METHODS
This application claims the benefit under 35 U.S.C.119(e) from U.S.
provisional application Serial No. 60/684,585, filed May 26, 2005.
FIELD OF THE INVENTION
The present invention relates to a conversion kit and the method of
use thereof for converting a two wheeled motorcycle to a three wheeled
motorcycle.
BACKGROUND
In many instances it is desirable to convert a two-wheeled motorcycle
into a three-wheeled motorcycle. For example a three-wheeled motorcycle is
desirable when persons wish to enjoy the open ride of a motorbike but with
greater
stability.
Various examples of three-wheeled motorcycles are disclosed in the
following US patents: 5,499,689 to Johnson, 4,325,449 to D'Addio et al.,
4,449,602
to Dittmann, Jr., 5,692,5577 to Dornbusch et al., 5,236,060 to Huber,
4,287,960 to
McConnell, 4,437,535 to Winchell et al., 5,899,291 to Dunmais, 4,905,787 to
Morin, 1,271,553 to Elliott, 1,933,102 to E. P. Du Pont et al., 1,956319 to E.
P. Du
Pont et al., and 5,785,141 to Breitkreutz et al.
In general prior art kits for converting a two-wheeled motorcycle into
a three-wheeled motorcycle have a poor finished appearance which is not
consistent with existing components of the original motorcycle. Furthermore
known
systems generally require complex mounting for proper alignment of the dual
rear
wheels with the direction of travel of the motorcycle, as well as proper
alignment of
the drive train and the suspension. Many attempts have been made to provide
generic kits which can be adjusted to various different types of motorcycles,
however, the generic nature of these kits requires different types of adaptive
connectors or numerous additional adjustments to be made once the kit is
installed
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in order to function properly. The use of extra connectors and subsequent
adjustments is time consuming and difficult to install. In addition prior art
kits
typical require either a poorly performing drive train without a differential
or a
complex drive shaft conversion is required.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a method
of converting a motorcycle having a frame with a pivot bolt assembly for
pivotally
supporting a rear wheel swing arm assembly thereon, the method comprising:
providing a replacement swing arm frame extending in a longitudinal
direction between a forward end and a rearward end thereof, the rearward end,
comprising a pair of spaced apart frame members extending in the longitudinall
direction;
pivotally connecting the front end of the swing arm frame to the pivot
bolt assembly of the motorcycle;
connecting the swing arm frame to an existing rear suspension of the
motorcycle;
supporting first and second axles rotatably on the frame members
respectively for rotation about a common axis lying perpendicularly to the
longitudinal direction;
connecting a pair of wheels to the first and second axles respectively;
connecting brakes to the first and second axles respectively;
connecting the first and second axles with a drive motor of the
motorcycle; and
adapting brake mounts and shock mounts of the replacement swing
arm frame for mounting suspension and brakes available from the same
manufacturer as the motorcycle being converted.
The kit according to the present invention is configured and
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specifically arranged in each embodiment for connection to one particular
model of
one brand of motorcycle to minimize any subsequent adjustments required when
installed on the motorcycle. The replacement swing arm frame includes
moun'ting
locations for mounting the existing components of the motorcycle and
additional
parts available from the same manufacturer as the original motorcycle for
installing
all of the components including the brake callipers, the brake rudders, the
shocks
and chain drive of the existing motorcycle. Replacement parts for any of these
components are thus available from the original manufacturer of the
motorcycle. In
particular, the use of a chain driven sprocket on the differential which is in
alignment with the existing drive sprocket of the motorcycle permits the use
of a
conventional chain connection therebetween to minimize complexity of the
conversion.
According to a second aspect of the present invention there is
provided a conversion kit for a motorcycle having a frame with a pivot bolt
assembly for pivotally supporting a rear wheel swing arm assembly thereon, the
kit
comprising:
a replacement swing arm frame extending in a longitudinal direction
between a forward end and a rearward end thereof, the forward end being
adapted
for pivotal connection to the pivot bolt assembly of the motorcycle and the
rearward end comprising a pair of spaced apart frame members extending in 'the
longitudinal direction;
shock mounts on the swing arm frame for connection to a rear
suspension of the motorcycle;
first and second axles rotatably supported on the frame members
respectively for rotation about a common axis lying perpendicularly to the
longitudinal direction;
a pair of wheels for connection to the first and second axles
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respectively;
brakes for connection to the first and second axles respectively; and
a differential operatively connecting the first and second axles, the
differential including a chain driven sprocket for chained connection to a
chain
drive sprocket of the motorcycle.
