A hydraulic transmission and parking brake device thereof

Abstract

The present invention relates to the field of vehicle transmission, and in particular to a hydraulic transmission and a parking brake device thereof. A parking brake device comprises a brake shaft positioned inside a transmission housing through a bearing, and a brake cover connected to the transmission housing; the transmission housing and the brake shaft are connected through an inner and outer friction plate pair, and a hydraulic drive assembly is connected to the inner end of the brake cover, and the output end of the hydraulic drive assembly can move along the axial direction of the brake shaft and act on the inner and outer friction plate pair. The advantages of this solution are that on the one hand, the transmission housing is directly connected to the brake shaft through the inner and outer friction plate pair, replacing the connection structure of multiple housings, so there is no need to worry about the self-strength and connection strength of the housing and the end cover; on the other hand, the brake clutch part of the parking brake device is completely in the transmission housing, and the lubrication system in the transmission housing can be shared, and there is no need to worry about the sealing problem of the connection parts of multiple housings and end covers.

Description

Technical Field

[0001] The invention relates to the field of vehicle transmission, and in particular to a hydraulic transmission and a parking brake device thereof. Background Art

[0002] Internal combustion forklifts are widely used in the material handling industry. The gearboxes used in internal combustion forklifts include common mechanical gearboxes and hydraulic gearboxes. Since the hydraulic gearbox transmits energy through hydraulic media (transmission oil), compared with the mechanical gearbox, it has the advantages of smooth transmission, low noise, and comfortable operation, and has been widely used. At present, the driving and parking brakes of the hydraulic gearbox are all integrated brakes, some of which use independent control of external accumulators to achieve parking, and some use internal dual-piston split control to achieve parking, but they are all wheel hub brakes. When the hydraulic system or single brake of this type of braking method fails, the reliability of the vehicle parking often poses a safety hazard.

[0003] Based on the above prior art, a parking brake is described in the Chinese invention patent publication with the publication number "CN107939864A", wherein the brake wheel is arranged on the brake shaft and the brake shaft can move axially along the brake wheel; the brake housing and the piston housing are fixed by bolts, and a brake assembly for limiting the rotation of the brake wheel is arranged between the brake housing and the piston housing; the flange is fixed on the end face of the brake shaft close to the brake housing; the spring seat is fixed on the piston housing, the piston is sleeved on the brake shaft and can move axially between the piston housing and the spring seat, and a clutch spring group for pushing the piston to move toward the flange side is sleeved on the spring seat, and an air inlet leading to the axial gap between the piston housing and the piston is arranged on the piston housing; the outer end face of the flange is provided with a tooth profile that matches the shaft end face of the axle wheel side transmission shaft. In the parking brake of this scheme, the friction plate group is arranged on the brake housing, and the clutch plate group is arranged on the brake wheel. The flange, brake shaft, brake wheel, bearing, brake housing, friction plate group, brake plate group, brake pad, brake spring group and piston housing together constitute the brake part. The brake spring group presses the friction plate group and the brake plate group through the brake pad to generate a braking torque; when parking is required, the braking torque is transmitted to the flange through the brake wheel and the brake shaft, and the flange and the axle wheel side drive shaft are meshed together, thereby realizing parking brake; when the parking brake needs to be released, the flange is separated from the axle wheel side drive shaft, the brake can be released, and the vehicle can operate normally. In the normal parking process, the friction plate group and the brake plate group have no relative sliding. When the parking torque is too large, such as: ramp heavy load parking, the friction plate group and the brake plate group produce relative sliding, and the parking brake is overload protected. The flange is provided with a tooth groove around the disc and the teeth provided around the shaft end face on the axle wheel side drive shaft, and the meshing and disengagement between the tooth groove of the flange and the teeth of the axle wheel side drive shaft are realized by the clutch part. The above-mentioned existing parking brake has a complex structure, and the brake housing, piston housing and spring seat need to be sealed and connected to ensure the braking effect of the parking brake.

[0004] The Chinese utility model patent with the announcement number "CN203035814U" records a normally closed wet parking brake, which relates to the field of vehicle brake manufacturing. The front and rear parts of the transmission shaft are respectively equipped with a left end cover and a right end cover, and the left and right end covers are respectively connected to the two ends of the static housing; the inner teeth of the dynamic friction plate are meshed with the transmission shaft, and the outer teeth of the static friction plate are meshed with the static housing; the end face of the small head of the piston contacts the dynamic friction plate, and the outer end face of the big head is uniformly processed with multiple inner holes for installing the spring assembly. There is an oil-filled cavity and an oil inlet between the left end face of the big head of the piston and the static housing, and a sealing ring is provided between the piston and the static housing. The left end cover against the static friction plate end face and the static housing, and the piston small head against the dynamic friction plate end face are all provided with a circulating oil flow groove for oil circulation in the closed cavity. The embodiment of the specification records: In normal state, under the elastic force of the spring assembly, the end face of the small head of the piston is pressed against the dynamic friction plate with a constant pressure, the friction plate is pressed together, and the brake is closed. When the vehicle is started, the parking brake handle is released to allow hydraulic oil to be injected into the oil chamber between the piston and the static housing. The piston moves right under the push of the hydraulic oil, compressing the spring assembly, the friction plate is loosened, and the transmission shaft and the dynamic friction plate rotate with the output shaft of the gearbox. When parking or emergency braking, the parking brake handle is pulled, the oil chamber between the piston and the static housing is connected to the return oil circuit, and under the action of the spring assembly, the piston moves left to press the dynamic friction plate, and the brake is closed. The shortcomings of the above scheme are: in the normally closed wet parking brake, the left and right end covers are respectively connected to the two ends of the static housing, and the left end cover is also connected to the gearbox housing by bolts. This scheme realizes braking through the gearbox housing, but uses left and right end covers and a static housing. The structure is complex and the self-strength and connection strength of the left and right end covers and the static housing need to be ensured to meet the braking strength requirements. In addition, it is also necessary to ensure the sealing of the connection parts of the left and right end covers and the static housing to avoid overflow of hydraulic oil or lubricating oil. Summary of the invention

[0005] In order to solve the above problems, the first purpose of the present invention is to provide a parking brake device. The advantages of this solution are that on the one hand, the gearbox housing is directly connected to the brake shaft through an inner and outer friction plate pair, replacing the connection structure of multiple housings, so there is no need to worry about the self-strength and connection strength of the housing and end cover; on the other hand, the brake clutch part of the parking brake device is completely in the gearbox housing, and the lubrication system in the gearbox housing can be shared, and there is no need to worry about the sealing problem of the connection parts of multiple housings and end covers.

