Veasey v Denver Rock Drill and Machinery Co Ltd

• Jurisdiction: South Africa
• Judge: De Villiers CJ, Wessels JA, Curlewis JA and Stratford JA
• Judgment Date: 09 October 1929
• Citation: 1930 AD 243
• Court: Appellate Division

Wessels, J.A.:

The plaintiff (appellant in this Court) instituted an action against the defendant company in the Transvaal Provincial Division for an interdict to restrain the defendant from infringing Union Letters Patent for rock-drill improvements Nos. 907/1921 and 942/1921, registered in the name of the plaintiff, as well as for damages and delivery of the rock-drills which in-fringe these patents. To this the defendant pleaded that both the Letters Patent are invalid because they were anticipated by public user and by previous specifications, and that they were not a proper subject-matter for a patent having regard to the common knowledge at the time they were taken out. The court below gave judgment for the defendant with costs. It is from this judgment that the plaintiff now appeals.

The defendant challenged the validity of the patents; in order to see whether this challenge has been made good we must understand the exact nature of the improvements to the Leyner type

Wessels, J.A.

of drill claimed by the plaintiff. When these patents were taken out there was a standard drill in use on the Rand mines which had been invented by one Leyner. His patent had expired, and almost all the manufacturers of rock drills adopted his pattern., varying it in minor details. of these drills there were several thousands on the Rand. The characteristic of this drill is that it cleans out with both air and water the chippings and rock dust in the holes as they are being drilled. It was a very efficient drill. Mr. Veasey, in a paper read by him to the South African Institute of Engineers in May, 1924, says that this method of simultaneously applying air and water both under pressure proved to be remarkably efficient from a purely mechanical point of view, and he points out that in July, 1919, at the Crown Mines, a hammer drill of the Leyner type, viz., the Holman Torpedo Sinker, put up the world's record of shaft-sinking of 310 feet in one month of thirty-one days. I shall endeavour to describe in language as free from technical terms as I can the essential parts of the Leyner type of drill in use on the Rand in 1918. The motive force is compressed air. In its general form the drill may be said to be composed of four essential parts. There is first a cylinder in which works a 'piston. Just as the piston of a steam engine has a piston rod which enables a wheel to turn and thus do the required work, so this piston has attached to it a solid rod called the nose, which acts as a hammer and does the work of drilling. The piston and the nose are all in one piece but of different diameters. The larger diameter runs in the cylinder and is the piston proper. It is hollow and rifled. The compressed air, by a valve arrangement, first enters the rear of the cylinder and pushes the piston with its nose piece forward to strike the blow: it then enters the front of the cylinder and drives the piston back again. The space between the rear of the cylinder and the rear of the piston is called the rear chamber of the cylinder, and the space between the front of the piston proper and the front cover of the cylinder is called the front chamber of the cylinder.

The next essential part is the front cover of the cylinder. This also is cylindrical and in it runs the nose part of the piston or' hammer which strikes the steel drill tool that does the actual boring of the 'hole. I will describe this nose more fully later.

Wessels, J.A.

The third essential part is the chuck. This consists of two parts, an outer cylindrical part fixed to the front cover of the cylinder, called the chuck casing, and an inner cylindrical part called the chuck sleeve, which can be made to rotate inside the chuck casing. It is this chuck sleeve which holds the upper end of the tool called the tool shank.

