阅读说明：本技术 一种八挡变速器挡位结构 (Eight keep off derailleur and keep off position structure ) 是由 刘晓雷 孙智金 严鉴铂 刘义 张海涛 殷崇一 杨林 杨东 于 2020-03-24 设计创作，主要内容包括：本发明公开了一种八挡变速器挡位结构,包括平行设置的多根拨叉轴,拨叉轴包括倒一挡拨叉轴、二三挡拨叉轴、四五挡拨叉轴、六七挡拨叉轴以及八挡拨叉轴；八挡拨叉轴位于五根平行设置的拨叉轴中除两侧以外的位置,四五挡拨叉轴位于五根平行设置的拨叉轴的一侧；其中四五挡拨叉轴的长度短于八挡拨叉轴的长度；本发明通过调整拨叉轴的长度以及位置排布后,八挡拨叉轴就可以从两根中间轴超速挡齿轮之间通过,不会与中间轴超速挡齿轮造成相互的影响,而且由于将四五挡拨叉轴的长度缩短后,四五挡拨叉轴无需穿过中间轴超速挡齿轮,因此在拨叉轴安装的过程中不会出现与超速挡齿轮之间的干涉,从而降低了拨叉轴安装高度以及拨叉强度增强。(The invention discloses an eight-gear transmission gear structure which comprises a plurality of shifting fork shafts arranged in parallel, wherein each shifting fork shaft comprises a reverse first-gear shifting fork shaft, a second-third-gear shifting fork shaft, a fourth-fifth-gear shifting fork shaft, a sixth-seventh-gear shifting fork shaft and an eight-gear shifting fork shaft; the eight-gear shifting fork shaft is positioned in the five parallel shifting fork shafts except the two sides, and the four-five-gear shifting fork shaft is positioned on one side of the five parallel shifting fork shafts; the length of the fourth-fifth gear shifting fork shaft is shorter than that of the eighth gear shifting fork shaft; according to the invention, after the length and the position arrangement of the shift fork shafts are adjusted, the eight-gear shift fork shaft can pass through between the two intermediate shaft over-speed gear wheels, and cannot cause mutual influence with the intermediate shaft over-speed gear wheels.)

1. A gear structure of an eight-gear transmission comprises a plurality of shifting fork shafts (1) which are arranged in parallel, wherein each shifting fork shaft (1) comprises a reverse first-gear shifting fork shaft (1-1), a second-third-gear shifting fork shaft (1-2), a fourth-fifth-gear shifting fork shaft (1-3), a sixth-seventh-gear shifting fork shaft (1-4) and an eight-gear shifting fork shaft (1-5); it is characterized in that the preparation method is characterized in that,

the eight-gear shifting fork shaft (1-5) is positioned in five parallel shifting fork shafts (1) except two sides, and the four-five-gear shifting fork shaft (1-3) is positioned on any side of the five parallel shifting fork shafts (1);

wherein the length of the four-fifth gear shifting fork shaft (1-3) is shorter than that of the eight-fifth gear shifting fork shaft (1-5).

2. The eight speed transmission gear configuration according to claim 1, wherein the plurality of parallel shift rails (1) includes a fourth-fifth speed shift rail (1-3), an eighth speed shift rail (1-5), a sixty-seventh speed shift rail (1-4), a second-third speed shift rail (1-2), and a reverse first speed shift rail (1-1) which are arranged in this order.

3. The gear structure of an eight-speed transmission according to claim 2, characterized in that the gear structure comprises a plurality of shift grooves (3), and the plurality of shift grooves (3) comprises a fourth-fifth shift groove (3-3), an eighth shift groove (3-5), a sixty-seventh shift groove (3-4), a second-third shift groove (3-2) and a reverse-first shift groove (3-1) which are arranged in sequence.