[0006] A second object of the present invention is to provide a hydraulic transmission having the above-mentioned parking brake device.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0008] A parking brake device, characterized in that it includes a brake shaft positioned inside a gearbox housing through a bearing, and a brake cover connected to the gearbox housing; the brake shaft is used to engage with the output shaft of the gearbox, the gearbox housing and the brake shaft are connected through an inner and outer friction plate pair, a hydraulic drive assembly is connected to the inner end of the brake cover, and the output end of the hydraulic drive assembly can move axially along the brake shaft and act on the inner and outer friction plate pair.

[0009] The present invention adopts the above technical solution, which relates to a parking brake device, which includes a brake shaft and a brake cover, wherein the brake shaft is positioned inside the gearbox housing through a bearing and meshes with the output shaft of the gearbox. The brake cover is connected to the gearbox housing in a detachable manner to facilitate the installation and maintenance of the brake clutch part inside the gearbox housing. On this basis, the gearbox housing in this solution is directly connected to the brake shaft through the inner and outer friction plate pairs, and the inner and outer friction plate pairs are controlled by a hydraulic drive component. When the hydraulic drive component presses the inner and outer friction plate pairs, the gearbox housing provides a braking torque to the brake shaft, further braking the output shaft of the gearbox to achieve the purpose of parking braking. Compared with the existing parking brake device, the advantages of this solution are that on the one hand, the gearbox housing is directly connected to the brake shaft through the inner and outer friction plate pairs, replacing the connection structure of multiple housings, so there is no need to worry about the inherent strength and connection strength of the housing and end cover; on the other hand, the brake clutch part of the parking brake device is completely in the gearbox housing, and the lubrication system in the gearbox housing can be shared, and there is no need to worry about the sealing problem of the connection parts of multiple housings and end covers; this solution only needs to ensure the sealing of the connection part between the gearbox housing and the brake cover.

[0010] Preferably, the hydraulic drive assembly includes a piston and a compression spring that drives the piston to reset; a hydraulic chamber is formed between the piston and the gearbox housing or the brake cover, one end of the compression spring abuts against the piston, and the other end abuts against the brake cover or the gearbox housing; pressure oil is passed through the hydraulic chamber so that the piston can move axially along the brake shaft and disengage from the inner and outer friction plates. In the above technical solution, the hydraulic drive assembly includes a piston and a compression spring, wherein the piston is hydraulically driven to approach the inner and outer friction plate pair, thereby pressing the outer friction plate and the inner friction plate, increasing the friction force between the outer friction plate and the inner friction plate; at this time, the clutch device is in a closed state. The compression spring pushes the piston away from the inner and outer friction plate pair after the hydraulic pressure is removed, reducing the friction force between the outer friction plate and the inner friction plate; at this time, the clutch device is in a disconnected state.

[0011] Preferably, the gearbox housing is provided with a radial extension portion arranged along the radial direction of the brake shaft, a hydraulic cavity is formed between the piston and the radial extension portion of the gearbox housing, and at least two side walls of the piston are respectively sealed against the inner wall of the gearbox housing and the inner wall of the radial extension portion; one end of the compression spring is against the piston, and the other end is against the brake cover. In this technical solution, a hydraulic cavity is formed between the piston and the radial extension portion of the gearbox housing, and the strength of the gearbox housing can fully meet the pressure resistance requirements of the hydraulic cavity; and the radial extension portion and the gearbox housing are integrally formed (the gearbox housing is mostly integrally formed), and there will be no pore oil leakage caused by other connection structures.

[0012] Preferably, a spring installation groove is provided on the inner end surface of the brake cover and the end surface of the piston close to the brake cover, and the two ends of the compression spring are respectively embedded in the spring installation grooves of the brake cover and the piston. The brake cover in this solution directly serves as a spring seat, thereby facilitating the installation of the compression spring and omitting the spring seat.

[0013] Preferably, the outer end of the brake shaft is positioned in a bearing cavity in the middle of the inner end surface of the brake cover through a bearing.

[0014] Preferably, the inner and outer friction plate pair comprises a plurality of outer friction plates and inner friction plates arranged at intervals, the outer friction plates are circumferentially positioned with the gearbox housing and can move axially relative to each other, and the inner friction plates are circumferentially positioned with the brake shaft and can move axially relative to each other.

[0015] Preferably, a baffle is connected and fixed to the inner end of the transmission housing, and the hydraulic drive assembly and the inner and outer friction plate pairs are installed in the area enclosed by the baffle, brake shaft, transmission housing and brake cover; a guide pin is fixed between the baffle above the inner and outer friction plate pairs and the transmission housing, and the guide pin is axially parallel to the brake shaft; the outer friction plate and the guide pin are circumferentially positioned and can move relative to each other axially.

[0016] Preferably, the lubricating oil fed into the oil inlet is provided by a lubricating oil system; a gearbox input shaft is provided inside the gearbox housing, and the outer end of the gearbox input shaft extends into the torque converter and is connected to the worm gear; the gearbox input shaft is a hollow shaft, and a PTO shaft is penetrated inside the gearbox input shaft, and the PTO shaft is concentrically arranged with the gearbox input shaft; the outer end of the PTO shaft is connected to the torque converter, and the inner end of the PTO shaft is connected to the oil pump of the lubricating oil system. In this structure, the gearbox input shaft adopts a hollow shaft, and the PTO shaft is penetrated inside the gearbox input shaft. In this arrangement, the PTO shaft can extend out of the gearbox along the shaft hole inside the gearbox input shaft and directly connect to the torque converter, and its inner end can also drive the oil pump to operate. Compared with the prior art, the PTO shaft and the input shaft assembly are driven by gears. This solution can directly drive the oil pump through the PTO shaft by the torque converter, which optimizes the transmission mode of the PTO shaft; and in terms of installation, since it does not need to be connected to the gearbox input shaft through gears, the installation structure is simplified, making the gearbox more compact and facilitating the optimization of the transmission structure space on the whole machine. Furthermore, the PTO shaft in this solution is inserted into the gearbox input shaft, and the PTO shaft does not even occupy other space inside the gearbox, which is equivalent to saving the space occupied by the PTO shaft device in the traditional gearbox.

