GB2116412A - Lawn scarifier - Google Patents

Abstract

An attachment for fitting to a cylindrical cutting reel of a lawnmower, the reel having means supporting at least one helical blade for rotation about a central axis, the attachment comprising a flexible tine (17) integral with or attached to a support member, and means (19) for releasably engaging the support member with the blade support means such that when the reel is rotated, the tip of the tine engages the ground once per revolution. The tine may be carried in a holder (32, Fig. 4) in a working position permitting deflection of the tine but being movable to a non-working position allowing lateral movement of the tine into and out of the holder. <IMAGE>

Description

SPECIFICATION Tine assemblies A device for scarifying or raking a lawn is already known which consists of two or more rows of radially disposed tines positioned symmetrically and helically about a central horizontal shaft. When the shaft is rotated, the tines describe a cylinder, the tines being forced through the surface of the turf to a depth which can be pre-adjusted. The tines are preferably flexible while being sufficiently stiff to ensure adequate scarification. Each tine may be provided, for example, by one end of a torsion spring.

One problem which is likely to occur with such devices is that of a tine becoming deformed or broken. For this reason it would be an advantage if the tines could be easily replaced. However, in the known devices, the springs are mounted on pins or axles so that only limited contraction of the spring is possible in response to an impact on the tine.

Moreoever, the known device is limited to scarifying or raking turf. Since a lawn generally requires this type of scarifying or raking treatment only occasionally, it would clearly be an advantage if a single machine could perform both conventional grass cutting as well as turf scarifying and/or raking.

In accordance with one aspect of the present invention there is provided an attachment for fitting to a cylindrical cutting reel of a lawn mower, the reel having means supporting at least one helical blade for rotation about a central axis, and the attachment comprising a flexible tine integral with or attached to a support member, and means for releasably engaging the support member with the blade support means of the cutting reel such that, when the reel is rotated, the tip of the tine engages the ground once during each revolution.

The blade support means of the cutting reel will normally include a central shaft carrying axially spaced spiders to which the blade or blades are riveted. The tine support member may then include a hub portion formed as a clip for clipping to the central shaft of the cutting cylinder. A further portion of the support member preferably abuts the, or one of the, helical blades when the reel is rotated so that the attachment is driven by the helical blade for rotation with the shaft.

In practice a set of these attachments could be sold as a kit for converting a cylinder lawnmower to a rake or scarifier. The tines of the successive attachments would be progressively staggered around the central shaft and would lie on a helical path.

Each support member may carry more than one tine so that successive members form successive sets of tines and, in which case, the corresponding tines in each set preferably lie on respective helical paths.

The tine preferably comprises one end of a metal coil spring, but may alternatively comprise, for example a metal or plastic cantilevered beam spring. The beam springs might extend, for example, from a metal or plastic tube releasably secured to the spiders along the central shaft.

In accordance with a further aspect of the present invention there is provided a tine assembly for a scarifier or raking device, the assembly comprising a tine and a tine holder, the tine being normally retained by the holder in a working position permitting deflection of the tine in a given plane but being movable out of its working position to a predetermined non-working position permitting lateral movement of the tine into and out of the holder.

The tine is preferably releasably retained in a sleeve holder, the tine being released from its holder in response to rotation of the tine into a predetermined position permitting axial movement of the tine in the holder. For example, the tine may comprise one end of a coil spring and the sleeve may be split longitudinally so that the coil can be moved axially in the sleeve when the tine is aligned with the resulting slit in the side of the holder. The holder will then include means for retaining the other end of the spring such that the tine is normally held out of alignment with the slit, the coil being released by rotating the tine manually in the opposite direction to that in which it is normally urged when raking the ground. In this manner a defective tine is easily removable from its holder.

The hub may include a central bore for receiving a drive shaft, and several units may then be mounted on the drive shaft with the units being interlocked with one another and progressively offset from one another so that the tines lie on a halical path, one of the units being driven from the shaft so that the units rotate in unison with the shaft.

