WO2005077140A1

WO2005077140A1 - Cover for power take-off

Info

Publication number: WO2005077140A1
Application number: PCT/AU2005/000149
Authority: WO
Inventors: Christopher David Lowe
Original assignee: Christopher David Lowe
Priority date: 2004-02-17
Filing date: 2005-02-07
Publication date: 2005-08-25

Abstract

A cover (20) for a telescopic power take-off shaft (1), the cover (20) extending between a tractor power take-off and an implement, the power take-off of the type comprising a pair of spaced universal joints, the shaft (1) extending between the pair of spaced universal joints and having a drive end and an implement end, and connection means for connecting the drive end to the traitor power take-off and the implement end to the implement, the cover (20) including a flexible section (30) extending from one of the universal joints to the other of the universal joints so that by an axial displacement of the flexible section (30) towards its centre an easy access is provided to the covered portion.

Description

COVER FOR POWER TAKE-OFF This invention relates to a cover for a power take-off. More particularly, this invention relates to a cover for a power take-off for agricultural machinery, such as tractors. Background Art Virtually every tractor in the world is designed to operate tow-behind and rear- mounted machinery. To provide driving power to a trailing or rear-mounted implement, tractors have a spline protruding from the rear and, sometimes, from the front of the tractor. This spline is connected to the gear box of the tractor so that it can rotate at various speeds and provide power to the implement. This is known as the "power takeoff ("PTO"). Each implement that requires power to operate typically also has a power take-off spline. A shaft connects the spline on the tractor and the spline on the implement. This shaft is known as the power take-off shaft. Because the movement of the implement and that of the tractor are not always synchronous, the power take-off shaft is typically made telescopic and is adapted to accommodate a certain degree of vertical, lateral and rotational movement of the implement relative to the tractor. This accommodation is achieved by the provision of a pair of spaced universal joints, one at each end of the shaft. The shaft is typically housed in a rigid, plastic casing known as a power take-off shaft cover. Generally the cover is also telescopic whereby to correspond to the movement of the telescopic shaft to prevent entanglement. Due to the high speed rotation of the shaft, sometimes up to 1000 RPM, and the sudden changes of angle to which the shaft is subjected whilst operating on agricultural land, the two universal joints must be greased regularly. However, currently available power take-off shaft covers make the proper greasing of the universal joint extremely difficult. Typically, holes are provided in the cover through which a grease gun may be inserted, but these rarely correspond to the position of the grease nipples on the universal joints due to relative shifting through use and over time. To grease the universal joints properly, one needs to remove the cover from the tractor to allow proper access to the grease nipples of the universal joints. This leads to two issues pertaining to convenience: (1) The machine is operated without a power take-off shaft cover to allow easy access to the grease nipples on the universal joints. This is highly dangerous and is discouraged by health and safety authorities. Moreover, dust and debris tend to accumulate on the PTO and its working parts, particularly where grease is present, providing a sticky surface for the collection of such grime. (2) The universal joints are not greased as regularly as they should be, if at all, because the whole procedure is inconvenient and, in the short term, unproductive. This leads to premature wear and failure of the universal joints, thereby leading to costly down time for the machines in the long term. As the universal joints collapse they can disintegrate and throw pieces of steel outward from the shaft, thereby constituting an extreme safety hazard. Ultimately and at the very least, these practices will interfere with the optimum operation of the PTO and therefore it is highly desirable that a satisfactory cover arrangement be provided which encourages compliant practices in maintaining the PTO and its cover. Another problem with power take-off shaft covers currently available is that they are not readily repairable. Available covers also are not made according to standardized or universal sizes, so that parts from one shaft cover rarely fit another. This leads to machinery being operated with damaged or deficient power take-off shaft covers, again possibly constituting a serious health and safety risk, or at the very least interfere with the optimum performance of the machinery. PTO covers which have significant shortcomings have been described but may not be widely known . For example, in GB 2121137 (Wakeling) there is described a PTO cover having telescoped tubes 9,10 attached at their resective free ends to funnel shaped end covers 12. Apart from the rigidity and overall lack of flexibility of this arrangement, the overall conically shaped end covers 12 of Wakeling would tend to permit the ingress of an unnecessarily large amount of mud or debris because of their shape. Moreover, the Wakeling PTO cover require significant labour to mount and secure including use of clamping rings which must be secured before the Wakeling PTO cover is operative. Such effort tends to dissuade compliance which may lead to PTO covers being incorrectly and dangerously mounted.

