Work machne with universal joint transmission

Abstract

The invention relates to a work machine (1) having a first axle (3), a transfer gearbox (6; 406) that is rigidly attached to the first axle (3) and configured to drive the first axle (3) and at least one electric motor (10; 101, 102; 401, 402) for driving the transfer gearbox (6; 406), wherein the electric motor (10; 101, 102; 401, 402) drives the transfer gearbox (6) via a reduction gear (9), the reduction gear (9) having an output shaft and the transfer gearbox (6; 406) having an input shaft, the output shaft being coupled to the input shaft via a transmission shaft (8), an axis of rotation of the transmission shaft (8) and an axis of rotation of the input shaft being non-parallel and intersecting, and the transmission shaft (8) and the input shaft being coupled by means of a first universal joint (7; 71; 717; 747).

Description

Work machine with universal joint transmission

[0001] The invention relates to the field of work machines. More particularly, the invention relates to the transmission of mechanical power to the wheels of the work machine. Technological background

[0002] Work machines, particularly load handling machines, are generally equipped with a transmission system including at least one engine, the transmission system rotating drive wheels connected by an axle.

[0003] The integration of environmental considerations (reduction of greenhouse gas emissions) and regulatory constraints (for warehouse handling, for example) has led to the electrification of work vehicles.

[0004] US 2020 / 0406681 A1 describes an electric work machine with an electric transmission, in which an axle is provided with an electric motor secured to an axle housing. A reduction gear and a transfer case are connected in series with the electric motor. The electric motor thus drives the axle via the reduction gear and the transfer case. Furthermore, the transfer case has an output shaft and the output shaft of the transfer case is connected, via a cardan joint, to a drive shaft connecting the axle to a second axle of the work machine.

[0005] However, to power the electric motor, it is also necessary to position on-board batteries on board the work machine. An arrangement where the electric motor is integral with the axle is not always compatible with the desired positioning of the batteries, particularly with a configuration where batteries must be positioned in the middle of the chassis. Summary

[0006] One idea behind the invention is to allow freer positioning of an electric motor within the chassis of a work machine.

[0007] According to one embodiment, the invention provides a work machine comprising a first axle and a second axle, a transfer case secured to one of the first axle and the second axle and configured to drive the first axle and the second axle, and at least one electric motor for driving the transfer case, wherein said electric motor drives the transfer case via a reduction gear, the reduction gear having an output shaft and the transfer case having an input shaft, the output shaft being coupled to the input shaft via a transmission shaft, an axis of rotation of the transmission shaft and an axis of rotation of the input shaft being non-parallel and intersecting, and the transmission shaft and the input shaft being coupled by means of a first universal joint.

[0008] The coupling described by means of a universal joint allows the reduction gear and the electric motor to be placed more freely within the chassis, in particular because the output shaft of the electric motor and the output shaft of the reduction gear do not need to be aligned with, or even close to, the input shaft of the transfer case. In other words, the electric motor and the reduction gear can be placed more freely, not being integral with the transfer case or the first axle or the second axle.

[0009] According to embodiments, such a work machine may comprise one or more of the following characteristics.

[0010] According to one embodiment, the work machine further comprises two side members parallel to each other and parallel to a central longitudinal axis of the work machine.

[0011] According to one embodiment, batteries used to power the electric motor are arranged between the side members.

[0012] Such a central position of the batteries ensures better mass distribution within the machine and also protects the batteries against damage caused by impacts.

[0013] According to one embodiment, the reducer and the transmission shaft are connected by a second universal joint.

[0014] According to one embodiment, the first universal joint and / or the second universal joint is a Cardan joint.

[0015] According to one embodiment, said electric motor is mounted on the reducer. According to one embodiment, the work machine further comprises a second electric motor also mounted on the reducer.

[0016] According to one embodiment, the first axle is a front axle, and the second axle is a rear axle.

[0017] According to one embodiment, a rear end of the transmission shaft is further from the central longitudinal axis than a front end of the transmission shaft, in particular when the transfer case is integral with the front axle.

[0018] This allows the reducer and electric motor to be placed off-center within the chassis, while not requiring the first universal joint to withstand too great an angle which would be detrimental to its lifespan.

[0019] According to one embodiment, the rear end of the transmission shaft is placed high up, in a vertical direction of the work machine, relative to the first axle.

[0020] This ensures that the drive shaft does not affect the ground clearance of the machine.