According to a further aspect of the present invention there is
provided a method of converting a motorcycle having a frame with a pivot bolt
assembly for pivotally supporting a rear wheel swing arm assembly thereon, the
method comprising:
providing a replacement swing arm frame extending in a longitudinal
direction between a forward end and a rearward end thereof, the rearward end
comprising a pair of spaced apart frame members extending in the longitudinal
direction;
pivotally connecting the front end of the replacement swing prm
frame to the pivot bolt assembly of the motorcycie;
connecting the swing arm frame to a rear suspension of the
motorcycie;
supporting first and second axles rotatably on the frame members
respectively for rotation about a common axis lying perpendicularly to the
longitudinal direction;
connecting a pair of wheels to the first and second axles respectivply;
connecting brakes to the first and second axles respectively;
providing a differential including a chain driven sprocket;
connecting the first and second axles with the differential; and
connecting the chain driven sprocket with a chained connection to a
chain drive sprocket of the motorcycle.
When a housing surrounds the axles and the differential, the housirhg
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is preferably fixed between the frame members.
The differential preferably comprises an outer housing fixed relative
to the frame and a rotatable housing carried therein within which the first
and
second axles are operatively connected wherein the chain driven sprockpt is
5 supported about the rotatable housing for rotation therewith.
Each frame member may comprise a pair of parallel and sppced
apart tubes supporting the first and second axles therebetween for sliding
movement in the longitudinal direction of the frame.
Fender mounts may be supported on the swing arm frame for pivotal
movement with the axles carried on the swing arm frame relative to the
motorcycle
frame. The fender mounts may be supported on a mounting plate carried by the
axle housing commonly with brake mounts for the brakes.
A chain tightener may also be carried on the swing arm frame.
In the illustrated embodiment, the forward end of the swing arm
frame is adapted for pivotal connection to the existing pivot bolt assembly of
a
Harley DavidsonTM motorcycle.
Two embodiments of the invention will now be described in
conjunction with the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view from a front end of a first embodiment
of the swing arm frame.
Figure 2 is a perspective view from a rear end of the first
embodiment.
Figure 3 and Figure 4 are respective top plan and side elevational
views of the frame according to Figure 1.
Figure 5 is a sectional view along the line 5-5 of Figure 4.
Figure 6 is a rear elevational view of the frame according to Figure 1;
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Figure 7 is a perspective view from a front end of a swing arm frame
according to a second embodiment.
Figure 8 is a perspective view from a rear end of a swing arm frame
according to the second embodiment.
Figure 9 and Figure 10 are respective top plan and side elevational
views of the frame according to Figure 7.
Figure 11 is a sectional view along the line 11-11 of Figure 10.
Figure 12 is a rear elevational view of the frame according to Figure
7.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
Referring to the accompanying Figures there is illustrated a kit
generally indicated by reference numeral 10. The kit 10 is particularly suited
for a
motorcycle (not shown) of the type having a frame including a rear wheel
assembly
pivotally supported on a pivot bolt assembly of the motorcycle.
The motorcycle for which the conversion kit is suited for, is
conventional and includes a rear suspension coupled between the rear wheel
assembly and the frame along with a chain connection between a drive sprocket
of
the motorcycle and the rear wheel. The kit 10 is intended to replace the
single rear
wheel assembly with dual rear wheels in a convenient manner which permits the
single rear wheel assembly to be reinstalled at a later time as desired.
Though two
embodiments are shown in the accompanying figures, the common feature of each
will first be described herein.
The kit generally comprises a replacement swing arm frame 20
extending in a longitudinal direction between a front end 22 and a rear end
24. Iin
the mounted position, the longitudinal direction is intended to be aligned
with a
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direction of travel of the motorcycle.
A transverse aperture 26 is defined at the front end which is adapted
for alignment with the pivot bolt assembly on the motorcycle. The transverse
aperture 26 is oriented perpendicularly to the longitudinal direction for
latoraliy
receiving a pivot shaft therethrough which secures the swing arm frame 20 for
pivotal movement about a horizontal axis relative to the motorcycle frame.
