Force and throw transformer for actuation linkages

The invention provides a simple method for reducing the amount of force required to actuate a motorcycle clutch. A miniature, lightweight housing means provides a pivot for a lever means to which is attached a short cable from the clutch actuation handle and also the original cable from the clutch. Because the two cable attachment points on the lever means are staggered, the lever means provides mechanical advantage and thereby reduces the manual force required to move the clutch actuation handle. The invention is designed to allow fast installation by providing cable slots in all parts and using cable sleeve tension to permit simple hook-on attachment of cable terminal hardware to the lever means. The housing means cover is used to exclude the environment and also to assure mechanical strength. The pivot pin and attachment hardware for anchoring the cables is locked into place by the covers.

BACKGROUND 
1. Field of the Invention 
The invention relates to force transmission through a mechanical linkage, 
especially a cable system which provides remote actuation of brake or 
clutch devices used on lightweight vehicles. 
2. Description of Prior Art 
Many lightweight vehicles such as motorcycles, bicycles, wheelchairs, 
aircraft, lawn mowers, etc. incorporate manually actuated mechanical 
linkages for clutches, brakes, gear changers and other devices. Manual 
actuation is usually achieved by hand grip control lever means or foot 
lever meanss. The actuation force available through manual effort is 
limited to the capacity of human strength. An average adult male can exert 
approximately 45 pounds of force on a one hand grip lever means with a 
throw (actuation distance) of about four inches. 
The actuating mechanism; hand lever means, foot pedal, etc. is designed to 
enable the user to exert enough force to overcome a return spring, cable 
and pulley friction and the resistance of the actuated device. The total 
force required is often greater than human capacity so that mechanical 
advantage is usually designed into the actuating mechanism and/or the 
actuated device. The cable linkage actuating control lever means is a good 
example of a prior art application of mechanical advantage. U.S. Pat. No. 
4,149,432, titled "Cycle Handlebar Lever For Brake Or Clutch Control", 
issued Apr. 17, 1979 to inventor Mark A. Costahaude, teaches a means for 
achieving mechanical advantage in order to reduce the manual force 
required to actuate a linkage system. U.S. Pat. No. 4,301,694, titled 
"Hand Operated Lever Linkage Control", issued Nov. 24, 1981 to inventor 
Larry J. Costa, shows a method for mechanical advantage with adjustable 
means mounted on a control lever. 
Cables are most often used in conjunction with mechanical linkages to 
transmit actuation forces over short distances. Actuation cables of this 
type usually side within a tight fitting, flexible, steel sleeve which 
need only be anchored at its end points. Other cable systems use free 
cables routed over pulleys in order to change direction, achieve 
mechanical advantage, etc. Other linkage systems use link bars or chains 
of various construction to achieve greater strength and flexibility. 
During the useful life of a mechanical linkage assembly, lubricants dry 
out, mechanical parts wear and the metal work hardening occurs in springs. 
The manual effort required for actuation tends to increase with the age of 
the linkage system. The operation of standard linkage systems by the very 
young, the very old, the infirm or others whose capabilities lie outside 
the range of strength for which a system is designed, presents a problem 
for which no simple prior art solution exists. No prior art device has 
been found which may be easily installed into existing linkage assemblies, 
without modifying them, which will reduce the manual force required for 
actuation. No prior art device has been found which is specifically 
designed to be retrofitted into an existing cable actuation system. 
OBJECTS AND ADVANTAGES 
The objects and advantages of the invention include its ability to increase 
or alternately reduce the force and the throw distance required to actuate 
a mechanical linkage assembly, said device having a means to adjust the 
force and throw distance required for such actuation, and which is simply 
and easily installed into an existing mechanical linkage assembly without 
altering or modifying the linkage assembly in any way, and said device 
being small and light enough so as to fit into a wide range of existing 
mechanical linkage assemblies. The unique combination of elements of the 
invention make it a valuable tool. 
Although the invention has a very broad range of usefulness, with 
applications for both increasing as well as reducing actuation force 
requirements and also in increasing as well as decreasing linkage throw 
distances, the preferred embodiment uses the force reduction aspect of the 
device. As applied to hand operated lever means control linkage systems on 
light vehicles, a reduction of manual force is often required by children, 
the aged, the infirm, and in some cases by small or weak adults. In cases 
such as a motorcycle used in motorcross racing, the operator uses the 
clutch constantly over extended periods of time so that a significant 
force reduction is necessary in order to stay within human muscle 
endurance limits. Many traditional devices and equipments were designed 
for the strength of a strong adult male. Today women often use these 
controls and require a force reduction to place the strength requirement 
within their range. 
