Title of Invention

AN IMPROVED TRANSMISSION SYSTEM FOR A VEHICLE

Abstract

Compound idler reverse drive mechanism in the trasmission system of a vehicle to achieve appropriate number of reverse speesds in a vehiclelike tractor (s) of similar vehicle(s). Provision of this mechansim helps inutilizing these vehicle(s)more effectively for non-agricultural operations eith increased utility, operational productivity, operatior's safety & minimizes trasmission system cost & size.

Full Text

FORM 2 [Refer section 10; rule 13] COMPLETE SPECIFICATION 1 TITLE OF THE INVENTION 2 APPLICANTS ANIMPROVED TRANSMISSION SYSTEM FOR A VEHICLE M/S MAHINDRA & MAHINDRA LTD GATEWAY BUILDING, APOLLO BUNDER, FORT, MUMBAI400001. MAHARASHTRA. INDIA A Company registered under the Indian Companies Act, 1913 NATIONALITY: INDIA The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- 2 Field of Invention The present invention relates to provision of compound idler reverse drive mechanism in the transmission system of a vehicle to achieve appropriate number of reverse speeds in a vehicle like tractor(s) or similar vehicle(s). Provision of this mechanism helps in utilizing these vehicle(s) more effectively for non-agricultural operations with increased utility, operational productivity, operator"s safety & minimizes transmission system cost & size. Background of the Invention The vehicles like tractor(s) or similar vehicle(s) are mainly used for the traditional operations like ploughing, cultivation, haulage, etc. Additionally these vehicles are also used for certain non-agricultural operation like leveling, dozing, loading is known prior art. The above non-agricultural operations require frequent forward and reverse movement of the vehicle at about equal speed. The typical tractor transmission system consists of main speed change unit, auxiliary speed change unit and final drive (differential) unit. This transmission arrangement gives certain number of speeds in forward direction and certain number of speeds in reverse direction depending upon the location of idler reverse drive mechanism. With combination of forward and reverse speeds traditional agricultural operations are carried out, whereas to perform non-agricultural operations a vehicle operator"s is required to operate both main speed and auxiliary speed shifting mechanisms. Thus the requirements of appropriate speed and shifting by single lever for non-agricultural operations are not fulfilled, thereby leading to operator"s fatigue and hampering vehicle productivity. Also while designing transmission system with idler reverse drive mechanism a desired reverse gear ratio needs to be maintained in single gear pair, thereby increasing gear size, which results in higher cost & size of the transmission. Shifting pattern with the typical tractor transmission system for main speed change & auxiliary speed change unit is shown in figure 2. 3 To cater to the requirements of vehicle productivity & operator"s comfort certain tractor manufacturers have developed separate features like forward reverse Shuttle, Hydraulically and / or Mechanically operated forward and reverse changeover assembly unit or apparatus in the transmission system of a vehicle. These features are referring to US patent 6612193 B2 titled "change speed apparatus for tractor", 4610174 titled "transmission for tractor", and 4484488 titled "forward reverse change over apparatus for working vehicle", which contribute to produce equal number of reverse speeds against the available forward speeds. The adaptation of these features in the transmission system of the vehicle has certain disadvantages like:- - Separate set of gears, their shifting mechanism, lubrication system and alike systems need to be provided in the transmission system for operation of these features. This increases number of components, which results in higher product cost and system complexities. - To accommodate these features a separate space is required in the transmission system, thereby compromising on the compactness of transmission housings. - Providing more number of reverse speeds is undesirable since operation of tractor at higher reverse speeds may lead to accidents thereby risking operator"s safety. Shifting pattern for main speed change & auxiliary speed change unit for tractor transmission system with additional feature called forward reverse shuttle or alike is shown in figure 3. The requirements of non-agricultural operations and the drawbacks of conventional solutions provided for the same calls for a provision of compound idler reverse drive mechanism in a transmission system, wherein certain forward & reverse speeds are nearly having equal speeds and shifting pattern is such that the operator will able to move the tractor in forward and reverse direction by operating single lever at a pre-selected speed. This increases vehicle productivity in non-agricultural operations like leveling, dozing, loading and operator"s comfort. Also the number of reverse speeds being less the tractor can now be operated in reverse direction without hampering operator"s safety. Since there is no additional feature in the typical tractor transmission system for achieving these forward and reverse speeds, there is no significant increase in product cost 4 Summary of the Invention It is an objective of this invention to provide a compound idler reverse drive mechanism in the typical tractor transmission system to produce