A TRAILER WITH . STEERABLE REAR WHEELS.
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A Resume of Recently. Published Patent Specifications.
NOT many inventions emanate from Holland, so the J.'11 trailer of the Naamloore Vennootschap Truch and Trailer Co., of Amsterdam, No. 242,932, is particularly interesting. The drawing shows the trailer, the motor vehicle being only shown in part on the left. Unfortunately
the specification is not very clear, the pivot which connects the trailer to the motor not being shown. We presume, however, that it is situated where the trailer rests on the motor vehicle.
The rod which extends towards the left is connected to the steering of the tractor and transmits movement to the rear wheels of the trailer by means of the vertical lever shown. This lever reverses the movement and carries it, by means of the rod shown, to the rear wheels of the trailer. We presume that these wheels are provided with steering heads similar to those used on front wheels, but no such heads are shown.
The inventors claim that the arrangement allows of steering of the rear wheels of the trailer, whether it is travelling in a forward or backward direction. A further claim is that the arrangement is not affected by the swing of the trailer. Both these claims seem to offer useful advantages, but it is unfortunate that the specification does not make matters clearer.
A Simple Method of Grinding Gear Teeth, A SIMPLE means of forming the emery wheels for grinding gear teeth is shown in specification No. 242,712, by Sylvain de Jong, of Antwerp. This invention applies to that class of grinding where a wheel of a certain form imparts the desired shape to the tooth, and not to that class of grinding where a rolling or developing movement of the wheel produces the form of the tooth. The upper and lower left-hand views show the process of forming the wheel to the exact desired shape on both sides.
The mandrel, on which the wheel to be ground is placed, Is temporarily removed, and is replaced by a mandrel carrying a forming disc or template at one end and a universal joint at the other end. To this joint is attached a lever, this at its middle carries a diamond and at its farthest end a follower, which rests on the cam portion of the disc, which imparts the right path to the diamond. The upper right-hand view is of a gear being ground on one side of its teeth by means of the formed emery wheel. In o u r opinion the former is shown on the wrong side of the follower, as any deviation from the path of the template would result in removing too much from the emery wheel, whereas if the follower were on the Opposite side of the cam it would
be impossible for the operator to deviate from the form set down, so long as he kept on turning away with his diamond until it would not cut any more.
A Short-wheelbase Tractor.
HWHITBY, in specification No. 248,155, shows a form
• of tractor which, he says, is particularly suitable for the type of six-wheeled vehicle in which a semi-trailer is used. To increase the load-carrying space without increasing the overall length of the vehicle he makes the tractor shorter than usual by placing the gearbox behind the rear axle. Several designs are shown, all of which tend to shorten the tractor.
Several Springs to a Valve.
JOHN A. PRESTWICH, of London, in his specification No. 244,811. shows a number of springs arranged round a valve stem and one central spring which holds the valve guide in place. By this means the load is distributed over a plurality of springs, which are, therefore, subjected to moderate stress only, and it is claimed that their life is considerably lengthened. The use of a split cone on the valve stem is mentioned in connection with the spring carrier.
A New Form of Valve Spring, JOHN MARSTON and J. E. Greenwood, both of Sun
beamland, in their specification No. 242,764, show a departure from the usual form of valve spring, which they describe as of the " mousetrap " type. The illustration makes the invention so clear that no further description is needed. We notice, however, that mention is made of the fact that this spring is prevented from moving round the valve stem. If this be the case we may presume that the valve will not creep round,, as most teethes have been allowed to do—a movement which has always been looked upon as an advantage, as it has kept the wear on the stem and the seating even all round.
A Novel Side Window.
HENRY ARTHUR LAMPLUGH, in specification No.
248,526, claims to have designed an improvement in the side windows of motor vehicles. He says, and truly, we think, that the ordinaey side window is but a poor ventilating device, and that it often introduces air in the form of a draught, which blows directly on the passengers, and that this is not the correct way to ventilate a vehicle.
He further points out that, if foul air be extracted, fresh air will find its way into any chamber from a number of sources; consequently, the passenger will not feel a draught, as is the case where the incoming air blows straight on him, therefore he arranges for the window to be pivoted vertically at the front and to open towards the rear. It would seem that the window might be a danger to passing vehicles, but there should be no need for it to extend at such a wide angle, as a very slight deviation from the line of the side of the vehicle would be sufficient to extract foul air.