Description:TECHNICAL FIELD
[001] The embodiments herein generally relate to transmission shift mechanisms in vehicles and more particularly to a system and a method of assembling a gear shift mechanism in a power transmission unit of the vehicle, which reduces assembly time.
BACKGROUND
[002] Generally, a gear shift mechanism is used in a manual transmission of a vehicle for manually selecting respective gears which are required for various driving conditions of the vehicle. Typically, the gear shift mechanism includes a gear shift lever, a plurality of shift rails, a plurality of shift forks, a plurality of shift bushes and a plurality of shift sleeves/ synchronizers. Each shift fork and shift bush is mounted onto respective shift rail. Each shift sleeve is connected to the respective shift fork. Each shift rail has a circular cross section and the ends of each shift rail is movably mounted onto a transmission housing. Assembling the aforementioned components of the gear shift mechanism is cumbersome and a time consuming process.
[003] Some vehicles use flat shift rails having rectangular cross section in the gear shift mechanism to simplify and reduce the expense of the shift rail housing assemblies. While the use of such flat shift rails is desirable, the means for mounting, guiding and retaining the flat shift rails within a shift rail housing assembly is difficult and is one of the challenges posed to the original equipment manufacturers (OEM).
[004] Therefore, there exists a need for a system and a method of assembling a gear shift mechanism in the power transmission unit of the vehicle, which obviates the aforementioned drawbacks.

OBJECTS
[005] The principal object of embodiments herein is to provide a system and a method of assembling a gear shift mechanism in the power transmission unit of the vehicle, which reduces assembly time.
[006] Another object of embodiments herein is to provide the system and a method of assembling the gear shift mechanism, which is inexpensive and easier to assemble, and disassemble shift rails from a transmission structure during service or maintenance.
[007] Another object of embodiments herein is to pre-assemble shift forks and shift bushes onto the shift rails in transmission assembly line.
[008] These and other objects of embodiments herein will be better appreciated and understood when considered in conjunction with following description and accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[009] The embodiments are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0010] Fig. 1 depicts a perspective view of a system for mounting a gear shift mechanism in a power transmission unit of a vehicle, according to first embodiments as disclosed herein;
[0011] Fig. 2A depicts a perspective view of a shift rail mounting member, according to first embodiments as disclosed herein;
[0012] Fig. 2B depicts a perspective view of another shift rail mounting member, according to first embodiments as disclosed herein;
[0013] Fig. 3 depicts an exploded view of the shift rail mounting members, the gear shift mechanism and a transmission structure, according to first embodiments as disclosed herein;
[0014] Fig. 4 depicts an exploded view of a system for mounting the gear shift mechanism to a transmission structure, according to second embodiments as disclosed herein; and
[0015] Fig. 5 depicts a flowchart indicating steps of a method of assembling the gear shift mechanism in the power transmission unit of the vehicle, according to first and second embodiments as disclosed herein.
DETAILED DESCRIPTION
[0016] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0017] The embodiments herein achieve a system and a method of assembling a gear shift mechanism in the power transmission unit of the vehicle, which reduces assembly time. Referring now to the drawings Figs. 1 through 5, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0018] Fig. 3 depicts an exploded view of shift rail mounting members (102A, 102B), a gear shift mechanism (10) and a transmission structure (25), according to the first embodiments as disclosed herein. Fig. 4 depicts an exploded view of a system (200) for mounting the gear shift mechanism (10) to the transmission structure (30), according to second embodiments as disclosed herein. In the first and second embodiments, the systems (100, 200) include a plurality of shift rail mounting members (102A, 102B, 202A, 202B) and a plurality of first fasteners (104, 204). For the purpose of this description and ease of understanding, the systems (100, 200) are explained herein with below reference to mounting a speed gear shift mechanism (10) to the transmission structure (25, 30) in a power transmission unit of an agricultural vehicle such as a tractor. However, it is also within the scope of the invention to use/practice the systems (100, 200) for mounting range gear shift mechanism or any other gear shift mechanism in manual power transmission unit or automatic power transmission unit of any other agricultural machines or any other off-road vehicles or any other vehicles without otherwise deterring the intended function of the systems (100, 200) as can be deduced from the description and corresponding drawings. The gear shift mechanism (10) includes a plurality of shift rails (12), a plurality of shift forks (14), a plurality of shift bushes (16), a plurality of ball retention springs (18), a plurality of balls (20) and a plurality of interlocking pins (22).