Each unit may include more than one sleeve holder and each holder may retain more than one spring. In particular each holder may retain a double coil spring, the inner ends of the two springs being joined and located in a recess in a wall of the holder.

Where each unit carries more than one spring so that successive units provide successive sets of tines, the corresponding tines in each set preferably lie on respective helical paths.

In order that the invention may be more clearly understood, two embodiments will now be described with reference to the accompanying drawings in which: Fig. 1 is an end view of a first tine assembly embodying the invention for attachment to the central spindle of the cutting reel of a cylinder lawn mower, Fig. 2 is an opposite end view of the assembly of Fig. 1, Fig. 3 is a front view of the assembly of Fig. 1, Fig. 4 is a perspective view of a second tine assembly embodying the invention, Fig. 5 is a front view of the double coil spring used in the assembly of Fig. 4, Fig. 6 is an end view of the double coil spring of Fig. 5, Fig. 7 is an end view of a carrier having four tine holders for receiving double coil springs as shown in Figs. 5 and 6, Fig. 8 is a front view showing a number of the carriers of Fig. 7 fitted with tines and mounted on a common shaft, Fig. 9 is a section on line B-B in Fig. 7, and Fig. 10 is a part section on line A-A in Fig. 9 shown with the tail of a double coil spring.

Referring first to Figs. 1 to 3, the illustrated tine assembly consists of a plastic moulding 10 housing a metal torsion spring 11.

The moulding 10 includes a C-shaped hub 1 2 designed to snap over the central spindle of the cutting cylinder of a conventional cylinder lawn mower, at least one helical blade being disposed about the spindle. Such cutting cylinders are well known and will not therefore be described further in the present ,pecification.

The plastic moulding 10 further includes two mutually perpendicalar webs 13, 14 which extend outwardly from the hub 1 2 and which merge to form a split sleeve 1 5 for receiving the torsion spring 11.

One end 17 of the coil is extended to form a tine. During insertion of the spring coil into the sleeve 15, the tine 1 7 is aligned with the slit 16.

When the tine 1 7 reaches the other end of the slit, the coil spring is rotated to the position shown in Figs. 1 and 2 with the tine 1 7 projecting outwardly from the sleeve and out of alignment with the slit 16. In this position the other end 18 of the coil spring 11 is located in a slot 19 formed in the web 14. The spring is thus anchored against rotation within the sleeve, but is able to contract within the sleeve should the tine meet substantial resistance when it engages the ground.

When the hub 12 is clipped on to the spindle of the cutting cylinder and the spindle is rotated in the direction shown by the arrows in Figs. 1 and 2, the moulding 10 will tend to rotate relative to the spindle due to the differential inertial force on the moulding as the spindle is accelerated. In addition, when the tip 1 8 of the tine 1 7 engages the turf, there will be an additional force tending to rotate the moulding about the spindle. As a result of these forces, the moulding 10 rotates about the spindle until the extended arm 19 of the moulding abuts one of the helical blades disposed around the spindle. Thereafter, the moulding 10 is maintained with the arm 1 9 abutting the helical blade, and the blade drives the moulding so that it rotates with the spindle.

Accordingly, when a number of these units are clipped on to the spindle, the tines 1 7 of the successive units engaging one of the helical blades will, in use, lie upon a helical path.

In practice, this means that the tines 1 7 will progressively engage the turf as the spindle is rotated in the same way as the helical blades progressively engage a fixed bottom blade of the lawn mower when the mower is being used in a conventional manner for cutting grass.

When fitted to a lawnmower the tine units thereby convert the mower to a powered lawn rake. The bottom blade of the mower is normally swung back and held by a retaining clip before the tine units are fitted. In addition, the chassis of the mower may be lowered closer to the ground, for example by removing front wheels of the chassis and replacing these with a front roller.

