TITLE OF THE INVENTION: Regenerative Brake System of Bicycle
FIELD OF INVENTION:
The invention relates a mechanical regenerative brake system of bicycle in which kinetic
energy of the bicycle is captured during braking phase and this stored energy is released
later to move the bicycle forward.
BACKGROUND OF THE INVENTION AND PRIOR ART:
The main problem associated with all the existing designs of mechanical regenerative brake
system for bicycle is that, these are very inconvenient for the actual implementation in a
bicycle for the lack of compactness and so, these are not well accepted in practical field.
In all these designs, gear or chain drive or belt drive with set of pulleys are implemented to
transfer the energy of wheel to the spring. For this reason existing mechanisms consist of
numbers of rotating parts for which high rate of transmission loss can not be avoided. For the
same reason, all these mechanisms occupied an extended space also. Moreover, only one
compression spring is implemented to store the energy in existing designs and for this
reason, dimension of the spring is so large that it is very difficult to provide the spring in
limited space available in a bicycle frame. Besides, in all these designs, stored energy is
released immediate after the release of brake lever for which the rider can not be able to
release the brake lever even he do not wants to move just after braking and it is very
inconvenient during actual riding of the bicycle because every time situation may not be
favourable for immediate forward motion of the bicycle just after braking such as application
of brake in a traffic signal or application of brake to keep the bicycle in a parking place.
Brief particulars of prior art as known through patent search and internet surfing is narrated
under-
Prof. Amitava Ghosh of NT, Kanpur tried to implement similar concept to cycle rickshaw but
that was not popular. Prof. Ghosh used gear trains as intermediate drive for power
transmission. The design may be suitable for rickshaw but it is a bit complicated. Bicycle
regenerative brake system need not required such complicated intermediate drive. His
design will become clear from the reference sketches when read in conjunction with
presently proposed design. Sketch of the design of Professor is attached as reference.
In regenerative brake arrangement of bicycle described in a paper (ME 599-2003-02 dated
15/12/2003) by Michael Rescinity Adi Peshkess and Peter Leonard, to impart drive to the
ratchet pinion of rear wheel during release of stored energy, sprocket of chain drive rotated
by the spring action but foot pedal is also rotated along with, which is not a user friendly
system. Components including set of pulleys of the said design are also occupied an
extended space and so, it is very inconvenient to fit in the confined space available in an
actual bicycle. Also, high rate of transmission loss can not be avoided in this mechanism for
large numbers of rotating part. A brief particular of the design is attached separately as
reference.
Spiral spring is used in regenerative brake system described in U.S patent No- 6557877.
Spiral spring is not at all suitable for sufficient energy storage. Weight of the spiral spring will
be 14.8kg if to store the equivalent amount of energy as designed to store in compression
springs of the proposed brake system. The design is also most complicated for the use of a
set of ratchet apparatus and other components. Brief description is enclosed in reference.
PAGE - 1

OBJECTS OF THE INVENTION:
There exists a need for designing a compact mechanism for bicycle regenerative brake
system which can be suitably fit in the confined space available in a bicycle.
Also, there is a need to eliminate intermediate drive i.e. pulley/chain/gear train for energy
transmission from main drive to compression spring and vice versa to avoid complicacy and
to reduce frictional loss in the mechanism and thus designing an effective regenerative brake
system with minimum essential components.
Yet there is a need to retain the strain energy in the spring even after release of brake when
rider wants to keep the bicycle in rest position just after the application of brake. Later the
rider can use this stored energy when he again wants to start cycling. This necessary
provision is not arranged in other systems for which the rider can not be able to release the
brake lever even he do not wants to move just after braking and it is very inconvenient during
actual riding of the bicycle.
It is therefore, one object of the present invention is designing a compact regenerative brake
mechanism suitable to fit in a bicycle.
It is another object to design a regenerative brake for bicycle with minimum components and
to eliminate intermediate drive for energy transmission.
It is yet another object to design a regenerative brake for bicycle in which energy captured
during braking can be stored until the rider desire to use it.
SUMMERY:
Applicant's bicycle regenerative brake mechanism capable to capture the kinetic energy of
the bicycle during braking and this stored energy is released either just after release of brake
lever or later as desired by the rider to move the bicycle forward and thus it will be possible to
eliminate the loss of muscle energy for braking.
Invented brake system is designed for rear brake only. Front wheel is to be equipped with
conventional brake as usual. Stopping distance of the bicycle is suitably selected as 2.5mts
at a speed of 12kmph by the application of rear brake alone when total weight of the bicycle
is 90kg including the rider. So, sufficient energy can be stored in the invented brake
mechanism and also through the application of this brake system, bicycle can be stopped
within shortest distance to avoid accident but at the same time the rate of deceleration also
comfortable to the rider.
