18-gear mechanical automatic transmission

Abstract

The utility model discloses an 18-gear mechanical automatic transmission which comprises a transmission shell formed by sequentially connecting a front auxiliary box, a main box and a rear auxiliary box, a first shaft, a second shaft and an auxiliary box main shaft are coaxially arranged along the central axis of the transmission shell, and a left intermediate shaft and a right intermediate shaft are symmetrically arranged on the two sides of the first shaft and the two sides of the second shaft. The first shaft is sleeved with a first synchronizer, a first shaft first differential gear, a first shaft second differential gear, a second synchronizer and a first shaft transmission gear in an empty mode, the second shaft is provided with a second shaft second-gear gear, a second shaft first-gear gear, a second shaft reverse-gear gear, a second-third-gear sliding sleeve and a reverse-first-gear sliding sleeve, and an auxiliary box driving gear is arranged at the tail end of the second shaft. The auxiliary box main shaft is sleeved with an auxiliary box synchronizer and an auxiliary box main shaft reduction gear in an idling mode, the third shaft is used for driving a power takeoff and a lubricating oil pump, and a third shaft transmission gear on the third shaft is meshed with a first shaft power takeoff speed measurement gear installed on the first shaft. The power takeoff can output the maximum torque, and the displacement of the oil pump is more stable.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of automobile technology relates to a transmission drive system, concretely relates to an 18 gear mechanical automatic transmission. BACKGROUND

[0002] Mechanical automatic transmission (AMT) compatible manual transmission (MT) transmission efficiency is high and automatic low cost advantage, in commercial vehicle market has gradually popularized application, penetration rate is increasing, according to the industry judgement, in heavy truck commercial vehicle market, with the engine horsepower bigger and bigger, future AMT transmission will be to higher torque, higher efficiency, longer life, more gear, more wide speed ratio range, higher reliability etc.

[0003] But the mainstream AMT transmission in the existing market has the following problems:

[0004] 1, most gear number is in 16 gears and below, transmission head gear ratio is limited, cannot better match the demand of big horsepower heavy load start, gear ratio level difference is big, cannot satisfy the requirement of gear shifting smoothness and vehicle comfort;

[0005] 2, the power take-off is mostly through the intermediate shaft power take-off, and the power take-off ratio is related to the transmission gear, thereby affecting the maximum output torque of the power take-off;

[0006] 3, the transmission internal lubricating oil pump is driven by the intermediate shaft, and the oil pump displacement is related to the gear, and the oil pump displacement is different at different gears, which seriously affects the whole tank lubrication. SUMMARY

[0007] In view of the deficiencies existing in the prior art, the utility model aims at providing an 18-gear mechanical automatic transmission, which can solve the technical problems of the existing transmission that cannot match the demand of big horsepower heavy load start, gear shifting smoothness and vehicle comfort, the power take-off cannot reach the maximum output torque, and the oil pump displacement is unstable.

[0008] In order to solve the above technical problems, the utility model adopts the following technical scheme to realize it:

[0009] An 18-gear mechanical automatic transmission comprises a clutch housing, a transmission housing and a rear cover housing connected in sequence from front to rear, and the transmission housing comprises a front auxiliary box, a main box and a rear auxiliary box connected in sequence from front to rear; an axle is arranged in the front auxiliary box, a second axle is arranged in the main box, and an auxiliary box main shaft is arranged in the rear auxiliary box; the axle, the second axle and the auxiliary box main shaft are coaxially arranged along the central axis of the transmission housing, the front end of the axle extends out of the front end of the clutch housing, and the rear end of the auxiliary box main shaft is connected with a flange plate through the rear end of the rear cover housing.

