WO2005118379A1

WO2005118379A1 - Axle for agricultural machines

Info

Publication number: WO2005118379A1
Application number: PCT/EP2005/052122
Authority: WO
Inventors: Guido Ciccarelli
Original assignee: Bargam S.P.A.
Priority date: 2004-05-26
Filing date: 2005-05-10
Publication date: 2005-12-15
Also published as: ITGE20040047A1

Abstract

An axle for agricultural machines, comprising a main frame (1) formed by a central body (101) and fixed tubular elements (201) provided at the sides of this central body (101), each containing a slide-out tubular element (2) for adjusting the track width (C) of the axle; the central body (101) houses a differential (26) contained in a corresponding casing (27) and interacting with halfshafts (21) positioned inside the slide-out tubular elements (2), and at the outer end of each of the slide-out tubular elements (2) there is provided a steering joint (5) connected to a support (8) of a hub (9) provided with a wheel flange (12); the casing (27) of the differential (26) is provided with an outer ring gear (29) interacting with a pinion (30) fixed to a shaft (32) connected to a power connector (31) of the axle and the outer end of each halfshaft (21) is connected, by means (6) for adjusting and varying the ground clearance (L) of the axle, to the hub (9) provided with the wheel flange (12); a sector (301) of the main frame (1) positioned close to the central body (101) houses a mechanical device (37, 39, 40) for locking the differential (26).

Description

TITLE: "Axle for agricultural machines"

DESCRIPTION

The present invention relates to an axle for agricultural machines, such as self- propelled spraying machines.

Two basic types of agricultural axles are currently available on the market: a first type comprises conventional straight or bridge-type mechanical axles. These types of axle have the characteristic of four-wheel steering, since good manoeuvrability is essential for increasing the efficiency of the machines, and good driveability, due to a mechanical differential locking mechanism which enables them to operate over a wide range of conditions and soil types. However, this first type of axle has two main drawbacks, in that the track width is fixed, and therefore it is extremely difficult to adapt the machine for passage between rows of mature crops of various types, and in that there is only a limited clearance between the ground and the base of the machine.

A second type of agricultural axle in the form of a mechanical structure has the characteristic of providing a variable track width, an adequate clearance between the ground and the base of the machine to which the axle is fitted, and four-wheel steering. This second type of agricultural axle is designed expressly for the machine to which it is to be fitted, a hydraulic motor for each wheel being used as the motive power for the machine. Clearly, this system has a high degree of complexity and moreover it does not have an optimal driveability; indeed, in order to overcome this lack of driveability, a series of hydraulic or electronic devices are used in this second type of axle, thus further increasing the cost and complexity of the machine.

The object of the present invention is therefore to overcome the drawbacks of the two main known types of axles mentioned above, with an axle for agricultural machines which has, in combination, four-wheel steering to provide high manoeuvrability, increasing the efficiency of the machine to which it is fitted; good driveability for operation on all soil types and conditions; a variable track width, to enable the machine to which it is fitted to travel with its tyres between the rows of mature crops; and the largest possible clearance, which may if necessary be adjustable, between the ground and the base of the machine.

This object is achieved according to the present invention by means of an axle for agricultural machines comprising a main frame formed by a central body and fixed tubular elements provided at the sides of this central body, each containing a slide- out tubular element for adjusting the track width of the axle; the central body houses a differential contained in a corresponding casing and interacting with halfshafts positioned inside the slide-out tubular elements, and at the outer end of each of the slide-out tubular elements there is provided a steering joint connected to a support of a hub provided with a wheel flange; characterized in that the casing of the differential is provided with an outer ring gear interacting with a pinion fixed to a shaft connected to a power connector of the axle and the outer end of each halfshaft is connected, by means for adjusting and varying the ground clearance of the axle, to the hub provided wit the wheel flange; a sector of the main frame positioned close to the central body houses a mechanical device for locking the differential.

Further objects and advantages of the present invention will be made clear in the course of the following description, to be considered as an example without restrictive intent, with reference to the attached drawings, in which: Fig. 1 shows a front view of an axle for agricultural machines according to the present invention, comprising a main frame provided with a central part, two fixed tubular elements and two slide-out tubular elements housed inside and coaxially with the fixed tubular elements;

Fig. 2 shows a front view of the axle of Fig. 1 in a position of maximum expansion of the track width achieved by sliding the slide-out tubular elements horizontally outwards with respect to the fixed tubular elements; Fig. 3 shows a view on a larger scale and in section of a detail relating to the left- hand area of the axle of Fig. 1 , comprising a sequence of gears to which is connected a support of a hub with a wheel flange; and

Fig. 4 shows a view on a larger scale and in section of the central part of the main frame of the present axle.