In this brake mechanism, a wheel gear is rotated with the wheel hub. During application of
rear brake, a brake disc is pressed against rotating wheel gear disc and through the
driveshaft and a rope pulley arrangement; a set of compression springs is compressed.
Thus, brake is applied by storing the kinetic energy of the running bicycle in the spring
assembly. After the release of brake lever, a ratchet and pawl mechanism if is in unlatched
position, springs return to its un-deformed stage and while returning to the original shape,
impart rotary motion to the wheel hub in forward direction through driveshaft, drive gear and
wheel gear. A freewheeling device prevents the rotation of drive shaft during normal running
of the bicycle. A ratchet and pawl mechanism is provided in addition in the brake system to
store the captured energy for later use even after release of brake lever. The whole
mechanism except spring set is provided in between chain stay pipes at the location of rear
wheel axle. Spring set is attached with bicycle mainframe.

The other objects, features and advantages of present invention will become clear from the
following description when read in conjunction with accompanying drawing.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING:
FIG.1- Shows the schematic view of regenerative brake mechanism of the present invention.
FIG.2- Shows the sketch of corrugated spring cage with three springs.
FIG.3- Shows the side view of brake mechanism housing in between "L'-shaped chain stay
pipes and in between rear wheel fork and location of spring cage in bicycle mainframe.
DETAILED DESCRIPTION:
The following description is provided to enable any person skilled in the art to make and use
the invention.
The mechanism is shown in Fig.1. A wheel gear (1) is fitted Inside of stepped wheel hub (2)
through tap bolts (3) and rotated with the hub. While rotated, it drives drive gear (4) through
pinion (5). All these gears are bevel gear type. Pinion is fitted inside of stationery gear
housing (6). On the outside circumference of a free wheeling device (7), drive gear hub is
press fitted and this free wheeling device is mounted on the drive shaft (8) through threaded
joint. The hollow drive shaft loosely enclosed the axle (9) and freely passed through the
large bore of the wheel gear. One end of the driveshaft is splined and a brake disc (10) is
splined over the driveshaft. Splined brake disc hub (11) is passed through the bore of the
narrowed diameter portion of stepped brake housing (12) and extended up to the larger
diameter portion of brake housing where brake disc operating mechanism (13), i.e. toggle
lever etc are provided. A pulley (14) is mounted on the other end of driveshaft and a set of
three compression springs (15) are compressed or decompressed through a wire (16) during
driveshaft forward or backward rotation for winding or unwinding of wire on the pulley.
Springs are kept inside of a corrugated shape common spring cage (17) as shown in Fig.2
which is secured diagonally by clamps with the bicycle mainframe (18) in left side (from near
the handlebar towards the rear wheel axle) as shown in Fig.3 and supported at its bottom on
stepped lower diameter portion of gear housing on a support block (19). The cage has a
clearance with mainframe pipes (clearance is necessary to align the pulley with drive wire in
the same plain). The spring actuating wire is fastened at its one end with the driveshaft
pulley and after two or three turns it passes through the axis of the middle spring of the
spring set and attached with common spring actuating plate (20). Set of three springs are
used to reduce diameter of the springs, otherwise, use of single spring of large diameter will
create obstruction during pedaling of the bicycle. A ratchet wheel (21) is mounted on the
drive shaft and a spring loaded pawl (22) pivoted in gear housing unlatched the ratchet tooth
when it is pulled by the release wire through a thumb operated release lever located in
bicycle handle. A locking slot is provided in bicycle handle to keep the release lever in pulled
position when desired. Gear housing and brake housing are fitted with the chain stay pipe
fork end (23) through axle (i.e. the position of these housings is in between rear wheel fork
legs-24 also). Stoppers (25) located at rear wheel fork legs prevent any undesirable rotation
of these housings. Wheel hub is mounted over these end housings through ball bearings
(26). Bore of the ratchet pinion (27) for normal chain drive is to be fitted on the stepped
smaller diameter portion of wheel hub. Rim spokes (28) are attached with the wheel hub at
larger diameter portion. To provide the whole mechanism in between chain stay pipes and in
between rear wheel fork legs, the distance in between the fork end of chain stay pipes and in
between rear wheel fork legs will be more than conventional type. Chain stay pipes will be
made L-shaped at its fork end (after spring cage, adjacent to gear housing). Diameter of
PAGE - 3

sprocket and pinion of chain drive are to be made larger than the sprocket and pinion of the
typical bicycle. Bicycle mainframe will also to be built robust (like existing sports bicycle) to
bear the load safely during spring actuation.