[0021] According to one embodiment, the transfer case is integral with the rear axle. In this case, a rear end of the transmission shaft may be further from the central longitudinal axis than a front end of the transmission shaft, and / or the front end of the transmission shaft may be placed high, in a vertical direction of the work machine, relative to the front axle.

[0022] According to one embodiment, a first angle between the input shaft of the transfer case and the transmission shaft is equal to a second angle between the transmission shaft and the output shaft of the reducer.

[0023] Thus, the first universal joint and the second universal joint are homokinetic. The first angle and the second angle have a value preferably between 0° and 15°. More preferably, the first angle and the second angle have a value between 11° and 15°. Even more preferably, the first angle and the second angle have a value of 14° each.

[0024] According to one embodiment, the first angle and the second angle are added together to ensure maximum distance of the reducer from the central longitudinal axis.

[0025] According to one embodiment, the transmission shaft is coaxial with the output shaft of the reducer. In other words, the axes of rotation of the transmission shaft and the output shaft of the reducer are coincident, or the second angle is zero.

[0026] Thus, assembly is easier since only the first angle needs to be adjusted. The first universal joint is preferably a constant velocity joint, allowing the first angle to be adjusted. The first angle is preferably between 12° and 20°. More preferably, the first angle is equal to 15°. The output shaft of the reducer and the transmission shaft may be connected by the aforementioned second universal joint or by other types of joints.

[0027] According to one embodiment, a rotational speed of the input shaft of the transfer case and a rotational speed of the output shaft of the reducer are identical.

[0028] According to one embodiment, the reducer is further away, in the longitudinal direction of the machine, from that of the first axle and the second axle to which the transfer box is secured than from the other of the first axle and the second axle.

[0029] According to one embodiment, the reducer and the electric motor are placed in a box, the box being fixed on a side face of the work machine, between the first axle and the second axle.

[0030] Thus, the reducer and the electric motor can be protected against external impacts by the box, while remaining easily accessible due to the positioning of the box.

[0031] According to one embodiment, the box comprises closable flaps.

[0032] This makes it easier to access the gearbox and electric motor for maintenance operations and protects the gearbox and electric motor against unauthorized intervention.

[0033] According to one embodiment, the box is raised, in the vertical direction of the work machine, relative to the first axle.

[0034] According to one embodiment, the reducer is placed in a rear half of the box along the longitudinal direction of the work machine, in particular when the transfer case is secured to the front axle. According to an embodiment where the transfer case is secured to the rear axle, the reducer is placed in a front half of the box along the longitudinal direction of the work machine.

[0035] According to one embodiment, the work machine further comprises a hydraulic motor and a hydraulic pump used to operate a lifting arm.

[0036] According to one embodiment, the hydraulic motor and the hydraulic pump are placed in the box.

[0037] According to one embodiment, the box is fixed to one of the two side members.

[0038] According to one embodiment, the reducer is fixed to said spar by means of a fixing element.

[0039] According to one embodiment, a passage space between an interior face of the box and said side member connects an interior of the box and a bottom of the chassis.

[0040] According to one embodiment, the transmission shaft connects the reducer and the first axle through the passage space in the box.

[0041] According to one embodiment, the transmission shaft is positioned at least partially under the side members. Brief description of the figures

[0042] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the accompanying drawings.

[0043] This is a perspective overview of a lifting machine.

[0044] This is a top view of the transmission of the lifting machine.

[0045] This is a side view of the transmission shown in the.

[0046] This is a schematic representation of the transmission shown in Figures 2 and 3, according to a variant.

[0047] This is a perspective view in projection in plane D of the transmission shown in la and la.

[0048] This is a rear view of the transmission shown in the, the and the, together with the frame of the lifting machine.

[0049] This is a perspective view of the chassis of the lifting machine according to one embodiment.

[0050] This is a view from below of the chassis of the lifting machine.

[0051] This is a view similar to the, showing another variant of the transmission shown in Figures 2 and 3.

[0052] This is a view similar to the, showing yet another variant of the transmission shown in Figures 2 and 3.

[0053] This is a perspective overview of a work machine, here implemented in the form of a lifting machine 1. The lifting machine 1 comprises a chassis 2 and a lifting arm 20. The arrow AA represents a front-rear median axis of the lifting machine 1, aligned with the middle of a front axle 3 and a rear axle 4. The front-rear median axis corresponds to a longitudinal direction of the lifting machine 1. An arrow A corresponds to this longitudinal direction.

