Transmission system

Abstract

A transmission system (100, Fig.2) for a working vehicle (see Fig.1) comprising a transmission casing 130 having a sump 136 for containing a lubricant, a component 112 positioned at least partially within the sump for distributing said lubricant about the transmission casing, a collection reservoir located above the sump, at least part of which is defined by a feature 140 provided in the transmission casing and a lubricant gallery (160, Fig.7a) for conveying lubricant from the reservoir to at least one component of the vehicle transmission system. The collection reservoir may be defined by a redundant feature such as an unused bearing bore 140 in the casing that may be re-purposed by providing a damming plate 142 extending across a portion of an opening of the redundant casing feature. The arrangement may further comprise a gutter plate 144 for guiding lubricant into the collection reservoir (see Fig.6) in a splash lubrication system. The transmission system may be a hydrostatic transmission system. At least part of the gallery may be integrally formed in the casing and may direct lubricant towards a bearing. The casing may comprise a pair of half shells.

Description

FIELD The present disclosure relates to a transmission system for a working vehicle, a working vehicle comprising said transmission system, and to a method of manufacturing the same. BACKGROUND Rotating components within mechanical systems often require a supply of lubricant (such as oil) to help lubricate the contacting parts of the system and to assist in dissipating locally generated heat. In the absence of an adequate supply of lubricant, the contacting parts of the system may experience premature wear and, ultimately, component failure. An example of a known system which requires a steady supply of lubricant is a vehicle transmission (or gearbox). In more complex transmission systems, the supply of lubricant is often provided by a dedicated lubrication circuit in which a hydraulic pump supplies lubricant to various parts of the transmission via a series of dedicated channels or conduits. However, such systems tend to add to the cost and complexity of the transmission. Consequently, more basic transmission systems tend to rely on "splash" lubrication wherein the motion of the rotating components of the transmission is used to transport (or "splash") lubricant from a sump to other areas about the transmission casing. However, when relying upon "splash" lubrication, it is often difficult to control the supply of lubricant to specific areas or components within the transmission casing. As such, transmission systems relying on "splash" lubrication may experience problems with some components contained within the transmission casing not receiving sufficient amounts of lubrication, which can lead to premature wear and failure. The present disclosure aims to address this problem. SUMMARY A first aspect of the disclosure provides a transmission system for a working vehicle comprising: a transmission casing having a sump for containing a lubricant; a component positioned at least partially within the sump for distributing said lubricant about the transmission casing; a collection reservoir, located above the sump, for collecting at least some of the lubricant distributed about the transmission casing by the component positioned at least partially within the sump, wherein at least part of the collection reservoir is defined by a feature provided in the transmission casing; and a lubricant gallery for conveying lubricant from the collection reservoir to at least one component contained within the transmission casing. Advantageously, the claimed disclosure provides an improved "splash" lubrication system in which the distribution of lubricant about the transmission casing can be better controlled and fed to specific components within the transmission casing without requiring a dedicated pumping system which would add cost and complexity to the system. Furthermore, since at least part of the collection reservoir is defined by a feature which is already provided in the transmission casing, the system can be implemented using existing transmission casing stock without having to re-design an entirely new casing. In exemplary embodiments, the component positioned at least partially within the sump may comprise part of a vehicle drivetrain. Advantageously, using an existing part of the vehicle drivetrain to distribute lubricant about the transmission casing avoids the need for a dedicated pumping means which helps to reduce the cost and complexity of the system. In exemplary embodiments, the component positioned at least partially within the sump may be a gear. Advantageously, using a gear to distribute lubricant about the transmission casing avoids the need for a dedicated pumping means which helps to reduce the cost and complexity of the system. In exemplary embodiments, the transmission system may comprise an output member, and the component positioned at least partially within the sump may be an output gear connected to said output member. Advantageously, using the output gear to distribute lubricant about the transmission casing avoids the need for a dedicated pumping means which helps to reduce the cost and complexity of the system. In exemplary embodiments, the lubricant gallery may further comprise: a first conduit for conveying lubricant from the collection reservoir to a first component contained within the transmission casing ; and a second conduit