The brake operates as follows:
While wheel gear is rotated with wheel hub it drives drive gear in opposite direction
(backward direction) through pinion. As drive gear assembled with drive shaft through free
wheeling device so the gear freely rotated on the shaft. When brake lever is pulled, the
splined brake disc hub slides over the splined portion of drive shaft and pressed against the
wall of the wheel gear disc, which acts as driving plate of the brake disc (both brake disc and
wheel gear disc facing brake disc provided with friction lining for better frictional effect). As a
result, drive shaft rotated along with wheel gear and springs are compressed for winding of
spring actuating wire on driveshaft pulley which resists the motion of wheel gear, i.e. motion
of wheel hub. Thus, brake is applied and kinetic energy of the bicycle is stored in the
springs. During this time, rotary motion of the drive shaft does not impose any effect on drive
gear for free wheeling device and this gear freely rotated in backward direction as before
until bicycle comes to rest. After braking when brake lever is released then ratchet and pawl
mechanism if is in released position, strain energy of the springs is released to impart
forward motion to the bicycle because during returning of spring assembly to its original
shape, drive shaft rotated in backward direction and as free wheeling device is jammed in
this direction of drive shaft motion, so this time drive gear is rotated by the drive shaft which
in turn through pinion, impart rotary motion to wheel gear, i.e. to wheel hub in forward
direction.
Ratchet mechanism is provided for convenient use of stored energy. When release of stored
energy just after release of brake lever is not desirable then immediate before releasing of
brake lever, rider should release the thumb operated release lever located at bicycle handle
to prevent the rotation of drive shaft in reverse direction by locking of ratchet wheel through
engaged pawl. When desire, i.e. when again to move, rider can pull the release lever to pull
the spring loaded pawl for unlatching the ratchet tooth for releasing stored energy. Normally
during cycling, this release lever may be remained in pulled position for the release of
energy just after releasing of brake lever for which locking slot is provided in bicycle handle
to keep the release lever in pulled position.
It is an interesting point that, total kinetic energy of the bicycle when exceeds the design
value then after compression of springs up to the limit, frictional force in between the brake
disk and driving plate will be less than the force required for further compression of springs
and brake disc will be slipped over the driving plate during remaining part of brake
application and at that time brake system will work as like as conventional brake. Also, when
comparatively slower releasing of stored energy is desired, rider can arrange for slow
release of energy by keeping brake lever in partially released position while energy is
releasing.
Detailed Engineering Design of Main Components:
Design based on 20 Inch. Hero Jet Master bicycle of Hero Cycle Ltd. Total weight of the bike
including rider is 90Kg and braking distance selected 2.5mt at a speed of 12kmph by the
application of rear brake only.

Nomenclature of bicycle-
Self Weight- 18Kg.
Weight with rider- 90kg.
Wheel Diameter- 65cm.
Wheel Spacing- 108.5cm.
Height of the Seat- 84cm.
C.G. Point taken- 95cm from the ground.
Static Load Distribution- Static load distribution was measured by the help of portable weigh
machine keeping both wheels in the same level. It has been observed that 58 Kg load is
distributed to rear wheel and rest 32Kg load distributed to front wheel i.e. nearly 65% of load
is taken by rear wheel and rest 35% load is taken by front wheel. During test, 170cm tall
rider of 72Kg weight was chosen to select total weight of 90kg of the bicycle. Same test was
also performed with other riders. Test also performed in a typical 22inch BSA bicycle but
percentage of static load distribution in all the cases found almost same. Actually, the
percentage of weight distribution on rear wheel will be more than 65% in the bicycle with
invented brake system because; the mechanism will be arranged at the location of rear
wheel hub of the bicycle. Self weight of the bicycle will also be increased.
Analytical design with specifications-
Normal speed of a bicycle generally ranges from 8 to 12 kilometres per hour. Considering
the speed of 12kmph (3.33 mt / sec), K.E. of the bike of total weight 90kg- 1/2 m v2 = 1/2 x 90 x
(3.33)2 = 499N.M = 499 / 9.81 = 50.86kg.mt.
Taking a suitable value of 2.5mt braking distance (by the application of rear brake only) -
Braking force = Total K.E / Braking distance = 50.86 / 2.5 = 20.34kg.
Due to inertia, weight transferred to front wheel during braking-
Braking force x C.G / Wheel base = 20.34 x 95 /108.5 = 17.8kg.
So, dynamic load on front wheel during braking = 32 + 17.8 = 49.8kg and dynamic load on
rear wheel = 58 - 17.8 = 40.2kg.
In order to avoid skid during braking phase, the maximum braking force must not exceed the
product of dynamic load and of coefficient of friction in between wheel tyre and road. Even
taking the lower value of coefficient of friction 0.6 (u ranges from 0.5 to 0.8 between rubber
tyre and asphalt road)-
In this particular case, 40.2 X 0.6 = 24.12kg, which is higher than braking force, so rear
wheel will not skid during braking.