With reference to the attached drawings, and with particular reference to Fig. 1 of the drawings, the number 1 indicates the main frame of an axle for agricultural machines, particularly for self-propelled spraying machines, comprising a central body 101 and two fixed tubular elements 201 connected rigidly to the said central body 1. Inside each of the said fixed tubular elements 201 there is housed a coaxial slide-out tubular element 2, the outer end of which can be seen in the figure. The outer end of each of the slide-out tubular elements 2 is connected to the inner end of a steering joint 5, whose outer end is connected to a sequence 6 of gears, which can rotate about a substantially vertical axis to enable the agricultural machine to be steered. Inside each of the said slide-out tubular elements 2 there is fixed the inner part of a steering cylinder 7 connected externally to the sequence of gears 6. The lower end of the said gear sequence 6 is connected externally to a support 8 of a hub 9 to which a wheel flange is to be attached. A device 10, for preventing the rotation of the slide- out tubular element 2 with respect to the fixed tubular element 201 in which it is housed, is also shown on each tubular element 201 of the main frame 1. The present figure shows the situation in which the axle has a minimum track width: this track width is substantially defined by the distance C between the axes of the tyres (not shown) of the wheels. On the other hand, the ground clearance L is defined as the vertical distance between the ground 11 and the lowest horizontal surface of the machine, disregarding the supports 8 of the tyres, although these must be as small as possible to avoid interference with the crops which are to be treated by means of the agricultural machine. Fig. 2 shows the axle of Fig. 1 in a situation in which it is expanded to provide a maximum track width C As can be seen, the slide-out tubular elements 2 slide horizontally with respect to the fixed tubular elements 201 housing them, and thus carry the support 8 of the hub 9 to a position further out than that shown in Fig. 1 , making it possible, if necessary, to move between rows of crops which are high and/or positioned in various ways on the ground 11.

We shall now examine in detail (see Fig. 3) the area of the axle located close to the wheel attachment hub 9, considering by way of example the sectional view of the left- hand area of the axle of Fig. 1. The hub 9 is connected externally to a wheel flange 12 and internally to a shaft 13 housed in the support 8. This shaft 13 is provided at each end with a supporting bearing 14 and 15, and its inner end is connected to a driven gear 106 of the sequence 6 of gears. This gear sequence 6 is completed by an intermediate idler wheel 206 and by an upper pinion 306 which is housed in a suitable casing 20. In the present example of embodiment of the invention, the said sequence 6 consists of three gear wheels, but a different number of wheels, with diameters chosen differently according to the requirements of the machine, could be provided in it. The driven wheel 106 receives its motion through the idler, wheel 206 and transmits it to the hub 9 by means of the shaft 13 to which the hub is fixed, while the idler wheel 206 transmits the motion from the pinion 306 to the driven wheel 106 and does not participate in the determination of the transmission ratio, but serves solely to adjust the ground clearance L according to its diameter and if necessary according to its alignment with respect to the pinion 306 and the driven wheel 106. Clearly, the pinion 306 and the idler wheel 206 are also fixed to corresponding support shafts 16 and 17 provided with corresponding support bearings 18 and 19 inside the casing 20 of the gear sequence 6. The pinion 306 is connected to, and receives its motion from, a halfshaft 21 consisting of two parts: a slidable outer part 121 connected by a constant velocity joint 22 to the pinion 306, and a fixed inner part 221 connected to a bevel gear 126 of a differential 26 (see Fig. 4) and separated from the slidable outer part 121 by a dividing partition 23 positioned inside a rotating sleeve 27. In turn, this rotating sleeve 27 is housed in a fixed cylindrical casing 28 by means of bearings 29, 30 and 31. The halfshaft 21 is formed from two outer and inner parts 121 and 221 , so that it can be telescopically adapted to variations of the track width C, for example from C to C or to intermediate values. The constant velocity joint 22 is connected, and transmits motion, between the outer slidable part 121 of the halfshaft and the shaft 16 of the pinion 306, and is contained in a housing 24 which also carries the joint 5 required for steering the agricultural machine. As can be seen, the slide-out tubular element 2, which houses the halfshaft 21 comprising the slidable outer part 121 and the fixed inner part 221 , is fitted between the casing 28 housing the rotating sleeve 27 and the fixed tubular element 201. A hydraulic cylinder 32 for expanding the track width is designed to be fixed between the outer end of the said slide-out tubular element 2 and the outer wall of the fixed tubular element. Essentially, when the length of the hydraulic cylinder 32 is modified by means of known operating devices, the slide-out tubular element 2 slides within the fixed tubular element 201, carrying with it the gear sequence 6 and the hub 9, on which the flange 12 is fixed, thus varying the track width C. Clearly, the slidable outer part 121 of the halfshaft 21 and the slide-out tubular element 2 are fixed to each other during the movements of the adjustment of the track width C.