[0019] In the first and second embodiments, the plurality of shift rail mounting members (102A, 102B, 202A, 202B) are adapted to mount the plurality of shift rails (12) to the transmission structure (25, 30). Each shift rail mounting member (102A, 102B, 202A, 202B) defines a plurality of shift rail receiving portions (102AR, 102BR, 202AR, 202BR) (as shown in fig. 2A, fig. 2B and fig. 4) adapted to receive respective ends of the shift rails (12) therein. Each shift rail (12) is adapted to pre-mount respective shift forks (14) and respective shift bushes (16) thereon. Each shift rail mounting member (102A, 102B, 202A, 202B) includes a main body (102AB, 102BB, 202AB, 202BB) (as shown in fig. 2A, fig. 2B and fig. 4). In the first embodiment, the main body (102AB) of respective shift rail mounting member (102A) defines a plurality of ball retention spring receiving portions (102AS) (as shown in fig. 2A). Each ball retention spring receiving portion (102AS) is adapted to receive respective ball retention spring (18) therein to engage respective ball (20) onto respective shift rail (12). In the second embodiment, the main body (202AB) of respective shift rail mounting member (202A) defines a plurality of ball receiving portions (202AS) (as shown in fig. 4), wherein each ball receiving portion (202AS) is adapted to receive respective ball (20) which is pushed against respective shift rail (12) by respective ball retention spring (18). In the second embodiment, respective ball retention spring (18) is received by respective ball retention spring receiving portion (not shown) defined in the transmission structure (30).
[0020] The plurality of shift rail receiving portions (102AR, 102BR, 202AR, 202BR) are defined in the main body (102AB, 102BB, 202AB, 202BB) of the shift rail mounting member (102A, 102B, 202A, 202B). Each shift rail receiving portion (102AR, 102BR, 202AR, 202BR) is considered to be a through hole. In the first embodiment, a bottom end of each ball retention spring receiving portion (102AS) adjoins respective shift rail receiving portion (102AR). In the second embodiment, a bottom end of each ball receiving portion (202AS) adjoins respective shift rail receiving portion (202AR). In the first embodiment, each ball retention spring receiving portion (102AS) is considered to be a through hole. In the second embodiment, each ball receiving portion (202AS) is considered to be a through hole.
[0021] The main body (102BB, 202AB) of respective shift rail mounting member (102B, 202A) defines a plurality of interlock pin receiving portions (102BP, 202AP) (as shown in fig. 2B and fig. 4), wherein each interlock pin receiving portion (102BP, 202AP) is adapted to receive respective interlocking pin (22) therein to engage the interlocking pin (22) with respective shift rail (12).
[0022] In the first embodiment, each shift rail mounting member (102A, 102B) includes a pair of arms (102AA, 102BA) (as shown in fig. 2A and fig. 2B), wherein each arm (102AA, 102BA) extends from corresponding end of the main body (102AB, 102BB). The arms (102AA, 102BA) of each shift rail mounting member (102A, 102B) is removably mounted onto the transmission structure (25). Each arm (102AA, 102BA) defines at least one first threaded hole (102AH, 102BH) (as shown in fig. 2A and fig. 2B) adapted to receive respective first fastener (104) therethrough to secure respective shift rail mounting member (102A, 102B) to the transmission structure (25). For the purpose of this description and ease of understanding, in the first embodiment, the transmission structure (25) is considered to be a transmission housing.
[0023] Further, in the first embodiment, the main body (102AB) of respective shift rail mounting member (102A) defines a plurality of second threaded hole (102AI) (as shown in fig. 2A), wherein each second threaded hole (102AI) is adapted to receive a respective second fastener (106) therethrough to engage a spring retainer (24) (as shown in fig. 1 and fig. 3) on the main body (102AB) thereby retaining ball retention springs (18) therein. The arms (102AA) of the shift rail mounting member (102A) is disposed on the transmission structure (25) at a higher level than respective arms (102BA) of another shift rail mounting member (102B). Each arm (102BA) of another shift rail mounting member (102B) defines a dowel pin receiving portion (102BD) (as shown in fig. 2B) adapted to receive a dowel pin (26) therethrough. The dowel pins (26) are adapted to locate the shift rail mounting member (102B) with respect to the transmission structure (25) thereby positioning the gear shift mechanism (10) with respect to gears of the power transmission unit.
