Multiple speed transmission for pedal powered vehicles

A ten-speed transmission which is located inside the hub of the driving wheel of a pedal powered vehicle, and which includes a pedal drive shaft mounted in bearings on the axis of the wheel, is used to provide a compact, low maintenance alternative to the chain and derailleur system used for conventional multiple speed bicycles. Three idler shafts divide the pedal torque between three gear teeth permitting the gear widths to be one third that which would be required for a transmission using a single idler shaft. The resulting narrow gears coupled with a shift arrangement which adds nothing to the transmission width, permits the width between the pedals to be approximately that of a conventional chain driven bicycle. This transmission is particularly well suited for use in recumbent front wheel drive bicycles and tricycles.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
This invention relates generally to multiple speed transmissions for 
bicycles and tricycles, and more particularly to bicycle drive 
transmissions of the chainless type. 
2. Description of the Prior Art: 
A standard ten-speed bicycle uses a chain and derailleur system. The chain 
requires periodic cleaning and oiling for efficient operation and to 
prevent premature chain failure, and it must be removed from the rear 
sprocket to change the rear tire. Also, when the rider is bearing down on 
the pedals on a hill, the derailleur usually will not carry the chain to a 
lower gear. Consequently, with a chain derailleur/system, the cyclist must 
anticipate the terrain and shift gears before getting onto the hill in a 
gear that is too high, since he will not be able to shift to a lower gear 
once he is on the hill. Further, all the gears of a conventional ten-speed 
are not efficiently usable because of the angle the chain makes with the 
sprockets. In addition, shifting is not done in a simple set sequence that 
is easily mastered. These problems are eliminated with the present 
invention, as will be seen. 
The transmission described in U.S. Pat. No. 2,505,464 by Debuit is located 
on the axis of the wheel concentric with the pedal drive shaft as is the 
present invention. However, Debuit's transmission carries the pedal torque 
through single gear teeth requiring heavy gears, is mounted alongside the 
wheel hub rather than inside it, is limited in the number of gear ratios 
it makes available (four plus a direct drive option), and uses rows of 
balls and internal pistons for locking the pinion gears mounted loose on a 
hollow axle to the axle. The arrangement does not appear to be practical 
because centrifugal force is continually pushing the balls outward into 
engagement with the pinions that are intended to slide freely on the 
hollow shaft. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a compact, durable, low 
maintenance, ten-speed alternative to the conventional chain/derailleur 
system, and which can be used for rear wheel drive bicycles and, more 
importantly, which can provide an efficient front wheel drive for 
comfortable, low drag, recumbent tricycles and bicycles. 
Briefly, the transmission of this invention includes a gear case located 
inside the wheel hub with a cylindrical extension of the gear case fixed 
to the vehicle frame on one side; a pedal drive shaft mounted in ball 
bearings on the axis of the wheel; a drive-gear-carrier mounted on and 
driven by the pedal drive shaft; two drive gears freely rotating on the 
drive-gear-carrier with a means for selectively locking one or the other 
of them to the carrier; three idler shafts mounted parallel to the pedal 
drive shaft on bearings in the gear case; a pair of gears fixed to each 
idler shaft and in constant mesh with the two driving gears; five gears 
freely rotating on each idler shaft with a means for selectively locking 
the same one of them on each idler shaft to its respective shaft; a 
cluster of five gears rigidly joined together and mounted on a ball 
bearing on the pedal drive shaft, with each of the five gears in constant 
mesh with one gear on each of the three idler shafts; and with a 
conventional free-wheel ratchet mechanism driving the wheel hub from the 
five-gear-cluster. 
The transmission provides speeds one through five with the smaller drive 
gear locked to the drive-gear-carrier, by sequentially locking the 
smallest to the largest of the five gears rotating freely on each idler 
shaft to its idler shaft, and speeds six through ten by going through the 
same sequence of locking gears to the idler shafts with the larger drive 
gear locked to the drive-gear-carrier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 3, the transmission in accordance with the present 
invention includes a wheel hub 1, a wheel hub driving plate 2, a gear case 
3, a gear case closing plate 4, a drive-gear-carrier 5, a split ring 6, a 
drive gear selector 7, a selector actuation cable 8, a return spring 9, 
left and right pedal crank arms 10L and 10R, and a pedal drive shaft 11. 