[0017] A hydraulic transmission comprises the parking brake device as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic diagram of the structure of the hydraulic transmission.

[0019] Figure 2 for Figure 1 Enlarged view of part A.

[0020] Figure 3 The present invention is a schematic diagram of a clutch device.

[0021] Figure 4 It is a schematic diagram of the structure of the parking brake device in the hydraulic transmission. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0027] like Figures 1 to 4 A hydraulic transmission shown in the figure includes a transmission assembly and a torque converter assembly. The transmission assembly includes a transmission housing 1, and a transmission input shaft 2, a forward clutch device, a reverse clutch device, an output shaft device and a parking brake device arranged in the transmission housing 1. The forward clutch device and the reverse clutch device in this embodiment have commonalities in structure. The clutch devices used in the forward clutch device and the reverse clutch device are specifically as follows:

[0028] like Figure 3 A clutch device shown includes a central rotating shaft 10, a gear clutch gear 20 mounted on the central rotating shaft 10 through a bearing sleeve, and a fixed gear 30 for transmitting external force to the central rotating shaft 10 or outputting the power of the central rotating shaft 10 to the outside. Based on the difference in the position of its application, the central rotating shaft 10 can be a gearbox input shaft 2, a forward shaft or a reverse shaft 51, that is, when the clutch device is a reverse clutch device, the central rotating shaft 10 is a reverse shaft 51; when the clutch device is a forward clutch device, the central rotating shaft 10 is a forward shaft; of course, it can also refer to the existing gearbox, where the forward clutch device is installed on the gearbox input shaft 2, and the central rotating shaft 10 is the gearbox input shaft 2. Similarly, the gear clutch gear 20 and the fixed gear 30 are called the forward clutch gear 41 and the first gear 42 in the forward clutch device; the gear clutch gear 20 and the fixed gear 30 are called the reverse clutch gear 52 and the second gear 53 in the reverse clutch device.

[0029] The gear clutch gear 20 is connected to the central shaft 10 or the fixed gear 30 through an inner and outer friction plate pair. The fixed gear 30 is integrally connected to the central shaft 10, and an axial extension portion 31 extending axially is provided on the radial outer end of the fixed gear 30; a hydraulic drive assembly is provided in the area enclosed by the axial extension portion 31 of the fixed gear 30, the main body and the outer wall of the central shaft 10; the output end of the hydraulic drive assembly can move axially along the central shaft 10 and act on the inner and outer friction plate pairs, a hydraulic cavity is formed between the hydraulic drive assembly and the main body of the fixed gear 30, and the driving end of the hydraulic drive assembly is sealed with the axial extension portion 31 of the fixed gear 30 and the outer wall of the central shaft 10. When the clutch device is in operation, the central shaft 10 and the fixed gear 30 thereon rotate, and the gear clutch gear 20 is selectively driven to rotate through the inner and outer friction plate pairs, thereby controlling the closing or opening of the clutch device. As described in the background technology, in the existing clutch device, an area for installing a piston is formed between the clutch hub and the intermediate shaft body and the radial extension, and the piston needs to form a hydraulic cavity between the clutch hub and the radial extension of the intermediate shaft. However, in this scheme, the area for installing the hydraulic drive assembly is formed by the central shaft 10 and the fixed gear 30 integrally connected thereto, and the axial extension 31 of the fixed gear 30 and the outer wall of the central shaft 10 can be sealed with the driving end of the hydraulic drive assembly, and a hydraulic cavity is formed between the hydraulic drive assembly and the body of the fixed gear 30. Since the central shaft 10 and the fixed gear 30 (body and axial extension 31) are formed in one piece, there will be no problems with welds and gaps, which ensures the strength and sealing requirements of the hydraulic cavity and eliminates safety hazards.

[0030] The above-mentioned clutch device can specifically adopt the following two clutch connection structures:

[0031] The first structure is as follows Figure 3 As shown in the figure, the clutch hub 32 is fixedly connected to the gear clutch gear 20, and the gear clutch gear 20 and the clutch hub 32 are fixed by rivets. The clutch hub 32 is connected to the central shaft 10 through an inner and outer friction plate pair; the inner and outer friction plate pair includes a plurality of outer friction plates 33 and inner friction plates 34 arranged at intervals, the outer friction plates 33 are circumferentially positioned with the clutch hub 32 and can move relative to each other in the axial direction, and the inner friction plates 34 are circumferentially positioned with the central shaft 10 and can move relative to each other in the axial direction. In this embodiment, the clutch hub 32 is connected and fixed to the gear clutch gear 20. In the existing scheme, the clutch hub 32 is welded and fixed to the central shaft 10. Therefore, in comparison, the installation method of the clutch hub 32 in this scheme is simplified, and the clutch hub 32 does not need to be integrally welded and carburized, so that the width of the slide groove on the clutch hub 32 can be precisely controlled, so as to meet the adaptation width with the outer friction plate 33, which can not only realize axial movement, but also avoid the shaking during use caused by circumferential looseness.

