Patent GB-804403-A (GB)
Title: Power lawn mower
IPC: A01D34/63
Filed: 1956-09-28
Abstract: 804,403. Lawn mowers. SUNBEAM CORPORATION. Sept. 28, 1956 [March 28, 1956], No. 29714/56. Class 6(3). [Also in Groups XXIV and XXXVI] A cast aluminium mower body has a peripheral flange 22a forming a chamber, in which two pairs of cutter blades 55 are rotated side by side, with two side-directed outlets 28, Fig. 2, for the grass clippings. Each pair of blades is formed on the opposite ends of a single strip of metal, Fig. 17 (not shown) or, as shown, is pivotally mounted on a disc 54 by means of bolts 57 with the interposition of spring washers, Fig. 5 (not shown), so that each blade 55 normally extends radially. Deformations 54a, Fig. 2, of the two discs 54 form stops against which centrifugal force holds the blades 55 until they strike an obstruction. Non-circular central openings 58, Fig. 2, in the cutter discs 54 fit on to correspondingly-shaped ends of shafts 48, 50, Fig. 3, before welding, so that the pairs of blades are held at right angles to one another, Fig. 2. The cutter shafts 48, 50 are journalled in bearings 47 at the ends of sleeves 22e, 22f formed in the top wall 22d of the cutter chamber. Oil can be supplied to the sleeve interiors through horizontal passages, Fig. 6 (not shown), formed on the wall 22d and then through inter-connected vertical passages normally closed by pivoted covers 90 and formed in enlargements 85 on a flange 22c. On the upper flange 22c of the mower body, a bottom bearing- plate 66 of an electric motor shaft 64 and two cover plates 92 are bolted. The vertical shaft 64 of the electric motor carries two toothed wheels 72, 73 on either side of an interlocking washer, all clamped between two friction washers, Figs. 13, 14 (not shown), to form a slip coupling (see Group XXIV). Toothed belts 82, e.g. of rubber, connect the wheels 72, 73 to further toothed wheels 80 on the cutter shafts 48, 50. A one horsepower motor is said to rotate the cutters at more than 4000 r.p.m. Cooling air is passed up, from slots 98 in the top of the flange 22c, over the motor, by a fan 97 mounted on the shaft 64 and it passes out through a space 101 between the motor casing 63 and a rain-shield cover 100 (see also Figs. 10, 11 (not shown)) through which passes a rubber grommet 105 (see Group XXXVI) for gripping the electric lead to the motor. The land wheels, with rubber tyres 41, rotate on axle bolts, Figs. 7, 8 (not shown), each secured in any one of the holes in a vertical row of holes (according to the height required for the mower body and cutters) formed in brackets 31, Fig. 2, integral with the main casting. A leaf mulcher may be attached to the main casting by means of tapped holes 160, Fig. 2. The forked end members 110 of the handle, Fig. 3, are pivoted, on bolts 128 in the flange 22c, on either side of the mower and may be held by a latch, Figs. 1, 9 (not shown), in a vertical position for storage or may be swung to one side or the other of the pivotal axis for convenience in pushing the mower in one or an opposite direction and for obviating turning round of the mower. In one of the latter positions the latch may be used to hold the handle in place, for use on steep ground. The fork members 110 are bolted, together with a bracket projection for use in storing a coil of electric lead, Fig. 15 (not shown), to two tubes, welded side by side for part of their length, but bent apart at their tops to form handle bars. The electric lead passes up one of the tubes and a switch is housed between the two tube bends, Fig. 12 (not shown). The mower is electrically earthed by rings of stainless steel wire 150, Fig. 2, on diagonally opposed tyres 41, each set in a groove between treads, the ends of the wire passing through the tyre wall, Figs. 7, 8 (not shown) and through the wheel to contact the latter.