The gear case closing plate 4 is supported by a pair of ball bearings 38, 
the inboard bearing 38 being seated on a cylindrical extension of the 
drive-gear-carrier 5, and the outboard bearing 38 being seated on a 
cylindrical extension of the pedal crank arm 10R. 
As seen in FIGS. 3 and 7, the two halves of the split ring 6 are installed 
in each of a pair of circumferential cutouts in the drive-gear-carrier 5, 
with the outside diameter of the split ring 6 matching the outside 
diameter of the drive-gear-carrier 5. An involute gear 42 is installed 
over the split ring 6 in the left cutout, and an involute gear 43 is 
installed over the split ring 6 in the right cutout. The inside diameter 
of the gears 42 and 43 is a slip fit on the outside diameter of the 
drive-gear-carrier 5, so that the gears and split rings slide freely on 
the carrier. As seen in FIG. 7, the split ring 6 has four projections 
which key it to the gear inside of which it is installed. 
The drive gear selector 7 is installed in the annular space between the 
outside diameter of the pedal drive shaft 11 and the inside diameter of 
the drive-gear-carrier 5. Four radial projections on the selector 7 slide 
in axial slots in the drive-gear-carrier 5 and engage an internal tooth 
form on the inside of the split ring 6 in the plane of which the selector 
7 is located. The selector 7 thus transfers torque from the 
drive-gear-carrier 5 through the split ring 6 to the drive gear in the 
plane of the gear in which it is located. 
As seen in FIGS. 3 and 4, the pedal drive shaft 11 has square ends for the 
transfer of torque from the pedal crank arms 10R and 10L to the 
drive-gear-carrier 5. The spanner bolt 12 fastens the crank arm 10R to the 
drive shaft 11 and, with the cylindrical extension on the crank arm 10R, 
keeps the drive-gear-carrier 5 firmly seated against a shoulder on the 
drive shaft 11. 
The axial position of the drive gears 42 and 43 is maintained by a shoulder 
on the left end of the drive-gear-carrier 5, a washer between the gears, 
and a snap ring on the right end of the carrier 5. The axial position of 
the drive gear selector 7 is controlled by the shift bar 30, the cable 8, 
and the return spring 9. As seen in FIG. 7, the bar 30 fits in a slot 
through the drive shaft 11, with its ends captive between shoulders on the 
selector 7. The spring 9 forces the bar 30 to the left end of the slot. 
The spring force is resisted by the cable 8, one end of which is captive 
in the bar 30. From the bar 30, the cable 8 passes out through a hole in 
the spanner bolt 12 to a mounting block 14 in the crank arm 10R. A cable 
actuation pin 13 clamps the end of the cable 8 to the mounting block 14 
and holds the block captive in the crank arm 10R. As seen in FIGS. 3 and 
4, the pin 13 can be positioned by either one of two shoulders integrally 
machined in the crank arm 10R. An exposed length of the pin 13 inboard of 
the crank arm 10R permits engagement with the vehicle shift mechanism when 
the crank arm is in a horizontal position, as will be described. 
As seen in FIGS. 1 and 2, the transmission 62 according to one embodiment 
of the present invention is installed in the front wheel 63 of a front 
wheel drive, rear wheel steer, recumbent tricycle, having a vehicle frame 
33, rear wheels 65, steering knuckles 66, and handlebars 67. The 
handlebars are clamped to a center post 71 mounted in a pair of axially 
spaced bearings 70 under a seat 69. The handlebars are connected to the 
steering knuckles 66 by a pair of struts 68. The steering geometry is 
established to provide the proper toe-in on turns. A gear shift lever 64 
is connected by an actuator rod 16 to a shift arm 15 which is pivoted from 
the frame 33. 