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art in Australia or elsewhere.

Statement of Invention

The present invention may be used to overcome the problems of the aforementioned prior art, or at least provide a useful alternative thereto. For example, the invention may ter alia address issues such as making the greasing operation an easier task, enabling a standardization of the PTO cover sizes, improving the resilience and flexibility of PTO covers and/or providing a mechanically more effective cover. Accordingly, in one aspect of the invention, there is provided a cover for a power take-off, the power take-off comprising: (a) A pair of spaced universal j oints ; (b) a telescopic power take-off shaft extending between the pair of spaced universal joints and having a drive end and an implement end ; and (c) connection means for connecting the drive end to a tractor power take-off and the implement end to an implement, the power take-off shaft cover including: (d) a flexible section extending from one said universal joint to the other universal joints. This may be so that easy access to the covered portion may be achieved by simple axial displacement of the flexible section towards its centre. The flexible section may be compressible and/or collapsible. The flexible section may be axially compressible and/or collapsible. The flexible section may be in the form of a hose or a sleeve. The flexible section may include a length of spirally wound wire or another resiliently deformable elongate element. The spirally wound element may be covered with flexible material, such as woven and/or polymeric material. The flexible material may be synthetic or natural rubber. The flexible section may be concertinaed. The flexible section may be a hose, sleeve or sheath made from polypropylene. In an axially compressed state, the flexible section is preferably adapted to cover at least the power take-off shaft. Preferably, the flexible section is axially, resiliently compressible so that its length is self-adjustable to accommodate and adjust to the length of the power take-of shaft. Either end of the flexible section may include a mounting ring mountable to a journalled or bearing member of the shaft, preferably corresponding to the neck region of the or each universal joint or an end portion of the shaft immediately adjacent the connection thereto. The flexible section is preferably axially compressible and resilient to resist axial compression thereby urging each end of the flexible section towards the universal joints. The power take-off shaft cover preferably includes an end cover for at least one of the universal joints and, preferably, for both universal joints. The or each end cover may be a cowl. The cowl may be cup-shaped, conical, funnel shaped or may be substantially cylindrical. Preferably, the end cover is substantially cylindrical with a tapering neck terminating in a collar. The collar is preferably adapted to be mounted to a concentric bearing member on the universal joint or the shaft at each end. The collar may include a shoulder against which the end, such as the mounting ring, of the flexible section bears to urge the end cover onto and covering the universal joint. The end cover is preferably made from a substantially rigid material. The end cover may be made from a metal material or, more preferably, from polymeric material, such as polypropylene, high density polyethylene and/or a polyamide. Unlike the prior art which requires that a hole in the end cover be in registration with a grease nipple in the universal joint, the present invention permits an operator to simply push back the end cover towards the centre of the flexible section to allow easy access to the grease nipple of the universal joint at each end. The cover may include a pair of wear rings or bearing rings which support each end of the flexible section or, more preferably, the or each end cover, to prevent the cover from wearing the shaft or, in turn, being abraded by the shaft. The wear or bearing rings may form part of the collar of the end cover or may be attached to the shaft or the universal joint preparatory to the cover being fitted. The wear ring is preferably clipped on to the shaft, the universal joint or connection means connecting the shaft and the universal joint. It can be seen that when the implement is being towed or worked in use, the flexible section is preferably held in a compressed state against an axial expansionary tendency by the universal joints to hold the flexible section and the cover ends in position against the universal joints. Brief description of the drawings Possible and preferred features of the present invention will now be described with particular reference to the accompanying drawings. However it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention. In the drawings: Figure 1 is a top plan cut-away view of a power take-off shaft cover according to a first embodiment of the invention; Figure 2 is a top plan view of a flexible section shown in an axially compressed state; Figure 3 is a top plan view of the flexible section shown in Figure 2 in an expanded state; and Figure 4 is a top elevation cut-away view of the first embodiment showing a part of a power take-off shaft cover including a wear ring. Detailed description of the drawings Referring to Figure 1, there is shown a power take-off shaft 1 axially connected to a universal joint 10 (partially shown). The shaft 1 and the universal joint 10 are surrounded by a power take-off shaft cover 20, including a flexible section 30 (shown only in part) and a cowl 40 surrounding one portion of the universal joint 10. Although only one end of the power take-off shaft cover 20 is shown in Figures 1 and 4, it will be understood that each end of the cover 20 is substantially identical, the only variation between the shaft ends being the provision for telescoping of the shaft 1 by the outer shaft member 3 travelling relative to the inner shaft member 5. The outer shaft 3 diameter at the other end (not shown) is preferably reduced to that of the inner shaft 5 at the end shown to ensure compatibility and universality with complementary components. The cover 20 is of a construction comprising