Let us selected 2mt braking distance when rear brake is hardly applied along with the light
application of conventional front brake.
Check for feasibility-
Total braking force = 50.86 / 2 = 25.43kg
Weight transfer = 25.43 x 95 /108.5 = 22.26kg
Dynamic load on rear wheel = 58 - 22.26 = 35.74kg
On rear wheel, product of dynamic load and coefficient of friction = 35.74 x 0.6 = 21.44kg,
which is still higher than the independed braking force of 20.34kg at rear wheel. In case of

emergency, when braking distance will be less than 2mt by strong application of both brakes
then rear wheel will skid and regenerative braking will not be effective.
Regenerative brake mechanism will be less complicated if implemented in front wheel for the
absence of sprocket pinion for chain drive in front wheel hub but this brake system is not
preferred for front wheel because, unless braking force is fairly low (2.5mt braking distance
at 9kmph speed), stored energy when released to accelerate the bicycle, front wheel will
spin freely for loss of gripping on road surface as product of dynamic load on front wheel
during acceleration and coefficient of friction will be less than acceleration force.
Arrangement for low brake power in front wheel is not suggested as front brake is more
effective for emergency stop and so it should be strong enough.
Axle Rod-
Material- Carbon steel, hardened and tempered
Static load on rear wheel = 58 kg. Static load on wheel will be increased for rider with higher
weight, during acceleration. Also, considering sudden shock on wheel due to pot hole, bump
etc. a factor of safety is taken 4 times of static bad = 4 x 58 = 232kg
Wheel is supported at two ends of the axle through wheel hub and stationary brake and gear
housing supports and so, load is divided in two parts which is equal to 232 / 2 = 116kg.
Location of rear wheel forks are considered at the axle ends at a distance of 1cm from
housing support ends. Therefore,
Bending moment M=116x1 = 116kg. cm
Again M =  /32xfbxd3
d = Diameter of axle
f b = permissible stress = 600kg / cm2
So, d3= 116x32/x 600= 1.97cm or d = 1.3cm
Drive Shaft-
Material- Carbon steel, case hardened
Taking inside diameter d marginally higher than diameter of axle and assumed 1.4cm
D= Outside diameter taken 1.5 times of inside diameter = 1.4 x 1.5 = 2.1cm
Checking failure against shear-
Fs=16TD/(D4-d4)
T = Braking torque = Braking force x Wheel radius = 20.34 x 0.325 = 6.61kg.mt. = 661kg.cm.
So, F s = 16 x 661 x 2.1 /  x (19.45 - 3.84) = 453.2kg / cm 2 which is less than permissible
stress of 600 kg / cm2 and so dimensions taken are safe against failure.
Shaft is designed with four splines.

Let D 1 = Distance in between two opposite splines. So, height of each spline = (D1 - D)/ 2
Taking D1 = 1.25 D
D, = 1.25x2.1 = 2.6cm
Height of spline = (2.6 - 2.1) / 2 = 0.25cm
Considering width of spline = 0.25 D 1
Width = 0.25 x 2.6 = 0.65cm
Crushing stress intensity = T/rm xnxa
T = Torque transmitted = 661kg.mt
rm= Mean radius = (D1 + D)/4 = (2.6 + 2.1)/4 = 1.2cm
n = No. of splines = 4
a = Bearing surface area of spline
Taking the value of crushing stress of 100kg / cm2
a = 661 /1.2 x 4 x 100 = 1.38sq.cm
As a = Length x height
So, Length of the spline = 1.38 / 0.25 = 5.5cm
Actual length of the spline is approximately 7cm as splined portion of the driveshaft is
extended through the narrowed bore of the brake housing up to the larger bore of brake
housing.
Brake Disc-
Lining material- Asbestos in rubber compound, compressed, on metal. Brake disc is
made of carbon steel and thickness of the plate will be 3mm.
Area of friction face- A = 2 r. b
r- Mean radius of friction lining.
b- Face width of lining, taken r / 4
Axial force acting on friction face W = A X p = 2 . r. b. p
p- Allowable pressure on friction surface, taken 5kg /cm2
Torque T =  W. r. n = u (2  r. b. p) r. n = u (2  r x r / 4 x p) r. n
T = 661 kg.cm
- Coefficient of friction, taken 0.4
n = 2, for friction lining at both sides
661 =/2 x 0.4 x r3 x 5 x 2
r 3= 105.25 or r = 4.7cm.