4. The eight speed transmission range structure according to claim 3, wherein said shift grooves (3) have a width D, D being a positive integer and having a unit of mm;

the four-five gear shifting groove (3-3) and the eight gear shifting groove (3-5) are provided with a neutral space with a 2D distance, one side of the eight gear shifting groove (3-5) is tightly attached to one side of the six-seven gear shifting groove (3-4), a 3D neutral space is arranged between the other side of the six-seven gear shifting groove (3-4) and one side of the two-three gear shifting groove (3-2), and the other side of the two-three gear shifting groove (3-2) is tightly attached to the reverse one gear shifting groove (3-1).

5. The eight-gear transmission gear structure according to claim 4, characterized in that the transmission gear structure further comprises a shift head (2), and a first shift head (2-1), a second shift head (2-2) and a third shift head (2-3) are arranged at the bottom end of the shift head (2).

6. The eight speed transmission gear configuration according to claim 5, characterized in that the distance between the first shift knob (2-1) and the second shift knob (2-2) is 4D, and the distance between the second shift knob (2-2) and the third shift knob (2-3) is D.

7. The eight speed transmission range configuration according to claim 6, wherein a neutral space having a width of at least 2D is further provided at a side of said fourteen gear shift grooves (3-3) remote from said eighty gear shift grooves (3-5).

Technical Field

The invention relates to a gear structure of a transmission, in particular to a gear structure of an eight-gear transmission.

Background

The conventional transmission has a gear structure as shown in fig. 1, which includes a shift lever a, a plurality of shift forks B, and a plurality of shift shafts C corresponding to the shift forks B, and the prior art transmission generally has six gears and one reverse gear, so that the shift forks include a reverse shift fork B1, a first/second shift fork B2, a third/fourth shift fork B3, and a fifth/sixth shift fork B4, and the corresponding shift shafts include a reverse shift fork C1, a first/second shift fork C2, a third/fourth shift fork C3, and a fifth/sixth shift fork C4, and the shift forks B sequentially decrease and increase in distance from the bottom end of the shift lever a on the shift shafts C, as shown in fig. 1, the reverse shift fork B1 and the fifth/sixth shift fork B4 have the greatest length from the bottom end of the shift lever a, the third/fourth shift fork B3 has the smallest length from the bottom end of the shift lever a, and a guide block D is further installed on the shift shaft C, drive shift fork B and gear laminating through guide block D, that is to say, be provided with a plurality of guide blocks D in the fender position structure of derailleur, seted up one on every guide block D and kept off the position recess, still be provided with a plurality of neutral gear recesses in addition, when the derailleur was in the neutral gear, each kept off position recess and neutral gear recess and align in horizontal plane, the selection fender shifting block of gear shift lever A bottom stretches into in the recess, when the derailleur carries out the selection fender, thereby gear shift lever A promotes to drive the selection fender shifting block and stretches into corresponding fender position recess along a plurality of declutch shift shaft C array orientation removal.

When the existing transmission gear structure is installed above a transmission, the transmission is generally a double-intermediate-shaft transmission, as shown in fig. 2, the transmission comprises an intermediate-shaft overdrive gear F and a secondary-shaft overdrive gear E, a shifting fork is attached to the overdrive gear E, the overlapped part in fig. 2 shows gear meshing, the included angle between the connecting line of the two intermediate shafts and the horizontal line is small, the included angle is generally 19 degrees and the arrangement is horizontal, the installation space of the shifting fork shaft C is sufficient, and the gear arrangement can adopt a mode that a normal overdrive (8-gear) shifting fork shaft is arranged at the leftmost side.