In older devices and mechanisms the actuation force required for normal 
operation has increased during years of use due to weakening of 
components, hardening of lubricants etc. The invention can improve 
operational performance without requiring an increase in manual effort. 
The preferred embodiment of the invention is specifically designed to mount 
in the clutch actuation cable assembly of a motorcycle and means is 
provided for quick and easy installation onto any standard motorcycle. 
Once mounted the invention provides the advantage of lessening the manual 
force required to squeeze the hand lever means which disengages the 
clutch. As described and shown herein, the preferred embodiment provides a 
choice of three mechanical advantage ratios. A simple means is provided 
for changing the selected ratio quickly and easily without tools other 
than a screwdriver to remove and replace the invention's cover. The 
invention is not anchored or bolted down in any way other than being 
installed into the cable drive train. In this regard, the lightness and 
small size of the invention are important. Installation requires no 
modification whatsoever to the invention or to the existing linkage system 
which the invention becomes a functioning part of. 
Further objects and advantages of the invention will become apparent from a 
consideration of the drawings and ensuing description.

DRAWING REFERENCE NUMERALS 
2: Housing means 
4: Tapped through hole 
5: Boss 
6: Cable entry slot for output cable 
7: Threaded hole 
8: Support for pivot pin 
10: Pivot pin aperture in housing means 
12: Cable entry slot for input cable 
20: Lever means 
22: Pivot pin aperture in lever means 
24: Cable entry slot 
26: Anchoring means 
30: Undercut 
40: Lock nut 
42: Cable adjuster 
44: Cable adjuster threaded end 
46: Pivot pin means 
48: Slot in cable adjuster 
60: Front cover 
61: Back cover 
62: Machine screw 
64: Rubber boot 
66: Cable sleeve for input cable 
67: Cable sleeve for output cable 
68: Sleeve terminal 
70: Input cable 
71: Output cable 
72: Cable terminal 
73: Cable end piece. 
DESCRIPTION OF THE INVENTION 
FIGS. 1 through 4 show the invention according to the preferred embodiment. 
Referring first to FIG. 3; the invention consists of housing means 2 having 
a boss 5 located at four places, each boss containing a tapped through 
hole 4. On the upper right side of housing means 2, cable entry slot for 
input cable 12 and threaded hole 7 is located. On the center of the left 
side of housing means 2, cable entry slot for output cable 6 and a second 
threaded entry hole 7 is located. In the interior of housing means 2, 
located at bottom center, support for pivot pin 8 which contains pivot pin 
aperture in housing means 10 is located. 
Referring to FIG. 4; lever means 20 contains undercut 30 which reduces the 
thickness of lever means 20 over the bottom one-third of its length. Pivot 
pin aperture in lever means 22, spaced to match pivot pin pivot pin 
aperture in housing means 10 are located along the center line of lever 
means 20. The upper half of lever means 20 contains cable entry slot 24 
which is wide enough to allow passage of cables 70 and 71. Two 
semi-circular shaped cutouts form anchoring means 26 on the left and right 
sides of lever means 20 and are wide enough to loosely cradle cable 
terminals 72. 
Referring to FIG. 2; lever means 20 is pivotally attached to support for 
pivot pin 8 with pivot pin 46 which is inserted into one of the three sets 
of pivot pin aperture in lever means 22 and matching pivot pin aperture in 
holder means 10. Lever means 20 is free to rotate about pivot pin 46 with 
its range of travel being restricted only by the sides of housing means 2. 
One cable adjuster 42 is installed into each threaded hole 7 by engaging 
cable adjuster threaded end 44. The slots 48 in cable adjusters 42 are 
aligned with cable entry slots 6 and 12. Cables 70 and 71 are inserted 
laterally through entry slots 12 and 6 respectively and then through slots 
48 in cable adjusters 42 and lock nuts 40. The interior of both cable 
adjusters 42 contain a clearance hole for cables 70 and 71. 
Referring to FIG. 1; cable sleeves 66 and 67 are free to slide along cables 
70 and 71 respectively. Cable sleeves 66, 67 have sleeve terminals 68 
fixedly mounted at each of their ends. The cable clearance hole in cable 
adjuster 42 is enlarged at the hexnut end to accept sleeve terminal 68, 
i.e., sleeve terminal 68 is inserted into the hexnut end of cable adjuster 
42. See FIG. 2. Rubber boots 64 are placed over cable adjusters 42 and the 
protruding cable entry slots 6 and 12. Front and rear covers 60 and 61 are 
attached to housing means 2 with four machine screws 62 each, which are 
engaged into tapped through holes 4. Cable end piece 73 is a small metal 
ball, one of which is soldered to each end of cables 70 and 71 and acts to 
capture cable terminal 72. 