for conveying lubricant from the collection reservoir to a second component contained within the transmission casing. Advantageously, the provision of a lubricant gallery having first and second conduits enables the collection reservoir to supply lubricant to multiple components within the transmission casing. In exemplary embodiments, the transmission casing may be provided as a pair of half shells, and at least part of the collection reservoir may be integrally formed as part of the one of the respective half shells. In exemplary embodiments, the lubricant gallery may be configured for conveying lubricant from the collection reservoir to at least one bearing contained within the transmission casing. Advantageously, conveying lubricant from the collection reservoir to one or more of the bearings contained within the transmission casing helps to ensure that such bearings are sufficiently lubricated thereby helping to prevent premature wear and failure during use. In exemplary embodiments, the first conduit may be configured for conveying lubricant from the collection reservoir to a first bearing contained within the first half shell. In exemplary embodiments, the second conduit may be configured for conveying lubricant from the collection reservoir to a second bearing contained within the second half shell. In exemplary embodiments, the transmission system may comprise an input member, and the at least one component may be a bearing configured for supporting said input member. Advantageously, conveying lubricant from the collection reservoir to one or more of the bearings supporting the input member helps to ensure that such bearings are sufficiently lubricated thereby helping to prevent premature wear and failure during use. In exemplary embodiments, the transmission system may comprise a layshaft, and the at least one component may be a bearing configured for supporting said layshaft. Advantageously, conveying lubricant from the collection reservoir to one or more of the bearings supporting the layshaft helps to ensure that such bearings are sufficiently lubricated thereby helping to prevent premature wear and failure during use. In exemplary embodiments, at least part of the collection reservoir may be defined by a redundant feature provided in the transmission casing. Advantageously, using a redundant feature to define at least part of the collection reservoir enables the system to be implemented using existing transmission casing stock without having to re-design an entirely new casing. In exemplary embodiments, the redundant feature may be integrally formed as part of the transmission casing. In exemplary embodiments, the redundant feature may be cast into the transmission casing. In exemplary embodiments, at least part of the collection reservoir may be defined by an unused bearing bore provided in the transmission casing. Advantageously, using an unused bearing bore to define at least part of the collection reservoir enables the system to be implemented using existing transmission casing stock without having to re-design an entirely new casing. In exemplary embodiments, the unused bearing bore may be integrally formed as part of the transmission casing. In exemplary embodiments, the unused bearing bore may be cast into the transmission casing. In exemplary embodiments, at least part of the lubricant gallery may comprise a channel provided in the transmission casing. In exemplary embodiments, the channel may be integrally formed as part of the transmission casing. In exemplary embodiments, at least part of the lubricant gallery may be defined by a redundant feature provided in the transmission casing. Advantageously, using a redundant feature provided in the transmission casing to define at least part of the lubricant gallery enables the system to be implemented using existing transmission casing stock without having to re-design an entirely new casing. In exemplary embodiments, the collection reservoir may comprise a volume having an opening, and a damming plate extending across a portion of said opening. Advantageously, the provision of a damming plate helps the system to collect lubricant more effectively within the collection reservoir. In exemplary embodiments, the collection reservoir may comprise a gutter plate for guiding lubricant distributed about the transmission casing into the collection reservoir. Advantageously, the provision of a gutter plate helps the system to collect lubricant more effectively within the collection reservoir. In exemplary embodiments, the gutter plate may be angled relative to the damming plate. Advantageously, it has been found that angling the gutter plate helps to further aid the transfer of lubricant from the gutter plate into the collection reservoir. In exemplary embodiments, the gutter plate may be inclined at an angle of approximately 45°. Advantageously, it has been found that angling the gutter plate helps to further aid the transfer of lubricant from the gutter plate into the collection reservoir. In exemplary embodiments, the transmission may be a hydrostatic transmission. A second aspect of the disclosure provides a working vehicle comprising the transmission system according to the first aspect of the disclosure. In exemplary embodiments, the working vehicle may be a telescopic wheel loader. A third aspect of the disclosure provides a method of manufacturing a transmission system according to the first aspect of the disclosure, the method comprising the steps of: providing a transmission