CA1098455A - Bicycle pedal actuated brake control and release system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A bicycle having front and rear wheel caliper brakes connected by cables to a plate member rockably mounted on a support rearwardly of the crankshaft; there being a latch arm engaged to said plate and having a cam follower portion for engaging a cam formed on the edge of a disc cam keyed on said crankshaft for mutual interengagement upon back pedaling action whereby said latch arm is translated rearwardly with consequent rocking of said plate member to apply a rearward pulling upon said cables for braking of the bicycle, A drive sprocket is carried upon the opposed end of said crankshaft for limited relative movement with respect thereto, there being an arcuate aperture in said drive sprocket receiving a pin from the adjacent pedal crank, which pin is relatively movable within said aperture so that after braking action said crankshaft may be rotated a predetermined distance prior to engagement of the finger with the forward end of the aperture for consequent concurrent rotation, said predetermined distance being adequate for disengaging said latch arm for brake releasing action. The brake release aspect of this invention may also be used with bicycles having front free wheel systems wherein an arrangement of intermeshing teeth are provided on the drive sprocket and a sleeve to allow for requisite relative movement.

Description

lOq~4~ .
This invention relates in general to bicycles and, more particularly, to pedal actuated braking systems ther~for.
This application is a division of Canadian Application Serial No. 315,694, filed October 31, 1978.
With the widespread usage of caliper bra'~es on hicycles there has understanclably been numerous efforts made or eliminating the necessity of operating such brakes by hand controls and substituting therefor pedal actuating means.
~mong such efforts are the systems disclosed in U. S. Patent Nos. 3,858,689; 3,966,299 and 4,030,774. ~lthough such prior art discloses various cam operated linkage means for effecting braking force upon the hrake control cahles, the same have been relatively complex in construction an~ have invariabl~
required the utilization of a manually operated releasing mechanism to return the system to unbraked condition. Thus, said systems heretofore known have not had the capability of permitting a brakin~ action without causing a locking of the brakes. I~ith the brakes thus in locked condition the tautness of the transmission cable inhibits any forward rotation of the pedal crankshaft until the brakes have been released.
Accordingly, it has been recognized that the prohlem to be resolved resides in preventing a locl;ing of the brakes while permitting bra};ing action so that forward travel could be promptly resumed without the intervention o some hand manipulation for brake release action.
In Patent No. 3,966,229 there are shown various e~pedients designed to create a slackness in tlle transmission ca~le during braking action for the purpose of allowing the crankshaft to turn for resuming forward travel from braked condition. If the crankshaft can turn forwardly and not be restrained by a taut chain, brake releasing could be brought about without independent operation. ~lowever, although effective, the structures set forth in said last-mentioned q~

~0'1'84~5 patent are indeed relatively complex and expensive to produce and install, Therefore, it is an object of the present invention to provide a brake control and release system for bicycles wherein despite chain tautness being brought about through braking action the crankshaft may turn in advance of rotation of the drive sprocket for resuming forward travel with concurrent brake release.
It is another object of the present invention to provide a pedal actuated brake assemhl~ for hicycles which incorporates a minimum number of components which are of dura~le sturdy construction so that malfunctioning is substantially eliminated.
It is another object of the present invention to provide a pedal actuated brake control assembly for bicycles which permits of braking act1on without causing the bicycle wheels to become in a fully locked state thereby according the operator a sensation of braking comparable to that of automobile power brakes.
It is a further object of the present invention to provide a pedal actuated brake control assembly for bicvcles which, at the option of the operator, may produce a wheel locking condition for parking purposes and with means for readil~
effecting release from such state, It is a still further object of the present invention to provide a pedal actuated brake control and release assembly for bicycles which is adapted, for incorporation upon existing bicvcles whether single speed, thrçe-speed or ten-speecl and including bicycles which are provided with front free wheel systems, such as identified by the name "Shimano"; with the installation of the present invention being achieved with : . .: . ;
:.