[0010] The left intermediate shaft and the right intermediate shaft are symmetrically arranged on both sides of the first shaft and the second shaft, and the auxiliary box intermediate shaft is arranged on both sides of the auxiliary box main shaft; the front ends of the left intermediate shaft and the right intermediate shaft are installed on the front end of the transmission housing through bearings, the rear ends of the left intermediate shaft and the right intermediate shaft are installed on the rear end of the transmission housing through bearings, and the rear end of the auxiliary box intermediate shaft is installed on the rear end of the rear cover housing through a bearing.

[0011] The first shaft is sequentially sleeved with a first synchronizer, a first speed dividing gear, a second speed dividing gear, a second synchronizer and a first shaft transmission gear from front to back; the second shaft is sequentially sleeved with a second shaft second gear, a second shaft first gear and a second shaft reverse gear from front to back, and the second shaft is provided with a groove and a spline pad for limiting the axial movement of the second shaft second gear, the second shaft first gear and the second shaft reverse gear; the second shaft is further provided with a second third gear sleeve and a reverse first gear sleeve, the second third gear sleeve is arranged at the front end of the second shaft second gear, the reverse first gear sleeve is arranged between the second shaft first gear and the second shaft reverse gear, the second third gear sleeve and the reverse first gear sleeve are matched with the outer spline on the second shaft through the inner spline, can move axially along the second shaft, and rotate with the second shaft, and the end of the second shaft is fixedly installed with an auxiliary box driving gear.

[0012] The left intermediate shaft and the right intermediate shaft are symmetrically arranged on both sides of the first shaft and the second shaft, and the auxiliary box intermediate shaft is arranged on both sides of the auxiliary box main shaft; the front ends of the left intermediate shaft and the right intermediate shaft are installed on the front end of the transmission housing through bearings, the rear ends of the left intermediate shaft and the right intermediate shaft are installed on the rear end of the transmission housing through bearings, and the rear end of the auxiliary box intermediate shaft is installed on the rear end of the rear cover housing through a bearing.

[0013] The utility model also includes the following technical features:

[0014] The first speed dividing gear, the second speed dividing gear, the third gear and the second gear are respectively installed on the intermediate shaft through cylindrical pins.

[0015] The transmission housing is further provided with a pair of reverse intermediate shafts, which are arranged on one side of the second shaft and the left intermediate shaft and on one side of the second shaft and the right intermediate shaft, respectively; the reverse intermediate shaft is provided with a reverse intermediate gear, which is in constant engagement with the reverse gear of the intermediate shaft and the reverse gear of the second shaft; the reverse gear of the intermediate shaft and the reverse gear of the second shaft are not directly engaged.

[0016] The left intermediate shaft is arranged below the left of the transmission housing, the right intermediate shaft is arranged above the right of the transmission housing, a third shaft is arranged below the right of the transmission housing, the front end of the third shaft is arranged on the front end of the transmission housing through a bearing, the rear end of the third shaft is arranged on the rear end of the rear cover housing through a bearing, a third shaft transmission gear and a power take-off gear are sequentially arranged on the third shaft, a first shaft power take-off speed measuring gear is fixedly arranged on the first shaft, the first shaft power take-off speed measuring gear is arranged between the first shaft first speed dividing gear and the first shaft second speed dividing gear, the third shaft transmission gear is always engaged with the first shaft power take-off speed measuring gear, and the power take-off gear is connected with a side power take-off arranged on the transmission housing.

[0017] The rear end of the third shaft extending out of the rear cover housing is provided with a spline, and the spline can drive a rear power take-off arranged on the rear cover housing.

[0018] The front end of the third shaft extending out of the front end of the transmission housing is provided with a lubricating oil pump driving structure, and the lubricating oil pump driving structure can drive a lubricating oil pump arranged in the clutch housing.

[0019] The first shaft power take-off speed measuring gear and the third shaft transmission gear are both straight tooth gears.