a pair of cowls 40 and a flexible section 30. The pair of spaced cowls 40 are interposed and spaced by the flexible section 30 extending therebetween and resisting axial compression, one cowl 40 towards the other, so that the length of the cover 20 automatically adjusts to the length of the shaft 1. Each cowl 40 is identical in the embodiment shown but may differ where the universal joints 10 differ in size or shape. The cowl 40 includes a substantially cylindrical section 41 terminating at a free end in an outwardly flared lip 42 and a conical section 43 extending from the other end of the cylindrical section 41 to taper concentrically to a collar 44. The lip 42 does not extend past the outermost pivot joint 11 of the universal joint 10 but extends sufficiently along the length of the universal joint 10 to protect the joint 11 against the ingress of a substantial amount of mud and debris into the area defined by the cowl 40. The outwardly extending lip 42 is shaped to reduce the abrasive wear of the universal joint 10 on the free end of the cowl 40 and is a preferred alternative to the overall conically shaped cowl described in GB 2121137 (Wakeling) which would tend to permit the ingress of an unnecessarily large amount of mud or debris because of its funnel shape. The collar 44 comprises a short cylindrical stub and an external shoulder 45 on which the respective ends 31 of the flexible section 30 snugly rest. The internal surface of the conical section 43 is urged against the connecting portion 7 connecting the inner shaft 5 to the universal joint 40 by the axially expansionary force of the flexible section 30. In use, the cowl 40 may be pushed towards the centre of the flexible section 30 against its expansionary force to give access to a grease nipple 46. A suitable amount of grease may be applied to the grease nipple 46 for proper and regular maintenance of the universal joint 10. Once the grease is applied, the cowl 40 may be allowed to return to its position surrounding the universal joint 10 and care may be taken to ensure the cowl's 40 correct orientation and positioning relative to the connection means 7. Surrounding the connection means 7 is a wear ring assembly 50 adapted to space the cover 20, and particularly in this embodiment, the cowl 40, from the rotating shaft 1 to prevent the cover 20 from wearing on the shaft 1. The cover 20 may be used without the wear ring 50 with expected greater short-term obsolescence. In such case, the cowl 20 may be made from a low friction material such as polytetrafluoro ethylene (Teflon ®) or a polymer or metal coated therewith or may be made from a polymer including low friction self-lubricating additives. However, it is preferred that the wear rings 50 be provided for extended life of the cover 20. The wear ring 50 may be made from a polymeric material including a self- lubricating material such as Teflon ® or may comprise a traditional ring bearing such as a ball bearing ring having an inner and outer casing as represented in Figure 4 where a clip- on wear ring 51 is shown. The clip on wear ring 51 provides increased centering and stability to the cowl 40 whereby to more effectively space the cowl 40 from the universal joint 10 to extend the life of the cowl 40. In any event, the power take-off shaft cover comprises a small number of distinct parts, namely the pair of cowls 40, the flexible shaft 30 and, optionally, the wear ring 50, thereby allowing easy replacement of broken or worn pieces. This may be contrasted with much of the prior art in which operators are faced with replacing a complete new power take-off shaft cover if one of the components thereof becomes broken, ineffective or dangerous through wear or fatigue. In its simplest and cheapest form, the PTO cover 20 may be integrally formed from a single material such as polypropylene, with the cowls 40 and the section 30 being made from the samer material. The flexible section 30 is preferably in the form of concertinaed polypropylene hose suitably manufactured with additives to ensure a relatively high melting temperature and resilience to repeated bending and flexing during use. However, other materials having suitable properties may be used alone or in a composite blend to make a workable flexible section 30, such as ceramic, glass, metal or cellulosic fibres, other plastics, and metals. The flexible section 30 may be made from blow moulding or any other suitable manufactming process. The cowl 40 may be made from metallic or polymeric materials and is preferably of a rigid construction. Accordingly, suitable materials for manufacture may be high density polyethylene, polypropylene, aluminium, stainless steel or the like. A wide range of moulding manufacturing processes may therefore be appropriate, depending on the material, including injection moulding or metal casting. Referring to Figures 2 and 3, the flexible section is shown in Figure 2 in a compressed state corresponding to the position assumed by the flexible section 30 when the cowl 40 is pushed away from the universal joint 10 for maintenance thereof. It will be understood, however, that the drawings are somewhat schematic and that compression of the flexible section 30 along its length will not necessarily be uniform - compression will normally be concentrated at the end of the flexible section which has been pushed away from the universal joint 10. It will be noted in Figure 2 that the flexible section 30 includes terminating ring members 32, corresponding to the terminal end 31 at each end of the flexible section 30 to ensure that the flexible section 30 is seated snugly on the cowl shoulder 45 and about the cowl collar 44. In Figure 3, the flexible section 30 is shown in its expanded state corresponding to the normal resting configuration of the flexible section 30 when the implement (not shown) connected to the universal joint 10 is in operation. When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. It is to be understood that various alterations, modifications and/or additions may be made to the features of the possible and preferred embodiment(s) of the invention as herein described without departing from the scope of the invention as defined in the appended claims.

