IMPROVING A MECHANICAL TIPPING GEAR.
Page 22
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A New Engine Attachment Employed in Conjunction with the F.W. Cear.
(\E N of the most interesting of the mechanical threekJ way tipping gears is that constructed by F. Walters and Co., of Albert Street, Rugby, and known as the F.W., this being made in various sizes suitable for loads ranging from 30 cwt. to 8 tons.
It is of the two-stage serew type, a short squarethreaded screw forming a sleeve within which works a secondary screw. The outer screw forming the sleeve is not threaded internally, as is-done in some cases, but is provided with a phosphor-bronze nut which carries the smaller screw.
The foot of the large screw is mounted in a spherical support known as the footstep, anti this is mounted in and driven by a spherical housing, the upper half of which is formed in one with a phosphor-bronze worm wheel, whilst the lower half is constructed of hardened steel and extended to form the cone of a ball race.
The drive between the spherical housing and the footstep is effected by the employment of special keys of an unusual shape, each key being formed as half a ball at one side and a segment of a ring at the other, the surface of this segment having a radius equal to the distance between the centre of the footstep and curved grooves or keyways in the housing, the arrangement being such that the footstep can, be inclined to the housing at any angle required by the lift and yet he driven quite smoothly.
The worm gearing is carried in a stout casing in the lower part,of which is a hardened steel cup, and balls are inserted between this cup and the cone at the bottom of the spherical housing, -thus forming a thrust race upon which the load of the body is carried. The chief alteration in the gear lies in the method of driving it from the engine. Formerly, this was effected by opposed bevel gears, a driving pinion being meshed with one or other of these gears, according to whether it was, desired to raise or lower the body. 1n the latest form the driving attachment consists of a longitudinal shaft having at its rear end the worm of the ,tipping gear and at the other end a chain sprocket froni, -which a chain passes to an intermediate shaft. The driving sprocket on the. last-named has secured to It a pinion around which can swing a casing carrying two other pinions, one of these being in mesh with the sprocket-driving pinion and the other in Mesh with its fellow in the casing.
When it is required to raise or lower the body, one or Other of the secondary pinions is brought into mesh with a bronze pinion on the clutch shaft, thus giving a forward or reverse motion as is required. The bronze pinion and its sleeve on the clutch shaft are split right through so that they can easily be attached by means of two clamp% each having two bolts.
The arrangement may appear somewhat complicated, but in actual practice it is quite simple, and being strongly made there is very little that can get out of order, particularly as the whole of the gearing is, normally, enclosed, although shown open in our illustrations.
The control is by one lever from the cab, and this is moved to one side or other of its neutral position for lifting or lowering, but at the extreme positions of the body it is locked in neutral so that the movements cannot be exceeded, although capable of being reversed. The angle of tip to the side is 45 degrees, and theexcellent angle of end tip afforded can clearly be seen from our view of the complete machine. This, incidentally, is a new 5-ton Berliet, which, with tipping gear, body and cab, Is priced at £635. The prices of the tipping gear alone are as follow :—G-ton, £52; 4-ton, £42; 21-ton, £34; 30-cwt., 125; the engine attachment being £15 extra in each case.