[0024] In the second embodiment, the main body (202AB, 202BB) of each shift rail mounting member (202A, 202B) defines a plurality of fastener receiving portions (202AF, 202BF) (as shown in fig. 4), wherein each fastener receiving portion (202AF, 202BF) is adapted to receive a respective fastener (204) therethrough to secure the shift rail mounting member (202A, 202B) to the transmission structure (30). For the purpose of this description and ease of understanding, in the second embodiment, the transmission structure (30) is considered to be a transmission top cover.
[0025] Fig. 5 depicts a flowchart indicating steps of a method (300) of assembling the gear shift mechanism (10) in the power transmission unit of the vehicle, according to first and second embodiments as disclosed herein. At step (302), the method (300) includes pre-assembling each shift fork (14) and each shift bush (16) onto a respective shift rail (12). At step (304), the method (300) includes inserting respective end of each shift rail (12) into a respective shift rail receiving portion (102AR, 102BR, 202AR, 202BR) defined in a main body (102AB, 102BB, 202AB, 202BB) of respective shift rail mounting member (102A, 102B, 202A, 202B). At step (306), the method (300) includes engaging, by respective ball retention spring (18), respective ball (20) against respective shift rail (12). At step (308), the method (300) includes mounting each shift rail mounting member (102A, 102B, 202A, 202B) to a transmission structure (25, 30).
[0026] The method step (308) includes securing, by a plurality of first fasteners (104, 204), one of a plurality of arms (102AA, 102BA) or the main body (202A, 202B) of each shift rail mounting member (102A, 102B, 202A, 202B) to the transmission structure (25, 30).
[0027] Further, in the first embodiment, securing, by a plurality of second fasteners (106), each spring retainer (24) onto the main body (102AB) of respective shift rail mounting member (102A) thereby retaining ball retention springs (18) therein prior to mounting each shift rail mounting member (102A, 102B, 202A, 202B) to the transmission structure (25) when the transmission housing is used as the transmission structure (25).
[0028] The method step (306) includes inserting respective ball retention spring (18) along with respective said ball (20) into respective ball retention spring receiving portion (102AS) defined in the main body (102AB) of respective shift rail mounting member (102A).
[0029] The technical advantages of the systems (100, 200) for mounting the gear shift mechanism (10) in the power transmission unit are as follows. The system (100, 200) enables preassembly of shift forks and shift bushes on the shift rail in transmission assembly line and reduces assembly time. The system (100, 200) is inexpensive and easier to assemble, and disassemble shift rails (12) from the transmission structure (25, 30) during service or maintenance.
[0030] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifications within the spirit and scope of the embodiments as described herein.
, Claims:We claim,
1. A system (100, 200) for assembling a gear shift mechanism (10) in a power transmission unit of a vehicle, said system (100, 200) comprising:
a plurality of shift rail mounting members (102A, 102B, 202A, 202B) adapted to mount a plurality of shift rails (12) to a transmission structure (25, 30),
wherein
each of said shift rail mounting member (102A, 102B, 202A, 202B) defines a plurality of shift rail receiving portions (102AR, 102BR, 202AR, 202BR) adapted to receive respective ends of said shift rails (12) therein; and
each of said shift rail (12) is adapted to pre-mount respective shift fork (14) and respective shift bush (16) thereon.
2. The system (100, 200) as claimed in claim 1, wherein each of said shift rail mounting member (102A, 102B, 202A, 202B) includes a main body (102AB, 102BB, 202AB, 202BB), wherein said main body (102AB) of respective said shift rail mounting member (102A) defines a plurality of ball retention spring receiving portions (102AS),
wherein
each of said ball retention spring receiving portion (102AS) is adapted to receive respective ball retention spring (18) therein to engage respective ball (20) onto respective said shift rail (12).
3. The system (100, 200) as claimed in claim 2, wherein the plurality of said shift rail receiving portions (102AR, 102BR, 202AR, 202BR) are defined in said main body (102AB, 102BB, 202AB, 202BB);
each of said shift rail receiving portion (102AR, 102BR, 202AR, 202BR) is a through hole;
a bottom end of each of said ball retention spring receiving portion (102AS) adjoins respective said shift rail receiving portion (102AR); and
each of said ball retention spring receiving portions (102AS, 202AS) is a through hole.
4. The system (100, 200) as claimed in claim 2, wherein said main body (102BB, 202AB) of respective said shift rail mounting member (102B, 202A) defines a plurality of interlock pin receiving portions (102BP, 202AP), wherein each of said interlock pin receiving portion (102BP, 202AP) is adapted to receive respective interlocking pin (22) therein to engage said interlocking pin (22) with respective said shift rail (12).