So, b = 4.7/4 = 1.2cm
Let r1 and r2 = Outer and inner radius of friction lining respectively. Since, radial width of
the lining is equal to the difference of outer and inner radius therefore
b = r1 - r2or r1 - r2=1.2-(i)
uniform wear, mean radius of lining r=(r1 + r2)/2or r1 + r2=2r

= 2 x 4.7 = 9.4cm (ii)
Equating (i) and (ii) r 1 = 5.3cm and r 2 = 4.1cm
Diameter of the brake disc hub is taken 1.5 times of the distance of opposite splines of the
drive shaft = 2.6 x 1.5 = 3.9cm. Length of the hub extended from brake disc is
approximately 6.5cm.
Axial force on friction face = 2 x x 4.7 x 1.2 x 5 = 177kg
Taking a mechanical advantage of 16 arranged both in brake disc actuating toggle lever
and brake operating lever in bicycle handle, brake operating lever provided in bicycle
handle is to be pulled by 177 /16 = 11kg force.
Toggle Lever-
Material- Carbon steel.
Taking mechanical advantage of 4 in toggle lever and taking length of the power arm of lever
from pivot =100 cm, bending moment near the pivot =177x10/4 = 442.5 kg.cm.
Assuming a rectangular section with depth equal to twice the width and a bending stress of
600kg / cm2
600 x 1 / 6 x t x 4 t 2 = 442.5
t = Width
t3 = 442.5 x 6 / 600 x 4 = 1.1 or t = 1.04 cm, say 1cm
So, width = 1 cm and depth = 2 x 1= 2cm
Freewheeling device-
Type- Over running clutch type worked on wedging principle with threaded inside bore
to fit over the drive shaft and drive gear is pressed fitted over the outer circumference of
freewheel.
Material- Forged steel, hardened steel ball in recess.
The balls inside should be able to bear the crushing force encountered, which can be
checked through the equation
Crushing force f c=2T/nXdx tan 
T = Torque transmitted = 661kg.mt
d = Diameter of ball
n = No. of balls, taken 8 in nos.
 = Angle between tangents to the cam contour and to the ball surface at the point of
contact, taken as 30 degree value of which is 0.5774. (For proper locking action, angle
between cam contour and to the roller surfaces at the point of contact must be less than
twice the angle of friction)
Taking permissible crushing stress of 600kg / cm 2 for hardened steel balls
d = 2 x 661 / 600 x 8 x 0.5774 = 0.48cm
Outside diameter D , of driving member is selected 2.5 times of the outside diameter of
drive shaft = 2.5 x 2.1 = 5.25cm, finally taken as 5.5cm.

Diameter of driven member shell D 2 is taken equal to 1.25 D 1 = 1.25 x 5.5 = 6.9cm.
Width of free wheeling device W is chosen 0.25 times of D 2 = 1.7cm.
Freewheeling device worked on wedging principle is chosen for its reliability because; the
following dangerous situations may arise for sudden malfunctioning of freewheeling device-
1. Free wheeling device in case becomes free in both direction of rotation; brake can be
applied but thereafter brake lever when released (provided ratchet mechanism is kept unlock
at that time) drive shaft will rotate freely without imparting forward motion to the bicycle wheel
but in case brake lever still remains in applied position after compression of springs then
bicycle wheel will try to rotate in reverse direction.
2. In case, free wheeling device suddenly jammed in both direction of rotation then If release
lever for ratchet and pawl is in pulled position brake wire will be wound-up in reverse direction
for the rotation of driveshaft in backward direction and so, without applying brake lever, brake
will be automatically applied first thereafter bicycle wheel will try to rotate in reverse direction.
If release lever for ratchet and pawl is not in pulled position at the time of sudden jamming of
free wheeling device then bicycle wheel will try to wind-up the brake wire in reverse direction
but ratchet and pawl mechanism prevent this reverse rotation of drive shaft and as a result
wheel will be either jammed suddenly just when free wheeling device is jammed or ratchet and
pawl teeth I pin may be broken.
Bevel Gear and Pinion-
Material- 0.4 %Carbon steel hardened and tempered.
Selecting pressure angle- 20 degree, circular pitch - 0.63 and No. of teeth in pinion-17
P.C diameter of bevel pinion at the large end = 17 x 0.63 /  = 3.4 cm.
Gear ratio-3.55:1
No. of teeth in bevel gearwheel = 17 x 3.55 = 60.35 say, 60
P.C diameter of gear at large end = 60 x 0.63 /  = 12cm
Pinion semi pitch cone angle YPP= tan-1 n p / n w, where, n p and n w are the no. of teeth in
the pinion and wheel respectively = tan -117 / 60 = tan -1 0.2833
So, Ypp = 0.2833 radian = 160 12'
Since the shafts are in right angle, wheel semi pitch cone angle Ywp = 900 -16012'
= 730 48'
Face width = 1 / 3 x pitch cone distance = w
Pitch cone distance L = D p / 2 sin ypp- = n p x p / 2  sin ypp,
Where, D p is the P.C diameter of pinion.
w= 1 /3 x np x p/2 sinYpp, = 1 /3 x 17 x 0.63/2 x 0.2790 = 2cm.
