240,882. Vickers, Ltd., Clark, W., and Sumpter, C. L., April 12, 1924. Hardening. - In the heat treatment of steel articles, especially for railway and tramway vehicle wheel tyres, the articles are heated to above the hardening temperature and the parts to be hardened are quenched successively and progressively by a jet or jets of water, preferably at a number of different circumferential parts simultaneously, and during this operation jets of water are caused to play on the quenched portion or portions to prevent re-heating. The quenching may be done by. inclined moving or stationary nozzles or by a combination of the two. As applied to the quenching of a tyre, the tyre a, Fig. 1, is quenched by inclined nozzles b fed by a fixed circular pipe b<1>, the nozzles being arranged in series 1-6 as indicated in Fig. 2. To prevent splashing of the water, guards c, c' are fixed as shown, a space c<2> being left between them to allow of the passage of the water from the jets b. The jets 1, 1 are allowed to impinge on the tyre first, then those marked 2-2 and so on until those marked 6-6 are in operation when all the 48 jets are acting on the tyre. In order that the jets may operate in this manner, a plate f is mounted outside the guards c, c<1>, its upper edge being formed as shown in Fig. 4 in a double step-like manner in four equal parts of its circumference, in which the width of the lowest step is such as to allow two jets g of water to pass through and the upper step is of the same width, the intermediate steps being of a width sufficient to allow one jet to pass through so that as the plate f is lowered a distance equal to the height of a step two jets 6-6 side by side are allowed to pass through, and when again lowered a similar distance two more jets, one on each side, are allowed to pass through so that at each downward movement of the plate eight jets are allowed to operate on different parts of the tread of the tyre. For the lowering of the plate, the plate f is mounted on four equidistant screwed supports f<1> working in screw boxes and geared together by chains f<3>, one of the supports f<1> being operated by a ratchet and lever h. In order that the jet of water may issue as a comparatively rigid rod of water which when it strikes the type a will flow smoothly over the surface, the nozzle is formed of glass tubing drawn in the shape shown in Fig. 5. To deflect the water sprayed on the tyre away therefrom, adjustable plates d, d' are mounted so as to fit the tyre circumferentially, packing being interposed between the plate d<1> and the tyre. To secure the plates lightly against the tyre, they are provided with overlapping ends, the ends of the plate d<1>, Fig. 6, being secured to pivoted levers d<2> by lever arms d<3> so that they can be drawn together. The plates d are connected in similar fashion by arms d<4> to the levers d<2>. The plates d, d' are also supported in a suction chamber e having an outlet pipe e<1> so that any water passing between the plate d and the tyre a is immediately removed by the pipe e<1>. In a modification, Fig. 9, in which rotary jets are combined with stationary jets as shown in Fig. 1, the quenching is first done by jets j, j<1> of the same size and form as the jets b. The jets j, j<1> are carried by rotary brackets k, k<1>, one mounted above the other, and are supplied with water by flexible pipes. In the initial position the nozzles j, j<1> are arranged as shown, and the brackets k, k' are rotated in opposite. direction so that the adjacent nozzles j, j<1> are gradually separated and approach the other nozzles j, j<1> moving in the opposite direction until the sections quenched meet or overlap. The jets j, j<1> may travel in steps or continuously, and the stationary jets b may operate so that after the jet j, j<1> a stationary jet immediately comes into action preferably by operating the plate f by the gears operating the brackets k, k<1>. In dealing with small articles a travelling jet with other jets to prevent re-heating the quenched portion may be used, or where stationary jets are employed they may be allowed to operate successively throughout the whole series.