Title of Invention

GEAR SELECTION SYSTEM

Abstract

In accordance with this invention, gear selection system comprises; a shifter shaft (1) rotateably mounted in the gear box casing configured to slide axially,plurality of recesses (2) provided on the cylindrical surface of said shifter shaft, at least one fork member (3) slidably mounted on the said shifter shaft through bearings.The said fork members (3) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said fork members (3) are preferably interchangeable. Each fork member (3) is free to slide on the said shifter shaft (1). The said fork members (3) comprises pin guides (4) for holding the locking pins (5).Said pin guides (4) hold the said locking pins (5) positively spring loaded against the cylindrical surface of the said shifter shaft (1). The pin guides (4) facilitate the locking pins (5) to slide towards or away from the cylindrical surface of the shifter shaft (1). The pin guides (4) may either be separate components attached to the fork members (3), or they may be integral with the fork members (3). A locking plate (6) is provided parallel to the shifter shaft (1). The said locking plate has holes (7) to engage the locking pins (5). The locking plate (6) may either be integral with the gearbox casing, or it may be a separate component fixed in place through suitable means.

Full Text

FORM 2 THE PATENTS ACT 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See Section 10; rule 13) TITLE OF THE INVENTION Gear Selection system APPLICANTS TATA MOTORS LIMITED, an Indian company Having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India INVENTOR Abhimanyu Singh Indian National of TATA MOTORS LIMITED, An Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed. FIELD OF INVENTION The present invention is related to multiple ratio gearboxes and more particularly it relates to gear selection system. BACKGROUND OF INVENTION Multiple ratio gearboxes typically consist of two or three shafts supporting intermeshing pairs of gears. These are generally known as output shaft, input shaft and/or lay shaft. A particular gear ratio is selected by either sliding the gears axially until they mesh, or by engaging dog clutches, synchroniser rings and similar devices. The sliding gears/dog clutches/synchroniser rings are usually handled by forks mounted on their respective rods/shafts/slides. Each fork usually selects one or two ratios by sliding in the required direction. The forks are operated by any suitable mechanism like toggle finger and electro pneumatic actuators etc. These type of gearboxes are common in automobiles, industrial machinery etc. Each fork is generally unique in design, and has a matching rod or shaft to support it. An interlock mechanism is sometimes provided to prevent two or more gear pairs from engaging simultaneously. The conventional gearboxes suffer from a complicated gear shift mechanism. Typically the major component comprising the gear shift mechanism are not interchangeable. Each selector fork is usually mounted on a dedicated guide rod. This increases the cost and weight of the mechanism. OBJECT OF INVENTION The main object of the present invention is to provide a gear selection system. Another object of the present invention is to provide a gear selection system which is simple in construction and light weight. Another object of the present invention is to provide a gear selection system which is interchangeable and cost effective. STATEMENT OF INVENTION Gear selection system comprises; shifter shaft rotatably mounted in the gear box casing configured to slide axially along the longitudinal direction, at least one fork member slideably mounted on the said shifter shaft through bearing, said fork members comprises pin guides for holding the respective locking pin members pressed against the cylindrical surface of the said shifter shaft, wherein said shifter shaft comprises plurality of recesses provided on the cylindrical surface of the said shifter shaft aligned with the said locking pin member for engaging the said fork member with said shifter shaft, locking plate member provided parallel to the said shifter shaft for locking the said fork member through holes provided on the said locking plate member which facilitates one end of the said locking pin to engage with the said holes when the other end of the said locking pin member is not engaged with the recess provided on the cylindrical surface of the said shifter shaft. Gear selection system in accordance with this invention, wherein said fork member is configured for engaging the gear ratio through a synchroniser cone or dog clutch. Gear selection system in accordance with this invention, wherein said fork member is preferably configured to be interchangeable and each of said forks are free to slide on the said shifter shaft. Gear selection system in accordance with this invention, wherein locking pin is positively spring loaded in the said pin guide against the cylindrical surface of said shifter shaft which facilitates said locking pin to move towards or away from the cylindrical surface of said shifter shaft during rotation. Gear selection system in accordance with this invention, wherein said pin guide is integral with the said fork member. Gear selection system in accordance with this invention, wherein said pin guide is separately connected to the said fork member. Gear selection system in accordance with this invention, wherein said locking plate is integral with the said gear box casing. Gear selection system in accordance with this invention, wherein said locking plate is separately connected with the said gear box casing. Gear selection system in accordance with this invention, wherein one end of said locking pin member engage the recesses provided on the shifter shaft and other end of said locking pin engages with holes provided on the said locking plate which facilitates the axial position of said locking pin with respect to the pin guide is governed by the angular position of the said shifter shaft. BRIEF DESCRIPTION OF INVENTION In accordance with this invention, gear selection system comprises; a shifter shaft (1) rotateably mounted in the gear box casing configured to slide axially, plurality of recesses (2) provided on the cylindrical surface of said shifter shaft, at least one fork (3) slidably mounted on the said shifter shaft through bearings. The said fork members (3) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said fork members (3) are preferably interchangeable. Each fork member (3) is free to slide on the said shifter shaft (1). The said fork members (3) comprises pin guides (4) for holding the locking pins (5). Said Pin guides (4) hold the said locking pins (5) positively spring loaded against the cylindrical surface of the said shifter shaft (1). The pin guides (4) facilitate the locking pins (5) to slide towards or away from the cylindrical surface of the shifter shaft (1). The pin guides (4) may either be separate components attached to the forks (3), or they may be integral with the fork members (3). A locking plate (6) is provided parallel to the shifter shaft (1). The said locking plate has holes (7) to engage the locking pins (5). The locking plate (6) may either be integral with the gearbox casing, or it may be a separate component fixed in place through suitable means. BRIEF DESCRIPTION OF DRAWINGS: Figure - 1 shows an isometric view of the complete system. Figure - 2 shows another isometric view of the complete system. Figure - 3 shows an isometric view of the system without the locking plate. Figure - 4 shows an isometric view of the shifter shaft, the pin guides and the pins. Figure - 5 shows an isometric view of