GB2155118A

GB2155118A - Bearing assembly more especially for an axle of a garden tool

Info

Publication number: GB2155118A
Application number: GB08501303A
Authority: GB
Inventors: Alan Trelford
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 1984-01-19
Filing date: 1985-01-18
Publication date: 1985-09-18
Also published as: GB8501303D0; GB2155118B

Abstract

A bearing assembly is described, which is particularly suitable for mounting a rotatable axle of a garden tool, especially an axle which carries a working element such as a lawn scarifying tine assembly. With a view to simplifying removal of the axle and/or working element from the tool, the bearing assembly (70) is constructed so that it can be disengaged from the tool and removed before the axle is removed. To this end, the bearing assembly comprises a plastics bearing housing (71), a sintered metal bearing (72), a plastics plug (73) and a spring washer (74), the housing having a cylindrical portion (75) formed with locking formations (76) which engage corresponding locking formations at the outlet of a recess on that part of the tool in which the bearing assembly is mounted. A resilient arm (80) projects from a hemispherical portion (77) of the housing and includes longitudinal and transverse ribs defining a gap (83). Upon assembly, the housing (70) is introduced into the recess at the said part of the tool and is then rotated until a wall extending upwardly from the recess snap fits into the gap (83). <IMAGE>

Description

SPECIFICATION Bearing Assembly, More Especially for an Axle of a Garden Tool This invention relates to a bearing assembly for mounting a first part of a device movably relative to a second part of a device. The invention relates more especially to a bearing assembly such as may be used to mount a rotatable working element of a garden tool, for example a lawn scarifier and or a grass cutter, and relates also to a garden tool including such a bearing assembly.

A conventional arrangement such as is used to mount the tine carriers of a lawn scarifier includes a solid steel rod axle of circular cross-section. Most of the length of the axle is used to mount the tine carriers but the ends of the axle extend beyond the tine carriers and are mounted in bearings.

Conventional arrangements are effective but also expensive and do not enable either the bearings or the axle to be readily detached from the tool.

The present invention provides a bearing assembly for mounting a first part of a device movably relative to a second part of the device, the bearing assembly comprising a bearing housing and a bearing received in the housing, wherein the bearing housing is provided with locking formations engageable with corresponding formations on the second part thereby to fasten the bearing assembly on the device, which locking formations can be disengaged upon movement of the bearing housing relative to the second part to release the bearing assembly from the device, the arrangement being such that the bearing assembly can be removed before the first and second parts are separated.

The said first part may be a rotatable working element, and in particular an axle, of a garden tool.

Through the use of the invention, the insertion and removal of the axle from the tool can be facilitated.

The bearing housing may be formed of a plastics material In one embodiment of the invention, the bearing housing has an open end through which the bearing is inserted and a plug member is fastenable over the open end to retain the bearing in the housing.

The locking formations may be such that the bearing assembly is mounted on the device by a bayonet fitting.

The locking formations include means engageable to prevent the said releasing movement of the bearing housing relative to the second part of the device. In an embodiment of the invention described herein, the said releasing movement is rotational movement of the bearing assembly relative to the second part of the device and the bearing housing includes a resilient member releasably engageable with the said second part to secure the bearing assembly against rotational movement. In this embodiment, the bearing assembly is inserted into and removed from the device in one orientation and is rotatable to a second orientation to fasten the bearing assembly to the device.

The mounting technique is of particular value for mounting a tine assembly of a scarifier or a cylindrical cutter of a mower where the ability to remove the working element from the rest of the tool easily and quickly is particularly advantageous.

When the said first part is an axle and, in particular, an axle of a garden tool, it may comprise a rod or tube on which a working element of the tool is to be mounted for rotation with the axle and a separate bearing member fixed to the end of the rod ortube and having a bearing portion by which the axle is rotatably mounted in the bearing assembly.

The present invention accordingly further provides a composite axle for a garden tool, the axle comprising a rod or tube on which a working element of the tool is to be mounted for rotation with the axle and a separate bearing member fixed to the end of the rod or tube and having a bearing portion by which the axle is rotatably mounted.

With such an arrangement it is not necessary for the part of the axle supporting the working element of the tool to be made with the accuracy necessary of a rotatable bearing. Indeed a length of ordinary metal tube may be used for that part. The bearing member, which may be relatively much shorter, has a bearing portion which can be manufactured to narrow tolerances.

Preferably a hollow tube is used for the part of the axle on which the working element is mounted. This reduces the amount of material used for this part of the axle and reduces the weight of the axle.

