Title of Invention

AN AUTOMATIC MECHANICAL WEAR-ADJUSTER

Abstract

.An automatic mechanical wear adjuster for the cam operated drum brake system of a motor vehicle comprising a first free- wheel device for imparting motion from the cam lever to the brake cam, through the said first free-wheel device, only during forward actuation of the brake cam; a rocker connected to a rocker-housing rigidly connected to a brake anchor panel so as to be movable with respect thereto; stopper arrangements provided on the rocker and on the rocker housing or on the brake anchor panel for lim iting the movem ent of the rocker t with respect to the brake anchor panel, to two opposite predeterm ined positions; a second free-wheel dcvice for imparting motion from th~ brake cam to the rocker, through the second free-wheel device, only during reverse movement of the brake cam; resilient means connected between the rocker and the rocker-housing or brake anchor panel for enabling the rocker to follow the brake cam during forward actuation, the retain ing force of the resilient means on the rocker being such as to enable the brake-shoe return springs to return the brakc shoes and rotate the rocker, the clamping torque of the second free-wheel device being sufficient to hold the brake cam against the retaining force of the brake shoe return springs exerted on the brake shoes and thence on the brake cam.

Full Text

This invention relates to "an automatic mechanical wear-adjuster", which is applicable for all mechanical cam operated drum brake systems, the transmission-clutch controlling systems, other non-limitative systems and the like, comprising the movable parts, which are specifically subjected by wear-out and are returnable by elastic-force In any known mechanical cam operated drum brake system for any automobiles specifically in 2-wheeled motor vehicle as the former of above said specific examples, there is a set of brake shoes of internally expanding type. One of which is known as the leading shoe and the other is trailing shoe. In another known art, these two shoes are also respectively employed as either leading or trailing shoes, for the design requirements. These shoes are actuated either by the rotation of brake-cam or with a plurality or the like to open out the brake shoes. Consequently the brake shoe is then normally pressed against the rotating brake drum either to slow down or to stop the wheel ulti¬mately resulting in retarding the moving vehicle. For each brake application, both brake shoe-liner and brake drum gets substantial wear-out, which is though with infinitesimal amount but the cumulative effect of these wear-out, results in increase in the clearance between brake drum and brake shoe-liner. After some period of usage or number of brake-applications, the brake shoe liner as well as the brake-drum-bore significantly wear out. As a consequence, the radial clearance between the brake shoe liner and brake drum bore increases more from the pre-setting value, which was initially provided to meet the ergonomic qualities on brake-pedal/control lever usage. This increase in clearance also increases the free-play of brake—control lever or brake pedal. To maintain the ergonomic qualities of the brake actuation with the same value manual effort for periodical checking and adjustments either by user or by atleast any skilled one. Moreover for the case of the above said brake systems, which have higher mechanical advantage (force-amplification) from brake-control-lever to the brake-cam functional contact-point with brake-shoe, the frequency of this adjustment is very high and thereby more significant. In all the above said known arts, the angle between the cam-lever and the brake-cable/rod is changed due to the consequence of these adjustments of brake-cam—lever with respect to the brake-rod or with brake-cable. This results in change of its effective mechanical advantage of brake-cam-lever. This will gradually vary the braking effectiveness after every adjustment of brake-cam-lever with respect to the brake-cam as another problem. In a known art of another applications, this manual wear adjustment is called "Slack adjuster", which is also periodically manually used with high adjustment-frequency. Another improvement of the former art is called "automatic slack adjuster". In this later known art, it consists of an actuation sensor like the actuation counter and a slack adjuster, which is constituted by the ratchet and pawl mechanism or with reducer. In this, by sensing each brake actuation the sensor or counter operates the ratchet and pawl mechanism to slack the return movement of the brake control lever of parts resulting, in huge