Title of Invention

GEAR CHANGE MECHANISM

Abstract

Gear change mechanism comprises of a guide member (1) revolute mounted in the gearbox casing. The guide member (1) is provided with plurality of circumferential grooves (2) and longitudinal channel (3) on its cylindrical surface. The said guide member (1) supports a sliding member (6) and shifter forks (4) through suitable bearings. The said shifter forks (4) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said shifter forks (4) are preferably identical in construction. Each of the said shifter forks (4) can slide on the said guide member (1). The said shifter forks (4) are provided with lugs (5). The said lugs (5) may either be integral with the said shifter forks (4) or separate components installed onto the said shifter forks (4). The said sliding member (6) is located in the said axial channel (3) present in the said guide member (1). The sliding motion of the said sliding member (6) is along the said axial channel (3). The said sliding member (6) comprises at least one recess (7) to engage the said lugs (5) on the said shifter forks (4). This arrangement provides an interlock between said shifter forks (4) and circumferential groove (2) of said guide member (1) which prevents accidental engagement of two gear ratios simultaneously. It doesn't utilise any spring loaded components. Lugs are fixed so it's having fewer moving parts. This makes the system more durable.

Full Text

FORM 2 THE PATENTS ACT 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See Section 10; rule 14) TITLE OF THE INVENTION Gear Change Mechanism 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 an 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 change mechanism. 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 shifter forks mounted on their respective rods/shafts/slides. Each fork usually selects one or two ratios by sliding in the required direction. The shifter forks are operated by any suitable mechanism. 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 components 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 change mechanism. Another object of the present invention is to provide a gear change mechanism which is simple in construction and light weight. Another object of the present invention is to provide a gear change mechanism, whose major components are interchangeable and cost effective. STATEMENT OF INVENTION Gear change mechanism comprises; guide member rotatably mounted in the gear box casing, at least one shifter fork slidably mounted on the said guide member through bearings for operating synchroniser cone and dog clutches, said guide member having plurality of circumferential grooves for locking the said shifter forks in neutral position, said shifter fork comprises lug for engaging the respective grooves on the said guide member, wherein said guide member comprises channel along longitudinal direction , sliding member slidebly disposed on the said channel which facilitate the longitudinal movement of the said sliding member engaged with the said shifter fork through the said lug for changing the gears. Gear change mechanism in accordance with this invention, wherein said shifter fork is configured for engaging the gear ratio through a synchroniser cone or dog clutch. Gear change mechanism in accordance with this invention, wherein said shifter fork is preferably configured to be interchangeable and each of said shifter forks are free to slide on the said guide member. Gear change mechanism in accordance with this invention, wherein said lug comprises projection for engaging with the said circumferential groove on the cylindrical surface of said guide member which facilitates said lug to lock the said shifter fork onto the said guide member. Gear change mechanism in accordance with this invention, wherein said lug is integral with the said shifter fork. Gear change mechanism in accordance with this invention, wherein lug is separately connected to the said shifter fork. Gear change mechanism in accordance with this invention, wherein the said sliding member comprises at least one recesses for engaging with the said projection of said lug upon the angular alignment of said guide member and locks the said shifter fork with the said sliding member. BRIEF DESCRIPTION OF INVENTION Gear selection mechanism comprises of a guide member (1) revolute mounted in the gearbox casing. The guide member (1) is provided with circumferential grooves (2) and an axial channel (3) on its cylindrical surface. The said guide member (1) supports a sliding member (6) and shifter forks (4) through suitable bearings. The said shifter forks (4) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said shifter forks (4) are preferably identical in design. Each of the said shifter forks (4) can slide on the said guide member (1). The said shifter forks (4) are provided with lugs (5). The said lugs (5) may either be integral with the said shifter forks (4) or separate components installed onto the said shifter forks (4) through suitable means. The said sliding member (6) is located in the said axial channel (3) present in the said guide member (1). The sliding motion of the said sliding member (6) is along the said axial channel (3). The said sliding member (6) incorporates recesses (7) to engage the said lugs (5) on the said shifter forks (4). BRIEF DESCRIPTION OF DRAWINGS Figure - 1 shows an isometric view of the complete system. Figure - 2 shows the isometric view of the system without the shifter forks. Figure - 3 shows the isometric view of the system without the shifter forks and lugs. Figure - 4 shows an isometric view of a shifter fork and lug. Figure - 5 shows a view of the shifter forks with their lugs. Figure - 6 shows the frontal view of the guide member, sliding member and a lug. Figure - 7 shows the frontal view of the guide member, sliding member and all lugs. Figure - 8 shows an isometric view of the complete system with shifter fork in engaged position. Figure - 9 shows an isometric view of the system without the shifter forks, with lug in engaged position. DETAILED DESCRIPTION OF THE 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 to figure-1 to 9, in accordance with this invention, gear selection mechanism comprises of a guide member (1) rotatably mounted in the gearbox casing. The guide member (1) is provided with circumferential grooves (2) for locking the shifter fork (4) in neutral position and an axial channel (3) on its cylindrical surface. The said guide member (1) supports a sliding member (6) and at least one shifter forks (4) slidably mounted