Five speed chainless drive for heavily loaded pedal powered tricycles

A chainless drive for pedal powered tricycles features a pedal drive shaft located on the axis of the driving wheel and a five speed planetary transmission mounted concentric with the drive shaft and housed within the hub of the wheel. The transmission drives the wheel with a torque which is a multiple of the pedal torque for the two lowest speeds, provides a direct drive for the third speed, and drives the wheel at a multiple of the pedal speed for the two highest speeds. When used as a torque multiplier in the two low speeds, the transmission can drive the wheel either forward or in reverse depending on the direction the pedals are rotated, but permits coasting with the pedals stopped in speeds three, four, and five. A tricycle using this invention with a bin or flatbed should be useful in the factory or on the farm for the transport of parts or produce, or useful as a two passenger taxi with a seat assembly. Because the drive is completely enclosed, it can be operated for extended periods without maintenance even in dusty areas.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
This invention relates generally to transmissions for pedal powered 
vehicles such as bicycles and tricycles and more particularly to tricycle 
drive mechanisms of the chainless planetary type. 
2. Description of the Prior Art: 
The most common multiple speed utility tricycle uses a bottom bracket and a 
pair of sprockets and chain to drive a three speed planetary transmission 
which drives one of a pair of rear wheels through an axle. This 
arrangement provides speed multiplication but the maximum wheel torque is 
usually a fraction of the pedal torque, and the chain requires periodic 
cleaning and oiling for efficient operation and to prevent premature chain 
failure. Chain maintenance is particularly troublesome if the tricycle is 
used on dirt roads or in dusty areas. The present invention eliminates the 
maintenance problem and should be particularly useful in the rural areas 
of developing nations. 
SUMMARY OF THE INVENTION 
An object of this invention is to provide a low cost, compact, durable, low 
maintenance multiple speed drive which will provide torque multiplication 
as well as speed multiplication for pedal powered utility tricycles. 
The five speed chainless drive in accordance with the present invention 
includes a planetary transmission housed within the hub of the driving 
wheel. The transmission includes a pedal drive shaft rotatably mounted on 
the axis of the wheel; a ring gear rotatably mounted concentric with the 
pedal drive shaft with its axial position fixed and with provisions for 
selectively locking it against rotation; a sun gear rotatably mounted 
concentric with the pedal drive shaft with its axial position fixed and 
with provisions for slectively locking it against rotation; a planet gear 
carrier rotatably mounted concentric with the pedal drive shaft; four 
equally spaced planet gears rotatably mounted on bearings in the planet 
gear carrier with each planet gear in constant mesh with both the ring 
gear and the sun gear; provisions for selectively driving the sun gear, 
the ring gear, or the planet gear carrier from the pedal drive shaft; a 
one way clutch driving the wheel hub from the ring gear and a second one 
way clutch driving the wheel hub from the sun gear with provisions for 
disengaging the respective clutch when either the ring gear or the sun 
gear is driven from the pedal drive shaft; and a driving plate for driving 
the wheel hub in either direction from the planet gear carrier with 
provisions for disengaging the driving plate from the wheel hub when the 
planet gear carrier is driven from the pedal drive shaft. 
First speed is achieved with the sun gear driven from the pedal drive shaft 
with the sun gear clutch disengaged, the ring gear locked against 
rotation, and the planet gear carrier driven the wheel hub. 
Second speed is achieved with the ring gear driven from the pedal drive 
shaft with the ring gear clutch disengaged, the sun gear locked against 
rotation, and the planet gear carrier driving the wheel hub. 
Third speed is achieved with the planet gear carrier driven from the pedal 
drive shaft with the driving plate disengaged, and both one way clutches 
driving the wheel hub. 
Foruth speed is achieved with the sun gear locked against rotation, the 
planet gear carrier driven from the pedal drive shaft with the driving 
plate disengaged, and the ring gear driving the wheel hub through the ring 
gear clutch. 
Fifth speed is achieved with the ring gear locked against rotation, the 
planet gear carrier driven from the pedal drive shaft with the driving 
plate disengaged, and the sun gear driving the wheel hub through the sun 
gear clutch. 