[0054] An arrow B corresponds to a transverse direction of the lifting machine 1, defined as perpendicular to the longitudinal direction and belonging to a plane of the chassis 2.

[0055] An arrow C corresponds to a vertical direction of the lifting machine 1, defined as perpendicular to the longitudinal direction and the transverse direction.

[0056] The chassis 2 is movable and displaceable on the ground surface (not shown), here by means of the front axle 3 carrying two front wheels 3A, one on the left and the other on the right, and the rear axle 4 carrying two rear wheels 4A, one on the left and the other right.

[0057] With reference to figures 1 and 6 to 8, the chassis 2 comprises two side members 30. The side members 30 are metal parts parallel to each other and perpendicular to a transverse direction of the lifting machine.

[0058] The side members 30 extend between a front face and a rear face of the lifting machine 1 and are flat pieces of low thickness, placed perpendicular to a plane of the chassis 2.

[0059] With reference to the, the lifting arm 20 is articulated to the two side members 30, between the two side members 30, so as to be pivotally movable relative to the two side members 30 around a pivot axis P. The pivot axis P is notably marked on the. The pivot axis P is parallel to the transverse direction of the lifting machine 1. Suitable means for making the lifting arm 20 pivotally movable are well known as such and are not described in detail here.

[0060] The lifting arm 20 can be made in various ways, in particular in the form of several telescopic sections, or alternatively in the form of an arm of fixed length. One end of the lifting arm 20 opposite the pivot axis P can carry a working tool or, as shown in the, a modular tool holder capable of receiving two working tools of several types, according to known technology. By working tool, for example, is meant a pair of forks, a bucket, a winch, a clamp, etc.

[0061] The lifting machine 1 further comprises a cabin 75 in which an operator of the lifting machine 1 can take place and a box 28 which can accommodate various equipment used for the operation of the lifting machine 1.

[0062] The cabin 75 is located on a first lateral side of the lifting machine 1 and the box 28 is located on a second lateral side of the lifting machine 1, the first lateral side and the second lateral side being on either side of the two side members 30 in the transverse direction of the lifting machine 1.

[0063] Referring to Figures 2 and 3, the front axle 3 and the rear axle 4 are connected by a connecting shaft 5 which is perpendicular to the front axle 3 and the rear axle 4.

[0064] A transfer case 6 is secured to the front axle 3. The transfer case 6 is connected to a transmission shaft 8 via a first cardan joint 7. The transmission shaft 8 is further connected to a reduction gear 9 via a second cardan joint 17 (not visible in figures 2 and 3 but visible in the).

[0065] The first cardan joint 7 and / or the second cardan joint 17 can be replaced by other types of universal joints, for example double cardan joints or tripod joints.

[0066] The reducer 9 is integral with an electric motor 10 and a fixing element 11 is attached to the reducer 9, for example by means of bolts (not shown). The fixing element 11 may further be attached to a fixed part of the machine, such as for example a side member 30, in order to stabilize a position of the reducer 9 and the electric motor 10.

[0067] The drive shaft 8 extends diagonally across one half of the chassis 2 delimited by the perpendicular connecting shaft 5. The drive shaft 8 forms an acute angle with the input shaft of the transfer case 6, thanks to the mechanical connection made by the first cardan joint 7.

[0068] The reducer 9 and the electric motor 10 are positioned eccentrically, on the same side of the shaft 5 in the transverse direction. According to a preferred embodiment, the reducer 9 is closer to the rear axle 4 than to the front axle 3.

[0069] With reference to the, the transmission shaft 8 is not placed in the plane of the front axle 3 and the rear axle 4. An elevation angle β between the transmission shaft 8 and the connecting shaft 5 is an acute angle allowing the reduction gear 9 and the electric motor 10 to be raised relative to the front axle 3 and the rear axle 4.

[0070] A variant of the transmission shown in Figures 2 and 3 is shown. The transmission shaft 8 is connected to the transfer case 6 by a double cardan joint 71. In addition, a first electric motor 101 and a second electric motor 102 are connected to the reduction gear 9. According to a preferred embodiment, the first electric motor 101 and the second electric motor 102 are arranged on either side of the reduction gear 9.