Fig. 4 is a partial illustration of both of the halfshafts 21 of the axle, whose fixed inner parts 221 are connected to the bevel gears 126 of a known differential 26. The differential 26 is contained in a corresponding housing casing 27 and comprises satellite gears 226 interacting with the said bevel gears 126. The casing 226 is supported by the inner wall of the central body 101 of the main frame 1 by means of two roller bearings 28 and is provided on its outer wall with a ring gear 29 which interacts with a pinion 30. This pinion 30 is at 90° to the halfshafts 21 and receives its motion from a power connector 31 , comprising a shaft 32 rotating in suitable support bearings 33 in a corresponding housing 34. The power connector 31 makes it possible to use a hydraulic motor for each axle, front and rear, or a single hydraulic motor, if suitable transmission means are provided between the said motor and the power connector of each front and rear axle. The illustrated differential 26 is of a known type and is completed by two cross shafts 326. The differential 26 has the function of transmitting the flow of power entering from the power connector 31 and dividing it into two flows which are not necessarily equal, to meet the requirements of the agricultural machine when it is being steered, and the speeds of the two tyres of each axle are not equal. The drawbacks of the differential 26 are seen when one tyre rotates very fast because it is no longer in contact with the ground or is on a surface with poor adhesion such as ice or mud, and the other tyre of the axle is practically stationary. In these conditions, the differential cannot transmit power to the stationary wheel, which is the only one which could transmit to the ground sufficient force to move the vehicle. The present axle provides a device for locking the differential 26, which prevents the operation of the said differential, as if the ring gear 29 were fixed directly to the halfshafts 21. The casing 27 of the differential 26 has at its lateral ends two peripheral portions 35 projecting laterally from the support bearings 28 and having grooves 36. In particular, the groove 36 of the peripheral portion 35 which is on the right when looking at the figure can be engaged by the end 37 of a sleeve 38 slidable along the surface of the fixed inner part 221 of the right-hand halfshaft 21. The sleeve 38 is fixed to, a suitably shaped piston 39, held in the illustrated position , by a spring or a plurality of springs 40. The sleeve 38 and the piston 39 are housed in a sector 301 of the main frame 1 of the axle.

During the operation of the present axle, therefore, as required by particular types of ground, pressurised fluid is introduced from the sector 301 of the main frame 1 through suitable passages 41 so that the piston 39 overcomes the force of the spring 40, thus compressing it, and moves to the left so that the end 37 of the sleeve 38 is engaged in the peripheral portion 35 projecting laterally from the casing 27 of the differential 26. Thus, as mentioned above, the effect is as though the ring gear 29, receiving its motion from the pinion 30 through the power connector 31, were connected directly to the halfshafts 21. It is then possible to use the hydraulic cylinders 32, remotely controlled by the driver of the agricultural machine by means of a known device, to pull out the slidable outer part 121 of the halfshafts 21 to provide a suitable expansion of the track width C, and it would also be possible to vary the ground clearance L by providing a different arrangement and/or size and/or number of the gears of the sequence 6, which in this exemplary embodiment is formed by three gear wheels, namely the pinion 306, the idler wheel 206 and the driven wheel 106.

By using the present axle, therefore, it is possible to have a track width C which is variable over a wide range of values; to vary this track width by remote control without the need for the operator to perform any direct manual operation on the axle; to maintain the steering function of the agricultural machine in complete safety and regardless of the track width position that may be assumed by the axle; to have a ground clearance L which is sufficient and possibly variable; to contain within the axle both the differential and the differential locking device, thus ensuring that the agricultural machine can be driven in any adhesion conditions and on all types of ground; and to fit a known braking device in any of the known types of embodiment.