[0032] The second structural diagram is omitted, and the structure disclosed in the patent document with the publication number "CN104315109A" can be referred to. Specifically, the fixed gear 30 is fixedly connected with a clutch hub 32, and the clutch hub 32 is connected to the gear clutch gear 20 through a pair of inner and outer friction plates 33. The inner and outer friction plates 33 include a plurality of outer friction plates 33 and inner friction plates 34 arranged at intervals. The outer friction plates 33 are circumferentially positioned with the clutch hub 32 and can move relative to each other in the axial direction, and the inner friction plates 34 are circumferentially positioned with the gear clutch gear 20 and can move relative to each other in the axial direction. In this embodiment, although the clutch hub 32 is still connected to the fixed gear 30 as in the prior art, the area for installing the hydraulic drive assembly has been formed by the central shaft 10 and the fixed gear 30 integrally connected thereto in the above-mentioned scheme. Therefore, the clutch hub 32 does not need to be connected to the fixed gear 30 by welding, but can be connected by a detachable connection method, such as bolt / rivet connection. Therefore, compared with the prior art method of welding and fixing the clutch hub 32 to the central rotating shaft 10 , this solution also simplifies the installation method of the clutch hub 32 .

[0033] In a further embodiment, the hydraulic drive assembly includes a piston 35 and a compression spring 36 for driving the piston 35 to reset. A hydraulic chamber 37 is formed between the piston 35 and the body of the fixed gear 30, and the two side walls of the piston 35 are sealed with the axial extension 31 of the fixed gear 30 and the outer wall of the central shaft 10. In a specific embodiment, a spring seat 38 is fixed on the outer wall of the central shaft 10, and spring mounting grooves 39 are provided on the opposite side walls of the piston 35 and the spring seat 38, and the two ends of the compression spring 36 are respectively installed in the spring seat 38 and the spring mounting groove 39 of the piston 35. In the above technical solution, the hydraulic drive assembly includes a piston 35 and a compression spring 36, wherein the piston 35 is hydraulically driven to approach the inner and outer friction plate pair, thereby pressing the outer friction plate 33 and the inner friction plate 34, increasing the friction between the outer friction plate 33 and the inner friction plate 34, and the clutch device is in a closed state. The compression spring 36 pushes the piston 35 away from the inner and outer friction plate pair after the hydraulic pressure is removed, thereby reducing the friction between the outer friction plate 33 and the inner friction plate 34. At this time, the clutch device is in a disconnected state.

[0034] The hydraulic oil delivery path of the above-mentioned clutch device is that a hydraulic oil channel 101 is provided inside the shaft of the central rotating shaft 10, the outer end of the hydraulic oil channel 101 is communicated with the shaft end of the central rotating shaft 10, and the inner end of the hydraulic oil channel 101 is communicated with the hydraulic chamber 37. As mentioned above, since the central rotating shaft 10 and the fixed gear 30 (body and axial extension 31) are formed as one piece, and a hydraulic chamber 37 that is sealed with the stroke of the piston 35 is required. In order to realize the hydraulic oil supply to the hydraulic chamber 37, a hydraulic oil channel 101 is provided inside the shaft of the central rotating shaft 10, and the setting of the hydraulic oil channel 101 can be realized while ensuring strength.

[0035] The lubricating oil delivery path of the above-mentioned clutch device is that a second lubricating oil passage 102 is provided inside the shaft of the central rotating shaft 10, the outer end of the second lubricating oil passage 102 is communicated with the shaft end of the central rotating shaft 10, and the inner end of the second lubricating oil passage 102 is provided with at least two third radial oil holes 103, which are respectively communicated with the inner and outer friction plate pairs, and the bearing between the gear clutch gear 20 and the central rotating shaft 10. In this technical solution, the second lubricating oil passage 102 is provided inside the shaft of the central rotating shaft 10, which also realizes the lubrication of the bearings and the inner and outer friction plate pairs, and simplifies the setting of the lubricating oil passage.

[0036] The above clutch device is adopted, and the hydraulic transmission in this embodiment specifically adopts the following structure. The following part, combined with the accompanying drawings, adopts the first clutch connection structure of the above clutch device. Of course, since the above clutch device also makes a detailed record of the second clutch connection structure, those skilled in the art can understand that it is applied to the hydraulic transmission. In addition, since the above clutch device is adopted, the effects recorded in the above scheme can also be applied to the forward clutch device and / or the reverse clutch device.

[0037] The outer end of the transmission input shaft 2 extends into the torque converter 9 and is connected to the worm gear, and the elastic plate 91 of the torque converter 9 is connected to the engine flywheel. The on-car clutch device in this embodiment is installed on the transmission input shaft 2, and the on-car shaft is not separately provided. Specifically, the on-car clutch device includes a on-car clutch gear 41 provided on the transmission input shaft 2 through a bearing sleeve, a first gear 42 connected to the transmission input shaft 2, and a clutch hub 32 connected and fixed to the on-car clutch gear 41. The clutch hub 32 is connected to the transmission input shaft 2 through an inner and outer friction plate pair. Among them, the inner and outer friction plate pair includes a plurality of outer friction plates 33 and inner friction plates 34 arranged at intervals. In the on-car clutch device, the inner friction plate 34 is circumferentially positioned with the transmission input shaft 2 and can move relative to each other in the axial direction, and the outer friction plate 33 is circumferentially positioned with the clutch hub 32 and can move relative to each other in the axial direction. The on-board clutch device also includes a hydraulic drive assembly, the output end of which can move axially along the gearbox input shaft 2 and act on the inner and outer friction plate pairs to adjust the friction force between the outer friction plate 33 and the inner friction plate 34.

[0038] Among them, the first gear 42 is integrally connected and fixed on the transmission input shaft 2, and an axial extension portion 31 extending axially toward the clutch hub 32 is provided on the radial outer end portion of the first gear 42. The hydraulic drive assembly is arranged in the area enclosed by the axial extension portion 31 of the first gear 42, the main body and the outer wall of the transmission input shaft 2. A hydraulic cavity 37 is formed between the hydraulic drive assembly and the main body of the first gear 42, and the driving end of the hydraulic drive assembly is sealed with the axial extension portion 31 of the first gear 42 and the outer wall of the transmission input shaft 2. Specifically, the hydraulic drive assembly includes a piston 35 and a compression spring 36 that drives the piston 35 to return. A hydraulic cavity 37 is formed between the piston 35 and the main body of the first gear 42, and the two side walls of the piston 35 are sealed with the axial extension portion 31 of the first gear 42 and the outer wall of the transmission input shaft 2. A spring seat 38 is fixed on the outer wall of the gearbox input shaft 2, and spring mounting grooves 39 are provided on the opposite side walls of the piston 35 and the spring seat 38. The two ends of the compression spring 36 are respectively installed in the spring seat 38 and the spring mounting grooves 39 of the piston 35.