So, L = 6cm.
Strength of Pinion and Gearwheel according to Lewis equation-
Virtual No. of teeth for pinion = 2x back cone radius of pinion / c.p at radius D p / 2
PAGE-9

Back pitch cone distance = D p / 2 cos YPP= 3.4 x 2 x 0.9603
So, virtual No. of teeth for the pinion = nvp = 2x 3.4/2x 0.9603 x 0.63
= np/COS Ypp= 17/0.9603 = 17.7
For 20 degree involute gear, for this No. of teeth, tooth factor y = 0.154 - (0.912 / 20) =
0.108
Correction factor =1-w/L=1-(2/6) = 0.667
Tangential load F at the pitch line = s. w. y. p x correction factor
s- Safe working stress
p- Circular pitch
Safe working stress = basic stress x velocity factor c v where velocity factor = 3 / (3 + v), in
which v is the peripheral velocity of pinion.
Peripheral velocity of the pinion =  x diameter of pinion x r.p.m of the pinion / 60
Where, r.p.m of the pinion = 3.55 x r.p.m of bevel gear i.e. 3.55 x r.p.m of the bicycle wheel
of diameter 0.65 mt at 12 kmph speed = 3.55 x 12000 / 60 x 0.65 x  = 347.69
So, peripheral velocity of pinion =  x 3.4 x 347.69 /100 x 60 = 0.619mt / sec.
Velocity factor = 3 / (3 + 0.619) = 0.829
Safe working stress = 3000 X 0.829 = 2487kg / cm 2
Taking basic stress as 3000kg per sq.cm, where, 6000kg. per sq.cm is the ultimate stress of
0.4 carbon steel which is divided by the safety factor of 2.
So, F = 2487 x 2 x 0.103 x 0.63 x 0.667 = 215.3kg.
Check for Gear Wheel-
Wheel semi pitch cone angle = 730 48'
Wheel pitch cone distance = 6cm. (same as for pinion)
Virtual No. Of teeth for gearwheels = n vw = n w / cos 730 48 '= 60 / 0.2790 = 215 Nos.
y = 0.154 - (0.912 / 215) = 0.15
F = 2487 x 2 x 0.15 x 0.63 x 0.667 = 313.5kg.
Information required for gear cutting and tooth proportions-
a. Tooth proportions at large end-
Addendum = cp / % = 0.63 /  = 0.2cm
Clearance = 0.157 addendum = 0.2 x 0.157 = 0.03cm
Dedendum = Addendum + Clearance = 0.2 + 0.03 = 0.23cm
Whole Depth of Tooth = Addendum + Dedendum = 0.2 + 0.23 = 0.43cm
b. Information for pinion-
Blank diameter D = Outer pc diameter + 2 addendum cos YPP
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= 3.4 + (2x0.2xcos16°12')
= 3.4 + (2 x 0.2 x 0.9603) = 3.78cm
Semi face angle = Pinion addendum angle + semi pitch cone angle
Pinion addendum angle = tan -1(addendum / cone distance) = tan -1 (0.2 / 6) = tan -1 0.033 =
1°54'
So, semi face angle = 1 ° 54'+ 16° 12' = 18°6'
c. Information for wheel-
Blank diameter D = Outside pc diameter + 2 addendum cos ywp
= 12 + (2 x 0.2 x cos 73° 48')
= 12 + (2 x 0.2 x 0.2790) = 12.11 cm say, 12cm
Semi face angle = 1 ° 54'+ 73° 48' = 75° 42'
d. Dedendum angle for both pinion and wheel = tan -1 dedendum / cone distance
= tan -1 0.23 / 6 = tan -1 0.0383 = 2° 12'
e. Face width = 2cm
f. Exact gearing ratio = 60:17 = 3.529:1
Compression Springs-
Material- Manganese steel
Corrugated shape Spring Cage is made from 2mm thick aluminium sheet. To avoid the
wear of aluminium cage due to friction, another cage made from 0.5mm thick stainless
steel sheet is push fitted inside of aluminium cage.
Mean diameter of each spring coil- 2.5cm.
Modulus of rigidity assumed- 840000 kg / cm 2
Permissible torsional shear stress taken- 4500 kg / cm2
Total axial load on 3 number springs during brake application = Braking torque x radius of
the drives haft pulley
Considering driveshaft pulley diameter as 7cm
Total Axial load = 661 x 2 / 7 = 188.85kg
So, axial load on each spring = 188.85 / 3 = 62.95kg.