size, highly complicated design and functions, more in the weight, initial cost, maintenance and the like. In a recent known art referred to the US Patent*^ No.5,848,672, brake lining wear sensing system incorporated with for automatic wear-adjusting system, has electronically controlled displacement sensors for r } detecting the displacement brake system, movable parts for wear-sensing. This is fed into the memory system controlled by atleast a microprocessor, and then this electronic system automatically adjusts the relative positions of the brake-system linkage system according to the amount of wear sensing. The problems in this art are that this system requires atleast electrical power source for its function resulting in power consumption, more number electronically sensitive parts which are complicate arrangements and prone to electronic failures at any time, lead to more initial cost, maintenance and serviceability. Also in another recent known art referred to the US Patent No.5,922,971, rotation-angle sensor for displaying a plurality of rotations of a shaft has a rotary potentiometer unit with a geared-down drive and the related parts is monitoring the continuous wear with a "wear-end" indication, brake functions using plausibility comparison of various brakes, simplifying the service and harmonizing of war between a plurality of axles. This recent known art also has the following inherent drawbacks. More number of mechatronic parts as well as electronically controlled system; Complication in assembly, more weight, more initial cost and prone to electronic-failures. The above said prior arts are neither cost-effective and compactness nor lighter weight for the lighter vehicles like 2 and 3-wheeled vehicles. Moreover the above known arts are also applicable to transmission-clutch controlling systems, other non-limitative systems and the like, comprising the movable parts, which are specifically subjected by wear-out and are returnable by elastic-force The automatic mechanical wear adjuster for the cam operated drum brake system of a motor vehicle, according to this invention, comprises a first free-wheel device for imparting motion from the cam lever to the brake cam, through the said first free-wheel device, only during forward actuation of th«» hnake cam; a rocker connected to Q rocker-housing rigidly connected to a brake anchor pane! so as to be movable with respect thereto; stopper arrangements provided on the rocker and on the rocker housing or on the brake anchor panel for limiting the movement of the rocker, with respect to the brake anchor panel, to two opposite predeterm ined positions; a second free-wheel device for imparting motion from the brake cam to the rocker, through the second free-wheel device, only during reverse movement of the brake cam; resilient means connected between the rocker and the rocker-housing or brake anchor panel for enabling the rocker to follow the brake cam during forward actuation, the retaining force of the resilient means on the rocker being such as to enable the brake-shoe return springs to return the brake shoes and rotate the rocker, the clamping torque of the second free-wheel device being sufficient to hold die brake cam against the retaining force of the brake shoe return springs exerted on the brake shoes and thence on the brake cam. In the drawings left with the provisional specification Figure 1 shows a pictorial view of a preferred embodiment of the brake anchor panel of drum-brake as a preferred example of the applications which comprises the automatic 8 mechanical wear-adjusting device according to this invention? FIGURE 2 shows orthographic full sectional vie»ii of the above across the axis and sectioned across the rocker? According to this invention, an automatic mechanical wear-adjusting device for all mechanical cam operated drum brake system and said drum brake systems, the transmission-clutch controlling systems, other non-limitative systems and the like, comprising the movable parts, which are specifically subjected by wear-out and are returnable by elastic-force a rocker S operatively connected to rocker-housing 6 which is either rigidly connected to or being an integral part of the said mounting-part 4 so as to be movable with respect to said mounting-part 4; c) stopper arrangements 5A and 6A or its plurality thereof which are respectively provided on said rocker S and either the rocker-housing & or the mounting-part 4 (not shown in Figures) so as to limit the movement of said rocker 5 with respect to said mounting-part 4 up to two extreme predetermined positions, which are directional- ly opposite to each other with a predetermined distance therebetween J