[0020] The front end of the left intermediate shaft extending into the clutch housing is provided with a brake, the brake comprises a brake disc arranged on the left intermediate shaft and a friction disc, the brake disc is fixedly arranged on the clutch housing through a cylindrical pin arranged in parallel with the left intermediate shaft, the friction disc is fixed on the left intermediate shaft through a spline, the brake disc and the friction disc can move along the left intermediate shaft in the axial direction, the friction disc can rotate with the left intermediate shaft, the front end of the left intermediate shaft is provided with a piston, and a return spring is arranged between the piston and the left intermediate shaft.

[0021] Compared with the prior art, the utility model has the following technical effects:

[0022] (Ⅰ) The transmission of the utility model adopts a "3X3X2" type three-section structure, 18 gears are realized through cooperation, the front auxiliary box has three gears, and all gears are provided with an idle position, gear switching is realized through cooperation of two synchronizers, compared with the same gear number transmission, the main box gear is less, the main box rotational inertia is reduced, the main box speed regulation is faster, the transmission is compact in structure, the gear is faster, the quality is lighter, a larger torque, a wider speed ratio range and a smaller speed ratio step difference can be transmitted, and the transmission reliability is improved.

[0023] (II) The utility model discloses a shaft is fixed with a shaft power take-off speed measuring gear on one axle, rotates with one axle, is used for the transmission through sensor monitoring transmission input speed, and can be combined with third axle and third axle power take-off transmission gear, and can take two power take-off devices and lubricating oil pump simultaneously, and all runs with the specific value of engine rotating speed, is irrelevant with transmission gear position change, guarantees that power take-off device can maximum output torque, and the displacement of oil pump is more stable, better lubricates transmission.

[0024] (III) The brake structure designed in the utility model replaces the function of the synchronizer, solves the problems that the synchronizer material is easy to wear and the structure is easy to be damaged, simultaneously reduces the cost and increases the service life of the transmission. DRAWINGS

[0025] Fig. 1 It is the whole structure schematic diagram of the utility model.

[0026] Fig. 2 It is the third axle structure schematic diagram of the utility model.

[0027] Fig. 3 It is the brake structure schematic diagram of the utility model.

[0028] The meaning of each reference numeral in the drawing is as follows:

[0029] 1, a shaft, 2, first synchronizer, 3, a shaft first speed dividing gear, 4, a shaft power take-off speed measuring gear, 5, a shaft second speed dividing gear, 6, right intermediate shaft, 7, second synchronizer, 8, a shaft transmission gear, 9, two three gear slide sleeve, 10, two shaft two gear, 11, two shaft one gear, 12, reverse one gear slide sleeve, 13, two shaft reverse gear, 14, auxiliary box driving gear, 15, auxiliary box synchronizer, 16, auxiliary box main shaft reduction gear, 17, auxiliary box main shaft, 18, intermediate shaft first speed dividing gear, 19, intermediate shaft second speed dividing gear, 20, intermediate shaft three gear, 21, left intermediate shaft, 22, intermediate shaft two gear, 23, intermediate shaft one gear, 24, two shaft, 25, reverse intermediate shaft, 26, intermediate shaft reverse gear, 27, auxiliary box intermediate shaft transmission gear, 28, auxiliary box intermediate shaft, 29, flange plate, 30, brake, 31, side power take-off device, 32, reverse intermediate shaft, 33, third axle, 34, rear power take-off device, 35, third axle power take-off transmission gear, 36, lubricating oil pump, 37, clutch housing, 38, transmission housing, 39, rear cover housing, 40, front auxiliary box, 41, main box, 42, rear auxiliary box, 43, auxiliary box intermediate shaft low gear, 44, power take-off device gear;

[0030] 301, brake disc, 302, friction disc, 303, piston, 304, return spring, 305, guide cylindrical pin.

[0031] The specific content of this utility model will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0032] Following the above technical solution, the following are specific embodiments of this utility model. It should be noted that this utility model is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solution of this application fall within the protection scope of this utility model.