However, in the case of a multi-countershaft transmission, such as a three-countershaft transmission, in which three countershafts are uniformly distributed at an included angle of 120 degrees, one of the countershafts is located right below a connecting line of the other two countershafts, as shown in fig. 3 and 4, and a countershaft overdrive gear F is the largest gear on the countershafts, if the arrangement of the conventional shift shafts is adopted, the overdrive shift shaft is located on the leftmost side of the gear, the reverse shift shaft is located on the rightmost side of the gear, but the reverse shift shaft is shorter and cannot reach the countershaft overdrive gear, the overdrive shift shaft is located very close to the countershaft overdrive gear, so as to avoid interference between the shift shafts and the overdrive gear, the vertical height of the shift shafts is increased, which results in a great increase in the mounting height of the shift fork, thereby increasing the height of the shift fork, greatly reducing the strength of the fork, and in order to ensure the strength of the fork, it is necessary to increase the thickness of the shift fork, resulting in an increase in the volume of the entire transmission.

Disclosure of Invention

The invention aims to provide an eight-gear transmission gear structure which is used for solving the problem that the strength of a shifting fork is reduced due to the fact that the mounting height of the shifting fork shaft of a gear shifting mechanism is increased when a transmission with multiple intermediate shafts is faced.

In order to realize the task, the invention adopts the following technical scheme:

a gear structure of an eight-gear transmission comprises a plurality of shifting fork shafts which are arranged in parallel, wherein each shifting fork shaft comprises a reverse first-gear shifting fork shaft, a second-third-gear shifting fork shaft, a fourth-fifth-gear shifting fork shaft, a sixth-seventh-gear shifting fork shaft and an eight-gear shifting fork shaft;

the eight-gear shifting fork shaft is positioned in the five parallel shifting fork shafts except for the two sides, and the four-gear shifting fork shaft and the five-gear shifting fork shaft are positioned on any side of the five parallel shifting fork shafts;

wherein the length of the fourth-fifth gear shifting fork shaft is shorter than that of the eighth gear shifting fork shaft.

Furthermore, the plurality of parallel shift fork shafts comprise a fourth-fifth shift fork shaft, an eighth shift fork shaft, a sixth-seventh shift fork shaft, a second-third shift fork shaft and a reverse-first shift fork shaft which are sequentially arranged.

Furthermore, the gear structure comprises a plurality of gear shifting grooves, and the gear shifting grooves comprise a fourth gear shifting groove, a fifth gear shifting groove, an eighth gear shifting groove, a sixth gear shifting groove, a seventh gear shifting groove, a sixth gear shifting groove and a sixth gear shifting groove which are sequentially arranged.

Furthermore, the width of each gear shifting groove is D, and D is a positive integer and has a unit of mm;

the four-five gear shifting groove and the eight gear shifting groove are provided with neutral space with 2D distance, one side of the eight gear shifting groove is tightly attached to one side of the six-seven gear shifting groove, the other side of the six-seven gear shifting groove and one side of the two-three gear shifting groove are provided with 3D neutral space, and the other side of the two-three gear shifting groove is tightly attached to the reverse one gear shifting groove.

Furthermore, the transmission gear structure further comprises a gear shifting head, and a first shifting head, a second shifting head and a third shifting head are arranged at the bottom end of the gear shifting head.

Further, the distance between the first shifting block and the second shifting block is 4D, and the distance between the second shifting block and the third shifting block is D.

Furthermore, a neutral space with the width of at least 2D is further arranged on one side, away from the eight-gear shifting groove, of the four-five-gear shifting groove.

Compared with the prior art, the invention has the following technical effects:

1. the eight-gear transmission gear structure provided by the invention has the advantages that the length of the four-five gear shifting fork shaft is shortened, then the position of the four-five gear shifting fork shaft is exchanged with the position of the eight gear shifting fork shaft, the eight gear shifting fork shaft can pass through two intermediate shaft over-speed gears, and cannot cause mutual influence with the intermediate shaft over-speed gears;

2. the eight-gear transmission gear structure provided by the invention has the advantages that the arrangement of the shifting fork shafts is adjusted, so that the position of the gear shifting groove is redesigned in order to ensure that the existing driving habit of a driver is not changed, and the safety of the driver in driving is improved;

3. the eight-gear transmission gear structure provided by the invention is designed to be matched with the design of the gear shifting groove, the structure of the gear shifting head is improved, the gear shifting head with three heads is matched with the gear shifting groove, the uniqueness of the rotation gear engagement of the gear shifting head is ensured, and the original driving habit of a driver can be kept, so that the safe driving of the driver is ensured.