The frame 20 includes two frame members 28 which eXtend
longitudinally from the front to the rear end 24. The frame members are spoced
apart at the front end and initially extend rearwardly at an outward incline
lat a
forward incline portion 30 thereof. Towards the rear end of the frame, the
frame
members 28 are spaced further apart than at the front end and extend parallel
to
the longitudinal direction and to each other over a main portion 32 of the
lerhgth
thereof.
Each frame member 28 comprises two vertically spaced apart tul~es
34 which are parallel to one another. The tubes are joined with one another at
the
inclined portion 30 to maintain the spacing thereof along the main portion 32.
A shock mount 36 in the form of transverse mounting apertures ore
also provided adjacent the front end 22 of the swing arm frame 20. Location of
the
shock mount 36 varies depending upon the particular model of motorcycle which
the frame is intended to be installed on so that the shock mount 36 can be
located
in the same position as the shock mount on the stock rear wheel swing anm
assembly of the motorcycle. The existing shocks can thus be coupled to the
shook
mount.
An anchor 28 is provided on each frame member 28 at a forward end
of the main portion 32 to span between the tubes 34 which define the frame
member. The anchor 38 includes an annular portion fixed onto each tube 34
respectively with a stem extending therebetween. An axial mounting block 40 i5
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similarly mounted to span the tubes 34 of each frame member 28 and serves to
mount first and second axles 42 and 44 on the frame members 28 respectively.
Each block 40 includes a top channel 46 and a bottom channel 48 which
receivels
the tubes 34 of the frame member therein. Clamping members 50 are provide at
each of the top and bottom sides for clamping the tubes within the channel 46
and
48 respectively.
An adjustment screw 52 is connected between the anchor 38 and the
mounting block 40 so that the longitudinal position of the each of the
mountino
blocks can be adjusted using the adjustment screw 52 prior to being clamped
down. Once the block is set in place, the top and bottom clamping members 50
ar'e
clamped into place using respective threaded fasteners.
Each of the first and second axles are rotatably carried within a
respective axle housing 54 which is in fixed connection with the respectivle
mounting block 40 within which it is carried. The axle housings 54 are thu,s
supported by the mounting blocks 40 between the tubes 34 of the frame members
28 respectively.
The axle housings 54 are rigidly connected by a casing 56 of a
differential 58 supported therebetween. The two axle housings and the casing
qf
the differential thus form a continuous housing which is rigidly connected
betweeh
the opposing frame members 28 to provide structural support at the rear of
thle
frame 20. The first and second axles are thus supported for rotation about a
common longitudinal axis lying perpendicular to the longitudinal direction of
thb
frame 20 and the tubes 34.
The interior ends of the axles 42 and 44 housed within the axfe
housings 54 each include an end face gear 60 such that the gears are
confronting
one another and mesh on opposing sides of a pair of idler gears 62
therebetweerl.
The idler gears 62 are diametrically opposite one another for rotation about
''a
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common shaft 64 extending therebetween in a manner similar to conventional
differentials. The common shaft 64 lies diametrically in relation to and
rotatos
about the common axis of the first and second axles 42 and 44 along with'a
surrounding rotatable housing 66 which carries the shaft 64.
The rotatable housing 66 includes a toothed outer periphery which
defines a driven sprocket 68 which lies in a common plane with the drive
sprock6t
of the motorcycle. Suitable apertures 70 are provided in the casing 56 of tfle
differential for receiving a chain connection therethrough which connects the
drivOn
sprocket 68 to the drive sprocket of the motorcycle.
A chain tightener mechanism is coupled to the casing 56 at an outor
side of the differential. The tightener 72 generally comprises an idler gear
T4
supported on a pivot arm 76 which is biased in a direction to urge the idler
74
against the chain connecting the driven sprocket with the drive sprocket of
the
motorcycle in a manner so as to add tension to the chain.
The axle housing extends through the mounting blocks from an inn~r
end spanning between the mounting blocks and the casing of the differential to
aln
outer end which projects outwardly beyond the mounting blocks externally of
the
frame members 28. The outer free ends of the axle housings 54 each include la
bolt flange 78 thereon which bolts a suitable upright mounting plate 80
thereon.
