CROSS REFERENCE TO RELATED APPLICATION

This application is based on and derives the benefit of Indian Provisional Application 202111051615 filed on 10/11/2021, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

[001] The embodiments herein relate generally to a power transmission system in vehicles, especially a tractor or other agricultural or construction vehicle, more particularly to a transmission system having a predetermined gear arrangement to achieve a final drive reduction in vehicles with variable (or adjustable) wheelbase.

BACKGROUND

[002] Agricultural vehicles such as tractors and other similar vehicles are primarily used in agricultural field operations. Further, agriculture has a tremendous need for tractors having various characteristics. This need has been met primarily by building a wide variety of tractors, including wheeled and tracked, of various wheelbase, heights and configurations. To achieve this, conventionally there are a number of wheel supporting structures for the vehicles which are adapted for level adjustment. This supporting structure includes a pair of link rods, parallel with each other and different in the length from each other, for the interconnection between a ground wheel and a vehicle body, and a hydraulic power cylinder for adjusting the working position of the parallel linkage, to thereby adjust the vertical position of the ground wheel relative to the vehicle body, thereby permitting the vehicle level to be adjusted. The variable wheelbase is a result of changing of the ground clearance of the agricultural tractor. Change of ground clearance results in shifting of center of gravity (CG) of the tractor. Hence, two variants of vehicle are made viz Low CG and High CG are achieved. The Low CG corresponds to low ground clearance whereas the High CG corresponds to high ground clearance.

[003] Further, various transmission systems having a speed reduction gear-set at each driven wheel of a motor vehicle have been employed for different purposes. For example, a conventional art describes a driveline for a tractor, in which the rear wheels are supported on a U-shaped frame having legs extending rearward. Power developed by an engine is transferred through a differential mechanism located forward of the axle shafts from a differential mechanism through chain drive mechanisms to the vicinity of the driven wheels. The chain drive mechanisms drive a simple speed reduction gear-set whose output is driveably connected to the corresponding axle shaft. This arrangement of the power flow provides a free space between the legs of the U-shaped frame between the rear wheels so that auxiliary units can be readily coupled to the frame of the tractor.

[004] Currently, speed reduction rotating power devices are generally classified into worm speed reducers and differential planetary gear speed reducers. With a simple structure, a worm speed reducer is easy to manufacture. But it has problems such as friction-induced wearing and heating, low efficiency, and less durability, which limits the scope of its use. A differential planetary speed reducer uses a profile shifted gear of which an amount of addendum modification (or addendum modification coefficient) is adjusted, which causes problems associated with noise, wear, and durability and it is difficult to manufacture the differential planetary speed reducer. Further, the speed reduction devices for the agricultural vehicles with variable wheelbase are more complex in design.

[005] Therefore, there exists a need for a transmission system having a predetermined gear arrangement to achieve a final drive reduction in vehicles with variable (or adjustable) wheelbase, which eliminates the aforementioned drawbacks. OBJECTS

[006] The principal object of an embodiment of this invention is to provide a transmission system having a predetermined gear arrangement to achieve a final drive reduction in vehicles with variable (or adjustable) wheelbase.

[007] Another object of an embodiment of this invention is to provide the transmission system which is adapted to provide a medium of power flow from a brake shaft (input shaft) to a rear axle shaft (output shaft) of the vehicle.

[008] Yet another object of an embodiment of this invention is to provide the transmission system which achieves final drive reduction in a lesser space.

[009] Still another object of an embodiment of this invention is to provide the transmission system which facilitates in easy assembly of the gears and other parts while switching variants from a low position of wheelbase (low CG) to a high position of the wheelbase (high CG) and vice-versa.

[0010] Yet another object of an embodiment of this invention is to provide the transmission system which facilitates easy assembly and serviceability.