appropriate number of reverse and forward speeds. This will cater to the requirement of appropriate speeds & shifting by single lever for non-agricultural operations, thereby increasing vehicle utility and operational productivity. Another object of this invention is to produce these reverse speeds without addition of separate feature as mentioned in the background of the invention leading to minimize tractor transmission cost and size. Another object of this invention is to provide easy / simple shifting pattern for forward and reverse direction of the vehicle, thereby increasing operator"s comfort and performance of shifting mechanism. Another object of this invention is to have limited number of reverse speeds thereby increasing operator"s safety aspect while driving the vehicle in the reverse direction. Other objects and features of the present invention will be apparent to those skilled in the art, based on the following description taken in combination with the accompanying drawings & can be used in other transmission system depending up on the requirements & benefits. Brief description of the drawings Figure 1 shows a schematic arrangement of a typical tractor transmission system used in a vehicle like tractor or similar vehicle(s). Figure 2 shows gear shifting pattern for typical tractor transmission system. Figure 3 shows gear-shifting pattern for tractor transmission system having additional feature called forward reverse shuttle or alike. Figure 4 shows detail view of currently used transmission system with idler reverse drive mechanism, located in the main speed change or auxiliary speed change compartment of tractor transmission system. Figure 5 shows detail view of improved transmission system with compound idler reverse drive mechanism, located in the main speed change or auxiliary speed change compartment of tractor transmission system to enable appropriate reverse speeds. 5 Figure 6 shows the shifting pattern with reference to improved transmission system as illustrated in figure 5, when located in the auxiliary speed change compartment. Figure 7 shows the shifting pattern with reference to improved transmission system as illustrated in figure 5, when located in the main speed change compartment. Detail description of the Preferred Embodiments A typical tractor transmission system comprises of a clutch unit, main speed change unit, auxiliary speed change unit and final drive (differential) unit. A schematic arrangement of transmission system used in a vehicle like tractor(s) or similar vehicle(s) is shown in figure 1, wherein power developed by an engine (1) is transferred to main speed change unit (3) through clutch unit (2). The number of required speeds are achieved through main speed change mechanism (not shown) located in the main speed change compartment After selecting a particular speed through this mechanism, the drive is transferred to auxiliary speed change unit (4) for further reduction to match the different operating conditions encountered during working for agricultural and non-agricultural operations. Drive after passing through main speed change & auxiliary speed change mechanism is then transferred to final drive unit (5) from where it is further transmitted to the rear wheels of a tractor. As per current practices for achieving appropriate number of reverse speeds certain manufacturers have provided idler reverse drive mechanism (14) in the main speed change unit (3) or auxiliary speed change unit (4). According to this transmission system as shown in figure 4, a separate set of gear pair (11 and 12) with idler reverse drive mechanism (14) is provided to achieve appropriate number of reverse speeds. This increases the space requirement and deflection due to increased bearing span of the second speed change shaft (16) (herein after mentioned as top shafts). At the same time the forward and reverse speeds required for non-agricultural operations are neither of equal magnitude nor in the same line of gear shifting pattern as shown in figure 2. According to this transmission mechanism (17) operator of the vehicle is required to operate both main speed change and auxiliary speed change unit (3 & 4) for achieving appropriate forward and reverse speeds of the vehicle. 6 An improved transmission system with compound idler reverse drive mechanism for achieving appropriate number of reverse speeds is shown in figure 5. The improved transmission mechanism (21) may be located in the main speed change compartment (not shown) or auxiliary speed change compartment (22) of typical tractor transmission system. Number of gear pairs (23 and 24), (25 and 26), (27 and 28) are provided to achieve different vehicle speeds in forward direction. This gears (23, 25, 27) & (24, 26, 28) are mounted on first speed change shaft (31) (herein after mentioned as counter shaft) and / or second speed change shaft (29) (herein after mentioned as top shaft). After receiving drive from main speed change unit (3) it is transferred to top shaft (29) of final drive unit (5) through one of the auxiliary speed change gear pair depending up on the selection. A means of engagement coupling(s) (30) are provided on counter shaft (31) and / or top shaft (29) for selecting the appropriate gear pair of auxiliary speed change mechanism. A reverse gear (32) is located on the counter shaft (31) or top shaft (29) on either side of gear pair (27 and 28) producing the vehicle speeds