Claims

The claims defining the invention are as follows:

1. A cover for a power take-off extending between a tractor power take-off and an implement, said power take-off of the type comprising:

(a) a pair of spaced universal joints; (b) a telescopic power take-off shaft extending between said pair of spaced universal joints and having a drive end and an implement end; and (c) connection means for connecting said drive end to said tractor power takeoff and said implement end to said implement, said power take-off shaft cover including: (d) a flexible section extending from one of said universal joints to the other of said universal joints.

2. A cover according to claim 1, wherein said flexible section is axially compressible so that, in the compressed state, said flexible section is biased to expand axially.

3. A cover according to claim 1 or 2, wherein said flexible section is concertinaed.

4. A cover according to any one of claims 1 to 3, wherein said flexible section is a hose or sheath.

5. A cover according to claim 4, wherein said flexible section is made by blow molding polypropylene.

6. A cover according to any one of claims 1 to 5, wherein said flexible section is made of composite materials including reinforcing spring metal or plastic in discrete annular sections or spirally wound and, extending between said reinforcing, a web of flexible material.

7. A cover according to claim 6, wherein said web material is made of plastic or of ceramic woven fibre.

8. A cover according to any one of claims 1 to 7, wherein said cover is integrally formed from blow moulded plastic.

9. A cover according to any one of claims 1 to 8, wherein said cover includes a joint cover for at least one of said universal joints, configured to protect the universal joint from the ingress of dust, grime and debris.

10. A cover according to claim 9, wherein the or each end cover is a cowl snugly fitting the universal joint and terminating at its free end with an outwardly extending lip to reduce wear on said cowl's free end.

11. A cover according to any one of claims 1 to 10, wherein said cover includes a pair of wear rings or bearing rings which attach to each end of the flexible section to reduce wearing of said shaft and wearing on said shaft.

12. A cover according to any one of claims 9 to 11, wherein the flexible section is compressible to permit the joint covers to be pushed towards the centre of the flexible section to allow access to grease nipples on the universal joints.

13. A cover according to any one of claims 1 to 12, wherein said flexible section is held in a compressed state against an axial expansionary tendency to hold said flexible section in position against said universal joints.

14. A cover according claim 13 when dependent on claims 9 to 13, wherein said flexible section is adapted in use to hold the or each joint cover in place over said universal joints and is sufficiently flexible to permit compression by an operator without additional tools to allow access to grease nipples on the universal joints.

15. A cover according to any one of claims 9 to 14, wherein the or each joint cover is a generally cylindrical housing with a conical shaped neck to configure to a joumalled or bearing member on said shaft.