[0011] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications. BRIEF DESCRIPTION OF DRAWINGS

[0012] The embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0013] Fig. 1 depicts an exploded view showing a wheel and a engine components of an agricultural vehicle with a low wheel base (i.e. low center of gravity), according to an embodiment of the invention as disclosed herein;

[0014] Fig. 2 depicts another exploded view showing the wheel and the engine components of the agricultural vehicle with high wheel base (i.e. high center of gravity), according to an embodiment of the invention as disclosed herein;

[0015] Fig. 3 depicts a cross sectional view of a final drive reduction unit of a modular transmission system, according to the embodiments as disclosed herein;

[0016] Fig. 4 depicts a superimposed view of transmission system at lower position of wheelbase and at higher position of wheelbase, according to the embodiments as disclosed herein; and

[0017] Fig. 5 depicts a cross sectional view of a brake housing and a spigot guide, according to the embodiments as disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0019] The embodiments herein achieve a modular transmission system with a final drive reduction unit for vehicles with variable wheelbase. Further, the embodiments herein achieve the transmission system which is adapted to provide a medium of power flow from a brake shaft to a rear axle shaft of the vehicle. Furthermore, the embodiments herein achieve the transmission system which achieves final drive reduction in speed in a lesser space. Additionally, the embodiments herein achieve the transmission system which facilitates in easy assembly of the gears and other parts while switching variants from a low position of wheelbase (low CG) to a high position of the wheelbase (high CG) and vice-versa. Also, the embodiments herein achieve the transmission system which facilitates easy assembly and serviceability. Referring now to the drawings, and more particularly to FIGS. 1 through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0020] Fig. 1 depicts an exploded view showing a wheel and engine components of an agricultural vehicle with a low wheel base (i.e. low center of gravity), according to an embodiment of the invention as disclosed herein. Fig. 2 depicts another exploded view showing the wheel and the engine components of the agricultural vehicle with high wheel base (i.e. high center of gravity), according to an embodiment of the invention as disclosed herein. For the purpose of this description and ease of understanding, the transmission system (100) is explained herein with below reference to a tractor (agricultural vehicle). However, it is also within the scope of the invention to practice and/or use the transmission system (100) in any other type of vehicles, without otherwise deterring the intended function of the transmission system (100) as can be deduced from the description and corresponding drawings. In an embodiment, the transmission system (100) is used in the agricultural vehicle in which the wheelbase can be adjusted in accordance to working conditions. For example, the wheelbase for the agricultural vehicle may be held at a low position (i.e. low wheelbase position or low center of gravity) and a high position (i.e. high wheelbase position or high center of gravity). The transmission system (100) is fabricated such that the transmission system (100) may be used for both the low wheelbase position and the high wheelbase position. The transmission system (100) derives power from a power supply means which is communicated to a brake shaft (i.e. an input shaft) (102) through engine and driveline. Further, the power is transmitted to a rear axle shaft (i.e. an output shaft (104) though a final drive reduction unit (200). The power transmitted to the output shaft (104) through the final drive reduction unit (200) is utilized for driving the wheels of the vehicle.

[0021] The transmission system (100) includes a final drive reduction unit (200) which is disposed between the input shaft (102) and the output shaft (104). The final drive reduction unit (200) is provided in the transmission system (100) to reduce power flow (or speed) transferred from the power supply means i.e. engine of the vehicle to the wheels of the vehicle. The final drive reduction unit (200) includes a first gear-set (108), a second gear-set (112), and a universal joint (114). [0022] Fig. 3 depicts a cross sectional view of a final drive reduction unit of a modular transmission system, according to the embodiments as disclosed herein. The final drive reduction unit (200) includes the first gear-set (108) which is engaged to the input shaft (102) which derives power from the power supply means. In an embodiment, the first gearset (108) is at least a pair of bevel gears. The first gear-set (108) includes a first bevel pinion (108a) having a first predetermined splines defined therein. The splines on the first bevel pinion (108a) is adapted to mesh with a plurality of splines (102s) defined in the input shaft (102). Further, the first gear-set (108) includes a first bevel gear shaft (108b) which is adapted to engage with the first bevel pinion (108a) at one end. Further, the first bevel gear shaft (108b) is coupled to the universal joint (114) at other end. The first bevel gear shaft (108b) is engaged transversely with the first bevel pinion (108a) i.e., the first bevel pinion (108a) and the first bevel gear shaft (108b) are located perpendicular to each other.