Drawings

FIG. 1 is a schematic diagram of a prior art gear configuration;

FIG. 2 is a schematic view of a prior art gear structure installed in cooperation with a gear;

FIG. 3 is a cross-sectional view of a gear structure and a gear assembly provided in an embodiment of the present invention;

FIG. 4 is a block diagram of a gear structure and a gear assembly provided in an embodiment of the present invention;

FIG. 5 is an enlarged schematic view of a gear configuration provided in an embodiment of the present invention;

FIG. 6 is a schematic view of a shift knob assembly provided in an embodiment of the present invention;

FIG. 7 is a shift ball gear position map provided in accordance with an embodiment of the present invention;

FIG. 8 is a schematic illustration of a neutral shift finger and shift slot position provided in an embodiment of the present invention;

FIG. 9 is a schematic diagram of a six-seven shift shifter and a shift slot according to an embodiment of the present invention;

FIG. 10 is a schematic illustration of the eight speed shifter and shift position provided in an embodiment of the present invention;

FIG. 11 is a schematic illustration of a two-third gear shift knob and shift groove position provided in an embodiment of the present invention;

FIG. 12 is a schematic illustration of a reverse one-gear shifter and shift slot position provided in an embodiment of the present invention;

fig. 13 is a schematic diagram of a gear structure of a conventional dual countershaft transmission.

The reference numbers in the figures denote: 1-shift rail, 2-shift head, 3-shift groove, (1-1) -reverse first shift rail, (1-2) -two-three shift rail, (1-3) -four-five shift rail, (1-4) -six-seven shift rail, (1-5) -eight shift rail, (3-1) -reverse first shift groove, (3-2) -two-three shift groove, (3-3) -four-five shift groove, (3-4) -six-seven shift groove, (3-5) -eight shift groove, (2-1) -first shift head, (2-2) -second shift head, (2-3) -third shift head, A-shift lever, B-shift fork, C-shift rail, b1-reverse shift fork, B2-first/second shift fork, B3-third/fourth shift fork, B4-fifth/sixth shift fork, C1-shift fork shaft, C2-first/second shift fork shaft, C3-third/fourth shift fork shaft, C4-fifth/sixth shift fork shaft, D-guide block, E-two-shaft overdrive gear, F-countershaft overdrive gear, X1-existing reverse-first shift fork shaft, X2-existing two-three shift fork shaft, X3-existing four-five shift fork shaft, X4-existing six-seven shift fork shaft, X5-existing eight shift fork shaft, Y1-existing reverse-first shift fork, Y2-existing two-three shift fork, Y3-existing four-five shift fork, Y4-existing seven shift fork, Y5-existing eight shift fork.

Detailed Description

The invention discloses an eight-gear transmission gear structure which comprises a plurality of shift fork shafts 1 which are arranged in parallel, wherein each shift fork shaft 1 comprises a reverse first-gear shift fork shaft 1-1, a second-third-gear shift fork shaft 1-2, a fourth-fifth-gear shift fork shaft 1-3, a sixth-seventh-gear shift fork shaft 1-4 and an eight-gear shift fork shaft 1-5;

the eight-gear shifting fork shaft 1-5 is positioned in the five parallel shifting fork shafts 1 except two sides, and the four-five-gear shifting fork shaft 1-3 is positioned on one side of the five parallel shifting fork shafts 1;

wherein the length of the fourth-fifth gear declutch shift shaft 1-3 is shorter than the length of the eighth gear declutch shift shaft 1-5.