[0033] In this utility model, unless otherwise stated, directional terms such as "upper", "lower", "left", and "right" are generally defined based on the drawing in the corresponding figure; "inner" and "outer" refer to the inner and outer contours of the corresponding components; and "longitudinal", "transverse", and "vertical" refer to the directions marked in the figure.

[0034] Example:

[0035] This embodiment provides an 18-speed mechanical automatic transmission, such as... Figs. 1 to 3 As shown, the transmission includes a clutch housing 37, a transmission housing 38, and a rear cover housing 39 connected sequentially from front to back. Inside the transmission housing 38, there are a front auxiliary gearbox 40, a main gearbox 41, and a rear auxiliary gearbox 42 connected sequentially from front to back. The whole structure adopts a 3x3x2 "cylindrical" structure. The front auxiliary gearbox 40 has 3 gears, the main gearbox 41 has 3 gears, and the rear auxiliary gearbox 42 has high and low gears. Through their cooperation, a total of 18 gears can be achieved. The front auxiliary gearbox 40 has a first shaft 1, the main gearbox 41 has a second shaft 24, and the rear auxiliary gearbox 42 has an auxiliary gearbox main shaft 17. The first shaft 1, the second shaft 24, and the auxiliary gearbox main shaft 17 are coaxially arranged along the central axis of the transmission housing 38. The front end of the first shaft 1 extends to the front end of the clutch housing 37, and the rear end of the auxiliary gearbox main shaft 17 extends out of the rear end of the rear cover housing 39 and is connected to a flange 29.

[0036] A left intermediate shaft 21 and a right intermediate shaft 6 are symmetrically arranged on both sides of the primary shaft 1 and the secondary shaft 24. A secondary gearbox intermediate shaft 28 is arranged on both sides of the secondary gearbox main shaft 17. The front ends of the left intermediate shaft 21 and the right intermediate shaft 6 are mounted on the front end of the transmission housing 38 through bearings, and the rear ends of the left intermediate shaft 21 and the right intermediate shaft 6 are mounted on the rear end of the transmission housing 38 through bearings. The rear end of the secondary gearbox intermediate shaft 28 is mounted on the rear end of the rear cover housing 39 through bearings.

[0037] The first synchronizer 2, the first shaft first speed gear 3, the first shaft second speed gear 5, the second synchronizer 7 and the first shaft drive gear 8 (also the third gear) are sequentially sleeved on the first shaft 1 from front to back; the second shaft two-gear gear 10, the second shaft one-gear gear 11 and the second shaft reverse gear 13 are sequentially sleeved on the second shaft 24 from front to back, and the second shaft is provided with a groove and a spline pad for limiting the axial movement of the second shaft two-gear gear 10, the second shaft one-gear gear 11 and the second shaft reverse gear 13; the second shaft 24 is further provided with a second-third gear sleeve 9 and a reverse-first gear sleeve 12, the second-third gear sleeve 9 is arranged at the front end of the second shaft two-gear gear 10, the reverse-first gear sleeve 12 is arranged between the second shaft one-gear gear 11 and the second shaft reverse gear 13, the second-third gear sleeve 9 and the reverse-first gear sleeve 12 are matched with the outer spline on the second shaft 24 through the inner spline, can move axially along the second shaft 24, and rotate with the second shaft 24, transmit torque through the spline, the end of the second shaft 24 is fixedly installed with the auxiliary gearbox drive gear 14 through the spline, the auxiliary gearbox drive gear 14 rotates with the second shaft 24, the auxiliary gearbox main shaft 17 is sequentially sleeved with the auxiliary gearbox synchronizer 15 and the auxiliary gearbox main shaft reduction gear 16 from front to back, the auxiliary gearbox main shaft reduction gear 16 can float on the auxiliary gearbox main shaft 17 through the spline pad, when the synchronizer 15 slides forward to combine the auxiliary gearbox drive gear 14, a high gear position is obtained, when the synchronizer 15 slides backward to combine the auxiliary gearbox main shaft reduction gear 16, a low gear position is obtained;