casing which can be used in a first configuration and a second configuration, wherein, when the transmission casing is used in the second configuration, at least one feature of the transmission casing is unused; and re-purposing said unused feature as a collection reservoir for use in a transmission system according to the first aspect of the disclosure. We consider the term "working vehicle" to be defined as an off-highway vehicle, for example those used in construction industries (e.g., backhoe loaders, excavators, slew excavators, telescopic handlers, forklifts, skid-steer loaders, dump trucks, bulldozers, graders), agricultural industries (e.g., tractors, combine harvesters, self-propelled harvesters, and sprayers), quarrying (e.g., loading shovels, dump trucks), and forestry (e.g., timber harvesters, feller bunchers). As used herein "redundant feature" means a feature whose primary intended function (or the function for which it was originally designed) is not being utilised in a given system. As used herein "splash lubrication" means a method of lubrication wherein lubricant is distributed about a system via the movement of component parts of said system (i.e., without using a dedicated pumping arrangement). As used herein "drivetrain" means to be defined as a group of components which transmit drive from a prime mover to a ground engaging propulsion structure, such as wheels or endless tracks, to cause a working machine to move, such as the transmission, differential, output member(s), and axles. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described by way of example only with reference to the accompanying figures, in which: Figure 1 is a side view of a telescopic wheel loader which is an example of one type of working vehicle to which the claimed disclosure may be applied; Figure 2 is a perspective view of a single speed transmission system; Figure 3 is a front cut-away view of a transmission system according to the claimed disclosure; Figure 4 is a perspective view of a hybrid hydrostatic and powershift transmission system; Figure 5 is a front view of the collection reservoir of the transmission system illustrated in Figure 3; Figure 6 is a side view of the collection reservoir illustrated in Figure 5; Figure 7a is a front view depicting a first part of the lubricant gallery of the transmission system illustrated in Figure 3; and Figure 7b is a front view depicting a second part of the lubricant gallery of the transmission system illustrated in Figure 3. DETAILED DESCRIPTION OF EMBODIMENT(S) In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and the teachings. However, those skilled in the art will understand that: the present teachings may be practiced without these specific details or with known equivalents of these specific details; that the present teachings are not limited to the described embodiments; and, that the present teachings may be practiced in a variety of alternative embodiments. It will also be appreciated that well known methods, procedures, components, and systems may not have been described in detail. References to vertical and horizontal in the present disclosure should be understood to be in relation to the machine when stood on horizontal ground in a non-working condition. The term axial is generally used in relation to the longitudinal axis of the machine. The term width is generally used in relation to the longitudinal length, that is, transverse to the length. Figure 1 shows a working vehicle 10 which is an example of one type of vehicle to which the transmission system of the claimed disclosure may be applied. A working vehicle is an off-highway vehicle, for example those used in construction industries (e.g., backhoe loaders, excavators, slew excavators, telescopic handlers, forklifts, skid-steer loaders, dump trucks, bulldozers, graders), agricultural industries (e.g., tractors, combine harvesters, self-propelled harvesters, and sprayers), quarrying (e.g., loading shovels, dump trucks), and forestry (e.g., timber harvesters, feller bunchers). In the illustrated embodiment, the working vehicle 10 is a telescopic wheel loader. However, it shall be appreciated that in other embodiments, the claimed disclosure may be applied to other forms of working vehicle. The working vehicle 10 depicted in Figure 1 is made up of a front chassis 12 and a rear chassis 22 which are coupled via an articulated connection 32, which allows the front chassis 12 to pivot relative to the rear chassis 22. A first set of wheels 14 are provided on the front chassis 12 for moving the front chassis 12 over the ground. The first set of wheels 14 are connected via a first axle (not shown). A working arm 16 is also attached to the front chassis 12 of the working vehicle 10. The working arm 16 includes a boom 16a which is pivotally attached to the front chassis 12, and an implement 16b which is pivotally attached to a free end of the boom 16a. In some embodiments, the implement may be a bucket, which is used for handling loose materials such as grain or aggregate. However, in alternative embodiments, numerous alternative implements may be used such as a pallet fork, silage or manure forks, a bale grab, or a lifting jib. The working arm 16 is operably connected to a series of hydraulic actuators (not shown) for raising and lowering the boom 16a and for tilting and operating the implement 16b attached to the free end of the boom 16a. The manner in which the working arm 16 is operated is not central to the present disclosure