In the embodiment, a gear structure special for a three-countershaft transmission and a three-countershaft transmission is provided, particularly, the three-countershaft transmission is designed, because the height of a gear of the three-countershaft transmission is higher than that of a gear of a traditional double-countershaft transmission, if the eight-gear shifting fork shafts 1-5 are installed in a traditional mode, the eight-gear shifting fork shafts can be influenced with the gear after passing through the position above a maximum overspeed gear wheel on a countershaft, in order to solve the problem, the installation height of the shifting fork shafts is increased, but the strength of shifting forks can be weakened along with the increase of the installation height of the shifting fork shafts, and a set of new shifting fork shaft arrangement scheme is designed for reducing the installation height of the shifting fork shafts and ensuring the strength of the shifting forks.

In the present embodiment, as shown in fig. 3 and 4, the eighth transmission shift rail includes reverse first-gear shift rail 1-1, second-third-gear shift rail 1-2, fourth-fifth-gear shift rail 1-3, sixty-seventh-gear shift rail 1-4 and eighth shift rail 1-5, and since the mounting position of the shift fork on fourth-fifth-gear shift rail 1-3 is closer to the center position of the shift rail, the length of fourth-fifth-gear shift rail 1-4 can be shortened compared with the length of eighth shift rail 1-5, so that in the present embodiment, by shortening the length of fourth-fifth-gear shift rail 1-4, the position of fourth-fifth-gear shift rail 1-4 is exchanged with the position of eighth-gear shift rail 1-5, as shown in fig. 3 and 4, at this time, eighth-gear shift rail 1-5 can pass through between two counter overdrive gears, therefore, no mutual influence is caused with the counter overdrive gear F, and since the lengths of the four-and-five shift rails 1 to 4 are shortened, the four-and-five shift rails 1 to 4 do not need to pass through the counter overdrive gear F and do not cause mutual influence.

Because the fourth-fifth gear shift fork shaft does not pass through the largest wheel (intermediate shaft overdrive gear) of the upper intermediate shaft assembly and according to the whole vehicle gear handball arrangement, as shown in fig. 7, the fourth-fifth gear is positioned at the middle and the eighth gear is positioned at the left; in order to reduce the overall installation height of the shifting fork shaft, the eight-gear shifting fork shaft is moved to the side close to the middle, the six-gear shifting fork shaft and the seven-gear shifting fork shaft are arranged on the most middle shaft, and the arrangement sequence of the shifting fork shafts is not consistent with the gear arrangement pattern of the whole automobile, so that the shifting head adopts an opposite design. The reverse shift rail does not pass through the largest wheel on the countershaft (countershaft overdrive gear) and therefore does not present an interference problem.

Therefore, adopt the 1 scheme of arranging of declutch shift shaft that provides in this embodiment, not only make the mounting height H of shift fork reduce by a wide margin, need not to increase the length of shift fork moreover to the intensity of shift fork has been guaranteed.

