Roman Roller CC and Another v Speedmark Holdings (Pty) Ltd

• Jurisdiction: South Africa
• Judge: Corbett CJ, E M Grosskopf JA, Nestadt JA, Van Den Heever JA and Schutz JA
• Judgment Date: 22 August 1995
• Citation: 1996 (1) SA 405 (A)
• Docket Number: 502/93
• Hearing Date: 05 May 1995
• Counsel: J W Louw SC (with him C J van der Westhuizen) for the appellants. A B S Franklin for the respondent.
• Court: Appellate Division

Corbett CJ:

This is a patent case with a difference. In 1985 and on the E application of a company known as F A Pressings (Pty) Ltd ('FA Pressings') patent No 84/3606, entitled 'Conveyor Roller and Method of Assembly Thereof' ('the patent'), was registered. The inventor was stated in the application to have been Gyula Laszlo Roman. He is now the second appellant and in these proceedings the admitted infringer of the patent. F In the original application for a provisional specification made by second appellant (at the time a shareholder and director of F A Pressings) on 13 May 1983 he subscribed the usual declaration that to his best knowledge and belief, if a patent were to be granted on the application, there would be no lawful ground for its revocation. As I shall show, he now contends that the patent is invalid and seeks its revocation. It is common cause G that the priority date of the patent is 13 May 1983.

In 1986 the patentee's rights under the patent were assigned to Process Plant (Pty) Ltd, which in turn assigned them to Brelko Manufacturing CC in 1988. In 1989 and effectively from 8 December 1988 the latter assigned H its patent rights to Speedmark Holdings (Pty) Ltd (respondent on appeal).

In 1989 the respondent became aware of the fact that a close corporation, Roman Roller CC (of which the second appellant was the sole member and which is the first appellant in this appeal) was manufacturing and disposing of conveyor rollers which fell within the scope of certain of the claims of the patent and thereby infringed the patent. Consequently I the respondent instituted action in the Court of the Commissioner of Patents, citing first and second appellants as defendants and claiming interdicts and certain ancillary relief. The action was defended by the appellants, who admitted infringement of certain of the claims in the patent, but (somewhat remarkably) denied the validity of the patent and J counterclaimed for its revocation on the

Corbett CJ

A grounds that the 'invention' was not new, that it was obvious, and consequently did not involve an inventive step, and that its claims were not clear.

The case was tried by MacArthur J, sitting as a Commissioner of Patents. At the inception of the trial the appellants formally abandoned the B defence and ground of revocation based on lack of novelty. MacArthur J found against the appellants on the remaining issues of obviousness and clarity, granted the relief prayed by the respondent and dismissed the counterclaim with costs. He further granted leave to appeal to this Court. (The judgment of MacArthur J has been reported: see Speedmark C Holdings (Pty) Ltd v Roman Roller CC and Another 1993 BP 397.)

On appeal counsel appearing on behalf of the appellants advanced the same two grounds of invalidity and revocation. Before dealing with them, I shall describe the patent in more detail.

The patent D

Under the heading 'Background to the invention', the body of the specification opens with the words:

'This invention relates to conveyor idlers or rollers of the type adapted to support conveyor belts used in mining, industrial and like applications.'

E As this quotation indicates - and as was confirmed in evidence - 'idlers' and 'rollers' are alternative terms for the same thing. The specification then proceeds (I have for convenience of reference numbered the quoted passages from the specification):

'1.

Conveyor rollers generally comprise a rigid sleeve or drum which is rotatably mounted by means of suitable bearings on a shaft, the F shaft being supported in a cradle or frame which in turn is mounted to a foundation. Generally the sleeve is formed from a steel tube. Problems with steel or metal sleeves occur when the idler jams due to bearing seizure or for other reasons. When this occurs, the belt runs over a stationary idler causing the steel sleeve to heat up and wear away, resulting in the belt being damaged.

2.

Other problems arise when the conveyor is carrying uneven loads G which form a protuberance on the underside of the belt which impinges on the conveyor idler as the protuberance passes over the idler. This can cause denting of the sleeve as well as jolting and possible damage to the bearing assembly.

3.

Further problems with conventional rollers occur because the outer surface of the sleeve is not absolutely concentric with the axis of rotation. Rotation of an eccentric roller causes rapid H deterioration of the bearing assembly as well as the setting up of harmonic vibrations in the belt. Also, because the steel sleeve is smooth, the belt will tend to "wander" relative to the idler which is considered undesirable.'