facility and without modification of the bicycle basic structure.
It is another object of the present invention to provide a brake control and release assembly which although being more readily adapted for use with a unitary crankshaft for pedal crank arrangement may also be used with multi-part pedal crank assemblies.
Thus broadly, the invention contemplates a brake release means for use with a bicycle having a frame, front and rear wheels supported on the frame, a pedal crank assembly having a crankshaft and first and second pedal cranks at opposite ends thereof, a drive sprocket carried on the crankshaft inwardly of the first pedal crank, a driven sprocket engaged upon the rear wheel, and a transmission chain interconnecting the drive and driven sprockets. The brake release means permits limited relative movement between the drive sprocket and the crankshaft after bicycle braking action whereby the crankshaft may turn prior to resumption of rotation of the rear wheel, and the means comprises a sleeve-forming member carried on the crankshaft with the drive sprocket having a central opening for extension there-through of the sleeve-forming member, circumferentially spaced-apart teeth provided on the sleeve-forming member with the drive sprocket having a circumferential series of notches projecting inwardly from the central opening for receiving the teeth of the sleeve-forming member, and with the ~otches being formed on a greater arc than the teeth, and resilient means urging the teeth toward one of the related notches.
In a further embodiment, the invention contemplates a brake control assembly for use with a bicycle having a frame with a hub-forming casing, front and rear wheels supported on the frame, a pedal crank assembly having a crankshaft extending through the hub-forming casing and pedal cranks projecting from each end of the crankshaft, and front and rear wheel caliper 1~9~55 brakes. The brake control assembly comprises a disc cam carried on the crankshaft having at least one cam working surface, rigid support means provided on the bicycle rearwardly of the cam, a plate member swingably mounted in its lower portion upon the support means with brake control cables extending from the front and rear caliper brakes, and means provided on the plate member upwardly of its pivotal mounting engaging the brake-remote ends of the brake cables A latch arm extends substantially longitudinally of the bicycle above the crankshaft and is engaged in its rearward portlon to the upper rearw.lrd pol-tion ` of the plate member, and a cam follower is formed on the latcharm in its lower portion for engagement with the cam working surface upon back pedaling action of the crankshaft whereby the latch arm is urged rearwardly to effect rocking of the ,~
plate member causing rearward pulling upon the brake cables for bicycle braking action.
..i .~A, Additionally, the brake control assembly can be furthcr ; characterized by brake cable guide means provided on the support means rearwardly of the crankshaft, with the guide means extending forwardly from the support means spacedly above the crankshaft, and with the engaging means being located rearwardly of the guide means and with the brake cables passing through the respective guide means.

'' lQ~55 In the drawings which illustrate embodiments of the invention FIGURE 1 is a side view of a bicycle having mounted thereon a pedal actuated brake constructed in accordance with and embody-ing the present invention.
FIGURE 2 is an enlarged, fragmentary side view, in partial section, taken substantially in the zone indicated at "2" in FIGURE 1 illustrating the brake mechanism in braking condition.
` FIGURE 3 is a top plan view taken on the line 3-3 of FIGURE 2.
FIGURE 4 is a vertical transverse sectional view taken on the line 4-4 of FIGURE 3.
FIGURE 5 is a fragmentary rear elevational view, in partial section, taken on the line S-S of FIGURE 3.
FIGURE 6 is a transverse view, in partial section, taken ~, on the line 6-6 of FIGURE 3.
:' - FIGURE 7 is a side view taken on the line 7-7 of FIGURE 3.
FIGURE 8 is a top plan view, in partial section, of a pedal crank assembly of a front freewheel system incorporating a brake release constructed in accordance with and embodying the present invention.
FIGURE 9 is a vertical view, in partial section, taken on the line 9-9 of FIGURE 8.