a fork with the pin guide and locking pin. Figure - 6 shows another isometric view of a fork with the pin guide and locking pin. DETAILED DESCRIPTION OF INVENTION: Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same, Now referring figure-1 to 6, In accordance with this invention, gear selection system comprises; a shifter shaft (1) rotateably mounted in the gear box casing configured to slide axially, plurality of recesses (2) provided on the cylindrical surface of said shifter shaft, at least one fork members (3) slidably mounted on the said shifter shaft through bearings. The said fork members (3) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said fork members (3) are preferably interchangeable. Each fork member (3) is free to slide on the said shifter shaft (1). The said fork (3) comprises pin guides (4) for holding the respective locking pins (5). Said Pin guides (4) hold the said locking pins (5) positively spring loaded against the cylindrical surface of the said shifter shaft (1). The pin guides (4) facilitate the locking pins (5) to slide towards or away from the cylindrical surface of the shifter shaft (1). The pin guides (4) may either be separate components attached to the fork members (3), or they may be integral with the fork members (3). A locking plate (6) is provided parallel to the shifter shaft (1). The said locking plate has holes (7) to engage the locking pins (5). The locking plate (6) may either be integral with the gearbox casing, or it may be a separate component fixed in place through suitable means. The locking pins (5) have one end pressed against the cylindrical surface of the shifter shaft (1). The one end locking pins (5) engage the recesses (2 ) provided on the shifter shaft (1) and other end of said locking pin (5) engages holes (7) provided on the said locking plate(6) . The axial position of a locking pin (5) with respect to the pin guide (4) is governed by the angular position of the shifter shaft (1) The shifter shaft (1) and locking pins (5) interact in the manner of a cam and follower, with the former as a cam and the latter as a follower. The rotation of the shifter shaft (1) exposes a recess (2) on its surface to the locking pin (5), which slides into the said recess (2). Further rotation will cause the locking pin (5) to be pushed out of the recess (2) in the shifter shaft (1) and pushed into the recess (7) provided in the locking plate (6). When a locking pin (5) is engaged with the shifter shaft (1) through a recess (2), said locking pin (5) locks the said fork members (3) onto the shifter shaft (1). Upon full engagement, the locking pin (5) is at the bottom dead centre of its travel into the recess (2) in the shifter shaft (1), the locking pin (5) disengages from the hole (7) in the locking plate (6), freeing the fork members (3) to move with the shifter shaft (1). The rotation of the shifter shaft (1) sequentially engages and disengages the locking pins (5) in the fork members (3) mounted on it. A locking pin (5) that is not engaged with the shifter shaft (1) will instead be engaged with the locking plate (6), thus holding its fork (3) in place. To engage a desired gear ratio, the shifter shaft (1) rotates until the required fork (3) is locked. The shifter shaft (1) then slides axially along with the fork members (3) in the longitudinal direction required to engage the gear pair. The recesses (2) on the shifter shaft (1) are provided in such a way that only one fork member (3) is locked at a time. This arrangement provides an interlock preventing accidental engagement of two gear ratios simultaneously. The shifter shaft can be rotated by various means, such as mechanical linkages, electric motors, hydraulics etc. The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof. WE CLAIM 1. Gear selection system comprises; shifter shaft rotatably mounted in the gear box casing configured to slide axially along the longitudinal direction, at least one fork member slideably mounted on the said shifter shaft through bearing, said fork members comprises pin guides for holding the respective locking pin members pressed against the cylindrical surface of the said shifter shaft, wherein said shifter shaft comprises plurality of recesses provided on the cylindrical surface of the said shifter shaft aligned with the said locking pin member for engaging the said fork member with said shifter shaft, locking plate member provided parallel to the said shifter shaft for locking the said fork member through holes provided on the said locking plate member which facilitates one end of the said locking pin to engage with the said holes when the other end of the said locking pin member is not engaged with the recess provided on the cylindrical surface of the said shifter shaft. 2. Gear selection system as claimed in claim 1, wherein said fork member is configured for engaging the gear ratio through a synchroniser cone or dog clutch. 3. Gear selection system as claimed in claim 1, wherein said fork member is preferably configured to be interchangeable and each of said fork are free to slide on the said shifter shaft. 4. Gear selection system as claimed in claim 1, wherein locking pin is positively spring loaded in the said pin guide against the cylindrical surface of said shifter shaft which facilitates said locking pin to move towards or away from the cylindrical surface of said shifter shaft during rotation. 5. Gear selection system as claimed in claim 1, wherein said pin guide is integral with the said fork member. 6. Gear selection system as claimed in claim 1, wherein said pin guide is separately connected to the said fork member. 7. Gear selection system as claimed in claim 1, wherein said locking plate is integral with the said gear box casing. 8. Gear selection system as claimed in claim 1, wherein said locking plate is separately connected with the said gear box casing. 9. Gear selection system as claimed in claim 1, wherein one end of said locking pin member engage the recesses provided on the shifter shaft and other end of said locking pin engages with holes provided on the said locking plate which facilitates the axial position of said locking pin with respect to the pin guide is governed by the angular position of the said shifter shaft. 10. Gear selection system as herein described substantially with respect to the accompanying drawings. Abstract Gear Selection System In accordance with this invention, gear selection system comprises; a shifter shaft (1) rotateably mounted in the gear box casing configured to slide axially, plurality of recesses (2) provided on the cylindrical surface of said shifter shaft, at least one fork member (3) slidably mounted on the said shifter shaft through bearings. The said fork members (3) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said fork members (3) are preferably interchangeable. Each fork member (3) is free to slide on the said shifter shaft (1). The said fork members (3) comprises pin guides (4) for holding the locking pins (5).Said Pin guides (4) hold the said locking pins (5) positively spring loaded against the cylindrical surface of the said shifter shaft (1). The pin guides (4) facilitate the locking pins (5) to slide towards or away from the cylindrical surface of the shifter shaft (l).The pin guides (4) may either be separate components attached to the fork members (3), or they may be integral with the fork members (3). A locking plate (6) is provided parallel to the shifter shaft (1). The said locking plate has holes (7) to engage the locking pins (5). The locking plate (6) may either be integral with the gearbox casing, or it may be a separate component fixed in place through suitable means.