Maximum torque on the section of each spring wire = Load x mean diameter of the coil / 2
= 62.95 x 2.5 / 2 = 78.69kg.cm
If d w be the diameter of the wire, then  / 16 d w 3 x fs = 78.69
Or, d w 3 = 78.69 x 16 / 4500 x % or, d w3 = 0.089cm,
So, d w = 0.447, assumed SWG- 7 wire whose diameter is 0,447mm.
Total deflection of springs = % x diameter of drive shaft pulley x Number of turns of bicycle
wheel to cover the braking distance
Number of turns of bicycle wheel to cover the braking distance = braking distance /
circumference of wheel = 2.5 /  x 0.65 = 1.22 turns

So, deflection =  x 7 x 1.22 = 26.83cm
Stiffness of the spring = Load / deflection = 62.95 / 26.83 = 2.34kg / cm
Spring index = Spring diameter / wire diameter = 2.5 / 0.447 = 5.59
Again, stiffness = Modulus of rigidity x diameter of wire / 8 x (spring index) 3 x number of
active turns of spring coil.
So, number of active turns = 840000 x 0.447 / 2.34 x 8 x (5.59) 3 = 114.83, considering
squared and ground ends, actual number of turns taken 116.83.
Solid length of the spring = Total number of coils x diameter of the wire = 52.22cm
Free length of the spring = Solid length + maximum deflection + clash allowance
Taking clash allowance 15% of the maximum deflection, free length of the spring = 52.22 +
26.83 + 4 = 83cm.
Volume of each spring = area of the spring wire x circumference of the coil x number of
turns =  x (0.447)2 x  x 2.5 x 116.83 x / 4 = 144cc
So, weight of each spring =Volume of the spring x specific gravity of steel spring = 0.144
x 7.8 = 1.12kg, so total weight of the spring set consists of three springs = 1.12 x 3 =
3.36kg.
In conventional bicycle, distance of bicycle mainframe from right side and left side food pedal
cranks are 5cm and 4cm respectively. The spring cage is arranged in left side of the bicycle
frame and so left side crank gap from mainframe of the bicycle with the invented brake
system is kept 5cm to avoid any obstruction during pedalling of the bicycle.
Steel Wire Rope-
3.175mm (1/8 inch) wire is selected for transmission of energy from drive shaft to
compression spring and vice-versa.
Checking failure against tensile load-
Factor of safety taken 4 times of normal axial load = 188.85 x 4= 755.4kg
Area of 3.175mm diameter wire =  x (3.175)2 / 4 = 7.9 mm 2
Taking tensile strength of wire taken -100kg / mm2
7.9 x 100 = 790kg is more than maximum designed load of 755.4 kg and so is safe against
failure.
Driveshaft Pulley-
To minimise bending stress diameter of the pulley is taken 20 times of the wire rope =
3.175 x 20 = 63.5mm, finally taken as 7cm as mentioned during the design of compression
spring. Groove with ample clearance is provided at the circumference of the pulley.

Ratchet and Pawl Mechanism-
Material- Carbon steel, hardened and tempered
Crushing stress intensity f c on locking tooth of ratchet wheel = T / r m x a
T- Transmitted torque = 550kg.mt
a- Bearing surface area at the locking end of the tooth
r m = Mean radius = (D 1 + D) / 4
D = Diameter of root circle of ratchet wheel, taken equal to 2 times of the outside diameter of
drive shaft = 2 x 2.1 = 4.2 cm and D 1 = Addendum circle diameter of the wheel, taken equal
to1.5xD = 1.5X4.2 = 6.3cm.
Height of the high end of each tooth is so, (6.3 - 4.2) / 2 = 1.05cm and r m = (6.3 + 4.2) / 4
= 2.6cm
Taking permissible crushing stress = 100kg / cm2
a = 550/100x2.6 = 2.1sq.cm
As a = Length x height and so, length of the tooth = 2.1 /1.05 = 2cm
Base width of the tooth is taken- 0.25 xD, = 0.25 x 6.3 = 1.57cm.
Tip edge of the pawl is slightly round in shape. Reason behind is that, in any case by mistake,
if release lever is released while stored energy is releasing, then knocking in between rotary
ratchet teeth and pawl may be the cause of damage of the tips of ratchet teeth or pawl. To
minimize the harmful effect of such knocking, tip edge of the pawl should not have any sharp
edges; rather tip edge is preferred slightly round in shape. Thus tip of the pawl will be slipped
over the ratchet teeth until pawl lock the ratchet wheel when rotational speed of ratchet
decreases.
Wheel Hub and Stationary Housings-
Wheel hub and other two stationary housings are made of die cast aluminium alloy.