The mounting plate includes mounting apertures formed therein spaced radialiy
outwardly from the axle housing such that a pair of the apertures defines
mounts
for brake callipers 82 while an additional pair of the apertures provides
mounts for
a fender 84 which can be mounted thereon for movement with the swing arm anld
wheels relative to the motorcycle frame. Spacing of the apertures in the
mountinlg
plate 80 is arranged to permit original equipment manufactured by the
origin$!I
motorcycle manufacturer so that existing parts can be used.
The first and second axles 42 and 44 project axial beyond the frele
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ends of the respective axial housing 54 sufficiently for supporting a brake
rotor 86
thereon in alignment with the brake clippers 82 and a wheel hub 88 for
supporting
one of the rear wheels thereon. The swing arm supports the first and second
axlQs
spaced from the pivot bolt assembly of the motorcycle greater than the rear
wheel
5 axle of the original signal rear wheel assembly by approximately 6 inches to
improve stability of the motorcycle.
Turning now to the embodiment illustrated in Figures 1 through 6, the
swing arm frame 20 as illustrated is particularly suited for attachment to the
Sdit
Tail model of Harley DavidsonTM motorcycle. The front end 22 of the frame in
this
10 instance includes two vertically oriented plates 90 which are parallel to
one anotho!r
and include centrally located apertures 26 therein in alignment with one
another fbr
connection to the pivot bolt assembly of the motorcycle. Top and bottom
crossba~s
92 span between the plates 90 at respective top and bottom ends thereof f4r
maintaining the plates parallel and spaced apart from one another.
The shock mount 36 in this instance is spaced below the transversle
aperture 26 and generally comprises a sieeve which is supported centrally in
frorht
of the lowermost crossbar 92.
The tubes 34 forming each of the frame members 28 are initially
spaced apart from one another at opposing top and bottom ends of plates 90 so
as
to taper towards one another over the length of the inclined portion 30 of the
frame
members. Crossbars 94 span between the tubes 34 of each frame membor
spaced rearwardly from the transverse aperture 26. The main portion of the
tubeis
extends rearwardly from the crossbars 94, parallel to one another.
Turning now to the embodiment illustrated in Figures 7 through 12,
the swing arm frame 20 is particularly suited for mounting on a four speed
Sportster model of a Harley DavidsonTM motorcycle. In this instance the
transversO
aperture 26 is defined by a sleeve 96 at the front end of the frame which is
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perpendicular to the longitudinal direction of the frame. The two tubes 34
forming
each frame member are joined directly one above the other at spaced positions
at
opposing end of the sleeve 96 at the front end. The tubes 34 of each frame
merrhe
remain joined through the inclined portion 30 at which point the tubes 34
diveroe
from one another and are reinforced by respective gussets 98 before spannihg
rearwardly, parallel and spaced from one another through the main portion of
each
of the members 28.
The shock mounts comprise a pair of vertical plates 100 mounted dn
the inclined portions 30 of the frame members respectively to locate
respectivle
mounting apertures therein which are higher than the transverse aperture
defineld
by the sleeve 96.
In both embodiments the rear ends of the frame members 28 project
rearwardly beyond the axle housings sufficiently for mounting a bumper at the
reor
end thereof while still providing clearance for the rear wheels ahead of the
bumpet.
Installation of the kit involves removing the original rear wheql
assembly from the pivot bolt assembly of the motorcycle so that the swing arm
frame 20 according to the present invention may be installed at the existing
pivdt
bolt assembly. Mounts are provided on the swing arm frame for reconnecting the
existing shocks on the shock mounts, connection of brake components includin o
callipers and rotors from the original manufacturer on the respective mounts
as
well as the use of wheel hubs and a chain drive which also meets
specifications of
Harley DavidsonTM parts to minimize adjustments required upon installation
whil$
ensuring the finished appearance of the converted motorcycle is consistent
with
the remaining original components on the motorcycle. Use of original equipment
parts ensures that the parts remain readily available for replacement during
futurt;
maintenance as required.
Since various modifications can be made in my invention as hereio
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above described, and many apparently widely different embodiments of same
made within the spirit and scope of the claims without department from such
spirit
and scope, it is intended that all matter contained in the accompanyiog
specification shall be interpreted as illustrative only and not in a limiting
sense.