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FIGU}~l~ 10 i~ a fra~m~ntary v~rtic~l vie~r, ~rtiall~
hroken away, talcen on tlle lin~ 10-10 Oe FI(~UR~ ~.
~.ferring nQW by reference numerals to the dra~in~s which illustrate the preferred embocliment of t~le ~resent invention, n yenerally clesignate~ a ~ic~cle includlnn a frame F havin~ a front fork 1 mounting a front l~heel 2, a ~ear for~
3 moun~ing a rear wheel 4, with th~re being a cros~ bar 5 connecting saia fork~ 1,3. ~rame 1~ also lncorporate~ Eront and rear ~iagonal ~ar~ 6,7, r~6~ectivelY, whicll at their lo~er enc~s merg~ lnto th~ usual hul? ~ t it~ orwar-~ u~-p~r en(l -~ front ~lagonal bar fi i5 int~gral ~ith the upper ~ortion of ~ost 9 o front fork 1, ~hile the u~T~er ~n~ of re.~r ~-lin~onal har 7 i5 unitary with the upp~r en~l of ~ork 3 an~ th~ rear;~ar~
~nd of cross bar 5; there h~ing thQ customarY rofl 1~ heinn .~ exten~ibly accommodated in rear diagonal bar 7 for sun~ortin~
:
: the u~ual seat 11. i`1ounted upon poat 9 are handle ~ars 12.
Divergiril~ rear~ardly from hub 8 are the usual support har~
13,14 for the rear axle ~ acllt~rheel 2,Q is of the spo.~e-tyl-e, embodying the customar~ rim 15 for receiving a tire lG.
llub n su~ports a ~haft 17 o a pe~al crank as~.e~ly P, which in most ~m2rican made l)icycles i3 of one ~iece constructlon, ~ith t~ aft 17 carryln~ at ~ach ~nfl therc~
: the u~ual pedal. crank 18,1~' ~ihich~ ~t th~lr ~e~p~cttve ~nd~, each carry a foot pedal 1~. A~ ~hown in FI~U~ oot ~lalæ
19 have enqa~e-l thereon bic~cle ~uPt~ort stan~ 5 ~hich ~a~ b~
of the type sho~rn in U.S. Patent Nos. 3,857,585; 3,877,726 and 4,030,774, the o~eration of whi.ch coor~inates ~ ith the hra~ina action, as mor~ fully ~evelo~e~ in the aforesaid ~atents.
Bicycle ~ is provided Wit]l caliper ~rakes 20,21 u~on front and rear wheels 2,4, respectively.
~ltilough the ~raking s~tem of the present invention is useful upon bicycles of variou3 types, suc~ a5 sln~le snee~, three-speed, and ten-speed; Bicycle ~, for purposes of simplicity of exposition, is shown herein as embodying a single front chain wheel or drive sprocket 22 mounted upon hub 8 in a manner to be described below and having engaged thereabou-t the orward end portion of the usual endless transmission or drive chain 23 which is engageable in its rearward end portion about a drive sprocket (not shown) or a predetermined driven sprocket of a cluster, customarily five, o driven sprockets, or so-called derailleur gears, mounted upon rear axle a in side-by-side xelationship on ten-speed bicycles.
Referring now particularly to FIGURE 4, it will be seen that shaft 17 immediately proximate crank 18 is externally threaded, as at 24, for threadedly engaging the inner racc 25 which is of general conical form of a ball bearing assembly 26 incorporating as an outer race 27 the inner cooperating portion of a cup 28 of a stationary bracket 29 of a braking assembly, indicated generally B; ball bearing assembly 26 being tllus of well-known construction does not form a part of the present invention, Cup 28 is pressed, as in the usual fashion, within the adjacent end of hu~ 8 which constitutes a crank housing. Bracket 29 integrally emhodies a peripheral flange 30 extending circumferentially about the normally open end of cup 28 which flange in its rearward portion (see FIGURE 2) is extended to provide an upper boss 31 wllich is inwardly offset from the major plane of flange 30, as at b (FIGU~E 5), Said Boss 31 is provided with laterally out-turned flange 32 provided with a pair of vertically aligned upper and lower apertures 33,34 for purposes presently appearing.
Do~nwardly of boss 31, brac~et 29 in its rearward edge is downwardly and rearwardly inclined, as at 35, with there being an inwardly turned detent or foot 36 extending immediately above bicycle frame support bar 13 and abutting the upper edge of the latter in the lower end portion o said detent 36 for inhibiting rotation of bracket 29 about shaft 17.
; Downwardly of marginal portion 35, brac]cet 29 embodies a boss 37 having an aperture 38 for purposes presently appearing.
It will thus be seen that bracket 29 is of general plate character but incorporating a stamped cup and oppositely extending flange 32 and detent 36. Keyed upon shaft 17, immediately outwardly of bearing 26, is a disc cam 39 incorpo-rating a pair of working edge portions 40,41 which are 180 apart, Serving to prevent untoward displacement of cam 39 is a retention nut 42 threadedly secured upon shaft 17 (FIGURE 4).
Provided for swingable movement with respect to bracket 29 is a pivot plate 43 having an opening 44 in its lower portion for alignment with aperture 38 of bracket 29 for extension therethrough of a rock pin 45. Above opening 44 the pivot plate 43 is outwardly offset, as at c,for cooperating with the offset b of bracket 29 to provide an intervening clearance or spacing d for purposes presently appearing. In its upper forward portion, pivot plate 43 is contoured to present a forwardly opening recess 46 which extends slightl~
downwardly and rearwardl~, as at 46'. Above recess 46 plate 43 is formed to provide an offset ear 47 extending laterally outwardly and in substantial registration with ~lange 32 of bracket 29; said ear having upper and lower openings 48,49 in alignment with upper and lower apertures 33,34 for purposes presently appearing, In the rearward upper portion of pivot plate 43 there is provided an opening 50 for alignment with an aperture 51 formed in the rearward end portion of a latch arm 52 for .