The specification then describes attempts to alleviate 'at least some' of these problems. These attempts have consisted in the development of I conveyor idlers formed of or having an outer cover of rubber or soft plastics, which absorbs some of the shocks to which the idlers are subjected. In this connection certain British patents are referred to, more particularly British patent No 1076499 which describes a roller having a cylindrical drum covered with a 'rubber sleeve'. But with rubber or 'like synthetic plastics materials such as polyethylene' there are, J according to the specification, other problems in that -

Corbett CJ

'4.

A . . . once the roller jams, the relative movement between belt and stationary roller causes rapid breakdown of the cover, eventually leading to damage to the belt. Also, such materials tend not to be dimensionally stable, and as soon as an eccentricity occurs in the roller, further rotation causes rapid deterioration of the eccentric condition.'

B The specification states that the object of the invention is to provide a conveyor roller which runs smoothly and which has superior wear or operational characteristics 'in at least some applications'. The invention is described thus:

'5.

According to the invention there is provided a conveyor roller comprising a drum rotatably supported on a shaft by a bearing assembly, the drum comprising a right circular cylindrical tubular C inner sleeve formed of metal, and coaxial right circular cylindrical outer sleeve formed of a hard, wear resistant, plastics material. Preferably the hard plastics sleeve will be self supporting and the metal sleeve will be formed of thin steel tube.

6.

Further there is provided for the plastics material to have self lubricating characteristics. Specifically it is envisaged that the D plastics material will have physical characteristics similar to that of rigid polyvinyl chloride (rigid PVC), polypropylene, or high density polyethelene.

7.

Further there is provided for the outer surface of the drum to be machine turned such that the axis of the outer surface is concentric with the axis of rotation of the roller. During turning a fine helical groove or a plurality of concentric circular grooves may be E cut into the outer surface of the plastics sleeve, along substantially the entire length of the sleeve. The fine groove will not materially affect frictional resistances to movement tangentially to the sleeve but will increase frictional resistance to movement parallel to the axis of rotation of the idler.

8.

The bearing assembly by means of which the drum is supported on the shaft may comprise a pair of roller bearings preferably mounted in F end caps formed of a hard plastics material. The plastics material of the end caps may be a nylon 66 derivative and will preferably be moulded to the required shape. The shape may include a ribbed formation.

9.

It is envisaged that the plastics material of the sleeve will have characteristics substantially as follows: G

mass density:	1350-1460 kg/m3
heat reversion:	less than 3,0%
specific heat capacity:	0,85- 2,10 kJ/kg
vicat softening point:	82-85°C
tensile strength @ 20°C:	56 MPa (at yield)
modulus of elasticity:	3,2 GPa
comprehensive strength:	80 MPa.' H

(It was common cause that the word 'comprehensive' was an error and should read 'compressive'.)

'10.

Further there is provided for the polymeric sleeve to comprise a length of rigid PVC piping which during assembly of the idler is heat shrunk onto the metal sleeve. This material is suitable as it has a I low coefficient of friction with a conveyor belt.

11.

It will also be possible for the plastics sleeve to have electrically conductive particles interspersed there through which will assist in reducing electrostatic build-up on the roller in use.

12.

The end caps may be press-fitted into the drum or alternatively may be screwed into thread formations formed on the inner surface of the J drum.'

Corbett CJ

A The specification then proceeds to describe a method of assembling such a conveyor roller. This consists essentially of what is referred to as heat-shrinking (see passage 10 above). The plastic outer sleeve is heated to a condition of 'slight plasticity'; the inner (steel) sleeve and the outer sleeve are placed end-to-end in a coaxial relationship; the outer B sleeve is urged over the inner sleeve so that they form a single composite drum; and the composite drum is then allowed to cool. Other methods described relate to the shaving of the outer surface of the outer sleeve to achieve concentricity; the cutting of circular or helical grooves into the outer surface of the outer sleeve; an hydraulic ram for urging the outer sleeve over the inner sleeve.

C The specification includes certain drawings, which are fully described in the body of the specification and descriptions of preferred embodiments of the invention. I shall return to some of these descriptions later.

The specification concludes...