To provide a more secure attachment for the hub 12, an additional arm 20 may be provided as shown in dashed outline in Figs. 1 and 2. This arm 20 terminates in a ramp surface 21. The arm 20 has sufficient flexibility that the ramp 21 can be progressively forced beneath the bottom edge of the helical blade as the moulding 10 is rotated on the central spindle. Eventually a point is reached when the ramp 21 finally clears the bottom edge of the blade and the arm 20 then springs back into the position shown in Figs. 1 and 2 with the blade being trapped between the face 22 of the ramp 21 and the opposed face 23 of the arm 1 9.

Referring to the assembly of Fig. 4, this shows a cylindrical hub 30 for receiving a spindle, and three regularly spaced, radially extending arms 31 each terminating in a split sleeve 32. Each sleeve 32 retains a double coil spring 33, the inner ends of each spring 33 being joined together and retained within a recess in the respective holder 32, and the outer ends of each coil spring being extended to form respective pairs of tines 34.

By assembling a stack of these units on a common spindle and interlocking the successive units so that the arms 31 of one unit are progressively offset from the corresponding arms of the successive units, the respective pairs of tines can each be made to lie on respective helical paths. If the successive units are interlocked with one another and one of the end units is driven from the spindle, the stack of units may then rotate in unison to provide a powered scarifier or raking device.

Figs. 5 and 6 illustrate the double coil springs 33 in more detail and show the inner ends 35 joined to form a U-shaped tail 41 which is located in a recess of the sleeve holder.

Referring next to Fig. 7, this illustrates a similar assembly to that of Fig. 4 but having four split sleeve holders 36 for retaining coil springs of the types shown in Figs. 5 and 6.

The holders 36 form part of an integral plastic moulding having a central hub 37, the holders being offset with respect to one another along the length of the hub. Accordingly, when each holder is fitted with a double coil spring as shown in Figs.

5 and 6, the respective pairs of tines are offset with respect to one another in an axial direction.

The moulding consists of a generally solid block having webs 38 and ribs 39, each holder 36 having an opening 40 extending along its base for receiving the tail 41 of the double coil spring.

The sleeve holders are also split along the side so that the springs are easily inserted into the holders by first aligning the tails 41 with the openings 40 and then rotating the leading tine 34 until it is aligned with the side slot 42.

Fig. 8 shows a number of the units of Figs. 7 and 8 mounted on a spindle 43 to form a powered scarifier or rake. One of the units is driven by a spring roll pin which passes through the spindle 43. The other units are then driven in sequence from this end unit, the units being interlocked means of projections 44 on one unit engaging in corresponding recesses in the next successive unit, the arrangement being such that each of the tine pairs 34 are progressively staggered around the shaft 43 and lie on a helical path.

Advantageoulsy, the springs 33 are free to contract within the sleeve holders 36 when the tines 34 engage the ground while raking or scarifying. Moreoever, should any one of the tines become deformed or broken, it is easily replaced by rotating one of the tines 34 into line with the slot 42 and then sliding the coil axially out of its holder, the tail 41 being retained in the groove 40.

As shown in Fig. 10, the tail 41 is aligned with a recess 53 in the groove 40 when the double coil spring is fully inserted in its holder 36. The tail 41 is then urged into this recess by the working force on the tine during raking. This further assists in preventing axial movement of the coil spring in the holder when the spring is in its working position.

Claims (24)

1. An attachment for fitting to a cylindrical cutting reel of a lawnmower, the reel having means supporting at least one helical blade for rotation about a central axis, and the attachment comprising a flexible tine integral with or attached to a support member, and means for releasably engaging the support member with the blade support means such that, when the reel is rotated, the tip of the tine engages the ground once during each revolution.

2. An attachment according to Claim 1 in which the blade support means includes a central shaft and the tine support member is adapted for releasable engagement with the central shaft, a further portion of the support member abutting the, or one of the, heiical blades when the reel is rotated whereby the attachment is driven by the helical blade for rotation with the shaft.