[0071] With reference to the, a first angle γ is defined and measured in the plane comprising the connecting shaft 5 and the transmission shaft 8. The first angle γ is defined as an angle between the input shaft of the transfer case 6 and the transmission shaft 8. The first angle γ corresponds to an angle of the first cardan joint 7.

[0072] A second angle δ is defined and measured in the plane comprising the connecting shaft 5 and the transmission shaft 8. The second angle δ is defined as an angle between the transmission shaft 8 and the output shaft of the reducer 9. The second angle δ corresponds to an angle of the second cardan joint 17.

[0073] The second angle δ is oriented so as to increase a distance of the reducer from the connecting shaft 5. Thus, a total angle ε between the reducer 9 and the connecting shaft 5 is equal to a sum of the first angle γ and the second angle δ.

[0074] According to a preferred embodiment, the first angle γ and the second angle δ are equal, which makes it possible to guarantee a homokinetic speed between an output shaft of the reducer 9 and an input shaft of the transfer box 6.

[0075] The first angle γ and the second angle δ have a value preferably between 0° and 15°.

[0076] More preferably, the first angle γ and the second angle δ have a value between 11° and 15°.

[0077] According to a preferred embodiment, the first angle γ and the second angle δ each have a value of 14°.

[0078] Thus, according to a preferred embodiment, the total angle ε has a value of 28°.

[0079] The first angle γ, the second angle δ and the total angle ε being measured in an oblique plane, they each have a horizontal component and a vertical component. Thus, the first angle γ, the second angle δ and the total angle ε contribute both to eccentric the reducer 9 by moving it away from the connecting shaft 5, and to lifting the reducer 9 relative to the ground.

[0080] In particular, with reference to the, an angle θ is defined as an angle between the horizontal axis and an axis passing through a projection of the input shaft of the transfer case 6 and the output shaft of the reducer 9 in a plane comprising the horizontal axis and the vertical axis.

[0081] The angle θ belongs to a range preferably between 15° and 40°. More preferably, the angle θ has a value between 25° and 35°. According to a preferred embodiment, the angle θ has a value of 30°. Such a value of θ makes it possible to improve the ground clearance of the lifting machine 1.

[0082] With reference to Figures 7 and 8, the lifting machine 1 comprises a side box 28. The side box 28 is attached to a side wall of one of the side members 30, more precisely the one on the side opposite the cabin 75. The side box 28 is placed between the front axle 3 and the rear axle 4.

[0083] The side box 28 receives the electric motor 10 and the reducer 9. In addition, the side box 28 can also accommodate other elements, such as for example a hydraulic pump (not shown) making it possible to activate a movement of the lifting arm 20.

[0084] The side box 28 comprises several exterior faces, and a support surface 37 on which interior elements of the side box 28 are placed. The support surface 37 is surrounded by the spar 30 and by one or more exterior faces.

[0085] The side box 28 comprises at least one closable flap 21. In a closed position, the closable flap 21 can be locked, thus preventing any unauthorized access to the interior of the side box 28. In a closed position of the closable flap 21, the electric motor 10 and the reducer 9 are further protected against external impacts.

[0086] In an open position of the closable flap 21, access to the electric motor 10 and to the reducer 9 is facilitated, thus making maintenance operations easier.

[0087] The reducer 9 is preferably placed near a rear face of the side box 28. The fixing element 11, bolted to the reducer 9, is fixed to the side member 30 by any suitable means.

[0088] With reference to figures 7 and 8, a passage space 29 is provided between the side box 28 and the side member 30. The transmission shaft 8 connects the reducer 9 located inside the side box 28 with the front axle 3, through the passage space 29.

[0089] The passage space 29 consists of a raising of a lower limit of the spar 30 so that the lower limit of the spar 30 is higher than an upper limit of an inner face 38 of the side box 29.

[0090] The passage space 29 is of a height at least equal to a diameter of the transmission shaft 8 and of a length such that the transmission shaft 8 passes diagonally through the passage space 29.

[0091] With reference to the drawings and in particular to the, it is understood that thanks to the positioning of the reducer 9 near a rear face of the side box 28 (or, more generally, in a rear half of the side box 28 in the longitudinal direction) combined with the presence of the passage space 29, it is easy to place the reducer 9 and the electric motor 10 at a desired location in the lifting machine 1, while not requiring the Cardan joints 7, 17 to withstand excessively large angles γ, δ which would be detrimental to their service life.