The fourth essential part is the tool, or steel. This is the part which does the chipping and makes the hole. It has a hole running down its axis. Through this hole pass air and water. The nose of the piston is fluted, whilst there are projections in the chuck sleeve which fit into the flutes or grooves of the piston nose. When these two engage they form, as it were, one, and when on its backward stroke the piston rotates, the chuck sleeve rotates with it, and as it holds the tool the latter also rotates. This rotation is effected by means of a rifled rod which runs in the hollow piston and engages corresponding rifling in the latter. There is a hole running through the whole machine and in this hole is a tube through which water is supplied to the front of the tool where the chipping takes place. The water runs through the rifled steel rod in the hollow part of the piston, through the piston nose and enters the hollow of the tool. The modus operandi is as follows. The compressed or live air, as it is often called, drives the piston forward. Without rotating it strikes a blow against the shank of the tool. It acts in fact as a hammer. The live air by a valve arrangement then drives the piston back and on its backward stroke it rotates'. This is brought about by a ratchet contrivance. Meanwhile water flows down the tube and mingles with the live air that comes from the chuck cavity into the hollow of the tool. As this chuck cavity plays such an important part in this case I shall describe it fully. In the Leyner type of machine, as used on the Rand in 1918, the flutes passed into the front chamber of the cylinder, and when on the backward stroke the live air forced the piston back, some of this air escaped down the flutes and came into an open space between the point of the nose or hammer and the shank of the tool (chuck cavity). Thence it passed down the hollow of the tool to the spot where the rock was being chipped. As the piston with its nose must move through some space in order to strike a blow against the tool, there must necessarily be a space between the point of the

Wessels, J.A.

nose and the end of the tool shank. In some of the machines in use there is a loose cylindrical piece of steel lying in this space called a tappet, but we will at present deal with the machines which have no tappet. Now this open space in the chuck sleeve is called the chuck cavity. The water passing through the axial tube and through the rotating hollow tool washes out the chips and fine dust caused by the bit of the tool, and the compressed air passing down and round the hollow tool from the chuck cavity aids the cleaning out of the hole. This is why the Leyner type of rock drill is described in Veasey's specification No. 942 in 'the following terms: "A machine of the kind in which water is passed, as by means of an axial water tube into the rear end of the hollow drill tool." Leyner's whole idea was to get as much air down the hollow tube to mingle with the water as was feasible and so to clear out the hole as quickly and completely as possible. Hence the extreme efficiency of the machine. But its very efficiency was in another direction its curse, so that it came to be called the deadly Leyner. Miners' phthisis, the enemy of the Rand miners, is caused by the very fine dust particles which result from the drilling of holes in- the rock. At first it was thought that the fine visible particles of dust which could be retained by the sugar test alone caused miners' phthisis, but later medical investigations showed that there were still finer and invisible particles, undetected by the sugar test, which were more serious in causing-miners' phthisis. As water was freely used in sludging out the holes, it was difficult to account for the microscopic particles of dust revealed by Sir Robert Kotze's konimeter. A suspicion arose that the microscopic particles were sent into the air in the bubbles caused by the vigorous blast of air mingling with the water in the hole. This suspicion proved afterwards to be well founded, and it became known that the more efficient the machine, the more invisible dust it produced. It was, however, against the interest of rock drill contractors to decrease the efficiency of the machine by diminishing the air or cutting it out. There is evidence upon the record that this theory of invisible dust was not acceptable to all drill contractors, and some years elapsed before the Mines Department took action in the matter and compelled rock drillers to cut off all air. In the meanwhile, however, the Chamber of Mines became interested, and many tests

Wessels, J.A.

were made with the Kotze konimeter in all the mines on the Rand. Mine managers began to experiment and to see how the dust conditions could be improved and miners' phthisis reduced. The appellant had attended a lecture on this dust problem, and from what he saw and heard at the lecture he set about to endeavour to reduce the fine particles of dust in the air. This is what he says: "If the Leyner was going to be proved deadly, the industry would be deprived of the use of its most efficient machine. I set about immediately to study the drill and see how we could convert it to change over from Leyner's method of sludging with air and water mixed, or co-mingling, to water only without buying a new drill, because I think the industry had about 3,000 in use at the time."

Upon that he took out patent 199 of 1918. This is not one of the patents directly involved in this case, though we shall have to deal with it in order to understand the patents challenged, The two patents involved in this case are Nos. 907 of 1921 and 942 of 1921. The patent 907 is for the purpose of effecting certain modifications of or improvements in an invention for which the plaintiff had obtained a patent in 1918 known as No. 199 of 1918.

In the specification for this patent (No. 199) the patentee states that his invention relates to rock drills, and that the object of the- patent is to minimise the formation and dissemination of injurious dust. This he proposes to do by...