on the said guide member through suitable bearings. The said shifter fork (4) engages a gear ratio through a synchroniser cone or a dog clutch. The said shifter forks (4) are preferably identical in design. Each of the said shifter forks (4) can slide on the said guide member (1). The said shifter forks (4) are provided with lugs (5). The said lugs (5) may either be integral with the said shifter forks (4) or separate components installed onto the said shifter forks (4) through suitable means. The dog clutches are splined on the out put shaft, the sliding of the said dog clutches are controlled by the said shifter fork (4). When a gear ratio has to be engaged, the respective dog clutches engages the gear and locks on the output shaft. The said sliding member (6) is located in the said axial channel (3) present in the said guide member (1). The sliding motion of the said sliding member (6) is along the said axial channel (3). The said sliding member (6) incorporates recesses (7) to engage the said lugs (5) on the said shifter forks (4). The said lugs (5) on the said shifter forks (4) engage the said circumferential grooves (2) in the said guide member (1) and the said recesses (7) in the said sliding member (6). The rotation of the said guide member (1) governs the angular position of the said sliding member (6) with respect to the said lugs (5) on the said shifter forks (4). Said lug comprises projection for engaging with the said circumferential groove on the cylindrical surface of said guide member which facilitates said lug to lock the said shifter fork onto the said guide member. Said sliding member (6) comprises at least one recesses(7) for engaging with the said projection of said lug (5) upon the angular alignment of said guide member (1) and locks the said shifter fork with the said sliding member(6). To engage a desired gear ratio, the said guide member (1) rotates until the said lug (5) of the respective shifter fork (4) is aligned with the said recess (7) in the said sliding member (6). Upon proper alignment with the said sliding member (6), the said lug (5) disengages the said circumferential groove (2) in the said guide member (1). The said sliding member (6) slides in the required direction, moving the said shifter fork (4) along with itself. The movement of the said shifter fork (4) engages the synchroniser cone or the dog clutch with the gear. The said lug's (5) angular positions with respect to said guide member (1) ensure that only one lug (5) is engaged at a time by the said sliding member (6). The lugs (5) that are not engaged with the said sliding member (6) are therefore engaged with the said circumferential grooves (2) provided in the said guide member (1). The said shifter forks (4) with their respective lugs (5) engaged with the said circumferential grooves (2) in the said guide member (1) cannot slide along the said guide member (1). This arrangement provides an interlock preventing accidental engagement of two gear ratios simultaneously. The said guide member (1) is rotated by various means, such as mechanical linkages, electric motors, hydraulics etc. The said sliding member (6) can be actuated by similar means. 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 change mechanism comprises; guide member rotatably mounted in the gear box casing, at least one shifter fork slidably mounted on the said guide member through bearings for operating synchroniser cone and dog clutches, said guide member having plurality of circumferential grooves for locking the said shifter forks in neutral position, said shifter fork comprises lug for engaging the respective grooves on the said guide member, wherein said guide member comprises channel along longitudinal direction , sliding member slidebly disposed on the said channel which facilitate the longitudinal movement of the said sliding member engaged with the said shifter fork through the said lug for changing the gears. 2. Gear change mechanism as claimed in claim 1, wherein said shifter fork is configured for engaging the gear ratio through a synchroniser cone or dog clutch. 3. Gear change mechanism as claimed in claim 1, wherein said shifter fork is preferably configured to be interchangeable and each of said shifter forks are free to slide on the said guide member. 4. Gear change mechanism as claimed in claim 1, wherein said lug comprises projection for engaging with the said circumferential groove on the cylindrical surface of said guide member which facilitates said lug to lock the said shifter fork onto the said guide member. 5. Gear change mechanism as claimed in claim 1, wherein said lug is integral with the said shifter fork. 6. Gear change mechanism as claimed in claim 1, wherein lug is separately connected to the said shifter fork. 7. Gear change mechanism as claimed in claim 1, wherein the said sliding member comprises at least one recesses for engaging with the said projection of said lug upon the angular alignment of said guide member and locks the said shifter fork with the said sliding member. 8. Gear change mechanism as herein described substantially with respect to the accompanying drawings. ABSTRACT Gear Change Mechanism Gear change mechanism comprises of a guide member (1) revolute mounted in the gearbox casing. The guide member (1) is provided with plurality of circumferential grooves (2) and longitudinal channel (3) on its cylindrical surface. The said guide member (1) supports a sliding member (6) and shifter forks (4) through suitable bearings. The said shifter forks (4) perform the function of engaging a gear ratio through a synchroniser cone or a dog clutch. The said shifter forks (4) are preferably identical in construction. Each of the said shifter forks (4) can slide on the said guide member (1). The said shifter forks (4) are provided with lugs (5). The said lugs (5) may either be integral with the said shifter forks (4) or separate components installed onto the said shifter forks (4) The said sliding member (6) is located in the said axial channel (3) present in the said guide member (1). The sliding motion of the said sliding member (6) is along the said axial channel (3). The said sliding member (6) comprises at least one recess (7) to engage the said lugs (5) on the said shifter forks (4). This arrangement provides an interlock between said shifter forks (4) and circumferential groove (2) of said guide member (1) which prevents accidental engagement of two gear ratios simultaneously. It doesn't utilise any spring loaded components. Lugs are fixed so it's having fewer moving parts. This makes the system more durable.