and hence shall not be described in further detail. A second set of wheels 24 are also provided on the rear chassis 22 for moving the rear chassis 22 over the ground. The second set of wheels 24 are connected via a second axle (not shown). The working vehicle 10 also includes a prime mover (not shown) mounted to the rear chassis 22. A cab 26 is further mounted to the rear chassis 22 forward of the prime mover. The cab 26 is provided with a collection of controls (not shown) for moving the working arm 16, manoeuvring the working vehicle 10 and / or controlling other functions of the working vehicle 10. The prime mover (not shown) converts chemical or electrical energy into mechanical energy for driving the wheels 14, 24 of the working vehicle 10. In the illustrated embodiment, the working vehicle 10 is powered by an internal combustion engine which converts chemical energy in the form of hydrocarbon fuel (e.g., diesel or gasoline) into mechanical energy for driving the wheels 14, 24 of the working vehicle 10. However, in other embodiments, the prime mover may be a hydrogen-fuelled internal combustion engine (or HICE), or an electric motor powered by a hydrogen fuel cell, or batteries, or a combination of the above. During operation, mechanical energy is transmitted from the prime mover to a transmission system which subsequently transmits the mechanical energy from the prime mover onto at least one of the first or second axles via a drivetrain (not shown). In some embodiments, the drivetrain may transfer the mechanical energy from the prime mover to both the first and second axles and hence the working vehicle 10 may have an all-wheel drive (or four-wheel drive) functionality. In other embodiments, the drivetrain may only transfer the mechanical energy to one of the first or second axles and hence in other embodiments the working vehicle may have a two-wheel drive functionality. An exemplary working vehicle transmission system 100 is shown in Figure 2. The transmission system 100 depicted in Figure 2 is a single speed transmission system made up of a first (or input) gear 102 which is connected to an input member 104 (e.g., an input shaft) which is drivable by the prime mover and a second (or output) gear 112 which is connected to an output member 114 (e.g., a driveshaft) of the working vehicle 10. In the illustrated embodiment, the transmission system 100 also comprises first 122a and second 122b intermediate gears supported on a lay-shaft 124 which operably couple the input 102 and output gears 112. However, it shall be appreciated that in other embodiments, a different number of gears may be provided. As illustrated in Figure 2, the first intermediate gear 122a is in permanent mesh with the first (or input) gear 102 and the second intermediate gear 122b is in permanent mesh with the second (or output) gear 112. In this way, a gear ratio between the first gear 102 and the second gear 112 can be set by selecting the number of teeth on the first and second intermediate gears 122a, 122b, without having to change the size of the first gear 102 or the second gear 112. In the illustrated embodiment, the first intermediate gear 122a has more teeth than the second intermediate gear 122b. In this way, a gear ratio between the first (or input) gear 102 and the second (or output gear) 112 can be influenced by the different number of teeth of the first and second intermediate gears 122a, 122b. In the illustrated embodiment, the transmission system 100 is a hydrostatic transmission system and hence the prime mover (not shown) is coupled to the input member 104 via a hydrostatic pump (not shown). However, it shall be appreciated that in other embodiments, the claimed disclosure may be applied to other types of transmission. Referring now to Figure 3, the respective gears 102, 112, 122a and 122b of the transmission system 100 are housed within a transmission casing. In the illustrated embodiment, the transmission casing is provided as a pair of half shells which are bolted together to form the transmission casing. In some embodiments, the half shells may be die-cast from a metallic material, such as cast-iron. However, it shall be appreciated that in other embodiments, the transmission casing may be provided via other manufacturing methods and from other types of material. A first half shell 130 which forms one half of the transmission casing of the illustrated embodiment is shown in Figure 3. The first half shell 130 has a body comprising a base 132 and a peripheral sidewall 134 which is arranged perpendicular to the base 132 and extends continuously around its circumference. A sump 136 is defined in the bottom of the first half shell 130 which together with a corresponding sump defined in the bottom of the second half shell (not shown) defines a lubricant sump in the bottom of the transmission casing for containing a lubricant (e.g., oil) to be distributed about the transmission casing during use. A series of bores are also formed in the first half shell 130 for housing various rotatable components of the transmission system 100. In the illustrated embodiment, the series of bores are integrally formed with the first half shell 130 as part of the casting process. However, in other embodiments, the series of bores may be machined into the first half shell 130 after it has been cast. In the illustrated embodiment, a first bore (not shown) is provided towards the bottom of first half shell 130 proximal to the sump 136 and is configured to house a bearing 