OPERATION OF THE INVENTION 
Installation 
The clutch cable system of a motorcycle consists of three components: an 
actuation handle mounted onto the motorcycle's handlebars, an 
interconnecting cable and a clutch mechanism mounted within the 
motorcycle's frame. 
To install the invention, the motorcycle's interconnecting cable is 
disconnected from the actuation handle and inserted instead into cable 
entry slot 24 in lever means 20 as shown in FIG. 4. The motorcycle's 
interconnecting cable functions as output cable 71. Next, input cable 70 
is inserted into cable entry slot 24 in lever means 20 as shown in FIG. 4. 
Lever means 20 with cables 70 and 71 is installed into housing means 2 
with pivot pin 46. Cable adjusters 42 are inserted into threaded holes 7 
and then cables 70 and 71 are inserted into slots 48 in cable adjusters 
42. Cable sleeves 66 and 67 are inserted into the ends of cable adjusters 
42 and are tensioned by appropriate thread engagement between cable 
adjusters 42 and threaded holes 7. Once cable sleeves 66 and 67 are 
tensioned so that no slack exists, lock nuts 40, which are threaded onto 
cable adjuster threaded ends 44, are tightened against housing means 2 to 
prevent loosening during motorcycle operation. Finally, front and rear 
covers 60 and 61 are installed with machine screws 62, and rubber boots 64 
are slid over cable adjusters 42 to help exclude dust and moisture from 
the interior of housing means 2. 
Operation 
In the preferred embodiment, the invention acts to reduce the manual force 
required at the clutch actuation handle mounted on the motorcycle 
handlebars. In this application the actuation handle disengages the clutch 
when it is squeezed. Before being actuated, lever means 20 is in its 
nominal position, i.e., at the left side of housing means 2. When the 
clutch actuation handle is squeezed by the rider's hand, input cable 70 is 
pulled and, in turn, pulls lever means 20, which rotates, pivoting at 
pivot pin 46 and moves toward the right side of housing means 2. At the 
same time, lever means 20 pulls on output cable 71 which therefore moves 
to the right also and actuates the remotely located clutch mechanism. When 
the rider releases the clutch actuation handle a return spring located at 
the clutch mechanism pulls the entire linkage system back to its original 
unactuated position. 
Because the pivot arm from pivot pin 46 to the center of input cable 70 is 
longer than the pivot arm from pivot pin 46 to the center of output cable 
71 the preferred embodiment provides a mechanical advantage or force 
amplification. The invention enables the motorcycle rider to actuate the 
clutch with less manual effort applied to the clutch lever means than 
would be required if the invention were not present. Because the invention 
shortens the throw distance, the rider must squeeze the clutch actuation 
handle further to achieve a desired level of clutch disengagement. 
In the preferred embodiment the mechanical advantage obtained depends upon 
which of the three apertures 10, 22 is selected. The bottom aperture 
provides the least mechanical advantage, while the top aperture provides 
the greatest. No matter which aperture is selected the relative position 
of lever means 20, with respect to housing means 2, does not change and 
cables 70 and 71 remain centered within cable adjusters 42. 
CONCLUSION, RAMIFICATIONS AND SCOPE OF THE INVENTION 
The invention provides a compact, rugged, and easily installed means for 
adjustably changing the mechanical characteristics of a linkage system 
without modifying the linkage system itself. While the above description 
contains many specificities, these should not be construed as limitations 
on the scope of the invention, but rather as an exemplification of one 
preferred embodiment thereof. Many other variations are possible. For 
instance the invention may be built much more ruggedly to meet the 
requirements of heavy duty linkage systems. Conversely, it may be built in 
miniature version to apply to tiny systems. It may be built with only one 
pivot point, or with more than three. Cable types and attachment methods 
may be modified to accept different styles of cable or other linkage 
components such as chains or bars. The length of lever means 20 and 
placement of pivot apertures may be changed to achieve any mechanical 
advantage ratio or throw distance ratio desired. More than one output 
cable may be attached to the lever means. This configuration allows the 
invention to act on two acutation devices simultaneously. The two output 
forces may both be step-up, or may both be step-down, or one may be 
step-up while the other is step-down. In the later case, the step-down 
cable is attached to the lever means so that its pivot arm is greater than 
that of the input cable. 
Accordingly, the scope of the invention should be determined not by the 
embodiment illustrated, but by the appended claims and their legal 
equivalents.