WO1989006325A1 - Power take off shaft cover system - Google Patents

Abstract

The end cover of a PTO guard system is held on the PTO shaft by a bearing ring permanently secured to the shaft which co-operates with a circumferential slot in the inner surface of the end cover. A clamping ring is preferably provided to provide greater security.

Description

POWER TAKE OFF SHAFT COVER SYSTEM The present invention relates to Power Take Off (PTO) shaft covers and more particularly to covers made of a plastics material.

PTO covers made from plastics material are known and a known design is described in British Patent No. 2,121,137 to the same applicant. This design provides a solution to the problem of accidental damage to the PTO cover by ensuring that the bearing ring on the PTO cover remains engaged with the shaft. The design has a number of disadvantages. Firstly to achieve security for the cover the bearing rings on the shaft and cover need to be closely sized and secondly the bearing rings need to be in good condition and not worn.

It is an object of the prevent invention to provide a PTO shaft cover system which obviates the above disadvantages.

The present invention therefore provides a power take off cover system including a pair of funnel shaped members each member being dimensioned to protect a universal joint structure on one end of a power take take off (PTO) shaft in which, at least one member being provided with a first bearing surface for mateable connection with a second bearing surface the PTO shaft the first bearing surface being formed as a circumferential slot in the first member.

Preferably each funnel shaped member is moulded with the slot integrally formed therein and preferably a circumferential lead in edge is provided adjacent the slot to allow easier assembly of the cover onto the PTC shaft.

Preferably the PTO shaft is provided with a bearing ring of standard outer diameter size the bearing ring being permanently attached to the shaft. The bearing rings are preferably supplied in a range of internal diameter sizes to fit various diameters of shaft.

Embodiments of the present invention will now be described with reference to the accompanying drawing which shows in cross-section a portion of a PTO cover and shaft according to the present invention.

The PTO cover system comprises a funnel-shaped member 10 which is permanently attached to )or formed integrally with) an elongate tube 12. In use in known manner and as described in British Patent No. 2,121,137 the tube 12 co-operates with a further tube shown) which preferably has an identical end construction, tubes 12 and 12' being preferably telescopically movable to accommodate different lengths of drive shaft 14.

Drive shaft 14 has attached rigidly thereto a universal joint of known construction which as shown comprises two portions 16, 18, portion 18 having a spliced end 20 which when connected to a tractor output drive rotates shaft 14. Such universal joints are well known and will not therefore be described further.

The cover 10, 12 is provided with a bearing surface 22 for co-operation with a bearing ring 24 mounted on shaft 14. Bearing surface 22 is formed as a circumferential slot in the funnel-shaped member 10.

Bearing ring 24 is preferably initially provided separately to shaft 14 and comprises an annulus which is sized to fit the diameter of shaft 14 on its inner circumference and sized to fit the diameter of the circumferential slot 22 on its outer diameter.

By providing a series of sizes of annul; 24 of various thicknesses shafts 14 of different sizes can be fitted with the same size of cover having the same diameter of circumferential slow 22. For accurate positioning of annulus 24 in the shaft 14 a collar 26 can be provided which abuts portion 16 of the universal joint and thereby annulus 24 can be welded in position in an accurate manner.

As in British Patent No. 2,121,137 the bearing joint 22, 24 is preferably held in position by a clamping ring 28 comprising a jubilee type clip.

The design of the internal surface of the cover includes a lead in edge 30 which assists in initial positioning of the slot 22 over the ring 24. Once snapped into position the cover 10, 12 is prevented from further movement in the direction A by a large shoulder 32 and from movement in direction B by a smaller shoulder 34. Movement in direction A even when the component parts are partially worn is virtually impossible and movement in direction B is difficult to achieve because of the positive snap over action of shoulder 34.

Thus the design is very much less susceptable to becoming disengaged in use.

As in previous known designs the bearing surfaces 22, 24 may be separated by ball races set for example into slot 22 as diagrammatically indicated by ball bearing 40 but this is not necessary in many applications.

Any suitable heavy grade industrial plastics material may be used to construct the parts 10. 12 etc of the cover. The cover or parts thereof could be made from a heavy duty rubber or even of metal.

The design provides a cover system which may be made in a standard size or limited number of standard sizes and by selection of the annulus 24 may be fitted into any diameter of shaft 14. The snap over method of connection provides positive location of the two bearing surfaces22, 24.

A modified embodimernt is shown in the inset which shows in greater detail the components within datted line 50. In this modification the outer ring 52 of substantially rounded as shown at 54 and 56. Rounding 56 allows easier positioning of slot 22 over ring 24, which is important because in cold conditions the heavy grade industrial plastics material from which funnel shaped number 10 is preferably made is not very pliable.

Rounding 54 allows, albeit with extreme force, the possibilit3' of separating funnel shaped member 10 from ring 24, by insertion of appropriate levers between ring 24 and member 10 at points indicated by arrow 58, after substantial loosening of clamping ring 28. This allows access to components 16, 18 should damage occur to for example one of the hinge pins 16', 18' (only 16' shown). Thus while with clamping ring 28 fully tightened it will still be impossible to separate member 10 from ring 24 (unless one or other component part is broken. the rounding 54 allows possible repairs to components 16, 18.

Where new products require PTO covers which can be designed initially ring 24 can be made an integral part of the shaft 14 since the size of member 10 will be known and also the diameter of shaft 14.

Claims

1. A power take off cover system including a pair of funnel shaped members each member being dimensioned to protect a universal joint structure on one end of a power take off (PTO) shaft in which at least one member is provided with a first bearing surface for mateable connection with a second bearing surface on the PTO shaft, the first bearing surface being formed as a circumferential slot in the first member.

2. A power take off cover system as claimed in claim 1 in which each member is moulded with the slot integrally formed therein.

3. A power take off cover system as claimed in claim 2 in which a circumferential lead in edge is provided adjacent the slot to allow easier assembly of the cover onto the PTO shaft.

4. A power take off cover as claimed in claim 3 in which the PTO shaft is provided with a bearing ring of standard outer diameter size, the bearing ring being permanently attached to the shaft.

5. A power take off cover system as claimed in claim 4 in which a range of bearing rings is provided each with the standard outer diameter and each with an internal diameter sized to fit various diameters of shaft, a ring being selected to fit the diameter of the shaft and being welded to the shaft, and in which a spacing is provided for positioning on the shaft between the selected ring and universal joint member secured to the shaft. the spacing ring thereby serving to accurately position the bearing ring on the shaft relative to the universal joint member.

6. A power take off system as claimed in claim 4 in which the outer rim of the bearing ring is rounded.

7. A power take off system as claimed in claim 2 in which a clamping ring is provided to surround the moulded member, adjacent to the c i rcum fe ren ti a l

ring being tightened onto the outer surface of the moulded member to prevent expansion of the moulded member adjacent to the circumferential slot.

8. A power take off system substantially as described with reference to the accompanying drawings.