Brake actuator for bicycles and the like

In a brake actuator for bicycles of the type housed within the bottom bracket of the bicycle, an actuating lever passing through the bottom bracket has a head housed within a slot within an annulus surrouding the pedal crankshaft of the bicycle within the bottom bracket. The annulus is provided with a torque spring providing a clutching action which tends to rotate the annulus with the crankshaft upon backpedalling. The lever acts upon bearing surfaces at opposite ends of the slot in the annulus, responsive to rotation of the latter, so as to exert a clamping action on the crankshaft between the lever and the annulus. The arrangement may be made sufficiently compact that it can be assembled into bicycles having small diameter bottom brackets. The slot and head of the lever are configured so that the lever head may be inserted through the bottom bracket and the slot from the outside, and then locked in place by insertion of the crankshaft.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to brake actuating means for pedal propelled 
vehicles such as bicycles. Although the invention is also applicable to 
pedal propelled vehicles having more than two wheels, e.g. tricycles, it 
will for convenience hereinafter be explained and described in relation to 
bicycles, which are by far the most common form of such vehicles, without 
thereby implying any limitation of the scope of the invention to bicycles. 
2. Review of the Art 
This invention relates to a development of the brake actuating means 
described in my U.S. Pat. Nos. 4,199,046, 4,313,530, 4,905,803, 4,603,764 
and 4,605,110, which are the most pertinent art known to me, particularly 
the last two patents listed. A further impression of the state of the art 
relating to actuators of the same general type may be obtained by 
considering the references discussed in the specifications of those 
patents are cited during their prosecution. 
In the actuators described in my U.S. Pat. Nos. 4,199,046, 4,313,530 and 
4,905,803, a one-way clutch element acting on the pedal crankshaft of a 
bicycle is formed by a spiral coil spring having a central bight engaging 
a yoke through which braking forces are transmitted, and oppositely handed 
spiral coils surrounding the crankshaft and extending axially outward 
along the crankshaft from opposite sides of the yoke. Outward portions of 
the coils are of relatively lighter gauge and are normally the only 
portions to engage the crankshaft, thus reducing frictional drag. 
Development has shown that this arrangement can operate very 
satisfactorily with very little drag during forward pedalling of the 
bicycle whilst requiring very little rearward angular motion of the pedals 
to produce engagement. 
Much thought has been given to alternatives to this spring type brake 
actuator as described in the above patents. For those North American 
manufactured bicycles that have large bottom brackets (approximately 2 
inches inside diameter), my U.S. Pat. Nos. 4,603,764 and 4,605,110 provide 
alternatives to the above coil type brake actuator. In those patents, 
there is disclosed a device for operating a brake of a pedal operated 
vehicle, comprising a brake operating lever projecting through an opening 
in a pedal crankshaft housing of the vehicle and having an inner end 
forming a first primary clutch element engageable with part of the 
circumference of a pedal crankshaft within the housing, a pilot clutch 
comprising two oppositely wound spring coils connected by a bight engaging 
a yoke the bight ends of the coils being directed in the direction of 
forward rotation of the crankshaft, the inner end of the lever having an 
end extending around the crankshaft circumference in the opposite 
direction to said yoke, means extending from the said end of the lever and 
wrapping around the crankshaft so as to form a second primary clutch 
element engageable with the circumference of the crankshaft at least in a 
zone opposite to that engageable by the lever, and means transmitting 
forces from the yoke to the distal end of said first primary clutch 
portion whereby to wrap the latter onto the crankshaft upon rearward 
motion of the crankshaft. The linkage in one preferred embodiment 
comprises a single link pivoted to the yoke in a C-formation, although 
alternative linkage may be formed by multiple links, a resilient strap, or 
a strap fastened at both ends to the yoke. In each case, the yoke in 
conjunction with the linkage provides, on movement of the crankshaft in 
one direction relative to the yoke, a self-servo effect, causing the shaft 
to be gripped between the yoke and the jaw, the latter being pulled into 
engagement with the shaft by the spring. The flexibility of the linkage 
means that the device can be manipulated to reduce its size during 
assembly of the actuator into the bottom bracket of the bicycle. 
Unfortunately, because of the space limitations in the pedal crankshaft 
housings formed by the small bottom brackets of non-North American 
manufactured bicycles, I have not hitherto been able to devise any 
alternative of comparable performance to my earlier spring type actuator 
for such bicycles, since it is difficult to assemble and to attain 
adequate strength in arrangements of the type shown in my U.S. Pat. Nos. 
4,603,764 and 4,605,110 if they are utilized with such bicycles. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide a brake actuator 
working on somewhat similar general principles to those disclosed in my 
U.S. Pat. Nos. 4,603,764 and 4,605,110 which is more suitable for 
installation in a bicycle having a small diameter bottom bracket. In such 
bicycles the annular gap within the bracket between the inside surface of 
the bracket and the outside surface of the pedal crankshaft is 
insufficient to permit the use of a pin jointed, C-clamp type actuator as 
described in my U.S. Pat. No. 4,603,764, because dimensional limitations 
on the pin joint and the C-clamp would result in them being too weak for 
the forces that may be applied to them during operation. Similar 
considerations would stand in the way of the adoption in such a bicycle of 
the alternative embodiments described in my U.S. Pat. Nos. 4,603,764 and 
4,605,110. 