[0092] The side box 28 is raised relative to the front axle 3 and the rear axle 4, in accordance with the ground clearance provided by the first cardan joint 7 and the second cardan joint 17.

[0093] Other elements may be included within the side box 28. For example, the side box 28 may contain an air cooling unit and electric drives. Liquid cooling circuits may be connected to the electric motor 10 to prevent it from overheating. Power cables output from the electric drives may power the electric motor 10.

[0094] With reference to Figures 5 to 8, the operation of the lifting machine 1 will be described.

[0095] A battery pack (not shown) may be placed between the side members 30. The battery pack is made by combining several battery cells together, so as to achieve a terminal voltage sufficient to enable the lifting machine 1 to operate, without the lifting machine 1 having to carry another powertrain such as an internal combustion engine. The battery cells may in principle be of any known type, for example of the lead-acid or lithium-ion type, and may be combined together and installed between the side members 30 in various ways.

[0096] The battery pack supplies direct current to the electric drive unit (not shown). The power cables (not shown) output from the electric drive unit supply the electric motor 10 with three-phase current.

[0097] The electric motor 10 is connected to the reduction gear 9, and the reduction gear 9 rotates the transmission shaft 8. The transmission shaft 8 rotates the transfer case 6, which directly drives the front axle 3, and which drives the rear axle 4 via the connecting shaft 5.

[0098] In particular, the first Cardan joint 7, arranged between the transmission shaft 8 and the transfer case 6, and the second Cardan joint 17, arranged between the transmission shaft 8 and the reducer 9, ensure a homokinetic rotation speed of the output shaft of the reducer 9 and the input shaft of the transfer case 6, the first angle γ and the second angle δ being equal.

[0099] This is a view similar to the, in which another variant of the transmission shown in Figures 2 and 3 is shown. In this figure, elements similar or identical to those described above bear the same reference signs and are not described again.

[0100] In this variant, the transmission shaft 8 is coaxial with the output shaft of the reducer 9, in other words the axes of rotation of the transmission shaft 8 and the output shaft of the reducer 9 are the same. In the example shown, the transmission shaft 8 is connected to the output shaft of the reducer 9 via a cardan joint 171; alternatively, the transmission shaft 8 may be connected to the output shaft of the reducer 9 by other types of universal joints, or more generally by other types of joints, as long as the transmission shaft 8 is coaxial with the output shaft of the reducer 9. The transmission shaft 8 is connected to the transfer case 6 via a universal joint 717.

[0101] It is understood that in this way, we have δ = 0° and ε = γ, and that the adjustment of ε = γ is determined by the adjustment of the universal joint 717, rather than by the combined adjustment of the cardan joints 7 and 17. Thus, the assembly of the transmission is easier. In particular, it is easier to ensure a homokinetic rotation speed of the output shaft of the reducer 9 and the input shaft of the transfer case 6. Preferably, the universal joint 717 is a homokinetic type joint, allowing the adjustment of ε = γ.

[0102] Preferably, ε is between 12° and 20°. More preferably, ε = 15°.

[0103] In this variant, the positioning of the transmission shaft 8, the reducer 9 and the electric motor 10, as well as the fixing of the reducer 9 and the passage of the transmission shaft 8 through the passage space 29, are identical to what has been described previously with reference to figures 2, 3, and 5 to 8.

[0104] This is a view similar to the, in which yet another variant of the transmission shown in Figures 2 and 3 is shown. In this figure, elements similar or identical to those described above bear the same reference signs and are not described again.

[0105] In this variant, a transfer case 406 is secured to the rear axle 4. The transfer case 406 is connected to the transmission shaft 8 via a universal joint 747, here a double cardan joint. A first electric motor 401 and a second electric motor 402 are connected to the reduction gear 9. According to a preferred embodiment, the first electric motor 401 and the second electric motor 402 are arranged on either side of the reduction gear 9.

[0106] In operation, the first electric motor 401 and the second electric motor 402 rotate the transmission shaft 8 via the reduction gear 9. The transmission shaft drives the transfer case 406, which directly drives the rear axle 4 and drives the front axle 3 via a connecting shaft 405.

[0107] The reducer 9 is received in the side box 28 described previously, here shown in dotted lines on the. In addition, the side box 28 receives the electric motors 401 and 402. In addition, the side box 28 can also accommodate other elements, such as for example a hydraulic pump (not shown) making it possible to actuate a movement of the lifting arm 20.