d) another free-wheel means 7,which is operatively connected between the said output-part 2 and said rocker 5 so as to impart motion from said output-part 2 to said rocker 5 through the said later free-wheel means 7 only during the reverse movement of output-part 2, which is opposite to the forward actuation and? e) a slaving means 8 or a plurality thereof which is fixedly and operatively connected between the aid rocker 5 and either said rocker-housing 6 or mounting-part so as to enable the said rocker 5 for substantially following the said output-part 2 while in the forward actuation; f) the retaining force of said slaving means 8 or its plurality thereof on the rocker 5 is so minimum that the salving means 9 substantially enables to return the output-part 2 and; g) the said retaining-force of said slaving means 8 or its plurality thereof is so sufficient as to rotate said rocker 5 by overcoming all the transmission losses between the corresponding movable partsj h) the clamping-torque of said later free-wheel means 8 or its plurality thereof is so sufficient to hold the said output-part 2 against the retaining-force of the slaving means 9 exerted thereupon 2. According to this invention, this automatic mechanical wear-adjusting device incorporated by a mechanical cam operated drum brake system as one of the specific examples, which is exemplified as follows, comprises: a) a free-wheel means 3, which is operatively connected between the cam lever 1 and the brake cam 2 so as to impart motion from the cam lever 1 to said brake cam 2, which is operatively connected to the brake anchor panel 4 or the brake anchor part of the crankcase system, through said free-wheel means 3 only during its brake actuation? b) a rocker 5 operatively connected to rockei—housing 6 which is either rigidly connected to or being stn integral part of the said brake anchor panel 4 so as to be movable with respect to said brake anchor panel 4| c) stopper arrangements 5A and 6A or its plurality thereof which are respectively provided on said rocker 5 and either the rocker—housing 6 or the brake anchor panel 4 said rocker 5 with respect to said brake anchor panel 4 up to two extreme predetermined positions, which are directionally opposite to each other with a predetermined distance therebetween; d) another free-wheel means 7,which is operatively connected between the brake cam 2 and said rocker S so as to impart motion from said brake cam 2 to said rocker 5 through the said later free-wheel means 7 only during the reverse movement of brake cam 2, which is opposite to that during the brake actuation and; e) a slaving means 8 or a plurality thereof which is fixedly and operatively connected between the said rocker 5 and either said rocker-housing 6 or brake- anchor-panel so as to enable the said rocker 5 for substantially following the said brake cam 2 while in the forward brake actuation; f) the retaining force of said slaving means 8 or its plurality thereof on the rocker 5 is so minimum that the brake shoe-return springs 9 substantially enables to return the brake-shoe 10 which in turn the rocker 5 via the brake cam 2 and; g) the said retaining-force of said slaving means B or its plurality thereof is so sufficient as to rotate said rocker 5 by overcoming all the transmission losses between the corresponding movable parts; h) the clamping-torque of said later free-wheel means 8 or its plurality thereof is so sufficient to hold the said brake cam 2 against the retaining-force of the brake-shoe-return-springs 9 exerted upon the brake-shoes which in turn transfers to the brake-cam 2. This invention described hereinabove substantially performs the following operations while using : During the forward brake actuation, the brake-cam 2 is rotated by said brake-cam-lever 1 through said former free-wheel means 3 to actuate the brake show 10 and said slaving means 8 simultaneously enables said rocker 5 to substantially follow said brake cam 2 by the retaining-force of said slaving means 8 on said rocker 5 in the said forward direction of said brake cam actuation. During the releasing of the brake cam 2 by the brake show return spring 9 through the brake shoes 10 and being directionally opposite to said forward brake actuation, the rocker 5 is rotated by the brake cam 2 through the later free-wheel means 7 in the reverse direction opposite to its forward brake actuation and by overcoming the elastic force of said slaving means; During the forward brake actuation and after brake shoes 10 just touch the brake drum (not shown in Figures), any further forward movement of brake cam 2, which is inevitable, is substantially allowed by the free-wheeling action of the