[0038] The left intermediate shaft 21 and the right intermediate shaft 6 are sequentially provided with the intermediate shaft first speed gear 18, the intermediate shaft second speed gear 19, the intermediate shaft third gear 20, the intermediate shaft two-gear gear 22, the intermediate shaft one-gear gear 23 and the intermediate shaft reverse gear 26 from front to back; the auxiliary gearbox intermediate shaft 28 is welded with the auxiliary gearbox intermediate shaft drive gear 27, and the auxiliary gearbox intermediate shaft 28 at the rear end of the auxiliary gearbox intermediate shaft drive gear 27 is machined with the auxiliary gearbox intermediate shaft low gear 43.

[0039] In the embodiment, the front auxiliary gearbox 40 works with the first synchronizer 1 and the second synchronizer 7 to realize gear shifting, the main gearbox 41 has fewer gears, the rotational inertia of the main gearbox 41 is reduced, the speed is adjusted faster, which helps to reduce the gear engagement time, the front auxiliary gearbox 40 has three gears, the total length of the gearbox is short, the gear engagement is fast, and the mass is light; the gears of the front auxiliary gearbox 40, the main gearbox 41 and the rear auxiliary gearbox 42 are all helical gears, and the double-intermediate-shaft structure is adopted, the gear gears on the second shaft 24 are in a "floating" state on the second shaft 24 through gear spacer rings and hexagonal keys, which can greatly reduce the machining and assembly precision of the second shaft assembly, reduce the manufacturing cost, and realize "power split", the same size gearbox can transmit larger torque.

[0040] Further, the intermediate shaft first gear 23 and the intermediate shaft reverse gear 26 are machined shaft gears, the intermediate shaft first sub-speed gear 18, the intermediate shaft second sub-speed gear 19, the intermediate shaft third gear 20 and the intermediate shaft second gear 22 are respectively installed on the left intermediate shaft 21 and the right intermediate shaft 6 through cylindrical pins, all gears on the intermediate shaft rotate with the intermediate shaft, when power transmission, the first synchronizer 2 and the second synchronizer 7 on the shaft 1 are switched to engage the gears on the shaft 1 with corresponding gears on the left and right intermediate shafts, power is transmitted to the left and right intermediate shafts through a specific set of gears in mesh, thereby driving the left intermediate shaft 21 and the right intermediate shaft 6 to rotate.

[0041] As a preferred scheme of the embodiment, a pair of reverse intermediate shafts 32 are further arranged in the transmission housing 38 in the embodiment, the pair of reverse intermediate shafts 32 are arranged on the side of the second shaft 24 and the left intermediate shaft 21 and the side of the second shaft 24 and the right intermediate shaft 6 respectively, the reverse intermediate shaft 32 is provided with a reverse intermediate gear 25, the reverse intermediate gear 25 is in constant engagement with the intermediate shaft reverse gear 26 and the second shaft reverse gear 13, the intermediate shaft reverse gear 26 and the second shaft reverse gear 13 are not directly engaged, for changing the direction of power transmission, so that the whole vehicle can move in reverse.

[0042] Taking the first gear as an example, the power transmission route of the utility model is as follows: when the transmission is engaged in the first gear, the second synchronizer 7 moves backward to engage with the shaft transmission gear 8, the reverse first gear sleeve 12 slides forward, the outer spline of the reverse first gear sleeve 12 engages with the inner spline of the combined gear ring on the second shaft first gear 11, the power of the engine is transmitted to the transmission shaft 1 of the utility model through the clutch, and then the power is branched to the intermediate shaft third gear 20 on the left intermediate shaft 21 and the right intermediate shaft 6 through the second synchronizer 7 and the shaft transmission gear 8, thereby driving the left and right intermediate shafts and the gears thereon to rotate together, the power is transmitted to the second shaft first gear 11 on the second shaft 24 through the intermediate shaft first gear 23, because the second shaft first gear 11 engages with the outer spline of the reverse first gear sleeve 12 through the inner spline of the combined gear ring, the second shaft first gear 11 can transmit power to the reverse first gear sleeve 12, the reverse first gear sleeve 12 is connected with the second shaft 24 through the spline, thereby transmitting the power from the shaft 1 to the second shaft 24, and the main tank part completes gear shifting, because the first gear is in the low gear range, the sub-tank part is in the low gear range, at this time, the synchronizer 15 slides backward to combine with the sub-tank main shaft reduction gear 16, the power from the second shaft 24 is transmitted to the sub-tank main shaft 17 through the sub-tank drive gear 14, the sub-tank transmission gear 27, the sub-tank intermediate shaft 28, the sub-tank main shaft reduction gear 16, the synchronizer 15, and then output through the flange plate 29, thereby completing power transmission.