The five speed chainless drive of the present invention is used in one 
embodiment in a rear wheel driven tricycle with front wheel rack and 
pinion steering, and a forward seat assembly suitable for use as a two 
passenger taxi. The seat assembly can be replaced with a parts bin or 
truckbed for transporting parts or produce.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 3, the five speed chainless drive according to the 
present invention includes a pedal drive shaft 15 located on the axis of 
the wheel hub 20. the opposite ends of the drive shaft 15 are supported 
inside inboard cylindrical extensions of the pedal crank arms 16 and 17 by 
sealed ball bearings 18 and 19 the outer races of which are clamped in 
rear dropouts on the tricycle frame as shown in FIG. 6. A reduced diameter 
integral cylindrical extension of a ring gear 22 is rotatably supported by 
an angular contact ball bearing 23 seated on the cylindrical extension of 
the right-side pedal crank arm 16. The right-side closing plate 21, which 
threads into the wheel hub 20 with right-hand threads, is supported by an 
angular contact ball bearing 24 with its inner race seated on the 
cylindrical extension of the ring gear 22. The spring loaded dogs 53 of a 
first one way clutch are mounted in the ring gear 22 on the pins 54 and 
engage conventional ratchet teeth on the right-side closing plate 21 for 
driving the closing plate 21 from the ring gear. a locking ring 25, which 
threads onto the cylindrical extension of the ring gear 22 with left-hand 
threads, retains the bearing 24 and permits the ring gear 22 to be 
selectively locked against rotation. 
An integral cylindrical extension of a sun gear 27 is supported by an 
angular contact ball bearing 28 with its inner race seated on the inboard 
cylindrical extension of the left-side pedal crank arm 17. A left-side 
closing plate 26, which is rigidly fastened inside the wheel hub 20, is 
supported by an angular ball bearing 29 with its inner race seated on the 
extension of the sun gear 27. The spring loaded dogs 51 of a second one 
way clutch are mounted on the sun gear 27 with the pins 52 and engage 
conventional ratchet teeth on the closing plate 26 for driving the 
left-side closing plate 26 from the sun gear 27. A locking ring 30, which 
threads onto the extension of the sun gear 27 with right-hand hreads, 
retains the bearing 29 and permits selectively locking the sun gear 
against rotation. 
Referring to FIGS. 3 and 4, oil-filled sintered bronze bearings 34 are 
press fit into four planet gears 32 which are mounted in a planet gear 
carrier 31 on polished steel pins 33. The pins 33 are retained in the 
carrier 31 by a driving plate 35 and an angle plate 36 which are clamped 
on opposite sides of the planet gear carrier 31 by four through bolts 37. 
As shown in FIG. 3 and 4, spline teeth extend along the entire length of 
the pedal drive shaft 15 for the transfer of torque from the pedal crank 
arms 16 and 17 to a pair of drive rings 42 and 43 which are slidably 
mounted on the drive shaft 15 with internal splines on the drive rings 42 
and 43 engaging the external spline on the drive shaft 15. The drive rings 
42 and 43 are each connected to a center pin 44 which in installed in a 
hole through the center of the drive shaft 15, by transverse pins 45 which 
pass through narrow axial slots in the drive shaft 15. The axial position 
of the drive rings 42 and 43 is controlled by a compression spring 48 and 
a small chain 55 which connects the pin 44 with a shift block 58 installed 
in a milled pocket in the pedal crank arm 16. The compression spring 48 
drives the center pin 44 and the pair of transverse pins 45 to the left 
end of the axial slots in the drive shaft 15. In this position, external 
teeth on the drive ring 42 engage internal teeth on the sun gear 27 for 
driving the sun gear from the pedal drive shaft and, as shown in FIG. 5 
the external teeth on the drive ring 42 rotate the clutch dogs 51 out of 
engagement with the ratchet teeth on the closing plate 26, and the closing 
plate 26 is driven by the planet gear carrier 31 through the driving plate 
35. 
The axial preload of the four angular contact ball bearings 23, 24, 28, and 
29 is adjusted with a thick washer 49 which is threaded into the left-side 
pedal crank arm 17 and which is clamped against the end of the drive shaft 
15 by a flush head screw 50 threaded into one end of the drive shaft 15. 
The axial preload is reacted by a spanner bolt 46 which is firmly seated 
against the other end of the drive shaft 15. The angular contact ball 
bearings maintain the axial position of the ring gear 22, sun gear 27, and 
wheel hub closing plates 21 and 26. 