Preferably a separate coupling member is fixed to the other end of the tube or rod and includes a drive coupling for coupling the axle to a rotary drive.

The bearing member may comprise a length of rod defining a stub axle which may be fixed inside the tube, for example by crimping.

The coupling member may also be fixed inside the tube, for example by crimping and may include longitudinal serrations engaged with the inside of the tube to lock the coupling member and the tube against relative rotation.

The coupling member may include a drive part for engagement with the working element to lock the working element against rotation relative to the coupling member.

The free end of the coupling member may be formed with a tapered bore to receive a complementary driving member of a rotary drive. A pin is passed through aligned holes in the coupling member and the driving member to lock the members together.

According to another aspect of the invention there is provided a garden tool including: a working element; an axle on which the working element is mounted for rotation therewith; a motor; and a rotary drive connected between the motor and one end of the axle, the other end of the axle being mounted in a bearing assembly releasably mounted on a part of the tool whereby the bearing assembly can be removed before the axle is separated from the tool.

The bearing assembly may comprise a bearing housing and a bearing received in the housing, wherein the bearing housing is provided with locking formations engageable with corresponding formations on the tool thereby to fasten the bearing assembly on the tool, which locking formations can be disengaged upon movement of the bearing housing relative to the tool to release the bearing assembly from the tool.

In particularly advantageous forms of the invention the garden tool is a raking or scarifying device, or a grass cutter.

By way of example certain embodiments of the invention will now be described with reference to the accompanying drawings, of which: Fig. 1 is a perspective view of a lawn scarifier, Fig. 2 is a sectional view of a rotary drive of the device, Fig. 3 is a plan view of a tine assembly of the device, Fig. 4 is a side elevation of a component of the tine assembly, Fig. 5 is a side elevation of another component of the tine assembly, Fig. 6 is a partly sectional view of the composite axle of the tine assembly, Fig. 7 is a side elevation view of a coupling member forming part of the tine assembly, Fig. 8 is a schematic view of a rotary cutter which may be mounted on the composite axle, Fig. 9 is a sectional side view of a bearing assemblyforthe tine assembly, Fig. is an end view of a bearing housing of the assembly shown in Fig. 9, Fig. 11 is a plan view of the bearing housing, Fig. 12 is a sectional view along the lines Xll-XIl of Fig. 10, Fig. 13 is an end view (in the opposite direction to Fig. 10) of a bearing of the bearing assembly, Fig. 14 is a sectional view along the lines XIV-XlV of Fig. 13, Fig. 15 is a side view of a part of the scarifier body on which the bearing assembly is mounted, and Fig. 16 is a sectional view along the lines XVI-XVl of Fig. 15.

The lawn scarifiershown in Fig. 1 has a body 1 a handle 2 (most of which is not shown), a tine assembly 3 rotated, in use, by a motor 4 and a rotary drive 5 (both of which are shown in Fig. 2 but are not visible in Fig. 1). The scarifier is supported on a pair of front wheels and a rear roller (not visible in Fig. 1).

The motor 4 and rotary drive 5 are assembled together to form the sub-assembly shown in Fig. 2 and that sub-assembly is fixed to one side of the scarifier and covered by one of the sides 30 of the body casing (Fig. 1). The motor 4 has an output shaft 31 carrying a pinion which meshes with a set of outer teeth 33 on a reducing gear 32. The reducing gear 32 also carries a set of inner teeth 34 which mesh with a gear 35 mounted on a drive shaft 36 at the end of which a driving member 37 having a hole 38 therethrough is formed. The driving member 37 is connected to the tine assembly 3 in a manner that will be described later.

The tine assembly 3 shown in Fig. 3, comprises an axle 40 (Fig. 6), a plurality of plastics components 41, each as shown in Fig. 4, and a retainer clip 42 (Fig. 5) for the components 41.

The component 41 of the tine assembly shown in Fig. 4 is a single piece moulding of a plastics material, for example acetal, and consists of three tine arms 11, 12, 13 that extend symmetrically from a common boss 14 of generally cylindrical form with a longitudinal bore 15. It will be appreciated that the boss 14, although integral with the tine arms, may be regarded as a tine carrier.

The end faces of the boss 14 are castellated, there being three equi-sized, axially-extending castellations 24 separated by equal gaps 25 on each face.

The castellations 24 on one face are rotated with respect to gaps on the other face by 6" about the longitudinal axis of the bore 5.