Diameter of wheel hub at larger portion is taken 16cm and diameter of stepped smaller
portion is chosen approximately 6.5 cm. Thickness of the hub shell is taken 2mm which
is checked against failure due to the stress developed for bending load. Thickness of
stationery housings are also taken 2mm.
Sprocket and Ratchet Pinion-
Ratchet pinion of chain drive mounted over the smaller diameter portion of the wheel hub
but even then, the pinion is approximately 1.5 times larger than pinion of chain drive of
typical bicycle. Accordingly, diameter of the sprocket is also 1.5 times of conventional
bicycle sprocket. Teeth dimensions of sprocket and pinion is however remained same
as conventional bicycle chain drive, only number of teeth is increased.
Rear Wheel Fork and Chain Stay Pipes-
Spacing in between the legs of rear wheel fork and chain stay pipes of the mainframe is
approximately 19cm. These components are made of carbon steel.

ATTACHED REFERENCE:
1. Sketch of Regenerative Brake Design of Prof. Amitava Ghosh, Dept. of Mechanical
Engineering, IIT, Kanpur for cycle rickshaw.
2. Regenerative Braking System (for Bicycles), ME 599-2003-02, by Michel Resciniti, Adi
Peshkess and Peter Leonard, dated-15/12/2003.
3. Regenerative Braking and Driving Apparatus, United States Patent 6557877
14

CLAIMS:
A regenerative brake mechanism of bicycle comprising:
1. A set of compression springs which compressed during braking phase and after
braking, stored energy is released from springs to impart forward motion to the bicycle.
A bevel gear train, freewheeling device, brake disc, driveshaft, and associated housings.
A ratchet and pawl mechanism to retain the strain energy in the spring even after release of
brake lever after braking.
2. The regenerative brake mechanism of claim 1, wherein, energy transmission is made
possible directly from main drive to compression springs and vice versa without the use of
intermediate transmission drive.
3. The regenerative brake mechanism of claim 1, wherein, compression spring set is kept
inside of a cage which is secured with the mainframe of the bicycle.
4. The regenerative brake mechanism of claim 1 and 3, wherein, a set of compression spring
is used in place of one large size compression spring to fit conveniently in the limited space
within the bicycle mainframe.
5. The regenerative brake mechanism of claim 1, wherein, except compression spring set,
the whole mechanisms is arranged in between the compact space of chain stay pipe ends at
the location of rear wheel axle.
6. The regenerative brake mechanism of claim 1, wherein, use of separate brake disc driving
plate is eliminated as brake disc is pressed directly against wheel gear disc.
7. The regenerative brake mechanism of claim 1, wherein, a ratchet and pawl mechanism is
implemented for which it is possible to retain the stored energy in springs even after release
of brake when rider wants to keep the bicycle in rest position after braking and use of this
stored energy is possible later by releasing of a release lever.
8. The regenerative brake mechanism of claim 1 and 7, wherein, tip edge of the pawl is
slightly round in shape so that if by mistake, the rider released release lever while stored
energy is releasing, tip of the pawl will be slipped over the ratchet wheel teeth until pawl lock
the ratchet wheel when rotational speed of ratchet wheel decreases. Otherwise, knocking in
between rotary ratchet teeth and pawl may be the cause of damage of the tips of ratchet
teeth or pawl.
9. The regenerative brake mechanism of claim 1, wherein, regenerative brake mechanism is
implemented in the bicycle without alternation of most of the conventional parts of an
existing bicycle.
10. The regenerative brake mechanism of claim 1, wherein, full kinetic energy of a bicycle
can be captured up to a speed of 12kmph when total weight of the bicycle is 90kg including
the rider.
NAME OF THE APPLICANT: Sankha Subhra Datta
SIGNETURE:

The invention provides a bicycle regenerative brake mechanism capable to capture the
kinetic energy of the bicycle during braking and this stored energy is released either just
after release of brake lever or later as desired by the rider to move the bicycle forward.
Invented brake system is designed for rear brake only. Front wheel is to be equipped with
conventional brake as usual. Stopping distance of the bicycle is suitably selected as 2.5mts
at a speed of 12kmph by the application of rear brake alone when total weight of the bicycle
is 90kg including the rider.
The mechanism consists of a set of compression springs which compressed during braking
phase and after braking, stored energy is released from springs to impart forward motion to
the bicycle provided a ratchet and pawl mechanism is in released position. The main
components of the mechanism are- compression spring set, bevel gear train, a freewheeling
device, brake disc, driveshaft, ratchet and pawl mechanism and associated housings. The
whole mechanism except spring set is provided in between chain stay pipes at the location of
rear axle. Spring set is attached with bicycle mainframe.
The novelty of the proposed brake system is that, the said mechanism is more compact with
minimum essential components and so more attractive than existing other designs.