[0023] The final drive reduction unit (200) includes the second gear- set (112) which is connected to the output shaft (104) which transmits power to wheels of the vehicle. In an embodiment, the second gear-set (112) is at least a pair of bevel gears. The second gear-set (112) includes a second bevel pinion (112a) having a second predetermined splines defined therein. The splines on the second bevel pinion (112a) is adapted to mesh with a plurality of splines (104s) defined in the output shaft (104). Further, the second gear-set (112) includes a second bevel gear shaft (112b) which is adapted to engage with the second bevel pinion (112a) at one end. Further, the second bevel gear shaft (112b) is coupled to the universal joint (114) at other end. The second bevel gear shaft (112b) is engaged transversely with the second bevel pinion (112a) i.e., the second bevel pinion (112a) and the second bevel gear shaft (108b) are located perpendicular to each other.

[0024] The final drive reduction unit (200) further includes the universal joint (114) which is connected between the first gear-set (108) and the second gear-set (112). The universal joint (114) is fabricated such that a motion of first bevel gear shaft (108b) is transferred to the second bevel gear shaft (108b). Further, the universal joint (114) includes a first end (114a) adapted to engage with the first bevel gear shaft (108b) and a second end (114b) adapted to engage with the second bevel gear shaft (112b). The universal joint (114) is adapted to transfer a predetermined torque from the first gear-set (108) to the second gear-set (112) and thereby transfer a predetermined power from the input shaft (102) to the output shaft (104).

[0025] Further, the final drive reduction unit (200) includes a first housing (106), a second housing (110) and a third housing (116). The first housing (106) is adapted to receive the input shaft (102) there within at one side i.e. one end of the input shaft (102) is disposed within the first housing (106). Further, the second housing (110) of the final drive reduction unit (200) is disposed parallel and in a spaced relation to said first housing (106). The second housing (110) is adapted to receive the output shaft (104) there within in a direction opposite to the input shaft (102) i.e. one end of the output shaft (104) is disposed within the second housing (110). Furthermore, the final drive reduction unit (200) includes the third housing (116) which is connected between the first housing (106) and the second housing (110). The third housing (116) is configured to cover the universal joint (114).

[0026] Fig. 5 depicts a cross sectional view of a brake housing and a spigot guide, according to the embodiments as disclosed herein. Furthermore, the transmission system (100) includes the first housing (106) having a spigot guide (118) (as shown in Fig. 5) defined adjacent to a brake housing. The spigot guide (118) is adapted to facilitate shifting of said final drive reduction unit (200) from a lower wheelbase position (low center of gravity) to a higher wheelbase position (high center of gravity) and vice-versa. The spigot guide (118) forms a pivot point about which the final drive reduction unit (200) is rotated for a predetermined angle. In an embodiment, the spigot guide (118) is disposed inwards to a pair of bearing of the input shaft (102). The spigot guide (118) is provided in the transmission system (100) along with the final drive reduction unit (200) so that the final drive reduction unit (200) is rotated about the pivot points without removal of the final drive reduction unit (200) and other parts from the vehicle assembly.

[0027] Fig. 4 depicts a superimposed view of transmission system at lower position of wheelbase and at higher position of wheelbase, according to the embodiments as disclosed herein. The final drive reduction unit (200) along with the output shaft (104) is rotated in one of first direction and second direction about an axis of the input shaft (102) to shift the final drive reduction unit (200) from the lower wheelbase position (low center of gravity) to the higher wheelbase position (high center of gravity) and from the higher wheelbase position to the lower wheelbase position, respectively. The aforementioned spigot guide (118) facilitates in shifting the final drive reduction unit easily. In an embodiment, the spigot guide (118) and the universal joint (114) provide a predetermined degree of freedom to rotate the final drive reduction unit (200) freely about the pivot point that was cumbersome with rigid shaft system (or conventional transmission system).

[0028] The technical advantages achieved by the embodiments disclosed herein includes light weight transmission system, facilitate easy assembly and serviceability, necessary final reduction of tractor in lesser space, and facilitates easy assembly while switching variants from Low CG to High CG and vice-versa.

[0029] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.