Afull description of the structure of a component similar to the component 41 is given in our British patent application, publication number 2 112 613A.

The component shown in Fig. 4 is one of aboUt twenty such components mounted upon the axle 40 to form the tine assembly shown in Fig. 3.

Referring to Fig. 6, the axle 40 comprises a standard metal tube 43 which in this example is made of aluminium, a stub axle 44 fixed in one end of the tube and a drive coupling 45 fitted in the other end of the tube. The stub axle 44 is formed with a circumferential groove 46 in the portion that is inserted into the tube 43 and is fixed to the tube by crimping the tube around this groove. The end of the stub axle 44 projecting from the tube 43 defines a bearing portion inserted into a bearing assembly 70 on the body 1 of the scarifier on the side opposite the rotary drive 5.

Referring now to Figs. 6 and 7, the drive coupling 45 has one end 47 of reduced diameter formed with longitudinal serrations around its outside. That end 47 is inserted into the tube 43 in which it is a tight fit and the tube is then crimped against the end locking the coupling 45 and the tube 43 together and in particular locking them against relative rotation.

Once crimped in position a peripheral surface 48 on the coupling 47 defines a smooth continuation of the outside of the tube 43 and the end of this surface 48 is defined by a circumferential flange 49 which on the surface facing the tube 43 has castellations 50 separated by gaps 51. The free end of the drive coupling 45 has a tapered axial bore 52 therein dimensioned to receive the driving member 37; holes 53 transverse to the bore 52 and in communication therewith are positioned so as to align with the hole 38 of the driving member 37 when it is received in the bore 52.

Once the axle 40 has been assembled, the components 41 are fitted over the stub axle 44. The castellations on the leading face of the first component to be fitted mate with the castellated face on the flange 49 of the drive coupling 45 and thereafter the castellated end face of adjacent components 41 are interengaged. The rotational offset of the castellations referred to above produces a spiralling of the tine members along the length of the axle. After the last component 41 has been fitted a spring 42, seen in Fig. 5, is fitted adjacent the last component to maintain the interengagement of the drive coupling and all the components 41.

Referring now to Figs. to 14, the bearing assembly 70 comprises a plastics bearing housing 71, a sintered metal bearing 72, a plastics plug 73 and a wavy spring washer 74. The housing 71 has a cylindrical portion 75 on which a pair of locking flanges 76 are formed, and a hemispherical portion 77 into which the bearing 72 is inserted through an open end 78 of the portion 77. After insertion of the bearing 72, the wavey washer 74 is inserted and the plug 73 is then snap-fitted over the open end 78 of the housing pressing the bearing 72 fully into the housing and thereby aligning the bearing with the housing. Four radial fins 79 project externally at 90 intervals around the portion 77.

A resilient arm 80 projects from the hemispherical portion 77 and carries-at its distal end longitudinal and transverse ribs 81 and 82 respectively defining a gap 83 therebetween. The depth of the rub 82 increases progressively towards the rib 81.

Figs. 15 and 16 show the area of the scarifier body 1 in which the bearing assembly 70 is received. An external cylindrical recess 84 is defined in the body and the bottom of this recess is generally open but partly closed buy a pair of locking flanges 85. Awall 86 extends upwardly from the recess 84 flush with the outer end of the recess.

The bearing assembly 70 is mounted on the body 1 by offering up the assembly 70 the recess 84 from the outside. The assembly 70 is then inserted into the recess 84 with the cylindrical portion 75 innermost and the assembly orientated so that the locking flanges 76 pass between the flanges 85 on the body 1. The assembly 70 is then rotated anticlockwise (as seen in Fig. 15) until the arm 80 comes into alignment with the wall 86. As this happens, the rib 81 rides over the wall 86 and the arm 80 clicks into position with the gap 83 between the ribs 81 and 82. In this position the flanges 85 on the body 1 are sandwiched between the flanges 76 and the fins 79 on the assembly 70 so that the assembly is held securely in place.To detach the bearing assembly, the distal end of the arm 80 is first pulled away from the body 1 of the scarifier to extract the wall 86 from the gap 83 and the above described sequence of operations is then reversed.