later free-wheel means 7. So it enables the brake cam 2 to actuate the brake shoes i0 against the rotating brake drum. While releasing of the brake, the said rocker 5 is meant for specifically limiting the return movement of said brake cam 2 with respect to said brake anchor panel 4 through its stopper arrangements 5 A and 6A only up to a predetermined distance. This predetermined distance is the substantially equal in magnitude of forward movement of the rocker 5 from its position being the same position of said brake cam 2 with which the brake control lever is at the normal positions to the other position of said brake cam 2 by which the brake shoes 10 just touch the brake drum. With respect to this invention, any further forward 14 movement of said brake cam 2 after the said brake shoes 10 just touch the brake drum due to the wear-out of said both brake-shoe liner and brake drum, irrespective of its the magnitude, is deduced from the brake cam return-movement during its brake-releasing at every brake application. Also any further return movement of cam lever 1 beyond its said predetermined position for which said brake cam movement is limited by said rocker 5 through said stopper mechanisms 5A and 6A on both said rocker 5 and rocker-housing 6, is facilitated by said first free-wheel means 3 being in the free-wheeling mode. Further, this movement of said cam lever 1 is ultimately limited when the brake control lever reaches at normal position by any one of its known stopper arrangements and This substantially enables to maintain the free-play of brake control lever by eliminating the effect of the cumulative wear-out of both brake show-liner and brake drum As the effect of the above-described operations, the free-play of brake control lever is maintained the same as in the beginning, resulting in the elimination of any manual adjustment of free-play or wear-out till the dismantling of above described brake system assembly or reaching the wear-liffl it whichever is earlier. Further the relative po8ition(s) of stopper arrangement SA and 6A of said rocker S and either said rocker-housing 6 or being an integral part with said brake-anchor-panel 4, are provided with preferably adjustable manner from each other so as to adjust the relative distance therebetween. This facilitates to vary and re-fix the brake-control-lever free-play as per the requirements. This invention described herein above is also applicable in the same manner for transmission-clutch controlling system, other n on-limitative systems and the like comprises the relatively movable parts which are specifically subjected by wear-out and are returnable by the elastic-force(s) of the slaving means acted upon the output-movable part. The terms and expressions used herein are ilhistrative and not limitative in any sense. We Claim : l.An automatic mechanical wear adjuster for the cam operated drum brake system of a motor vehicle comprising a first free¬wheel device for imparting motion from the cam lever to the brake cam, through the said first free-wheel device, only during forward actuation of the brake cam; a rocker connected to a rocker-housing rigidly connected to a brake anchor panel so as to be movable with respect thereto; stopper arrangements provided on the rocker and on the rocker housing or on the brake anchor panel for limiting the movement of the rocker, with respect to the brake anchor panel, to two opposite predetermined positions; a second free-wheel device for imparting motion from the brake cam to the rocker, throvgh the . second free-wheel device, only during reverse movement of the brake cam; resilient means connected between the rocker and the rocker-housing or brake anchor panel for enablig the rocker to follow the bridce cam during forward actuation, the retaining force of Ae resilient m cans on tiie rocker being such as to enable the brake-shoe return springs to return the brake shoes and rotate the rocker, the clamping torque of the second free-wheel device being sufficient to hold the brake cam against the retaining force of the brake shoe return springs exerted on the brake shoes and thence on the brake cam.

Documents:

0233-mas-2002 claims duplicate.pdf

0233-mas-2002 claims.pdf

0233-mas-2002 correspondence-others.pdf

0233-mas-2002 correspondence-po.pdf

0233-mas-2002 description (complete) duplicate.pdf

0233-mas-2002 description (complete).pdf

0233-mas-2002 description (provisional) duplicate.pdf

0233-mas-2002 description (provisional).pdf

0233-mas-2002 drawings duplicate.pdf

0233-mas-2002 drawings.pdf

0233-mas-2002 form-1.pdf

0233-mas-2002 form-19.pdf

0233-mas-2002 form-26.pdf

0233-mas-2002 form-4.pdf

0233-mas-2002 form-5.pdf