118 which supports a first end of the output member 114. The first bore (and the bearing 118 housed therein) are positioned such that, upon assembly, at least a part of the output gear 112 (which is supported on the output member 114 and forms part of the vehicle drivetrain) is positioned within the lubricant sump 136 defined in the bottom of the transmission casing. As such, upon rotation of the output member 114, lubricant contained within the lubricant sump is flicked or splashed out of the sump 136 via the output gear 112 thereby distributing the lubricant about the transmission casing without the need for a dedicated pumping system. This method of lubrication is often referred to as "splash lubrication". In other words, the transmission system 100 of the illustrated embodiment is a "splash lubrication" transmission system. It shall also be appreciated that in alterative embodiments, other components of the transmission system 100 such as the input gear 102 and / or one or more of the intermediate gears 122a,122b may be positioned at least partially within the lubricant sump in addition to, or in place of, the output gear 112. A second bore (not shown) is positioned above the first bore at approximately a mid-height of the first half shell 130. The second bore (not shown) is configured to house a bearing 128 which supports a first end of the layshaft 124. A third bore (not shown) is provided towards the top of the first half shell 130, above the second bore. The third bore (not shown) is configured to house a bearing 108 which supports a first end of the input member 104. A corresponding second half shell (not shown), which is a mirror image of the first half shell 130 illustrated in Figure 3, is also provided which forms the other half of the transmission casing. A series of bores are also formed in the second half shell (not shown) for housing various rotatable components of the transmission system 100. A first bore (not shown) is provided towards the bottom of second half shell and is configured to house a bearing which supports a second end of the output member 114 (the first end of the output member 114 being supported by the bearing 118 housed in the first bore of the first half shell 130). A second bore (not shown) is positioned above the first bore at approximately a mid-height of the second half shell. The second bore (not shown) is configured to house a bearing which supports a second end of the layshaft 124 (the first end of the layshaft 124 being supported by the bearing 128 housed in the second bore of the first half shell 130). A third bore (not shown) is also provided towards the top of the second half shell above the second bore. The third bore (not shown) is configured to house a bearing which supports a second end of the input member 104 (the first end of the input member 104 being supported by the bearing 108 housed in the third bore of the first half shell 130). As set out previously within the present application, the exemplary transmission system 100 illustrated in Figure 2 is a single speed transmission system and hence comprises four gears supported on three shafts. However, the transmission casing of the illustrated embodiment is configured to house multiple different types of transmission. For example, the transmission casing may be useable in a first configuration for housing a first type of transmission system and may also be useable in a second configuration for housing a second type of transmission system. This allows the manufacturer to stock and manufacture a single transmission casing design which can be used with multiple different types of transmission, thereby saving time and manufacturing costs. In the illustrated embodiment, the transmission casing is designed to house a hybrid hydrostatic and powershift transmission system when in its first configuration and is designed to house a single speed transmission system when in its second configuration (as shown in Figure 3). An exemplary hybrid hydrostatic and powershift transmission system 300 is illustrated in Figure 4. As with the single speed transmission system 100 depicted in Figure 2, the hybrid hydrostatic and powershift transmission system 300 depicted in Figure 4 includes a first input gear 302a which is connected to a first input member 304a and an output gear 312 which is connected to an output member 314. The hybrid hydrostatic and powershift transmission system 300 illustrated in Figure 4 also includes first 322a and second 322b intermediate gears supported on a first lay-shaft 324 which operably couple the first input gear 302a to the output gear 312. However, unlike the single speed transmission system 100 illustrated in Figure 2, the hybrid hydrostatic and powershift transmission system 300 also features a second input gear 302b which is connected to a second input member 304b and an idler gear 326 supported on a second lay-shaft 328 which operably couples the second input gear 302b to the output gear 312. Consequently, a pair of additional bores are provided in the first 130 and second half shells for housing the respective bearings (not shown) which support the second input member 304b and the second lay-shaft 328 when the transmission casing is used in the first configuration to house a hybrid hydrostatic and powershift transmission system. However, when the transmission casing is used in the second configuration to house a single speed transmission system (as shown in Figure 3) the pair of additional bores become redundant. As