To mount the tine assembly on the scarifier, the assembly 3 is first connected to the driving member 37 via the drive coupling 45 by a pin fastened through the holes 53 and 38. Atthis stage the bearing assembly 70 is detached. Because of the absence of the bearing assembly 70 the tine assembly can easily be fitted onto the drive coupling 45 with the stub axle 44 projecting into the recess 84 on the tool body. The cylindrical portion 75 of the bearing assembly is then located over the stub axle 44 and inserted into the recess 84 in the manner described above so that the stub axle is journalled in the bearing 72. The ability of the bearing assembly to be attached and detached while the tine assembly remains on the scarifier makes the replacement of the tine assembly a quick and easy operation.

In use, when the motor 4 is switched on, the driving member 37 is rotated at reduced speed by the rotary drive 5, and the rotation of the member 37 is transmitted to the components 41 via the drive coupling 45 so that the whole tine assembly 3, including the axle 40, rotates as a unit.

It will be appreciated that the details of the construction of the components 41 is not an important feature of the present invention and many different forms of tines may be employed. One alternative arrangement would be to provide a tine sub-assembly consisting of tines mounted on a tine carrier along the central axis of which was a bore to receive the composite axle 40.

The composite form of axle 40 described above is of simple and cheap construction and is light in weight. The major part of the axle 40 is made up from a plain aluminium tube while the ends of the axle are made from specially shaped members which provide the required precision. It is not, however, essential to employ an axle of composite construction: a one piece axle could be used instead, the axle being formed from a single length of tubing with suitably-machined ends. For example, one end of the length of tubing can be swaged to provide the bearing portion for insertion in the bearing assembly 70 and the other end can be reamed to receive the driving member 37. A pin passing through the reamed end and the driving member 37 is then used, as with the axle of Fig. 6, to connect the driving member to the axle.A short distance along the axle from this pin is a second pin which passes through the axle adjacent the first tine component 41 and engages the castellations on the leading face of that component to couple the tine assembly 3 to the axle.

Fig. 8 shows a rotary cutter 60 which may be mounted on the axle 40 in place of the components 41 in order to convert the machine into a grass cutter. The rotary cutter 60 is constructed as a unit having an axial bore through which the axle 40 may be inserted. An end face of the cutter is castellated in the same manner as the components 41 and this face is engaged with the castellated flange on the drive coupling 45. The clip 54 is again used to hold the cutter in place.

The detailed design of the rotary cutter is not of relevance to the present invention and will not be described in detail. A ledger blade is preferably mounted on the body 1 of the tool below the rotary cutter.

Claims

1.A A bearing assembly for mounting a first part of a device movably relative to a second part of the device, the bearing assembly comprising a bearing housing and a bearing received in the housing, wherein the bearing housing is provided with locking formations engageable with corresponding formations on the second part thereby to fasten the bearing assembly on the device, which locking formations can be disengaged upon movement of the bearing housing relative to the second part to release the bearing assembly from the device, the arrangement being such that the bearing assembly can be removed before the first and second parts are separated.

2. A bearing assembly as claimed in claim 1, in which the said first part is an axle and the bearing assembly has a bore in which the axle is locatable to co-operate with the bearing.

3. A bearing assembly as claimed in claim 1 or claim 2, in which the bearing housing is formed from a plastics material.

4. A bearing assembly as claimed in any one of the preceding claims, in which the bearing housing has a plug at one end, which is removable to provide an opening through which the bearing can be located in the housing.

5. A bearing assembly as claimed in claim 4, in which the plug is a snap-fit in the housing.

6. A bearing assembly as claimed in claim 4 or claim 5, in which the plug presses the bearing into the housing.

7. A bearing assembly as claimed in claim 6, in which the plug acts on the bearing via a resilient member located between the plug and the bearing.

8. A bearing assembly as claimed in any one of the preceding claims, in which the bearing housing has a hemispherical portion in which the bearing is located.

9. A bearing assembly as claimed in claim 8 when appendentto claim 2, in which the bearing housing has a cylindrical portion extending from the hemispherical portion to receive the axle.

10. A bearing assembly as claimed in claim 9, in which locking formations are provided on the cylindrical portion.

11. A bearing assembly as claimed in any one of the preceding claims, in which the bearing housing includes a member engageable with the second part of the device to prevent the said releasing movement of the bearing housing.

12. A bearing assembly as claimed in claim 11 when appendent to claim 8, in which the said member is a resilient arm extending from the hemispherical portion of the bearing housing.

13. A garden tool having a rotatable axle mounted in a bearing assembly as claimed in any one of the preceding claims.

14. A garden tool as claimed in claim 13, in which a working element of the tool is mounted on the axle for rotation therewith.