[0043] The power transmission of other gears is similar, when the transmission is in the high gear position, only the sub-tank synchronizer 15 is mainly slid forward to engage with the sub-tank drive gear 14, and at the same time, the appropriate shaft transmission gear pair is selected according to the gear position, which is not described in detail here.

[0044] As a preferred scheme of the embodiment, the left intermediate shaft 21 is arranged below the left of the transmission housing 38, the right intermediate shaft is arranged above the right of the transmission housing 38, the third shaft 33 is arranged below the right of the transmission housing 38, the front end of the third shaft 33 is mounted to the front end of the transmission housing 38 through a bearing, the rear end of the third shaft 33 is mounted to the rear end of the rear cover housing 39 through a bearing, the third shaft transmission gear 35 and the power take-off gear 44 are sequentially arranged on the third shaft 33, the one-axle power take-off speed measuring gear 4 is fixedly arranged on the one-axle first speed gear 3 and the one-axle second speed gear 5, the third shaft transmission gear 35 is always engaged with the one-axle power take-off speed measuring gear 4, so as to drive the third shaft 33 to rotate with the one-axle 1, the power take-off gear 44 rotates with the third shaft 33, and the rotation speed of the power take-off gear 44 is always a specific value of the rotation speed of the one-axle, the power take-off gear 44 is connected with the side power take-off 31 arranged on the transmission housing 38, and drives the side power take-off 31 to rotate.

[0045] Further, the one-axle power take-off speed measuring gear 4 and the third shaft transmission gear 33 are both straight-toothed gears.

[0046] Further, the rear end of the third shaft 33 extending out of the rear cover housing 39 is provided with a spline, the spline can drive the rear power take-off 34 arranged on the rear cover housing 39, the third shaft 33 can drive the above two power take-offs at the same time, and the two power take-offs rotate at a specific value of the rotation speed of the engine, which is irrelevant to the gear shifting of the transmission.

[0047] Further, the front end of the third shaft 33 extending out of the transmission housing 38 is provided with a lubricating oil pump driving structure, the lubricating oil pump driving structure can drive the lubricating oil pump 36 arranged in the clutch housing 37, the lubricating oil pump 36 can also rotate at a specific value of the rotation speed of the engine, the rotation of the lubricating oil pump 36 is only related to the rotation speed of the engine, and the oil pump displacement is more stable, which better lubricates the transmission.