shown in Figure 3 and in Figures 5 to 7, the first half shell 130 features a first redundant bore 140 which is provided proximal to the top of the first half shell 130 directly above the sump 136 and a second redundant bore 150 which is provided proximal to the centre of the first half shell 130, between the first redundant bore 140 and the sump 136. Similarly, the second half shell (not shown) also features corresponding first and second redundant bores provided at corresponding positions to those which are provided in the first half shell 130. However, it shall be appreciated that in other embodiments, the first and second redundant bores may be positioned at different locations about the first and second half shells. It shall also be appreciated that in alternative embodiments, the transmission casing may be designed to house transmission systems having a different number of gears and shafts to those of the illustrated embodiment. As such, it shall be appreciated that the first and second half shells according to alternative embodiments may comprise more than five bearing bores or less than five bearing bores, and may comprise a different number of redundant features to those of the illustrated embodiment, such as 0, 1, 3, 4, 5 etc. As set out within the Background section, when relying upon "splash" lubrication, it is often difficult to control the supply of lubricant to specific areas or components within the transmission casing. In the case of the illustrated embodiment, the applicant has found that there is no direct "line of splash" between the output gear 112 and the bearings which support the input member 104. As such, it has been found that the amount of lubricant that tends to reach these components during use is not sufficient, particularly when the transmission system is operating at low speeds. As such, in order to address this problem, in the illustrated embodiment the transmissions system is provided with a collection reservoir which has a direct "line of splash" to the output gear 112. In the illustrated embodiment, the collection reservoir is provided in the first half shell 130 (which forms the rear portion of the transmission casing) and is configured to collect at least some of the lubricant distributed about the transmission casing by the output gear 112. However, it shall be appreciated that in other embodiments, the collection reservoir may instead be provided in the second half shell (which forms the front portion of the transmission casing), or, in further alternatives, separate collection reservoirs may be provided in both the first and second half shells. A lubricant gallery 160 is also provided for conveying the collected lubricant, under the influence of gravity, from the collection reservoir to one or more components located within the transmission casing. The provision of a collection reservoir helps to ensure that components provided within the transmission casing which do not have a direct "line of splash" to the output gear 112 (or other rotatable component located at least partially within the lubricant sump) remain adequately lubricated during use. In the illustrated embodiment, the lubricant gallery 160 is a "cross-casing" gallery configured to convey lubricant from the collection reservoir to the bearings which support the respective ends of the input member 104. However, it shall be appreciated that in other embodiments, the lubricant gallery may be configured to convey fluid to other components within the transmission casing (such as the bearings which support the layshaft 124). It shall also be appreciated that in other embodiments, a different number of collection reservoirs and associated galleries may be provided such as 1, 3, 4, 5 etc. The collection reservoir and lubricant gallery of the illustrated embodiment shall now be described in greater detail with reference to Figures 5 to 7b. As shown in Figures 5 and 6, the collection reservoir has a volume for collecting and containing a supply of lubricant and an opening 146 for allowing lubricant distributed about the transmission casing to flow into said volume. In the illustrated embodiment, the volume of the collection reservoir is defined by the first redundant (or unused) bearing bore 140 which allows the system of the claimed disclosure to be applied to existing transmission casing stock without requiring significant levels of modification or redesign. However, it shall be appreciated that in other embodiments, the volume of the collection reservoir may be defined by another feature provided in the transmission casing (such as the second redundant bearing bore 150 or a volume defined between a pair of strengthening ribs). In the illustrated embodiment, in order to convert the first redundant bore 140 into the collection reservoir, a damming plate 142 is secured about its opening 146 which seals a portion of the volume of the reservoir to prevent the lubricant collected therein from flowing out of the reservoir via the opening 146 during use. However, it shall be appreciated that in other embodiments, the first half shell may be manufactured with a region of thinned or frangible material which covers and seals a portion of the opening 146 of the bore 140. The thinned orfrangible material may be removed when the transmission casing is used in the first configuration and may be left intact when the transmission casing is used in the second configuration, thereby sealing a portion of the volume of the reservoir. As illustrated in Figure 5, the