Claims

1. Axle for agricultural machines, comprising a main frame (1) formed by a central body (101) and fixed tubular elements (201) provided at the sides of the said central body (101), each containing a slide-out tubular element (2) for adjusting the track width (C) of the axle, the central body (101) housing a differential (26) contained in a corresponding casing (27) and interacting with halfshafts (21) positioned inside the slide-out tubular elements (2), while at the outer end of each of the slide-out tubular elements (2) there is provided a steering joint (5) connected to a support (8) of a hub (9) provided with a wheel flange (12), characterized in that the said casing (27) of the differential (26) is provided with an outer ring gear (29) interacting with a pinion (30) fixed to a shaft (32) connected to a power connector (31) of the axle and the outer end of each halfshaft (21) is connected, by means (6) for adjusting and varying the ground clearance (L) of the axle, to the said hub (9) provided with the wheel flange (12), a sector (301) of the main frame (1) positioned close to the central body (101) housing a mechanical device (37, 39, 40) for locking the differential (26).

2. Axle according to Claim 1 , characterized in that each of the said means (6) of adjusting and varying the ground clearance is connected to the outer end of the halfshaft (21) by means of a constant velocity joint (22) contained in a corresponding housing (24), the said means (6) being positioned in a casing (20) connected to the said housing (24) by means of the said steering joint (5) and the said housing (24) being fixed to or formed in one piece with the support (8) of the said hub (9).

3. Axle according to Claim 1 , characterized in that the said means of adjusting and varying the ground clearance comprise a sequence (6) of gears, the upper gear (306) being connected by means of a corresponding shaft (16) to the said constant velocity joint (22) and the lower gear (106) being connected by means of a corresponding shaft (13) to the said hub (9).

4. Axle according to Claim 3, characterized in that the said gear sequence (6) comprises an upper pinion (306), an intermediate idler wheel (206) and a lower driven wheel (106).

5. Axle according to Claim 2, characterized in that each of the said halfshafts (21) comprises a slidable outer part (121 ) connected to the said constant velocity joint (22) and a fixed inner part (221) separated from the said slidable outer part (121) by a dividing partition (23) and connected to a bevel gear (126) of the differential (26).

6. Axle according to Claim 5, characterized in that the slidable outer part (121) of each of the said halfshafts (21) is contained in a rotating sleeve (27) housed by means of suitable support bearings (29, 30, 31) in a fixed casing (28) located inside and coaxially with the slide-out tubular element (2).

7. Axle according to Claim 1 , characterized in that provision is made to fit a hydraulic cylinder (32) for expanding the track width (C), operated remotely by suitable means, between the outer end of the said slide-out tubular element (2) and the outer wall of the fixed tubular element (201 ).

8. Axle according to Claim 2, characterized in that it comprises, on each side of the axle, a steering cylinder (7) connected between the outer wall of the slide-out tubular element (201 ) and the casing (20) of the said gear sequence (6).

9. Axle according to Claim 5, characterized in that the said device for locking the differential (26) comprises a piston (39) fixed to one end (37) of a sleeve (38) slidable on the fixed inner part (221) of one of the two halfshafts (21) and capable of engaging with a peripheral portion (35) of the casing (27) of the differential (26) projecting from suitable bearings (28) for supporting the said casing (27) in the main frame (1), the said piston (39) and the said sleeve (38) being held in a position remote from the said peripheral portion (35) by means of a spring or a plurality of springs (40) and passages (41) being formed in the said sector (301) for the introduction of a fluid capable of acting on the said piston (39) against the action of the said spring (40) to engage the said end (37) of the sleeve (38) in the said peripheral portion (35) of the differential (26).

10. Axle according to Claim 1, characterized in that a device (10), for preventing the rotation of the slide-out tubular element (2) with respect to the fixed tubular element (201) in which it is housed, is provided on each fixed tubular element (201) of the main frame (1 ).

11. Axle according to Claim 1 , characterized in that a hydraulic motor provided with a wheel flange (12) and connected to the said means (6) for adjusting and varying the ground clearance (L) is flanged onto the said support (8).