GB2384160A

GB2384160A - A rotary implement

Info

Publication number: GB2384160A
Application number: GB0229939A
Authority: GB
Inventors: Christopher Martin Lole
Original assignee: Spearhead Machinery Ltd
Current assignee: Spearhead Machinery Ltd
Priority date: 2002-01-18
Filing date: 2002-12-20
Publication date: 2003-07-23
Anticipated expiration: 2022-12-20
Also published as: GB0229939D0; GB2384160B

Abstract

A rotary implement comprises a rotor 1 , a rolling element bearing 10 to support the driven end of the rotor 1 and a mechanical coupling (9) mounted concentrically to the said rolling element bearing 10 to connect the rotor 1 to a rotary drive. Together, the torque transmission surfaces of the coupling 9 and of the rotary drive define a feed channel which conducts lubricant to the said surfaces and either to or from the rolling element bearing.

Description

DESCRIPTION "A ROTARY IMPLEMENT" The present invention relates to a rotary implement and is concerned with the provision of lubrication to the power input bearing thereof. More specifically, it relates to a flail cutter such as is commonly used for hedge and verge trimming, and the maintenance of grassed areas in which flails extend from a rotor which is driven at one end by a coaxial motor, such as an hydraulic motor.

In a flail cutter of the aforementioned type it is general practice to provide rolling element bearings at each end of the rotor, and to connect the motor drive shaft to the rotor with a spline coupling. Generally, the casing of the drive motor is attached to the frame heading of the flail cutter and the same frame heading encases the outer race of a rolling element bearing on which the rotor turns.

In such an arrangement both the spline coupling and the rolling element bearing have to be lubricated at regular intervals during service. The known method of supplying such lubrication is by way of a channel drilled through the frame heading into one side of the space in which the bearing is located. Since one end of the spline coupling is in the same space, lubricant can reach both components on injection. Normally, excess lubricant escapes from the space at the side of the bearing opposite to that from which the lubricant is injected in. In fact lubricant in the system tends to move to and through the rolling elements of the bearing because of centrifugal effects.

It is often found that in working conditions the spline coupling and/or the

associated bearing wears out prematurely even if the operator follows correct maintenance procedure. Thus, experience shows that with known arrangements for providing lubrication the supply of lubricant to the coupling and/or the bearing can be inadequate or unequal.

It is an object of the present invention to provide means for distributing lubricant to the bearing and coupling of a rotary implement such that each receives an adequate supply thereof, given normal maintenance procedure.

According to the present invention there is provided a rotary implement comprising a rotor, a rolling element bearing to support the driven end of the rotor and a mechanical coupling mounted concentrically to the said rolling element bearing to connect the rotor to a rotary drive, wherein together the torque transmission surfaces of the coupling and of the rotary drive define a feed channel conducts lubricant to the said surfaces either to or from the rolling element bearing.

Preferably, a space or lubricant reservoir is provided for the supply of lubricant to the torque transmission surfaces and to the rolling element bearing.

Preferably, the volume of this space is at least comparable with the free space within the rolling element bearing.

In a preferred embodiment of the invention the lubricant reservoir is integral with the said coupling and is located upstream thereof with reference to the normal flow of lubricant.

Preferably, the feed channel/lubricant reservoir is connected to a filling connection located on the outer surface of the rotor.

Preferably, a seal is provided on the downstream side of the said rolling element bearing. The seal allows excess and spent lubricant to escape from the bearing whilst preventing water and other contaminants reaching the bearing.

Conveniently, the rotary implement comprises a frame heading which facilitates attachment of the rotary implement to a rotary drive and an annular gap is provided between the frame heading and the rotor through which excess and spent lubricant escaping past the rolling element bearing can pass out of the rotary implement.

The junction between the face of the casing of the rotary drive and the corresponding face of the frame heading may be adapted to prevent access between the junction faces of water, foreign material or air to the space between the coupling and the bearing.

In the rotary implement according to the preferred embodiment of the invention the supply of lubricant to the bearing is substantially equal to that to the mechanical coupling because lubricant must pass through the mechanical coupling to reach the bearing. Each time lubricant is injected at periodic maintenance the space upstream of the coupling is filled to provide a reserve during the subsequent operating period.

Preferably, the mechanical coupling is a splined coupling. Conveniently, that portion of the mechanical coupling positioned concentrically to the rolling element bearing is internally splined.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing which shows a cross sectional view of a rotor implement in accordance with the present invention, together with a side elevation of part

of a drive motor separated from the rotary implement for clarity of explanation.

Referring to the drawing there is shown the end of a cylindrical rotor 1, being a component of a cutting head. For simplicity and ease of understanding, projections from the outer surface of the rotor 1, which would, for example, carry cutting flails, have been omitted from the drawing. On the centered axis of the rotor 1, but separated longitudinally from it for clarity, is an hydraulic drive motor 2, the drive shaft of which terminates in a male splined drive coupling 3. A bearing housing 4 at the end of the cutting head facing the motor 2 includes a surface to which the motor 2 is bolted on assembly thereto.