I have now determined that a brake actuator having the generic features set 
forth above in relation to my U.S. Pat. Nos. 4,603,764 and 4,605,110 can 
be installed in a small diameter bottom bracket, if the second primary 
clutch element is formed by a major peripheral portion of an annulus 
surrounding the pedal crankshaft within the pedal crankshaft housing, and 
the first primary clutch element is received within an arcuate slot 
through a remaining peripheral portion of the annulus, bearing surfaces on 
the annulus at opposite ends of said arcuate slot providing respectively 
the means transmitting forces from the yoke to the distal end of the 
primary clutch portion, and a fulcrum for engagement by a proximate end of 
said primary clutch portion, such that the pedal crankshaft can be clamped 
between the primary clutch portion and the secondary clutch element. 
Since the primary clutch element is formed as a continuous annulus, whose 
axial extent can be as great as necessary, and no pivot pin is required to 
connect the primary and secondary clutch portions, a very strong assembly 
can be provided even where the space between the crankshaft and the bottom 
bracket is very limited. 
Preferably the arcuate slot and the inner end of the lever have 
configurations such that, when the first and second clutch elements are 
substantially concentric, the inner end of the lever cannot be withdrawn 
outwardly through the slot, but when the crankshaft is not present, the 
inner end of the lever can be manipulated inwardly through the slot. This 
feature greatly facilitates assembly of the actuator, since the lever can 
be inserted through the slot into the annulus after insertion of the 
latter into the bottom bracket, at which time it can be projected through 
the opening in the bottom bracket and the slot, and then locked in place 
by insertion of the crankshaft. 
Further features of the invention will become apparent from the following 
description of a preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the actuator of the present invention, the annulus 1 replaces the 
C-clamp disclosed in the actuator described in my U.S. Pat. No. 4,603,764, 
the disclosure of which is herein incorporated by reference. Lever 2 
serves the same purpose as its counterpart in my previous patent, although 
fulcrum 3 formed at one end of a slot 10 in the ring 1 replaces the pin 
joint of my previous patent. The pedal crankshaft 4, bottom bracket 5 and 
double torsion spring 6 are similarly constructed and have similar 
functions to the corresponding parts in my previous patent, although the 
radial spacing between the external diameter of the shaft 4 and the 
internal diameter of the bottom bracket or crankshaft housing 5 need not 
be as great. A further bearing surface 9 is formed between the lever 2 and 
the opposite end of the slot 10 in the annulus. The lever 2 extends 
through a slot 11 in the bracket 4. 
In use, when the rider of a bicycle B (See FIG. 3) to which the actuator is 
applied back pedals and turns the shaft 4 in a counter clockwise 
direction, the double torsion spring 6 grips the shaft 4 and turns the 
annulus 1 in a counter clockwise direction as shown in FIG. 1. This moves 
lever 2 from left to right which movement is resisted by a brake linkage 
21 that is attached to the lower end of lever 2 and to a brake 20 (See 
FIG. 3). This resistance results in lever 2 pivoting about fulcrum 3 and 
thus causing the shaft 4 to be gripped between an arcuate surface 7 on the 
inner end of the lever forming a primary clutch element and an arcuate 
surface 8 forming a secondary clutch element on the inner periphery of the 
annulus 1 opposite the surface 7. The torque from the crankshaft 4 is thus 
transmitted to the annulus 1 and the lever 2 through the surfaces 7 and 8, 
as well as the fulcrum 3 and a bearing surface 9 between the annulus 1 and 
the lever 2 at the opposite end of the slot 10. 
In one approach to assembly of the arrangement described above, the lever 2 
is assembled into the annulus 1 by inserting it from the bottom (referring 
to the orientation shown in FIG. 1) through the slot 10, and pushing it up 
to the position shown in broken lines in FIG. 1 so that the annulus 1, 
together with the lever 2 and the double torsion spring 6 may be inserted 
into the bottom bracket 5. The lower end of the lever 2 is then lowered 
through the slot 10 and the opening 11 in the bottom bracket 5 and held in 
place whilst the crankshaft 4 is passed through the annulus 1 and the 
double torsion spring 6. The head of the lever and the slot 10 are 
configured so that the head of the lever cannot be withdrawn outwardly 
through the slot once the primary and secondary clutch elements are 
retained in substantially concentric relationship by the crankshaft 4. The 
lever is thus retained within the slot 10 once the crankshaft 4 is in 
place. The lever is somewhat necked adjacent its inner end so that the 
latter can be manipulated inwardly through the slot 10 when the crankshaft 
is not in place. 
In a much preferred assembly technique, permitted by the improvements of 
the present invention, the annulus 1 and spring 6 are placed in the bottom 
bracket 5 prior to insertion of the lever, with the slot 10 aligned with 
the opening 11. The head of the lever 2 is then manipulated through the 
opening and the aligned slot from the outside before being locked in place 
by insertion of the crankshaft. This both simplifies assembly, and also 
provides the advantage that the length of the lever is not limited by any 
requirement that it fit within the annulus during insertion of the latter. 
The annulus 1 can be reduced in width over that portion of its periphery 
which does not contain the slot 10, in order to reduce its weight. The 
extent of this reduction is limited by the necessity for keeping 
deformation of the annulus 1 under load sufficiently low to enable proper 
operation within the space available. The annulus should also have 
sufficient width in the region of the slot 10 so as to form a dirt shield 
resisting the entry of dirt into the interior of the bottom bracket 5 
through the opening 11. Any local reduction of the width of the annulus 
must be such that a bight of the spring 6 can engage the yoke shown in the 
annulus without the spring being unduly stressed by contact with other 
portions of the annulus. 
Whilst the arrangement described has particular utility in relation to 
bicycles having a small diameter bottom bracket, there is of course no 
reason why it may not be used in bicycles having a larger diameter bottom 
bracket.