As shown in FIGS. 2 and 4 a notch in the shift arm 15 can be pulled into 
engagement with the cable actuation pin 13 by the actuator rod 16 when the 
pedal crank arm 10R is properly positioned. By movement of the gear shift 
lever 64 coupled with a slight rocking of the pedal crank 10R, the cable 
actuation pin 13 can be moved between the retaining shoulders in the crank 
arm 10R, with the cable 8 moving the drive gear selector 7 from one to the 
other of the drive gears 42 and 43. When the gear shift lever 64 is 
released, a torsion spring on the pivot of the shift arm 15 swings it 
forward against a stop so that the shift arm 15 clears the pin 13 when the 
crank arm 10R is rotated by pedaling. 
Referring now to FIG. 3, a slotted pin 29 is installed parallel to the 
pedal drive shaft 11 in the gear case 3. As shown in FIG. 5, the slotted 
pin 29 is installed in three locations 120 degrees apart and the left end 
supported in the gear case 3 is square in a square hole so that the pin 29 
is restrained from rotating. The right end of the pin 29 is supported in 
the gear case closing plate 4, as shown in FIGS. 3 and 8. The left end of 
an idler shaft 17 is supported on a ball bearing 41 seated on the slotted 
pin 29. The right end of the idler shaft 17 is supported inside a ball 
bearing 40 which is seated in the gear case closing plate 4. 
Two gears 49 and 50 are rigidly fixed on the idler shaft 17 and are in 
constant mesh with the drive gears 42 and 43, respectively. A split ring 
18 is installed in each of five circumferential cutouts in the idler shaft 
17 and the five idler gear 44, 45, 46, 47 and 48 are installed over the 
split rings 18. The inside diameter of the idler gears is a slip fit on 
the outside diameter of the idler shaft 17 so that the gears rotate freely 
relative to the idler shaft. 
As shown in FIG. 6, the split ring 18 has four radial projections which key 
it to the gear installed over it. An idler gear selector 19 has four 
radial projections which slide in axial tracks in the idler shaft 17. The 
depth of the tracks in the idler shaft 17 is preferably limited to two 
thirds its thickness so that they do not impair its torsional integrity. A 
tooth form on the ends of the projections on the idler gear selector 19 
matches an internal tooth form on the split rings 18. The gear selector 19 
thus transfers torque from the idler shaft 17 to the gear in the plane of 
which it is located, while the other four gears slide freely on the idler 
shaft 17. 
As seen in FIGS. 3, 6 and 8, the axial position of the gear selector 19 is 
controlled by a split collar 20, a flanged bar 32, a cable 22, and a 
return spring 21 which is installed over the slotted pin 29. The idler 
gear selector 19 rotates freely between the two halves of the split collar 
20. The flanged bar 32 is installed in the slotted pin 29 inside the left 
half of the split collar 20 with flanges on the ends of the bar 32 
engaging the left flange on the split collar 20. The force from the spring 
21 is reacted by tension in the cable 22, one end of which is fixed in the 
flanged bar 32, and the other end of which is clamped in a winch 23 
located between the bearings 38 supporting the gear case closing plate 4. 
As shown in FIG. 8, the extruded aluminum winch 23 has three axial slots. A 
cable clamping screw 24, washer 26, and threaded collar 25 are held 
captive in each of these slots by the gear case closing plate 4 within 
which the winch 23 rotates. The radius of the winch 23 is chosen so that 
90 degrees of winch rotation moves the idler gear selector from a location 
centered inside gear 44 to one centered inside gear 48, as shown in FIG. 
3. Tension in the three actuation cables 22 is maintained by the three 
return springs 21, and applies a counterclockwise torque to the winch 23, 
as viewed in FIG. 8. An exploded view of the components for clamping the 
ends of the cables 22 in the winch 23 is shown in FIG. 8A. The cable is 
clamped between the screw 24 and the washer 26 by the threaded collar 25. 
A balancing clockwise torque on the winch 23 is applied by a winch 
actuation cable 27 which wraps around the outboard end of the winch, 
passes out through a hole in the gear case closing plate 4, and terminates 
in a shift assembly 72, as shown in FIG. 2 and in an enlarged view of the 
left side of the shift assembly 72 shown in FIG. 9. 