15. A garden tool as claimed in claim 14, in which the working element is a grass cutting or scarifying assembly.

16. A garden tool as claimed in any one of claims 13 to 15 in which the bearing assembly is releasably fastened in a housing wall of the tool.

17. A garden tool as claimed in claim 16, in which the locking formations are such that the bearing assembly is fastened in the housing wall by a bayonet fitting.

18. A garden tool as claimed in claim 16 or claim 17, in which the bearing assembly is located in a cylindrical opening in the housing wall, and the locking formations comprise flanges extending from the bearing housing and from the cylindrical opening such that the bearing assembly can be inserted into and removed from the cylindrical opening in one orientation and is rotatable to a second orientation to fasten the bearing assembly in the opening.

19. A garden tool as claimed in claim 18 when dependentfrom claim 12, in which the resilient arm is engageable with a wall portion extending radially from the cylindrical opening to secure the bearing assembly in the second orientation against rotation in the opening.

20. A garden tool including a working element; an axle on which the working element is mounted for rotation therewith; a motor; and a rotary drive connected between the motor and one end of the axle, the other end of the axle being mounted in a bearing assembly releasably mounted on a part of the tool whereby the bearing assembly can be removed before the axle is separated from the tool.

21. A garden tool as claimed in claim 20, in which the bearing assembly comprises a bearing housing and a bearing received in the housing, wherein the bearing housing is provided with locking formations engageable with corresponding formations on the tool thereby to fasten the bearing assembly on the tool, which locking formations can be disengaged upon movement of the bearing housing relative to the tool to release the bearing assembly from the tool.

22. A garden tool as claimed in any one of claims 13 to 21, in which the axle comprises a rod or tube and a separate bearing member fixed to the end of the rod or tube and having a bearing portion by which the axle is rotatably mounted in the bearing assembly.

23. A garden tool as claimed in claim 22, in which the bearing member comprises a length of rod, defining a stub axle, which is fixed inside the tube.

24. A garden tool as claimed in claim 23, in which a separate coupling member is fixed to the other end of the tube or rod and includes a drive coupling for coupling the axle to a rotary drive.

25. A garden tool as claimed in claim 24, in which the coupling member is fixed inside the tube.

26. A garden tool as claimed in claim 25, in which the coupling member includes longitudinal serrations engaged with the inside of the tube to lock the coupling member and the tube against relative rotation.

27. A garden tool as claimed in any one of claims 24 to 26, in which the coupling member includes a drive part for engagement with a working element on the axle to lock the working element against rotation relative to the coupling member.

28. A garden tool as claimed in any one of claims 24 to 27, in which the free end of the coupling member is formed with a tapered bore to receive a complementary driving member of a rotary drive.

29. A garden tool as claimed in claim 28, in which a pin is passed through aligned holes in the coupling member and the driving member two lock the members together.

30. A composite axle for a garden tool, comprising a rod or tube on which a working element of the tool is to be mounted for rotation with the axle and a separate bearing member fixed to the end of the rod ortube and having a bearing portion by which the axle is rotatably mounted.

31. A composite axle as claimed in claim 30, in which the part of the axle on which the working element is to be mounted is a hollow tube, and in which the bearing member comprises a length of rod, defining a stub axle, which is fixed inside the tube.

32. A composite axle as claimed in claim 30, in which a separate coupling member is fixed to the other end of the tube or rod and includes a drive coupling for coupling the axle to a rotary drive.

33. A composite axle as claimed in claim 32, in which the part of the axle on which the working element is to be mounted is a hollow tube, and in which the coupling member is fixed inside the tube.

34. A composite axle as claimed in claim 33, in which the coupling member includes longitudinal serrations engaged with the inside of the tube to lock the coupling member and the tube against relative rotation.

35. A composite axle as claimed in any one of claims 32 to 34, in which the coupling member includes a drive part for engagement with a working element on the axle to lock the working element against rotation relative to the coupling member.

36. A composite axle as claimed in any one of claims 32 to 35, in which the free end of the coupling member is formed with a tapered bore to receive a complementary driving member of a rotary drive.

37. A composite axle substantially as described herein with reference to, and as shown in, Figs. 6 and 7 of the accompanying drawings.

38. A bearing assembly substantially as described herein with reference to, and as shown in Figs. 9 to 14 of the accompanying drawings.

39. A garden tool including a composite axle as claimed in claim 37 or a bearing assembly as claimed in claim 38.

40. A garden tool substantially as described herein with reference to, and as shown in the accompanying drawings.