Documents:

189-MUM-2008-ABSTRACT(18-3-2014).pdf

189-MUM-2008-ABSTRACT(29-11-2012).pdf

189-mum-2008-abstract.doc

189-mum-2008-abstract.pdf

189-MUM-2008-CLAIMS(AMENDED)-(18-3-2014).pdf

189-MUM-2008-CLAIMS(AMENDED)-(29-11-2012).pdf

189-mum-2008-claims.doc

189-mum-2008-claims.pdf

189-mum-2008-correspondence(25-2-2008).pdf

189-mum-2008-correspondence-received.pdf

189-mum-2008-description (complete).pdf

189-MUM-2008-DRAWING(29-11-2012).pdf

189-mum-2008-drawings.pdf

189-MUM-2008-FORM 1(29-11-2012).pdf

189-mum-2008-form 1(7-2-2008).pdf

189-MUM-2008-FORM 13(18-3-2014).pdf

189-MUM-2008-FORM 13(29-11-2012).pdf

189-mum-2008-form 18(25-2-2008).pdf

189-MUM-2008-FORM 2(TITLE PAGE)-(29-11-2012).pdf

189-MUM-2008-FORM 26(18-3-2014).pdf

189-MUM-2008-FORM 3(18-3-2014).pdf

189-mum-2008-form 8(25-2-2008).pdf

189-mum-2008-form 9(25-2-2008).pdf

189-mum-2008-form-1.pdf

189-mum-2008-form-2.doc

189-mum-2008-form-2.pdf

189-mum-2008-form-26.pdf

189-mum-2008-form-3.pdf

189-MUM-2008-MARKED COPY(18-3-2014).pdf

189-MUM-2008-MARKED COPY(29-11-2012).pdf

189-MUM-2008-REPLY TO EXAMINATION REPORT(29-11-2012).pdf

189-MUM-2008-REPLY TO HEARING(18-3-2014).pdf

189-MUM-2008-SPECIFICATION(AMENDED)-(18-3-2014).pdf

189-MUM-2008-SPECIFICATION(AMENDED)-(29-11-2012).pdf

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