In this embodiment, compared to the conventional dual countershaft transmission, as shown in fig. 13, the conventional dual countershaft transmission also has 5 shift shafts, and the shift shafts from far to near in fig. 13 are respectively the conventional reverse first shift shaft X1, the conventional second third shift shaft X2, the conventional fourth fifth shift shaft X3, the conventional sixth seventh shift shaft X4, the conventional eighth shift shaft X5, the reverse first shift fork Y1 mounted on the shift shafts, the conventional second third shift fork Y2, the conventional fourth fifth shift fork Y3, the conventional sixth seventh shift fork Y4, and the conventional eighth shift fork Y5, and the gear structure provided in the present invention adjusts the arrangement and length of the shift shafts 1 so that the transmission can be used with three or more shift forks, and the number of the countershafts and the number of the guide blocks in the conventional dual countershaft transmission adopt the prior art, designing the number and the structure of the guide blocks and the shifting forks according to different gear engaging positions; for example, as shown in fig. 3, a configuration is adopted in which a four-five shift fork (in fig. 3, a portion connected to the four-five shift fork shaft 1-3 is a connecting end of the four-five shift fork), a two-three shift fork (in fig. 3, a portion connected to the two-three shift fork shaft 1-2 is a connecting end of the two-three shift fork), an eight shift block (in fig. 3, a portion connected to the eight shift fork shaft 1-5 is a connecting end of the eight shift block) and an eight shift fork (in fig. 13, the eight shift fork) are provided on the eight shift fork shaft 1-5, a six-seven shift block (in fig. 3, a portion connected to the six-seven shift fork shaft 1-4 is a connecting end of the six-seven shift block) and a six-seven shift fork (in fig. 13), a reverse one-gear guide block (in fig. 3, the part connected with the reverse one-gear shift fork shaft 1-1 is the connecting end of the reverse one-gear guide block) and a reverse one-gear shift fork (in fig. 13, the reverse one-gear shift fork are adopted), are arranged on the reverse one-gear shift fork shaft 1-1, wherein the reverse one-gear guide block, the six-seven-gear guide block, the eight-gear guide block, the four-five-gear shift fork and the two-three-gear shift fork are all arranged right below the gear shifting head.

Optionally, the plurality of parallel shift fork shafts 1 include a fourth-fifth shift fork shaft 1-3, an eighth shift fork shaft 1-5, a sixteenth shift fork shaft 1-4, a second-third shift fork shaft 1-2 and a reverse first shift fork shaft 1-1, which are arranged in sequence.

In the present embodiment, as shown in fig. 3 and 4, the plurality of parallel shift rails 1 are a fourth-fifth shift rail 1-3, an eighth shift rail 1-5, a sixteenth shift rail 1-4, a second-third shift rail 1-2, and a reverse first shift rail 1-1 in sequence from left to right.

In the present embodiment, according to the gear shift pattern, the eighth gear is located on the left side of the sixth-seventh gear, which can be theoretically designed to the intermediate position, but does not bring about a reduction in the installation height of the overall shift rail, because the sixth-seventh gear is also located at the position of the eighth gear, and in addition, the eighth gear is located on the most intermediate shaft, which makes the shift head design difficult to implement, so the eighth gear shift rails 1 to 5 are located on one side of the most intermediate position in the present embodiment.

Optionally, the gear structure further comprises a plurality of shift grooves 3, and the plurality of shift grooves 3 comprise a fourth-fifth gear shift groove 3-3, an eighth gear shift groove 3-5, a sixteenth gear shift groove 3-4, a second-third gear shift groove 3-2 and a reverse first gear shift groove 3-1 which are arranged in sequence.

In this embodiment, the shift grooves 3 are disposed above the guide block or the shift fork, and the position of each shift groove 3 is determined to be specifically disposed on the guide block or the shift fork according to actual needs.

In the present embodiment, as shown in fig. 5 and 8, the four-five shift grooves 3-3, the six-seven shift grooves 3-4, the two-three shift grooves 3-2, and the reverse one shift groove 3-1 are symmetrically disposed, and the eight shift groove 3-5 has one side for eight and the other side for neutral.

Optionally, the width of the shift grooves 3 is D, D is a positive integer and the unit is mm;

a neutral space with a 2D distance is formed between the four-fifth gear shifting groove 3-3 and the eight-seventh gear shifting groove 3-5, one side of the eight-fifth gear shifting groove 3-5 is tightly attached to one side of the six-seventh gear shifting groove 3-4, a 3D neutral space is formed between the other side of the six-seventh gear shifting groove 3-4 and one side of the two-third gear shifting groove 3-2, and the other side of the two-third gear shifting groove 3-2 is tightly attached to the reverse one-gear shifting groove 3-1.