Referring to the left side view of the shift assembly 61 shown in FIG. 9, 
the actuation cable 27, on entering the open end of the shift bracket 53, 
passes through the guide bushing 55, wraps around the cable drum 51, and 
terminates in the attachment pin 59 in the cable release arm 52, which is 
joined to the cable drum by the pin 60. Five notches in the shift bracket 
53 match the five positions required for the idler gear selector 19. When 
the handles of the cable drum 51 and the cable release arm 52 are squeezed 
together, the cable drum can be freely swung around to position the cable 
attachment pin 59 in any one of the five notches. 
Referring again to FIG. 3, the right side of the wheel hub 1 is supported 
on a ball bearing 39 seated on the gear case closing plate 4. As shown in 
FIG. 4, the two flats 73 on an integral cylindrical extension of the 
closing plate 4 engage a slot in the vehicle frame 33 and prevent the gear 
case from rotating. 
The left side of the wheel hub 1 is supported by the wheel hub driving 
plate 2, which is supported by a ball bearing 36 seated on the pedal drive 
shaft 11. A free-wheel assembly 28 is supported on a ball bearing 37, also 
seated on the pedal drive shaft 11. Each of five gears rigidly fixed to 
the free-wheel assembly 28 is in constant mesh with one of the five idler 
gears freely rotating on each of the three idler shafts 17. Torque from 
the free-wheel assembly 28 is transferred to the wheel hub driving plate 2 
by a conventional free-wheel ratchet arrangement, as shown in FIG. 5, with 
two spring loaded dogs 31 mounted in the driving plate 2 engaging cogs in 
the free-wheel assembly 28. 
A vehicle frame interface fitting 34 is supported on a ball bearing 35 
seated on a cylindrical extension of the left pedal crank arm 10L. As 
shown in FIG. 4, locking screws 72 in the vehicle frame 33 engage both the 
gear case closing plate 4 and the frame interface fitting 34, and prevent 
the transmission from separating from the frame when the front of the 
vehicle is lifted off the ground. 
28 pitch involute gears were selected for the design example developed to 
illustrate the present invention. The number of teeth in each gear and the 
resulting gear ratios are given in the table below. The first number given 
is the number of teeth in the driving gear (gear 42 or 43) on the 
drive-gear-carrier 5; the second, the number of teeth in the mating gear 
(gear 49 or 50) driving the idler shaft 17; the third is the number of 
teeth in the idler gear on the idler shaft in the plane of which the gear 
selector 19 is located; and the fourth is the number of teeth in the 
mating gear on the free-wheel assembly 28. 
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Speed Gear Ratio 
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first 60/39 51/48 1.635 
second 60/39 54/45 1.846 
third 60/39 57/42 2.088 
fourth 60/39 60/39 2.367 
fifth 60/39 63/36 2.692 
sixth 72/27 51/48 2.833 
seventh 72/27 54/45 3.200 
eighth 72/27 57/42 3.619 
ninth 72/27 60/39 4.102 
tenth 72/27 63/36 4.667 
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To shift anywhere between the first and fifth speeds, or anywhere between 
the sixth and tenth speeds, the shift assembly 52 is used, as shown in 
FIGS. 2 and 9, and the pedals can be in motion or stopped. However, to 
shift between the fifth and sixth speeds, the pedals must be stopped with 
the cranks in a horizontal position with the right crank arm 10R facing 
aft, so that the shift arm 15 can engage the cable actuation pin 13, as 
described before. 
While this invention has been described in terms of a few preferred 
embodiments, it is realized that persons skilled in the art will, upon 
reading the written description and studying the drawings, be able to 
visualize many possible variations and alterations. For example, if three 
gears were used on the drive-gear-carrier instead of two, with four gears 
on the idler shaft, a twelve speed transmission would result with the same 
total number of gears as in the design illustrated. While this would 
require two pedal stops instead of one to cover the whole range of speeds, 
some applications might benefit from such a change. The invention should 
not be considered as limited to the number of speeds, gear ratios, or 28 
pitch gears illustrated. 
It is therefore intended that the following appended claims be interpreted 
as including all such variations, alterations, and modifications as fall 
within the true scope and spirit of the present invention.