5. The system (100) as claimed in claim 2, wherein each of said shift rail mounting member (102A, 102B) includes a pair of arms (102AA, 102BA), wherein each of said arm (102AA, 102BA) extends from corresponding end of said main body (102AB, 102BB),
wherein
said arms (102AA, 102BA) of each of said shift rail mounting members (102A, 102B) is removably mounted onto said transmission structure (25).
6. The system (100) as claimed in claim 5, wherein each of said arm (102AA, 102BA) defines at least one first threaded hole (102AH, 102BH) adapted to receive a respective first fastener (104) therethrough to secure respective said shift rail mounting member (102A, 102B) to said transmission structure (25);
said transmission structure (25) is a transmission housing; and
said main body (102AB) of respective said shift rail mounting member (102A) defines a plurality of second threaded hole (102AI), wherein each of said second threaded hole (102AI) is adapted to receive a respective second fastener (106) therethrough to engage a spring retainer (24) on said main body (102AB) thereby retaining said ball retention springs (18) therein.
7. The system (100) as claimed in claim 5, wherein said arms (102AA) of said shift rail mounting member (102A) is disposed on said transmission structure (25) at a higher level than respective said arms (102BA) of another said shift rail mounting member (102B);
each of said arm (102BA) of another said shift rail mounting member (102B) defines a dowel pin receiving portion (102BD) adapted to receive a dowel pin (26) therethrough; and
respective said dowel pin (26) is adapted to locate said shift rail mounting member (102B) with respect to said transmission structure (25) thereby positioning said gear shift mechanism (10) with respect to gears of said power transmission unit.
8. The system (200) as claimed in claim 2, wherein said main body (202AB, 202BB) of each of said shift rail mounting member (202A, 202B) defines a plurality of fastener receiving portions (202AF, 202BF), wherein each of said fastener receiving portion (202AF, 202BF) is adapted to receive a respective fastener (204) therethrough to secure said shift rail mounting member (202A, 202B) to said transmission structure (30);
said transmission structure (30) is a transmission top cover;
said main body (202AB) of respective shift rail mounting member (202A) defines a plurality of ball receiving portions (202AS), wherein each of said ball receiving portion (202AS) is adapted to receive respective ball (20) which is pushed against respective shift rail (12) by respective ball retention spring (18);
a bottom end of each of said ball receiving portion (202AS) adjoins respective shift rail receiving portion (202AR); and
respective said ball retention spring (18) is received by a respective ball retention spring receiving portion defined in the transmission structure (30).
9. A method (300) of assembling a gear shift mechanism (10) in a power transmission unit of a vehicle, said method (300) comprising:
pre-assembling each shift fork (14) and each shift bush (16) onto a respective shift rail (12);
inserting respective end of each of said shift rail (12) into a respective shift rail receiving portion (102AR, 102BR, 202AR, 202BR) defined in a main body (102AB, 102BB, 202AB, 202BB) of respective said shift rail mounting member (102A, 102B, 202A, 202B);
engaging, by respective ball retention spring (18), respective ball (20) against respective said shift rail (12); and
mounting each of said shift rail mounting member (102A, 102B, 202A, 202B) to a transmission structure (25, 30).
10. The method (300) as claimed in claim 9, wherein mounting each of said shift rail mounting member (102A, 102B, 202A, 202B) to said transmission structure (25, 30) includes,
securing, by a plurality of first fasteners (104, 204), one of a plurality of arms (102AA, 102BA) or said main body (202A, 202B) of each of said shift rail mounting member (102A, 102B, 202A, 202B) to said transmission structure (25, 30),
wherein
said transmission structure (25, 30) is one of a transmission housing or a transmission top cover.
11. The method (300) as claimed in claim 10, wherein said method (300) includes, securing, by a plurality of second fasteners (106), each spring retainer (24) onto said main body (102AB) of respective shift rail mounting member (102A) thereby retaining said ball retention springs (18) therein prior to mounting each of said shift rail mounting member (102A, 102B, 202A, 202B) to said transmission structure (25) when the transmission housing is used as said transmission structure (25),
wherein
engaging, by respective said ball retention spring (18), respective said ball (20) against respective said shift rail (12) includes inserting respective ball retention spring (18) along with respective said ball (20) into respective ball retention spring receiving portion (102AS) defined in said main body (102AB) of respective said shift rail mounting member (102A).