damming plate 142 has a substantially semi-circular shape and is secured about the opening 146 via a set of three respective fasteners 142a-c. However, it shall be appreciated that in other embodiments, the damming plate may have any other suitable shape or configuration and may be secured about the opening via another suitable fastening means (e.g., welding). In the illustrated embodiment, the damming plate 142 covers approximately the bottom two-thirds of the opening 146. As such, the volume of the collection reservoir can be split into two parts, a first "dammed portion" of the volume 140a in which lubricant contained within the reservoir is unable to flow out into or out of the opening 146, and a second "undammed portion" of the volume 140b in which lubricant is able to flow into and out of the collection reservoir via the opening 146. In the illustrated embodiment, since the damming plate 142 covers approximately the bottom two-thirds of the opening 146, the first "dammed" portion 140a of the volume extends to a height of Hi which is approximately two-thirds of the total height of the reservoir volume. Meanwhile, the "undammed" portion 140b of the volume constitutes approximately the upper-most third of the reservoir volume. However, it shall be appreciated that in other embodiments, the damming plate 142 may be positioned at different heights about the opening 146 and hence the "dammed" and "undammed" portions may constitute different amounts of the total reservoir volume. For example, in embodiments wherein the damming plate 142 covers the lower half of the opening, the "dammed" portion and "undammed" portion may each constitute approximately 50% of the total reservoir volume. A gutter plate 144 is also provided for guiding lubricant splashed about the transmission casing into the collection reservoir via the opening 146. As shown in Figure 6, the gutter plate 144 is secured about the opening 146 and protrudes outwardly away from the opening 146 of the collection reservoir. In the illustrated embodiment, the gutter plate 144 is inclined at an angle a relative to the horizontal. In the illustrated embodiment, the angle a is approximately 45°. Advantageously, it has been found that inclining the gutter plate 144 at an angle of approximately 45° helps to better aid the transfer of lubricant from the gutter plate 144 into the collection reservoir. However, it shall be appreciated that in alternative embodiments, the gutter plate 144 may be inclined at a different angle relative to the horizontal, such between 1° and 10°, between 10° and 20°, between 20° and 30°, between 30° and 40°, between 40° and 50°, between 50° and 60°, between 60° and 70°, between 70° and 80°, or between 80° and 90°. It shall also be appreciated that in some embodiments, the gutter plate 144 may be omitted. The lubricant gallery 160 associated with the first half shell 130 is illustrated in Figures 7a and 7b and is configured to convey fluid, under the influence of gravity, from the collection reservoir to the third bore 108c which houses the bearing 108. In the illustrated embodiment, the lubricant gallery 160 is made up of two channels 162, 164 which are formed in the body of the first half shell 130. The first channel 162 is substantially horizontally orientated and extends from a first opening 162a, which is in fluid communication with the collection reservoir 140, to a second opening 162b, provided at the opposite end of the first channel 162. As can be seen in Figure 6, the first opening 162a is located proximal to the "dammed" portion 140a of the collection reservoir 140. The second channel 164 is substantially vertically orientated and extends from a first opening 164a, which is in fluid communication with the second opening 162b of the first channel 162, to a second opening 164b, which is in fluid communication with the bore 108c (i.e., the third bore) formed within the first half shell 130 which houses the bearing 108. As such, the first 162 and second channels 164 together form a first conduit for conveying lubricant from the collection reservoir to the bearing 108 housed within the third bore 108c of the first half shell. Corresponding channels (not shown) are also provided in the second half shell which together form a second conduit for conveying lubricant from the collection reservoir to the bearing (not shown) housed within the corresponding third bore of the second half shell. In the illustrated embodiment, the first and second channels are formed from redundant lubricant channels which are integrally formed into the body of the first half shell 130 during manufacture for use when the transmission casing is used in the first configuration to house hybrid hydrostatic and powershift transmission system (such as the one which is shown in Figure 4). This allows the system of the claimed disclosure to be applied to existing transmission casing stock without requiring significant levels of modification or redesign. 5 However, it shall be appreciated that in other embodiments, the lubricant gallery may have any other shape or configuration. For example, in some embodiments the gallery may be provided as a piping arrangement rather than being formed into the body of the transmission casing or may be drilled into the body of transmission 10 casing after it has been cast or otherwise manufactured. The one or more embodiments are described above by way of example only and it will be appreciated that the variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