L5~5 receiving a pin, rivet, or other suitable fastening element 53, said latch arm 52 extending into the spacing d. Latch arm 52 is relatively elongated and proceeds forwardly from its point of attachment to pivot plate 43, upwardly of cam 39 to a point spacedly forwardly of hub 8 for engagement to a bracket 54 to which latter is engaged the lower end portion of brake release cable 55 which extends upwardlY to a noint for convenient manipulation by the bicycle operator, such as to a tube 56 depending rom bic~cle cross bar 5 or, if desired, to a bracket (not shown) mounted upon bicycle frame F at a Point convenient for the operator. Latch arm 52, in its lower central portion, is contoured to define a forwardly presented, depending cam follower edge 57 adapted for engaging cam working edge portions 40,41 in a manner and for purposes to be described below, In the upper rearward edge of latch arm 52 there is formed a depression or shoulder 58 for engaging the upper end of a tension spring 59, the lower end of which is suitably fixed within an opening 60 provided in the lower rearward portion of pivot plate 43; said spring 59 thus serves to urge latch arm 52 generally dot~nwardly for maintenance of contact with the periphery of cam 39.
With reference to FIGURE 2 it will be scen thnt ~urin~
forward motion of bicycle A, as indicated by the arrow, cam 39 will rotate freely without impedance by latch arm 52 with the edge portion thereof extending rearwardly from cam follower 57 - riding upon said cam 39.
Front and rear caliper brakes 20,21 are connected to brake assembly B by the customary brake ca}~les 61,62, respectively, encased within the usual flexible sleeves 63,G4, respectively. Cables 61,~2 extend beyond the rearward ends of sleeves 63,64 with cable 61 projecting through lower aperture 34 and lower opening 49 of flange 32 and ear 47, _g_ 345^5 respectivel~, and cable 62 extending through upper aperture 33 and upper opening 48 o said fl~nge 32 and ear 47 ! respectively.
The rearward projecting ends of said cables 61,62 are suitably secured against displacement as by members 65,66, respectively.
With brake assembly B in normal, operative, bicycle-riding condition, wherein ear 47 will abut flatwise against flange 32;
with brake release cable 55 slack; and with latch arm 52 freely riding over cam 39, bicycle ~ may be braked by rearward pedaling action, causing shaft 17 to rotate in a direction opposite to that indicated by the arrow in FIGURE 2 with the more proximate cam working edge portion 40,41 being brought into camming relationship with cam follower edge 57 of latch arm S2. Such engagement will cause a translation of the rearward force caused by the back pedaling to be effected upon latch arm 52 whereby the same is driven rearwardly as into the position shown in FIGURE 2 forcing pivot plate 43 to rock in its upper portion rearwardly about the axis developed by roc~
pin 45 thereby causing a pulling upon cables 61,62 by virtue of the rearward travel of ofset ear 47, separating same from flange 32. Thus, by such action brakes 20,21 are placed into wheel braking condition. Spring 59 serves to maintain the engagement between the particular cam working edge portion 40 or 41, as the case may be, Wit}l cam follow~r ed~e 57 so that reliable bralced condition is assured.
The foot operated brake assemhly B in actuality pxovides the operator with a sensation similar to that of power brakes on an automobile. Except in an emergency, the operator will withdraw force on the brake assembly, or let up as it were, just before coming to a complete stop so that the wheels are still turning. Thus, despite the application of the brakes in the condition just described, the operator may immediately s thereupon resume forward travel without hindrance as crank 17 may be rotated forwardly (in a direction as that indicated b~ the arrow in FIGURE 2) and thus remove the engaged cam 40 or 41, as the case mav ber from follower 56 thereby releasin~