[0048] Since the main box 41 adopts the sliding sleeve shift with higher reliability, longer service life and lower cost, and the sliding sleeve shift itself has no synchronization function, as a preferred scheme of the embodiment, the front end of the left intermediate shaft 21 extends into the clutch housing 37 and is provided with a brake 30, the brake 30 includes a brake disc 301 and a friction disc 302, the brake disc 301 is fixedly installed on the clutch housing 37 through a guide cylindrical pin 305 arranged in parallel with the left intermediate shaft 21, the friction disc 302 is fixed on the left intermediate shaft 21 through a spline, the brake disc 301 and the friction disc 302 can move axially along the left intermediate shaft 21, the friction disc 302 can rotate with the left intermediate shaft 21, the front end of the left intermediate shaft 21 is provided with a piston 303, a return spring 304 is arranged between the piston 303 and the left intermediate shaft 21, when the transmission needs to be upshifted or started, the brake 30 works, the vehicle compressed gas passes through the brake 30, pushes the piston 303 to move to the right, compresses the return spring 304, the brake disc 301 and the friction disc 302, and reduces the rotating speed of the left intermediate shaft 21 to perform synchronous shift, when the shift is completed, the air supply is stopped, the return spring 304 pushes the piston 303 away through its own elastic force, the brake disc 301 and the friction disc 302 are automatically separated without pressure, at this time, the brake braking force disappears, the brake 30 is provided to replace the function of the synchronizer, solves the problems that the synchronizer material is easy to wear and the structure is easy to damage, and also reduces the cost and increases the service life of the transmission.

Claims

1. An 18-speed mechanical automatic transmission, comprising a clutch housing (37), a transmission housing (38), and a rear cover housing (39) connected sequentially from front to back, wherein the transmission housing (38) contains a front auxiliary gearbox (40), a main gearbox (41), and a rear auxiliary gearbox (42) connected sequentially from front to back; characterized in that, The front auxiliary gearbox (40) is provided with a shaft (1), the main gearbox (41) is provided with a second shaft (24), and the rear auxiliary gearbox (42) is provided with a main shaft (17). The first shaft (1), the second shaft (24) and the main shaft (17) are coaxially arranged along the central axis of the transmission housing (38). The front end of the first shaft (1) extends to the front end of the clutch housing (37), and the rear end of the main shaft (17) passes through the rear end of the rear cover housing (39) and is connected to a flange (29). The first shaft (1) and the second shaft (24) are symmetrically provided with a left intermediate shaft (21) and a right intermediate shaft (6) on both sides. The auxiliary gearbox main shaft (17) is provided with an auxiliary gearbox intermediate shaft (28) on both sides. The front ends of the left intermediate shaft (21) and the right intermediate shaft (6) are mounted on the front end of the transmission housing (38) by bearings. The rear ends of the left intermediate shaft (21) and the right intermediate shaft (6) are mounted on the rear end of the transmission housing (38) by bearings. The rear end of the auxiliary gearbox intermediate shaft (28) is mounted on the rear end of the rear cover housing (39) by bearings. The first shaft (1) is fitted with a first synchronizer (2), a first gear (3), a second gear (5), a second synchronizer (7), and a transmission gear (8) from front to back. The second shaft (24) is fitted with a second gear (10), a first gear (11), and a reverse gear (13) from front to back. The second shaft is provided with grooves and spline pads to restrict the axial movement of the second gear (10), the first gear (11), and the reverse gear (13). The second shaft (24) is also provided with a second and third gear sliding sleeve (9) and a reverse gear sliding sleeve. (12) The second and third gear sliding sleeves (9) are located at the front end of the second gear (10) of the second shaft, and the first gear sliding sleeve (12) is located between the first gear (11) and the second gear (13) of the second shaft. The second and third gear sliding sleeves (9) and the first gear sliding sleeve (12) are respectively connected to the external spline on the second shaft (24) through the internal spline. They can move along the axial direction of the second shaft (24) and rotate with the second shaft (24). The end of the second shaft (24) is fixedly installed with the auxiliary gearbox drive gear (14). The auxiliary gearbox main shaft (17) is sequentially fitted with the auxiliary gearbox synchronizer (15) and the auxiliary gearbox main shaft reduction gear (16) from front to back. The left intermediate shaft (21) and the right intermediate shaft (6) are respectively arranged from front to back as the intermediate shaft first speed gear (18), intermediate shaft second speed gear (19), intermediate shaft third gear (20), intermediate shaft second gear (22), intermediate shaft first gear (23) and intermediate shaft reverse gear (26); the auxiliary gearbox intermediate shaft (28) is welded with the auxiliary gearbox intermediate shaft transmission gear (27), and the auxiliary gearbox intermediate shaft (28) at the rear end of the auxiliary gearbox intermediate shaft transmission gear (27) is machined with the auxiliary gearbox intermediate shaft low gear (43).