1. A transmission system for a working vehicle comprising:a transmission casing having a sump for containing a lubricant;a component positioned at least partially within the sump for distributing said lubricant about the transmission casing;a collection reservoir, located above the sump, for collecting at least some of the lubricant distributed about the transmission casing by the component positioned at least partially within the sump, wherein at least part of the collection reservoir is defined by a feature provided in the transmission casing; anda lubricant gallery for conveying lubricant from the collection reservoir to at least one component contained within the transmission casing.

2. The transmission system according to claim 1, wherein the component positioned at least partially within the sump comprises part of a vehicle drivetrain.

3. The transmission system according to claim 1 or 2, wherein the component positioned at least partially within the sump is a gear.

4. The transmission system according to claim 3, wherein the transmission system comprises an output member, and wherein the component positioned at least partially within the sump is an output gear connected to said output member.

5. The transmission system according to any preceding claim, wherein the lubricant gallery comprises:a first conduit for conveying lubricant from the collection reservoir to a first component contained within the transmission casing; anda second conduit for conveying lubricant from the collection reservoir to a second component contained within the transmission casing.

6. The transmission system according to claim 5, wherein the transmission casing is provided as a pair of half shells, wherein at least part of the collection reservoir is integrally formed as part of one of the respective half shells.

7. The transmission system according to any preceding claim, wherein the lubricant gallery is configured for conveying lubricant from the collection reservoir to at least one bearing contained within the transmission casing.

8. The transmission system according to claim 7, wherein the transmission system comprises an input member, and wherein the at least one bearing is a bearing configured for supporting said input member.

9. The transmission system according to any preceding claim, wherein at least part of the collection reservoir is defined by a redundant feature provided in the transmission casing, and optionally wherein at least part of the collection reservoir is defined by an unused bearing bore provided in the transmission casing.

10. The transmission system according to any preceding claim, wherein at least part of the lubricant gallery is integrally formed as part of the transmission casing.

11. The transmission system according to any preceding claim, wherein the collection reservoir comprises a volume having an opening, and a damming plate extending across a portion of said opening.

12. The transmission system according to any preceding claim, wherein the collection reservoir comprises a gutter plate for guiding lubricant distributed about the transmission casing into the collection reservoir.

13. The transmission system according to any preceding claim, wherein the transmission system is a hydrostatic transmission system.

14. A working vehicle comprising the transmission system according to any preceding claim, and optionally wherein the working vehicle is a telescopic wheel loader.

15. A method of manufacturing a transmission system according to any one of claims 1 to 13, the method comprising the steps of:providing a transmission casing which can be used in a first configuration and a second configuration, wherein, when the transmission casing is used in the second configuration, at least one feature of the transmission casing is unused, and re-purposing said unused feature as a collection reservoir for use in a transmission system according to any one of claims 1 to 13.

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