Documents:

336-mum-2008-abstract.doc

336-mum-2008-abstract.pdf

336-MUM-2008-CLAIMS(AMENDED)-(19-3-2014).pdf

336-MUM-2008-CLAIMS(AMENDED)-(20-11-2012).pdf

336-MUM-2008-CLAIMS(MARKED COPY)-(19-3-2014).pdf

336-MUM-2008-CLAIMS(MARKED COPY)-(20-11-2012).pdf

336-mum-2008-claims.doc

336-mum-2008-claims.pdf

336-mum-2008-correspondence(28-2-2008).pdf

336-mum-2008-correspondence-received.pdf

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

336-mum-2008-drawings.pdf

336-mum-2008-form 18(28-2-2008).pdf

336-MUM-2008-FORM 26(19-3-2014).pdf

336-MUM-2008-FORM 3(19-3-2014).pdf

336-mum-2008-form 8(28-2-2008).pdf

336-mum-2008-form 9(28-2-2008).pdf

336-mum-2008-form-1.pdf

336-mum-2008-form-2.doc

336-mum-2008-form-2.pdf

336-mum-2008-form-26.pdf

336-mum-2008-form-3.pdf

336-MUM-2008-REPLY TO EXAMINATION REPORT(20-11-2012).pdf

336-MUM-2008-REPLY TO HEARING(19-3-2014).pdf

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