The axial position of the planet gear carrier 31 is controlled by an 
angular contact ball bearing 38 the outer race of which is captive between 
internal teeth on the angle plate 36 and an internal retainer ring 40 
installed in the angle plate, and by a compression spring 39 which is 
installed between the inner race of the bearing 38 and an external 
retainer ring 41 on the drive shaft 15. The compression spring 39 drives 
the angle plate 36 to the left forcing the planet gear carrier 31 against 
the closing plate 26 and maintaining the axial position required for 
engagement of external teeth on the driving plate 35 with internal teeth 
on the closing plate 26. 
Referring to FIGS. 3 and 6, the chain 55 wraps around an internal radius in 
the bolt 46 and is connected to a pin 56 which is threaded into a square 
bushing 57 seated in the block 58. The compression spring 48 pulls the 
block 58 to the inboard end of the milled pocked 68 in which position the 
drive ring 42 is located for driving in the sun gear and the drive ring 43 
rotates freely with the drive shaft 15. As shown in FIG. 6, a latch 59 and 
spring 60 can hold the block 58 in either of two outboard positions 
through engagement of the latch 59 with a latch stop 67 which is riveted 
to a cover 64 clamped to the crank arm 16 with screws 65. In the inner of 
these two positions external teeth on the drive ring 43 engage internal 
teeth on the rear gear 22 and rotate the clutch dogs 53 out of engagement 
with ratchet teeth on the closing plate 21, and the drive ring 42 is moved 
out of engagement with the internal teeth on the sun gear 27. In the outer 
of the two positions, the drive ring 43 is moved out of engagement with 
the ring gear 22, the external teeth on the drive ring 42 engage internal 
teeth on the angle plate 36, and the drive ring 42 forces the bearing 38 
to the right compressing the spring 39 and moving the driving plate 35 out 
of engagement with the hub closing plate 26. With the block 58 in this 
position, the planet gear carrier is driven from the pedal drive shaft 15 
and both of the one way clutches are operative. 
As shown in FIGS. 3 and 6, a pin 61 which extends through the outboard end 
of the block 58 provides the means for moving the block 58 to any one of 
its three required positions through engagement with cams 69 and 70. The 
latch 59 is riveted on one end of the pin 61, and a latch release 63 is 
riveted on the other end. A flanged sleeve 62, which is press fit in the 
block 58, is located between the latch 59 and the latch release 63 with a 
slot shield 66 located inside the flange of the sleeve 62 to minimize the 
intrusion of dirt into the crank arm 16. 
As shown in FIG. 6, a pin 72 which is welded to the seat fork member 71, 
extends out through a slot through both cams 69 and 70 with the cams 
retained on the pin by a washer and snap ring. A pin 74 which is rigidly 
attached to a cam guide 73, extends out through an elongated hole in the 
inboard cam 70 and through a tight fitting hole in the outboard cam 69 
with the cams retained on the pin with a washer and snap ring. The pin 76 
which is rigidly fastened to the cam guide 75, extends out through a tight 
fitting hole in the inboard cam 70 and through an elongated hole in the 
outboard cam 69 with the cams retained on the pin 76 with a washer and 
snap ring. The cam guides 73 and 75 fit under flanges on the seat fork 
member 71 which prevent outward movement of the guides but permit them to 
slide axially. Compression springs 78 and 80 drive the guide 73 and 75 
down with the downward travel terminated by the upper end of the axial 
slot bearing on the fixed pin 72. Both cams 69 and 70 are raised with the 
turnbuckle 77 and cable 83. When the crank arms are rotated with the cams 
raised, the flanged sleeve 62 comes in contact with the cam 69 and moves 
the block 58 outward. When both cams are raised with the cable 83, the cam 
70 does not contact the latch release 63 which is located inboard of the 
cam 69 in the plane of the cam 70. But when the cam 70 is raised relative 
to the cam 69 with the turnbuckle 79 and cable 87, the latch release 63 
contacts the cam 70 which rotates the latch 59 out of contact with the 
latch stop 67 permitting the compression spring 48 (shown in FIG. 3) to 
lower the block 58 as the cable 87 is lowered. 