the rearward pressure upon latch arm 52 which, in turn, permits pivot plate 43 to be rocked forwardly with the removal of the applied force upon brake cables 61,62 so that the associated brakes 20, 21, respectivel~, may return to open or unbraked condition, with ear 47 and flange 32 in surace abutting relationship.
If the operator desires to park bicycle A witll the wheels 2,4 thereof in locked condition, brake assembly B may be braked as above described so that wheels 2,4 ma~ still turn;
that is, wherein maximum forceful engagement between cams 40,41, as the case may be, and cam follower 57 has not bee~jattained.
The operator dismounts and then rolls bicycle A rearwardly which movement will cause crank 17 to rotate in a rearward direction (opposite to that shown by the arro~ in FIGURE 2) and bring about full forceful engagement between the cams 40 or 41 and cam follower 57 so that a fully wheel-locked state is brought about, When the rider desires to resume operation, it will be necessary to lift upwardl~ on relea~e cable 55 to remove latch arm 52 from engaged position with the particular cam 40 or ~1 and thereby free bicycle l~ for travel.
Release cable SS is utilized only when the wheels have been locked prior to parking. It is understood that in the event bicycle A were rolled rearwardly in a free fashion, cable 55 would have to be held in upper position to prevent enaagement of latch arm 52 with disc cam 39 until wheel~locking was desired.
It should be understood that the upper course of drive chain 23 becomes taut upon application of the brake a~seml~l~v ~ when 1~ Q ~ 5 the wheels are locked and will xemain in such state through the associated derailleur system so that only through release of cable 55 is crank l7 then freed for forward rotation.
Brake assembly B may be thus easily provided upon existing bicycles with minimum difficult~ and expense and with the same being especially suitable for ~merican made bicycles wherein the shaft and pedal cranks are of unitary construction. The components of said assembl~ B are few in number and ma~ be most economicall~ produced as by stamping and with cup portion 28 being of simple, stamped form and insertable within hub 8.
Accordingly, it will be seen that brake assembly B is uniquely comprised of a marked paucity o components which are most simple in construction; which may be produced most economically; and which coact in a fu11~ reliable manner.
Efforts have been made heretofore to prevent the brakes from locking in an emergency stop, as distinguished from a parking stop, by causing the development of slack in the upper course of the transmission chain as the brakes were applied.
In this connection U.S. Patent No. 3,966,299 demonstrates various arrangements for producing such chain slack. I~!ith such slack the rider could then easily resume travel from an emergency stop with the crank bein~ allowed to unbrake prior to the turning of the locked rear wheel bec~use of the capacity of the drive sprocket to appl~ a orward pulling on the chain by reason of its limited slackness, Bicycle ~ of the present invention is uniquel~ equipped with a means, now to be described, which will allaw limited rotation of the crank shaft 17 after braking action so that the rider may resume travel without the necessity of taking positive steps to disengage latch arm 52 from cam 39. Attention is now directed to FIGURES 6 and 7. The crankshaft 17 in its lQ~aS~