3. An attachment according to Claim 2 in which the support member includes a hub portion formed as a clip for clipping to the central shaft.

4. An attachment according to Claim 3 in which the clip is generally C-shaped.

5. An attachment according to Claim 3 or Claim 4 in which the support member further comprises a first arm extending outwardly from the hub for rotation about the hub axis, the first arm carrying the tine; and wherein the said further portion of the support member comprises a second arm extending from the first arm generally perpendicular to the axis of rotation.

6. An attachment according to any one of the preceding claims in which the tine is releasably retained within a tine holder.

7. An attachment according to Claim 6 in which the holder normally retains the tine in a working position permitting deflection of the tine in a given plane, and in which the tine is laterally movable relative to the holder only when the tine is rotated from its predetermined working position to a predetermined non-working position.

8. An attachment according to any one of the preceding claims in which the tine comprises one end of a coil spring, and the tine support member includes means retaining the other end of the spring to prevent rotation of the coil relative to the support member when the tine engages the ground.

9. An attachment according to Claim 8 in which the support member carries a second tine which also comprises one end of a coil spring, the non active ends of the two coils being joined to one another and retained within the support member.

10. A kit-of-parts for converting a cylinder lawn mower to a rake or scarifier, the kit comprising a set of attachments according to any one of the preceding claims.

11. A tine assembly for a scarifier or raking device, the assembly comprising a tine and a tine holder, the tine being normally retained by the holder in a working position permitting deflection of the tine in a given plane but being movable out of its working position to a predetermined nonworking position permitting lateral movement of the tine into and out of the holder.

12. A tine assembly according to claim 11 in which the tine comprises one end of a coil spring releasably retained in the holder, the coil spring being axially movable in the holder only when the tine is in its non-working position.

13. A tine assembly according to Claim 12 in which the holder is a sleeve holder, the coil spring being released from its holder by rotating the spring and/or the tine until the tine is aligned with a longitudinal slot in the sleeve.

14. A tine assembly according to Claim 12 or Claim 13 further comprising means for retaining the other end of the spring to prevent rotation of the coil within the holder when the tine is in its working position.

1 5. A tine assembly according to any one of the Claims 12 to 1 4 further comprising a second coil spring retained within the holder, the inner ends of the two coils being joined to form a double coil and the outer end of the second coil extending outwardly from the holder to form a second tine.

1 6. A tine assembly according to any one of the Claims 11 to 1 5 in which the holder includes a hub which, in use, is mounted for rotation about a predetermined axis spaced from the tine.

17. A tine assembly according to Claim 16 in which the hub includes a bore for receiving a drive shaft.

18. A scarifier or rake comprising a plurality of tine assemblies according to Claim 17, the hubs of successvie assemblies being mounted for rotation about a common drive shaft.

19. A scarifier or rake according to Claim 1 8 in which the respective holders are interlocked with one another while being progressively offset from one another along the shaft such that the tines lie on a helical path, one of the assemblies being directly or indirectly driven from the shaft whereby the assemblies are driven in unison and rotate with the shaft.

20. A tine assembly according to Claim 16 in which the hub comprises a clip for clipping over the central spindle of a cutting cylinder for a cylinder lawn mower.

21. A tine assembly according to Claim 20 in which the clip is generally C-shaped.

22. A tine assembly according to Claim 20 or Claim 21 in which the holder further comprises means extending generally perpendicular to the axis of rotation for engaging a helical blade of the cutting cylinder when the hub is clipped to the said central spindle whereby the helical blade drives the tine assembly for rotation with the spindle.

23. A tine assembly substantially as herein described with reference to Figs. 1 to 3 of the accompanying drawings.

24. A tine assembly substantailly as herein described with reference to Figs. 4 to 10 of the accompanying drawings.