[0039] The reverse clutch device comprises a reverse shaft 51, a reverse clutch gear 52 mounted on the reverse shaft 51 through a bearing sleeve, and a second gear 53 connected and fixed to the reverse shaft 51. The reverse clutch gear 52 is fixedly connected to a clutch hub 32, and the clutch hub 32 is connected to the reverse shaft 51 through an inner and outer friction plate pair. Similarly, the inner and outer friction plate pair comprises a plurality of outer friction plates 33 and inner friction plates 34 arranged at intervals, the outer friction plates 33 are circumferentially positioned with the clutch hub 32 and can move relative to each other in the axial direction, and the inner friction plates 34 are circumferentially positioned with the reverse shaft 51 and can move relative to each other in the axial direction. The reverse clutch device also comprises a hydraulic drive assembly, the output end of which can move axially along the reverse shaft 51 and act on the inner and outer friction plate pair to adjust the friction between the outer friction plates 33 and the inner friction plates 34.

[0040] Among them, the second gear 53 is integrally connected and fixed on the reverse shaft 51, and an axial extension portion 31 extending axially toward the clutch hub 32 is provided on the radial outer end portion of the second gear 53. The hydraulic drive assembly is arranged in the area enclosed by the axial extension portion 31 of the second gear 53, the main body and the outer wall of the reverse shaft 51. A hydraulic chamber 37 is formed between the hydraulic drive assembly and the main body of the second gear 53, and the driving end of the hydraulic drive assembly is sealed with the axial extension portion 31 of the second gear 53 and the outer wall of the reverse shaft 51. Specifically, the hydraulic drive assembly includes a piston 35 and a compression spring 36 for driving the piston 35 to return. A hydraulic chamber 37 is formed between the piston 35 and the main body of the second gear 53, and the two side walls of the piston 35 are sealed with the axial extension portion 31 of the second gear 53 and the outer wall of the reverse shaft 51. A spring seat 38 is fixed on the outer wall of the reverse shaft 51 , and spring mounting grooves 39 are provided on the opposite side walls of the piston 35 and the spring seat 38 . The two ends of the compression spring 36 are respectively mounted in the spring seat 38 and the spring mounting grooves 39 of the piston 35 .

[0041] The output shaft device includes an output shaft 61 and an output gear 62 connected to the output shaft 61. The second gear 53 in the above scheme is meshed with the first gear 42, and the forward clutch gear 41 and the reverse clutch gear 52 are meshed with the output gear 62 respectively.

[0042] 1. The power output process of the hydraulic transmission: the elastic plate 91 on the torque converter 9 is connected to the engine flywheel, the torque converter 9 transmits the power to the transmission input shaft 2 through the turbine, and after the clutch device is engaged, the power is transmitted to the clutch gear 41, and the clutch gear is engaged with the output gear 62, and the power is transmitted to the output shaft 61 for output.

[0043] 2. The reverse power output process of the hydraulic transmission: the elastic plate 91 on the torque converter 9 is connected to the engine flywheel, the torque converter 9 transmits the power to the transmission input shaft 2 through the turbine, the first gear 42 is meshed with the second gear 53 to transmit the power to the reverse shaft 51, and the reverse clutch gear is meshed with the output gear 62 to transmit the power to the output shaft 61 for output.

[0044] The forward clutch device and reverse clutch device of the above-mentioned hydraulic transmission are different from the existing clutch devices;

[0045] On the one hand, the clutch hub 32 in the forward clutch device and the reverse clutch device is connected and fixed with the forward clutch gear 41 / reverse clutch gear 52, while the existing schemes all weld and fix the clutch hub 32 to the central rotating shaft 10. Therefore, in comparison, the installation method of the clutch hub 32 in this scheme is simplified, and the clutch hub 32 does not need to be integrally welded and carburized, so that the width of the slide groove on the clutch hub 32 can be precisely controlled to meet the adaptation width with the outer friction plate 33, which can not only realize axial movement, but also avoid shaking during use caused by circumferential looseness.

[0046] On the other hand, in the existing clutch device described in the background technology, an area for installing the piston 35 is formed between the clutch hub 32 and the intermediate shaft body and the radial extension, and the piston 35 needs to form a hydraulic chamber 37 between the clutch hub 32 and the radial extension of the intermediate shaft. In the forward clutch device of this scheme, the area for installing the hydraulic drive component is formed by the gearbox input shaft 2 and the first gear 42 integrally connected thereto. In the reverse clutch device, the area for installing the hydraulic drive component is formed by the reverse shaft 51 and the second gear 53 integrally connected thereto. Since an integrated forming process is adopted, there will be no problems with welds and gaps, which ensures the strength and sealing requirements of the hydraulic chamber 37 and eliminates safety hazards.

[0047] Furthermore, the hydraulic transmission of the present embodiment further comprises a parking brake device, which comprises a brake shaft 71 positioned inside the transmission housing 1 through a bearing, and a brake cover 72 connected to the transmission housing 1. The gear on the brake shaft 71 meshes with the output gear 62 on the transmission output shaft 61, and the outer end of the brake shaft 71 is positioned in the bearing cavity in the middle of the inner end surface of the brake cover 72 through a bearing. The transmission housing 1 and the brake shaft 71 are connected through an inner and outer friction plate pair, and a hydraulic drive assembly is connected to the inner end of the brake cover 72, and the output end of the hydraulic drive assembly can move axially along the brake shaft 71 and act on the inner and outer friction plate pair. The parking brake device comprises a brake shaft 71 and a brake cover 72, wherein the brake shaft 71 is positioned inside the transmission housing 1 through a bearing and meshes with the transmission output shaft 61. The brake cover 72 is connected to the transmission housing 1 in a detachable manner to facilitate the installation and maintenance of the brake clutch part inside the transmission housing 1. On this basis, the gearbox housing 1 in this solution is directly connected to the brake shaft 71 through the inner and outer friction plate pairs, and the inner and outer friction plate pairs are controlled by the hydraulic drive assembly. When the hydraulic drive assembly presses the inner and outer friction plate pairs, the gearbox housing 1 provides a braking torque to the brake shaft 71, further braking the output shaft 61 of the gearbox to achieve the purpose of parking braking. Compared with the existing parking brake device, the advantage of this solution is that on the one hand, the gearbox housing 1 is directly connected to the brake shaft 71 through the inner and outer friction plate pairs, replacing the connection structure of multiple shells, so there is no need to worry about the self-strength and connection strength of the shell and end cover. On the other hand, the brake clutch part of the parking brake device is completely in the gearbox housing 1, and the lubrication system in the gearbox housing 1 can be shared, and there is no need to worry about the sealing problem of the connection parts of multiple shells and end covers. This solution only needs to ensure the sealing of the connection part between the gearbox housing 1 and the brake cover 72.