end portion remote from pedal cran]c 19 is externall~ threadcd as at 67, for engaging the internal threads o an inner conically shaped ~ace 68, of conventional design, of a hall bearin~ 69 incorporating an outer race 70 formed in the usual manner within a stamped cup e which is press-fitted within the proximate end opening of hub 8. As will be seen inner race 68 is provided within the outward opening recess 71 thereof with an annular central shoulder 72 for abutment against the outer end edge of a circular spacer sleeve 73 surrounding the adjacent portion of shaft 17 and with the outer edge of said sleeve 73 snug a~ainst a circumferential shoulder 74 developed by a diametrally increased portion 75 of said shaft 17 which constitutes a hub for drive sprocket or front chain wheel 22.
Immediately adjacent and outwardly of portion 75, shaft 17 is formed to present an enlarged flange 76 of greater diameter than portion 75 so as to be presented against the confronting portion of drive sprocket 22 for preventing displacement of ~ the same axially inwardly of shaft 17. Said drive sproc};et 22 ; is restrained on its opposite face against inadvertent shifting axially outwardl~ of shaft 17 by virtue of the base 77 of l?all bearing inner race 68, Thus, by the structure descrihed, drive sprocket 22 is maintained in proper operating position~
Integrally formed with pedal crank l8' and extending outwardly from the lower outer portion thereof, proximate the zone of merger with shaft 17 and substantiall~ axially parallel therewith is a finger 78 for projection into a slot-like aperture 79 formed in the internal support structure 80 of drive sprocket or front chain wheel 22. 1~1ith reference to FIGURE 7 it will be seen that aperture 79 is radially spaced inwardly from the outer operating teeth-formin~ edge of drive sprocket 22 as well as being radially spaced from the hub 75 for said sprocket 22, Said aperture 79 is of greater length than the cross-section of finger 78 so as to permit relative movement there-between for purposes now to be described. However, said aperture 79 is on an arc having the same number of degrees as that arc through which cams 40 or 41 and cam follower 57 travel in engaged condition for causing application of brakes 20,21, as above described. Finger 78 is normally urged toward the rearward or trailing end 82 of aperture 79 by a tension spring 83, the rearward end of which latter is engaged, as at 84, to the support structure of front chain wheel 22 and with the forward end being disposed about finger 78 (see FIGURES 6 and 7). During forward travel of bicycle ~, finger 78 through action of crank 17 will be pulled forwardly into abutment against the forward or leading end 81 of aperture 79 with stress being thus developed in spring 83. However, when back pedaling is effected for bra]cing action finger 78 will thus be mo~ed toward the rearward or trailing end of aperture 79 with spring 83 thus losing its stress. Since cam 39 is keyed ~irectly to crankshaft 17 the pressure exerted by finger 78 against the rearward end 82 of said aperture 79 ~
substantially correspond to the rearward ~ressure actin~ on latch arm 52 through engagement of cams 40 or 41 with cam ; follower 57, When it is desired to resume travel after braking action, the operator in forwardly rotating pedal cran~ 18' will pull finger 78 toward the forward end 81 of aperture 79 with concurrent-stressing of the spring 83, but such action will have permitted crankshaft 17 to have moved through the arc permitted by aperture 79 whereby the engaged cam 40 or 41, as the case may be, is removed from engagement with cam follower 57 suficiently to release latch arm 52 from rear~ardly translated position thereby releasing the bicycle brakes 50 that forward travel can be continued.
It is to be particularly noted that aperture 79 thus permits crankshaft 17 to move despite the fact that the upper course of transmission chain 23 is taut because of braking, In the absence of aperture 79 and associated finger 78, crankshaft 17 would not be permitted to move relative to drive sprocket 22 as the same is held ~y the taut transmission chain. Thus, the incorporation of this finger-aperture arrangement allows crankshaft 17 to unlock the braking condition regardless of how hard the operator may have applied the brakes, as in an emergency, and without any need for use of release cable 55.
However, if it were desired to apply the parking brakes, the operator after dismounting would move bicycle A l~ackwards a few inches, as it were, causing the upper course of transmission chain 23 to pull drive sprocket or front chain wheel 22 rearwardly which would have the effect of causing finger 78 to move relatively forwardly within aperture 79 into the forward end portion thereof. It will be seen that in this condition the par];ing brakes can only be released b~ liftin~
of cable 55 since finger 78, being at the forward end oE
aperture 79, has caused crankshaft 17 to be denied the requisite arc of travel for normal brake unlocking condition as above described.
The above described system for releasing the bicycle brakes may be adapted for ut.ilization with bicycles incorporating what is currently kno~ as a front free ~heel system, such as of the "Shimano" manufacture, wherein the front chain wheel can over-run the pedal crank as the rear friction free wheel maintains the chain in a moving condition `