which are normally used for the non-agricultural operation like leveling, dozing, loading etc. A compound idler reverse drives mechanism (34) is provided on either side of counter shaft (31) or top shaft (29), which transmits power from reverse gear (32) to speed change gear (28) in reverse direction. A compound idler reverse drives mechanism (34) comprising cluster gear (38) having gear (35 and 36) opposite to each other. One of the gear (35) of cluster gear (38) meshes with reverse gear (32), whereas another gear (36) meshes with the speed change gear (28) located on top shaft (29). Said cluster gear (38) is freely rotating on an idler shaft (37), which is supported at two ends in the speed change compartment (22). The vehicle operation during non-agricultural operations like loading, dozing & leveling is explained by considering provision of this improved transmission system (21) in the auxiliary speed change compartment. The required speed in forward direction is selected by operating main speed shifting lever (not shown), which is linked to main speed change mechanism and auxiliary speed shifting lever (not shown) linked to auxiliary speed change mechanism (21). Gear pair (27 and 28) from auxiliary speed change mechanism (21) is selected to perform above non-agricultural operation with an appropriate tractor speed in forward direction. Whenever operator"s wants to move the tractor in reverse direction, simply he has to put the auxiliary speed shifting lever in opposite direction to that of selected auxiliary 7 speed change gear pair (27 & 28). In this situation the drive coming from main speed change unit (3) is transferred to top shaft (29) of final drive unit (5) in reverse direction while passing from counter shaft (31), engagement coupling (30), reveres gear (32), cluster gear (38) and auxiliary speed change gear (28), which is located on top shaft (29). Hence compound idler reverse drive mechanism (34) maintaining a reverse gear ratio by considering two gear pairs (32 & 35, 36 & 28). This help in designing compact transmission mechanism compared to the tractor transmission system with idler reverse drive mechanism (14). Also the reverse gear ratio may be adjusted in such a way to produce higher speed that of auxiliary gear pair (27 & 28), thereby increasing operational efficiency in applications like loading, dozing, leveling. Thus with this improved tractor transmission system appropriate number of reverse speeds are achieved corresponding to pre-selected forward speeds only by operating a single lever in opposite direction that of selected position (M) as shown in figure 6. Shifting pattern as illustrated in figure 2 3 & 6, in which M representing engagement of gear pair (27 & 28), R representing engagement of reverse gear (32), H & L for remaining auxiliary gear pairs (23 & 24), (25 & 26) with neutral position (N) in between. Therefore limited numbers of forward & reverse speeds are achieved for non-agricultural operations like loading, dozing & leveling with minimum tractor transmission cost, compact size & maximum operator"s comfort and safety. As various changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description & shown in the accompanying drawings shall be interpreted as illustrative & not in a limiting sense. We claim: 1. An improved transmission system for a vehicle like tractors or similar vehicles with appropriate reverse speeds, comprising: a speed change compartment (22), gear pairs (23,24), (25,26), (27, 28) mounted in said speed change compartment (22), a first speed change shaft, being a counter shaft (31), a second speed change shaft, being a top shaft (29), a reverse gear (32), an engagement coupling (3) linked to said counter shaft (31) and said top shaft (29); conventional bushes and bearings; characterized in that said gear pairs (23,24), (25,26), (27, 28) are mounted on said counter shaft (31) and/or said top shaft (29); a compound idler reverse drive mechanism (34) is provided in the speed change compartment (22) on either side of said counter shaft (31); said reverse gear is located on either said counter shaft (31) or said top shaft (29) and in front of said gear pair (27, 28); cluster gear (38), on the gears (35) of said cluster gear (38) meshing with said reverse gear (32); one said gear pairs (23,24), (25,26), (27, 28), being a speed gear (28), said speed gear (28) meshing with another gear (36) of said cluster gear (38). 2. An improved transmission system as claimed in claim 1 wherein said gears (35) and (36) of said cluster gear (38) are mounted opposite each other, said cluster gear being mounted on an idler shaft (37) for free rotation with respect to each other, said idler shaft (37) being supported at its two ends in said speed change compartment (22). Dated this 17th day of November 2004 / Shyam Sunder Iyer Agent for the Applicants

Documents:

1233-mum-2004-abstract.pdf

1233-mum-2004-claims.doc

1233-mum-2004-claims.pdf

1233-mum-2004-correspondence(ipo).pdf

1233-mum-2004-correspondence.pdf

1233-mum-2004-description(granted).doc

1233-mum-2004-description(granted).pdf

1233-mum-2004-drawing.pdf

1233-mum-2004-form 1.pdf

1233-mum-2004-form 19.pdf

1233-mum-2004-form 2(granted).doc

1233-mum-2004-form 2(granted).pdf

1233-mum-2004-form 2(title page).pdf

1233-mum-2004-form 3.pdf

1233-mum-2004-form 5.pdf

1233-mum-2004-power of attorney.pdf

1238-MUM-2004-CORRESPONDENCE 16-6-2008.pdf

123mum-2004-abstract.doc