2. The 18-speed mechanical automatic transmission as described in claim 1, characterized in that, The intermediate shaft first gear (23) and intermediate shaft reverse gear (26) are machined shaft teeth. The intermediate shaft first speed gear (18), intermediate shaft second speed gear (19), intermediate shaft third gear (20) and intermediate shaft second gear (22) are respectively installed on the left intermediate shaft (21) and right intermediate shaft (6) by cylindrical pins.

3. The 18-speed mechanical automatic transmission as described in claim 1, characterized in that, The transmission housing (38) is also provided with a pair of reverse gear intermediate shafts (32). The pair of reverse gear intermediate shafts (32) are respectively provided on the side of the second shaft (24) and the left intermediate shaft (21) and on the side of the second shaft (24) and the right intermediate shaft (6). A reverse gear intermediate wheel (25) is provided on the reverse gear intermediate shaft (32). The reverse gear intermediate wheel (25) is constantly meshed with the reverse gear of the intermediate shaft (26) and the reverse gear of the second shaft (13). The reverse gear of the intermediate shaft (26) and the reverse gear of the second shaft (13) do not directly mesh.

4. The 18-speed mechanical automatic transmission as described in claim 1, characterized in that, The left intermediate shaft (21) is located at the lower left of the transmission housing (38), and the right intermediate shaft (6) is located at the upper right of the transmission housing (38). A third shaft (33) is located at the lower right of the transmission housing (38). The front end of the third shaft (33) is mounted on the front end of the transmission housing (38) via a bearing, and the rear end of the third shaft (33) is mounted on the rear end of the rear cover housing (39) via a bearing. A third shaft transmission gear (35) and a power take-off gear (44) are sequentially mounted on the third shaft (33). A power take-off speed measuring gear (4) is fixedly mounted on the first shaft (1). The power take-off speed measuring gear (4) is located between the first shaft first speed dividing gear (3) and the first shaft second speed dividing gear (5). The third shaft transmission gear (35) and the first shaft power take-off speed measuring gear (4) are constantly meshed. The power take-off gear (44) is connected to the side power take-off (31) mounted on the transmission housing (38).

5. The 18-speed mechanical automatic transmission as described in claim 4, characterized in that, The third shaft (33) extends out of the rear end of the rear cover housing (39) and is machined with splines, which can drive the rear power take-off (34) mounted on the rear cover housing (39).

6. The 18-speed mechanical automatic transmission as described in claim 4, characterized in that, The third shaft (33) extends out of the front end of the transmission housing (38) and is provided with a lubricating oil pump drive structure, which can drive the lubricating oil pump (36) installed in the clutch housing (37).

7. The 18-speed mechanical automatic transmission as described in claim 4, characterized in that, The first-axis force-taking speed measuring gear (4) and the third-axis transmission gear (35) are both spur gears.

8. The 18-speed mechanical automatic transmission as described in claim 1, characterized in that, A brake (30) is installed in the clutch housing (37) at the front end of the left intermediate shaft (21). The brake (30) includes a brake disc (301) and a friction disc (302) mounted on the left intermediate shaft (21). The brake disc (301) is fixedly mounted on the clutch housing (37) by a guide cylindrical pin (305) arranged parallel to the left intermediate shaft (21). The friction disc (302) is fixed on the left intermediate shaft (21) by a spline. Both the brake disc (301) and the friction disc (302) can move axially along the left intermediate shaft (21). The friction disc (302) can rotate with the left intermediate shaft (21). A piston (303) is provided at the front end of the left intermediate shaft (21). A return spring (304) is provided between the piston (303) and the left intermediate shaft (21).

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