[0048] The hydraulic drive assembly and inner and outer friction plate pair of the parking brake device are the same as those of the above-mentioned forward clutch device and reverse clutch device, but the installation positions thereof are different, as follows:

[0049] The hydraulic drive assembly includes a piston 35 and a compression spring 36 for driving the piston 35 to return to its original position. A hydraulic chamber 37 is formed between the piston 35 and the gearbox housing 1 or the brake cover 72. One end of the compression spring 36 abuts against the piston 35, and the other end abuts against the brake cover 72 or the gearbox housing 1. In the above technical solution, the hydraulic drive assembly includes a piston 35 and a compression spring 36, wherein the piston 35 is hydraulically driven to approach the inner and outer friction plate pair, thereby pressing the outer friction plate 33 and the inner friction plate 34, and increasing the friction force between the outer friction plate 33 and the inner friction plate 34. At this time, the clutch device is in a closed state. The compression spring 36 pushes the piston 35 away from the inner and outer friction plate pair after the hydraulic pressure is removed, reducing the friction force between the outer friction plate 33 and the inner friction plate 34, and at this time, the clutch device is in a disconnected state. The gearbox housing 1 is provided with a radial extension portion arranged along the radial direction of the brake shaft 71, and a hydraulic chamber 37 is formed between the piston 35 and the radial extension portion of the gearbox housing 1. At least two side walls of the piston 35 are respectively sealed against the inner wall of the gearbox housing 1 and the inner wall of the radial extension portion. One end of the compression spring 36 abuts against the piston 35, and the other end abuts against the brake cover 72. In this technical solution, the hydraulic chamber 37 is formed between the piston 35 and the radial extension portion of the gearbox housing 1, and the strength of the gearbox housing 1 can fully meet the pressure resistance requirements of the hydraulic chamber 37. In addition, the radial extension portion and the gearbox housing 1 are integrally formed (the gearbox housing 1 is mostly integrally formed), and there will be no pore oil leakage caused by other connection structures. The inner end surface of the brake cover 72 and the end surface of the piston 35 close to the brake cover 72 are provided with a spring installation groove 39, and the two ends of the compression spring 36 are respectively embedded in the spring installation grooves 39 of the brake cover 72 and the piston 35. The brake cover 72 in this solution directly serves as the spring seat 38 , thereby facilitating the installation of the compression spring 36 and omitting the spring seat 38 .

[0050] The inner and outer friction plate pair includes multiple outer friction plates 33 and inner friction plates 34 arranged at intervals. The outer friction plates 33 are circumferentially positioned with the gearbox housing 1 and can move relative to each other in the axial direction. The inner friction plates 34 are circumferentially positioned with the brake shaft 71 and can move relative to each other in the axial direction. A baffle plate 73 is connected and fixed to the inner end of the gearbox housing 1. The hydraulic drive assembly and the inner and outer friction plate pair are installed in the area surrounded by the baffle plate 73, the brake shaft 71, the gearbox housing 1 and the brake cover 72. A guide pin 74 is fixed between the baffle plate 73 above the inner and outer friction plate pair and the gearbox housing 1. The guide pin 74 is axially parallel to the brake shaft 71. The outer friction plate 33 and the guide pin 74 are circumferentially positioned and can move relative to each other in the axial direction.

[0051] In a further scheme, the gearbox input shaft 2 in the hydraulic gearbox is a hollow shaft, and a PTO shaft 8 is inserted inside the gearbox input shaft 2, and the PTO shaft 8 is arranged concentrically with the gearbox input shaft 2. The outer end of the PTO shaft 8 is connected to the worm gear in the torque converter 9, and the inner end of the PTO shaft 8 is connected to the oil pump coupling. Specifically, the outer end of the gearbox input shaft 2 is connected to the worm gear in the torque converter 9 through a turbine, and the outer end of the PTO shaft 8 is connected to the worm gear of the torque converter 9. This technical scheme relates to a PTO shaft setting structure. In this structure, the gearbox input shaft 2 adopts a hollow shaft, and the PTO shaft 8 is inserted inside the gearbox input shaft 2. In this arrangement, the PTO shaft 8 can extend out of the gearbox along the shaft hole inside the gearbox input shaft 2 and directly connect to the torque converter 9, and its inner end can also drive the oil pump to operate. Compared with the prior art, the PTO shaft 8 and the input shaft assembly are driven by gears. In this solution, the oil pump can be driven directly by the torque converter 9 through the PTO shaft 8, thereby optimizing the transmission mode of the PTO shaft 8. In terms of installation mode, since it is not necessary to connect the transmission input shaft 2 through a gear, the installation structure is simplified, the transmission can be made more compact, and it is also convenient to optimize the transmission structure space on the whole machine. Furthermore, the PTO shaft 8 in this solution is inserted into the transmission input shaft 2, and the setting of the PTO shaft 8 does not even occupy other space inside the transmission, which is equivalent to saving the space occupied by the PTO shaft 8 device in the traditional transmission.