l~ SS

even when the rider discontinues pedaling. Such eature makes it possible for the operator to shift into low gear while coasting and braking with the back pedaling as a stopping point is approached. In the drawings the numeral 90 designates a crankshaft illustrated as being integrally formed with peclal cranks 91,92 which latter are respectively of like construction as shaft 17 and cranks 18,18' above described. Crankshaft gn is externally threaded in each of its end portions, as suggested at 93, for engaging and supporting the usual bearings in a system of this type, being indicated generall~ at 94, as the same do not form a part of the present invention. Said bearings are received within a relatively thin walled casing 95 of a sleeve 96 carried upon crankshaft 90j there being integrally formed with casing 95 a laterally outwardlv projecting annular portion 97, the periphery of which is provided with a circumferentially spaced apart series of teeth 98 with intervening notches 99. Teeth 98 are receivable within notches 100 developed between teeth 101 provided circumerentially about the central opening 102 of drive sprocket or front chain wheel 103. Front chain wheel 103 is locked to sleeve 96 by a snap ring 104, Also interengaging sleeve 96 and front chain wheel 103 is a spring 105, one end of which is engaged to said front chain wheel 103 and the opposite end within a suitable opening, as at 106, formed in casing 95. With reference to FIGURE 9 it will be seen that spring 105 biases sleeve 96 rearwardly so that teeth 98 of sleeve 96 would be urged against what might be considered the trailing or rearward edge of notches 100. Thus, during forward travel of the bicycle spring 105 would be stressed by reason of teeth 98 abutting the normally forward or leading edge of the engaged notch 100.

S~

With particular reference being made to FIGURE 10 it is to be observed that teeth 98 are of less circumferential extent than the related notches 100 whereby such differential permits of relative movement between said sleeve 96 and front chain wheel 103. In the present invention the num~er of tceth 98 and 101 are fewer in number than found in the current construction of front free wheel systems wherein there is customarily a relatively close meshing relationship. ~
reducing the number of teeth the intervening notches 99,100, as the case may be, are perforce increased in extent therebv providing adequate spacing for the indicated relative movement.
It will thus be seen that upon back pedaling teeth 98 will be at the rearward ends of their receiving notches 100 and be in such state during braking or fully braked condition.
Upon resumption of forward travel crank 90 may rotate through an arc commensurate with the path of travel of teeth 98 in the associated notches 100 independently of any movement of front chain wheel 103 so that the brake assembly ~, as above described, if provided upon said bicycle ma~ be released and forward travel resumed.

Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. For use with a bicycle having a frame, front and rear wheels supported on said frame, a pedal crank assembly having a crankshaft and first and second pedal cranks at opposite ends thereof, a drive sprocket carried on said crankshaft inwardly of said first pedal crank, a driven sprocket engaged upon said rear wheel, a transmission chain interconnecting said drive and driven sprockets, brake release means permitting of limited relative movement between said drive sprocket and said crankshaft after bicycle braking action whereby said crankshaft may turn prior to resumption of rotation of the rear wheel, said means comprising a sleeve-forming member carried on said crankshaft, said drive sprocket having a central opening for extension therethrough of said sleeve-forming member, circumferentially spaced-apart teeth provided on said sleeve-forming member, said drive sprocket having a circumferential series of notches pro-jecting inwardly from said central opening for receiving the teeth of said sleeve-forming member, said notches being formed on a greater arc than said teeth, and resilient means urging said teeth toward one of the related notches.

2. For use with a bicycle, brake release means as defined in Claim 1 and further characterized by each of said drive sprocket notches having a leading edge and a trailing edge, said resilient means urging said teeth toward the rearward edge of the related notch whereby during forward travel of the bicycle the teeth will be engaged against the leading edges of said notches with said resilient means under stress.

3. For use with a bicycle, brake release means as defined in Claim 2 and further characterized by said resilient means being a spring having one end engaged to said drive sprocket and the other engaged to said sleeve.