The bearing housing 4 also includes a generally cylindrical portion 5, which is concentric with the cylindrical rotor I but separated from it by a small clearance 6.

A plate 7 is secured across the inside of the rotor 1 and a hub 8 is bolted to the plate 7 (only one of a number of bolts being shown in the drawing). The axis of the hub 8 is coincident with the axis of the rotor 1. A female splined drive coupling 9 to match the male splined coupling 3 is present inside the hub 8. The hub 8 is supported in the cylindrical portion 5 of the bearing housing 4 by a rolling element bearing 10 with which is associated a bearing seal 11.

A hole or feed duct 12 is drilled radially in the plate 7, and is fitted with a greasing nipple 13 flush with the surface of the rotor 1. The hole 12 communicates with a hole 14 drilled axially in the plate 7 to communicate with a space or cavity formed at the inner end of the hub 8.

It can be seen that, given the motor 2 is assembled to the bearing housing 4 with

the male side 3 of the coupling engaged in the female part 9 of the coupling, injection of grease into the nipple 13 fills the inside of the hub 8, where it forms a reservoir of grease.

In a splined coupling the diameters of the convex and concave cylindrical surfaces differ by a small amount because of manufacturing tolerances. Moreover, the widths of the spline flutes and teeth provide some circumferential clearance. Consequently when the coupling is transmitting a drive torque (i. e. when the coupling surfaces are pressed together) each such drive contact surface is adjacent to a flute space or channel extending through the coupling. As further grease is injected grease passes along the channels formed between the male 3 and female 9 parts of the drive coupling, thus lubricating the drive transmitting surfaces thereof. It then passes out beyond the coupling and into the space inside the bearing housing 4, leading to the rolling elements of the bearing 10. As the grease advances during the initial operation, air is displaced through the seal 11.

Further supply of grease under pressure results in it passing the seal 11 into the space communicating with the sleeve gap 6 at the end of the rotor 1. The seal 11 is adapted to allow grease under pressure to pass in the direction described, but it prevents water, dust and foreign material in the sleeve gap 6 reaching the rolling elements of the bearing 10.

When the flail cutter is in operation and the rotor 1 is rotating grease inside the hub 8 is carried with the hub 8 and pressed centrifugally against its cylindrical wall exerting hydrostatic pressure at the ends of the splines of the coupling components 3 and 9. Grease in the space at the motor ends of the splines is in a state of shear between stationary surfaces and surfaces in motion as part of the rotor assembly. Hydrostatic

pressure at the motor ends of the splines will tend to be lower than at the grease reservoir in the hub 8. Lubricant therefore tends to flow from the grease reservoir in the hub 8 through the spline coupling towards the bearing 10.

Actual transference of grease in this way can occur providing there is escape of used and spent grease from the bearing 10 through the seal 11. Such transference of grease causes a void to appear in the reservoir volume in the hub 8. This void should draw in sufficient air to approach atmospheric pressure before the rotor next comes to rest, otherwise grease moving back into the void could be drawn away from the bearing 10. However, any air entrained in the grease will tend to migrate back into the void.

During regular maintenance grease injected into the nipple 13 replenishes the reservoir space in the hub 8.

Whilst the present invention has been described with reference to a rotary implement in which lubricant is conducted through the torque transmission surfaces to the bearings, it should be understood that the invention also envisages the possibility of lubricant being conducted in the opposite direction. In this alternative embodiment a lubricant reservoir is located beyond the bearings and lubricant is conducted from the reservoir firstly to the bearing and then through the feed channel defined between the torque transmission surfaces.

Claims

1. A rotary implement comprising a rotor, a rolling element bearing to support the driven end of the rotor and a mechanical coupling mounted concentrically to the said rolling element bearing to connect the rotor to a rotary drive, wherein together the torque transmission surfaces of the coupling and of the rotary drive define a feed channel which conducts lubricant to the said surfaces and either to or from the rolling element bearing.

2. A rotary implement according to claim 1, further comprising a space or lubricant reservoir.

3. A rotary implement according to claim 2, wherein the volume of this space is at least comparable with the free space within the rolling element bearing.

4. A rotary implement according to claim 2 or 3, wherein the lubricant reservoir is integral with the said coupling and is located upstream thereof with reference to the normal flow of lubricant.

5. A rotary implement according to any preceding claim, wherein the feed channel/lubricant reservoir is connected to a filling connection located on the outer surface of the rotor.

6. A rotary implement according to any preceding claim, wherein a seal is provided on the downstream side of the said rolling element bearing.

7. A rotary implement according to any preceding claim, wherein the rotary implement comprises a frame heading which facilitates attachment of the rotary

implement to a rotary drive.

8. A rotary implement according to claim 6, wherein an annular gap is provided between the frame heading and the rotor through which excess and spent lubricant escaping past the rolling element bearing can pass out of the rotary implement.

9. A rotary implement according to any preceding claim, wherein the mechanical coupling is a splined coupling.

10. A rotary implement according to claim 9, wherein that portion of the mechanical coupling positioned concentrically to the rolling element bearing is internally splined.

11. A rotary implement substantially as hereinbefore described with reference to the accompanying drawing.