[0052] In this solution, at least two sets of bearings are provided between the inner and outer end side walls of the PTO shaft 8 and the inner wall of the shaft hole of the gearbox input shaft 2 to achieve the circumferential relative rotation of the PTO shaft 8 and the gearbox input shaft 2. In addition, a sealing component is provided between the outer end side wall of the PTO shaft 8 and the inner wall of the shaft hole of the gearbox input shaft 2. Or the bearing between the outer end side wall of the PTO shaft 8 and the inner wall of the shaft hole of the gearbox input shaft 2 is a sealed bearing assembly to achieve the sealing between the PTO shaft 8 and the gearbox input shaft 2. In the above technical solution, the PTO shaft 8 is inserted into the gearbox input shaft 2 and can achieve the circumferential relative rotation of the two, which can be achieved by using two sets of bearings at the inner and outer ends of the PTO shaft 8. On this basis, in order to prevent the oil in the torque converter 9 from flowing between the PTO shaft 8 and the gearbox input shaft 2, it is necessary to seal the outer end side wall of the PTO shaft 8 and the inner wall of the shaft hole of the gearbox input shaft 2. There are two sealing solutions, one of which is to directly set a sealing component (such as a sealing ring) for sealing. Another method is to select the bearing at this location as a sealed bearing assembly, such as a bimetal sliding bearing 81 (as shown in the figure), which can also achieve the sealing purpose.

[0053] Based on the above structure, the lubrication structure of the hydraulic transmission in this scheme is as follows:

[0054] 1, a first lubricating oil passage 104 is provided inside the side wall of the gearbox input shaft 2, the outer end of the first lubricating oil passage 104 is communicated with the shaft end of the gearbox input shaft 2, the inner end of the first lubricating oil passage 104 is provided with a first radial oil hole 105 opened on the inner wall surface of the gearbox input shaft 2, and at least two second radial oil holes 106 opened on the outer wall surface of the gearbox input shaft 2. The first radial oil hole 105 is communicated with the gap between the gearbox input shaft 2 and the PTO shaft 8, and the two second radial oil holes 106 are respectively oriented to the inner and outer friction plate pairs, and the bearing between the on-board clutch gear 41 and the gearbox input shaft 2; the inner end of the second radial oil hole 106 can be directly communicated with the first lubricating oil passage 104 or with the gap between the gearbox input shaft 2 and the PTO shaft 8. On the basis of the above scheme, this scheme also needs to solve the problem of bearing lubrication set between the inner and outer end side walls of the PTO shaft 8 and the inner wall of the shaft hole of the gearbox input shaft 2, as well as the lubrication problem in the on-board clutch device. Therefore, further, the present solution sets a first lubricating oil passage 104 inside the side wall of the gearbox input shaft 2, and the outer end of the first lubricating oil passage 104 is opened on the shaft end of the central rotating shaft 10, which can be used to connect the oil circuit. The inner end of the first lubricating oil passage 104 is opened on the inner wall surface of the gearbox input shaft 2, and the lubricant can enter the gap between the PTO shaft 8 and the gearbox input shaft 2 from there, and flow to the axial ends to lubricate the bearings on both sides respectively. At the same time, considering the lubrication of the on-board clutch device on the outside of the gearbox input shaft 2, a plurality of second radial oil holes 106 are also set at the inner end of the first lubricating oil passage 104 for delivering lubricating oil to the outside of the gearbox input shaft 2. Through the above structure, the scheme can achieve targeted lubrication of the inner and outer friction plate pairs and bearings in the clutch device. The lubrication efficiency is higher, that is, lubrication is achieved with a smaller amount of lubricating oil.