Referring to FIGS. 1 and 7, a shift assembly 82 is located on the frame top 
tube 81. The cable 83 is attached to a handle 84 and the cable 87 is 
attached to a handle 88. When the handle 84 is rotated aft, a semicircular 
cutout in it engages a pin connecting the cable 87 to the handle 88 and 
both handles rotate together lifting the cams 69 and 70 with the position 
of the cams relative to each other unchanged. When the handle 84 is 
rotated to carry a latch 85, which is mounted on the side of the handle 
84, past a first notch in the shift assembly 82, and the crank arms ar 
rotated to carry the pin 61 over the cams, the latch 59 moves past the 
first notch in the latch stop 67, and when the handle 84 is released the 
latch 59 holds the block 58 in the position required for driving the ring 
gear 22 from the drive shaft. When the crank arms are rotated with the 
handle 84 rotated aft to carry the latch 85 past a second notch in the 
shift assembly 82, the latch 59 holds the block 58 in the position 
required for driving the planet gear carrier from the pedal drive shaft. A 
spring 86 holds the latch 85 in engagement with the shift assembly 82 
until the handle 88 is rotated aft relative to the handle 84 to bring a 
pin 89, which extends out from the side of the handle 88, up against the 
latch 85 rotating it back against the spring force. When the crank arms 
are rotated with the handles 84 and 88 squeezed together, the latch 
release 63 contacts the cam 70 and rotates the latch 59 out of contact 
with the latch stop 67 so that when the handles 84 and 88 are rotated 
forward while still squeezed together and with the pin 61 located near the 
center of the cams, the block 58 is moved to the inboard end of the milled 
pocket. When the handle 84 is released in any position, the cams 69 and 70 
drop back to a position where neither the sleeve 62 or the latch release 
63 contacts them, so that the only purpose of the latch 85 is to indicate 
the position of the drive rings 42 and 43. 
Referring to FIGS. 1 and 6, a strut 91 connects a ring gear locking block 
90 which is slidably mounted in a track on the inboard side of the seat 
fork member 71, to a bell crank fastened on one end of an axle rotatably 
mounted in a bracket 93 located on the aft side of the seat post 94. A 
locking handle 92 is rigidly fastened to the center of the axle, and a 
second bell crank which is oriented 180 degrees from a first bell crank, 
is fastened on the other end of the axle and is connected by a second 
strut to a sun gear locking block slidably mounted in a track on the 
inboard side of opposite seat fork member. The locking handle 92 can be 
positioned in any one of three notches in a semicircular extension of the 
bracket 93. With the handle 92 in the center position both the ring gear 
and the sun gear are free to rotate. With the handle 92 in the forward 
position the sun gear is locked against rotation and the ring gear rotates 
freely. With the handle 92 in the aft position the ring gear is locked 
against rotation and the sun gear rotates freely. 
When the sun is driven from the pedal drive shaft with the ring gear locked 
and the planet gear carrier driving the wheel, the gear ratio is given by 
R=n/(n+N) where n is the number of the teeth on the sun gear and N is the 
number of teeth on the ring gear. When the ring gear is driven from the 
pedal drive shaft with the sun gear locked and the planet gear carrier 
driving the wheel, the gear ratio is R=N/(n+N). When the planet gear 
carrier is driven from the pedal drive shaft with both the sun gear and 
the ring gear free to rotate the drive is direct (R=1.000). When the 
planet gear carrier is driven from the drive shaft with the sun gear 
locked, and the ring gear driving the wheel, the gear ratio is R=1+n/N. 
When the planet gear carrier is driven from the pedal drive shaft with the 
ring gear locked and the sun gear driving the wheel, the gear ratio is 
R=1+N/n. 
In the example design developed to illustrate the present invention, 20 
pitch involute gears are used with a 20 degree pressure angle and 72 teeth 
for the ring gear, 40 teeth for the sun gear, and 16 teeth for the planet 
gears. The resultant pitch diameter for the ring gear is 3.6 inches. The 
gear ratios, equivalent wheel diameter for a 26 inch driving wheel, and 
speed for a pedal speed of 90 rpm are presented for the example design in 
the table below. 
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GEAR RATIO EQUIV. DIA. (INCHES) 
MPH 
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FIRST .357 9.282 2.5 
SECOND .642 16.692 4.5 
THIRD 1.000 26.00 7.0 
FOURTH 1.555 40.43 10.8 
FIFTH 2.80 72.80 19.5 
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While this invention has been described in terms of a preferred embodiment, 
it is anticipated that person reading the preceding descriptions and 
studying the drawings will realize many possible modifications thereof. It 
is therefore intended that the following appended claims be interpreted as 
including as such modifications as fall within the true scope and spirit 
of the present invention.