[0108] Alternatively, a single electric motor 401, 402 can be connected to the reducer 9.

[0109] In the example shown in 1a, the reducer 9 is placed near a rear face of the side box 28. However, it is preferable for the reducer 9 to be placed near a front face of the side box 28, for example by being placed in a front half of the side box 28 in the longitudinal direction. By analogy with 1a and 1a, it is understood that in this way, the reducer 9 can be arranged in the side box 28 while still making it possible to obtain a desired angle between the transmission shaft 8 and an input shaft of the transfer case 406.

[0110] In this variant also, a fixing element 11 bolted to the reducer 9 can be fixed to the side member 30 (partially shown in the) by any suitable means.

[0111] Although the invention has been described in connection with several particular embodiments, it is obvious that it is in no way limited thereto and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0112] The use of the verb "comprise", "comprise" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

[0113] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Work machine (1) comprising a first axle (3) and a second axle (4), a transfer case (6; 406) integral with one of the first axles (3) and the second axle (4) and configured to drive the first axle (3) and the second axle (4), and at least one electric motor (10; 101, 102; 401, 402) for driving the transfer case (6; 406), wherein said electric motor (10; 101, 102; 401, 402) drives the transfer case (6; 406) via a reduction gear (9), the reduction gear (9) having an output shaft and the transfer case (6; 406) having an input shaft, the output shaft being coupled to the input shaft via a drive shaft (8), a rotation axis of the drive shaft (8) and an axis of rotation of the input shaft being non-parallel and intersecting, and the transmission shaft (8) and the input shaft being coupled by means of a first universal joint (7; 71; 717; 747). Work machine (1) according to claim 1, comprising two parallel longitudinal members (30) parallel to each other and parallel to a central longitudinal axis of the work machine (1). Work machine (1) according to the preceding claim, in which batteries (40, 140) for powering the electric motor (10) are arranged between the longitudinal members (30). Work machine according to any one of the preceding claims, in which the reducer (9) and the transmission shaft (8) are connected by a second universal joint (17, 171). Work machine according to any one of the preceding claims, wherein the first universal joint (7) and / or the second universal joint (17, 171) is a Cardan joint. Work machine according to any one of the preceding claims, in which the electric motor (10; 101, 102; 401) is mounted on the reducer (9). Work machine according to any one of the preceding claims, wherein a rear end of the drive shaft (8) is further from the central longitudinal axis than a front end of the drive shaft. Work machine according to any one of the preceding claims, wherein the rear end of the transmission shaft (8) is placed high, in a vertical direction of the work machine, relative to the first axle (3). Work machine according to any one of the preceding claims, wherein a first angle between the input shaft of the transfer case (6) and the transmission shaft (8) is identical to a second angle between the transmission shaft (8) and the output shaft of the reducer (9). Work machine according to the preceding claim, wherein an inclination of the output shaft of the reducer (9) with respect to the central longitudinal axis is greater than an inclination of the transmission shaft (8) with respect to the central longitudinal axis. Work machine according to any one of the preceding claims, in which the reducer (9) and the electric motor (10) are placed in a box (28), between the first axle (3) and the second axle (4) along a longitudinal direction of the work machine. Work machine according to claim 11, in which the box (28) has closable flaps (21). Work machine according to claim 11 or 12, in which the box (28) is raised, along the vertical direction of the work machine, relative to the first axle (3). Work machine according to any one of claims 11 to 13, wherein the reducer (9) is placed in a rear half of the box (28) along the longitudinal direction of the work machine. Work machine according to any one of claims 11 to 14, further comprising a hydraulic motor and a hydraulic pump for operating a lifting arm (20), the hydraulic motor and the hydraulic pump preferably being located in the box (28). Work machine according to any one of claims 11 to 15 in combination with claim 2, wherein the box (28) is fixed to one of the two longitudinal members (30). Work machine according to the preceding claim, in which the reducer (9) is fixed to said longitudinal member (30) by means of a fixing element (11). Work machine according to claim 16 or 17, wherein a passage space between an inner face of the box and said longitudinal member (30) connects an interior of the box (28) and an underside of the chassis (2). Work machine according to claim 18, in which the transmission shaft (8) connects the reducer (9) and the first axle (3) through the passage space (29). Work machine according to the preceding claim, in which the transmission shaft (8) is positioned at least partially under the longitudinal members (30).

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