[0055] 2. A second lubricating oil passage 102 is provided inside the shaft of the reverse shaft 51, and the outer end of the second lubricating oil passage 102 is communicated with the shaft end of the reverse shaft 51. The inner end of the second lubricating oil passage 102 is provided with at least two third radial oil holes 103, which are respectively communicated with the inner and outer friction plate pairs, and the bearing between the reverse clutch gear 52 and the reverse shaft 51. This technical solution is for lubricating the parts in the reverse clutch device, and is similar to the above-mentioned forward clutch device. Its effect is also to achieve targeted lubrication of the inner and outer friction plate pairs and bearings in the clutch device, and the lubrication efficiency is higher, that is, lubrication is achieved with a smaller amount of lubricating oil.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0057] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A hydraulic transmission, comprising a transmission assembly and a torque converter assembly; the transmission assembly comprises a transmission housing (1), and a transmission input shaft (2), a forward clutch device, a reverse clutch device, an output shaft device and a parking brake device arranged in the transmission housing (1), characterized in that: The parking brake device comprises a brake shaft (71) positioned inside a gearbox housing (1) via a bearing, and a brake cover (72) connected to the gearbox housing (1); the brake shaft (71) is used to mesh with an output shaft (61) of the gearbox, the gearbox housing (1) and the brake shaft (71) are connected via an inner and outer friction plate pair, a hydraulic drive assembly is connected to the inner end of the brake cover (72), and the output end of the hydraulic drive assembly is capable of axially moving along the brake shaft (71) and acting on the inner and outer friction plate pair; The hydraulic drive assembly comprises a piston (35) and a compression spring (36) for driving the piston (35); a hydraulic chamber (37) is formed between the piston (35) and the gearbox housing (1); one end of the compression spring (36) abuts against the piston (35), and the other end abuts against the brake cover (72) or the gearbox housing (1); pressurized oil is passed through the hydraulic chamber (37) so that the piston can move axially along the brake shaft (71) and break away from the inner and outer friction plates; The gearbox housing (1) is provided with a radial extension portion arranged along the radial direction of the brake shaft (71); a hydraulic chamber (37) is formed between the piston (35) and the radial extension portion of the gearbox housing (1); at least two side walls of the piston (35) are respectively sealed against the inner wall of the gearbox housing (1) and the inner wall of the radial extension portion; one end of the compression spring (36) abuts against the piston (35), and the other end abuts against the brake cover (72); The inner end surface of the brake cover (72) and the end surface of the piston (35) close to the brake cover (72) are provided with a spring mounting groove (39), and the two ends of the compression spring (36) are respectively embedded in the spring mounting grooves (39) of the brake cover (72) and the piston (35); The inner and outer friction plate pair comprises a plurality of outer friction plates (33) and inner friction plates (34) arranged at intervals, the outer friction plates (33) being circumferentially positioned with the gearbox housing (1) and being capable of axial relative movement, and the inner friction plates (34) being circumferentially positioned with the brake shaft (71) and being capable of axial relative movement; A baffle (73) is connected and fixed to the inner end of the gearbox housing (1); the hydraulic drive assembly and the inner and outer friction plate pair are installed in an area enclosed by the baffle (73), the brake shaft (71), the gearbox housing (1) and the brake cover (72); a guide pin (74) is fixed between the baffle (73) above the inner and outer friction plate pair and the gearbox housing (1); the guide pin (74) is axially parallel to the brake shaft (71); the outer friction plate (33) and the guide pin (74) are circumferentially positioned and can move relative to each other in the axial direction; The outer end of the transmission input shaft (2) extends into the torque converter (9) and is connected to the turbine, and the elastic plate (91) of the torque converter (9) is connected to the engine flywheel; the on-wheel clutch device is installed on the transmission input shaft (2), and the on-wheel clutch device includes a on-wheel clutch gear (41) mounted on the transmission input shaft (2) through a bearing sleeve, a first gear (42) connected to the transmission input shaft (2), and a clutch hub (32) connected and fixed to the on-wheel clutch gear (41); the clutch hub (32) is connected to the transmission through an inner and outer friction plate pair. The input shaft (2) is connected, and the inner and outer friction plate pairs include a plurality of outer friction plates (33) and inner friction plates (34) arranged at intervals; the inner friction plates (34) are circumferentially positioned with the transmission input shaft (2) and can move relative to each other in the axial direction, and the outer friction plates (33) are circumferentially positioned with the clutch hub (32) and can move relative to each other in the axial direction; the on-board clutch device also includes a hydraulic drive component, the output end of which can move axially along the transmission input shaft (2) and act on the inner and outer friction plate pairs to adjust the friction between the outer friction plates (33) and the inner friction plates (34); The first gear (42) is integrally connected and fixed to the transmission input shaft (2); an axial extension portion (31) extending axially toward the clutch hub (32) is provided on the radial outer end portion of the first gear (42); a hydraulic drive assembly is arranged in an area enclosed by the axial extension portion (31) of the first gear (42), a main body portion and an outer wall of the transmission input shaft (2); a hydraulic cavity (37) is formed between the hydraulic drive assembly and the main body portion of the first gear (42); a driving end of the hydraulic drive assembly is in sealing cooperation with the axial extension portion (31) of the first gear (42) and the outer wall of the transmission input shaft (2); the hydraulic drive assembly The component comprises a piston (35) and a compression spring (36) for driving the piston (35) to return to its original position; a hydraulic chamber (37) is formed between the piston (35) and the main body of the first gear (42); the two side walls of the piston (35) are in sealing cooperation with the axial extension (31) of the first gear (42) and the outer wall of the gearbox input shaft (2); a spring seat (38) is fixed on the outer wall of the gearbox input shaft (2); spring mounting grooves (39) are provided on the opposite side walls of the piston (35) and the spring seat (38); and the two ends of the compression spring (36) are respectively mounted in the spring seat (38) and the spring mounting grooves (39) of the piston (35); The reverse clutch device comprises a reverse shaft (51), a reverse clutch gear (52) mounted on the reverse shaft (51) via a bearing sleeve, and a second gear (53) connected and fixed to the reverse shaft (51); a clutch hub (32) is fixedly connected to the reverse clutch gear (52), and the clutch hub (32) is connected to the reverse shaft (51) via an inner and outer friction plate pair; similarly, the inner and outer friction plate pair comprises a plurality of outer friction plates (33) and inner friction plates (34) arranged at intervals, the outer friction plates (33) and the clutch hub (32) are circumferentially positioned and can move relative to each other in the axial direction, and the inner friction plates (34) and the reverse shaft (51) are circumferentially positioned and can move relative to each other in the axial direction; the reverse clutch device also comprises a hydraulic drive assembly, the output end of which can move axially along the reverse shaft (51) and act on the inner and outer friction plate pair to adjust the friction between the outer friction plates (33) and the inner friction plates (34); The second gear (53) is integrally connected and fixed on the reverse shaft (51); an axial extension portion (31) extending axially toward the clutch hub (32) is provided on the radial outer end portion of the second gear (53); the hydraulic drive component is arranged in an area enclosed by the axial extension portion (31) of the second gear (53), the main body and the outer wall of the reverse shaft (51); a hydraulic cavity (37) is formed between the hydraulic drive component and the main body of the second gear (53); a driving end of the hydraulic drive component is in sealing cooperation with the axial extension portion (31) of the second gear (53) and the outer wall of the reverse shaft (51); the hydraulic drive component The invention comprises a piston (35) and a compression spring (36) for driving the piston (35) to return to its original position; a hydraulic chamber (37) is formed between the piston (35) and the main body of the second gear (53); the two side walls of the piston (35) are sealingly matched with the axial extension (31) of the second gear (53) and the outer wall of the reverse shaft (51); a spring seat (38) is fixed on the outer wall of the reverse shaft (51); spring mounting grooves (39) are provided on the opposite side walls of the piston (35) and the spring seat (38); and the two ends of the compression spring (36) are respectively mounted in the spring seat (38) and the spring mounting grooves (39) of the piston (35).

2. A hydraulic transmission according to claim 1, characterized in that: The outer end of the brake shaft (71) is positioned in a bearing cavity in the middle of the inner end surface of the brake cover (72) through a bearing.

3. A hydraulic transmission according to claim 1, characterized in that: A gearbox input shaft (2) is provided inside the gearbox housing (1), and the outer end of the gearbox input shaft (2) extends into the torque converter (9) and is connected to a turbine in the torque converter; the gearbox input shaft (2) is a hollow shaft, and a PTO shaft (8) is passed through the gearbox input shaft (2), and the PTO shaft (8) and the gearbox input shaft (2) are arranged concentrically; the outer end of the PTO shaft (8) is connected to the torque converter (9), and the inner end of the PTO shaft (8) is connected to an oil pump of a lubricating oil system.

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