In this embodiment, since the arrangement of the shift fork shaft 1 is adjusted, the shift sequence of the shift lever needs to be adjusted, which may cause driver confusion when driving the vehicle and cause traffic accidents, in order to ensure that the current driving habits of the driver do not change, as shown in fig. 5, the arrangement of the gears at the handball of the cab is not changed, in this embodiment, the position of the shift slot 3 is redesigned, as shown in fig. 8, a blank square in the figure represents a neutral space with a width D, the neutral space is through, and both front and rear are unlimited, so when the shift knob extends into the neutral space, it is neutral at this time.

Optionally, the transmission gear structure further comprises a gear shifting block 2, and a first shifting block 2-1, a second shifting block 2-2 and a third shifting block 2-3 are arranged at the bottom end of the gear shifting block 2.

In the present application, the adjustment of the gear arrangement of the entire vehicle is caused by the adjustment of the sequence of the shift fork shaft, and in order to adapt to the adjustment of the gear arrangement of the entire vehicle and keep the existing driving habit unchanged by the driver, in the present embodiment, as shown in fig. 6, a gear shifting block 2 with three shifting blocks is designed.

Optionally, the distance between the first dial 2-1 and the second dial 2-2 is 4D, and the distance between the second dial 2-2 and the third dial 2-3 is D.

In this embodiment, by matching the shift rod 2 of the three-shift-head with the shift groove 3, it is ensured that the driver can shift according to the shift mode shown in fig. 7, specifically, as shown in fig. 8, when the shift rod 2 is in the neutral position (i.e., the fourth-fifth gear position), the first shift head 2-1 of the shift rod 2 is aligned with the fourth-fifth gear shift groove 3-3, the second shift head 2-2 and the third shift head 2-3 both correspond to the neutral space, and the position at this time is only the fourth-fifth gear (neutral) position;

as shown in fig. 9, when the gear selection shift (i.e. the width D of the shift slot) is moved to the left, the second shift element 2-2 of the shift lever 2 is aligned with the sixty-seven gear shift slot 3-4, and the first shift element 2-1 and the third shift element 2-3 correspond to the neutral space;

as shown in fig. 10, after moving two gear selecting shifts (2D) to the left, the second shift head 2-2 of the shift lever 2 is aligned with the eight-gear shift slot 3-5, and the first shift head 2-1 and the third shift head 2-3 both correspond to the neutral space;

as shown in fig. 11, when the shift knob 2 moves from the neutral position to the right by a shift selection displacement (D), the third knob 2-3 is aligned with the second and third shift slots 3-2, and the first knob 2-1 and the second knob 2-2 correspond to the neutral space;

as shown in fig. 12, when the shift knob 2 moves two shift selection shifts (2D), the third shift knob 2-3 is aligned with the reverse-one shift slot 3-1, and the first shift knob 2-1 and the second shift knob 2-2 correspond to the neutral space;

the shape of the shifting block 2 that provides in this embodiment and the position overall arrangement cooperation of shift groove 3, when shifting the shifting block and remove one or two and select to keep off the shift groove 3 on aligning a certain guide block after, all the other two shifting blocks all are in the neutral space to guarantee the uniqueness that the rotatory gear of shifting block 2 shifted, and still guaranteed that the driver can keep original driving habit, thereby guarantee driver safe driving.

Optionally, a neutral space with a width of at least 2D is further provided on a side of the four-five shift groove 3-3 away from the eight shift groove 3-5.

In this embodiment, as shown in fig. 10, when the second bar 2-2 of the shift bar 2 is aligned with the eight-gear shift groove 3-5, the first bar 2-1 of the shift bar is two shift selection displacements (2D) away from the four-five shift groove 3-3, and in order to enable smooth rotation and engagement after the shift bar 2 is aligned with the eight-gear shift groove 3-5, a neutral space with a width of at least 2D is further disposed on the side of the four-five shift groove 3-3 away from the eight-gear shift groove 3-5.

The scheme that provides in this embodiment makes shift fork mounting height reduce about 33mm, has promoted the bending strength of shift fork greatly to the reliability of shifting of derailleur has been promoted.