LIGHT FRAMES FOR MASS-PRODUCED BODIES.
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The Recently Patented Knibson Form of Body Construction Uses Armoured-plywood Pillars and no Cross-bearers.
/TIRE' body constructed almost entirely / of timber has two main disadvantages, namely, its heaviness in relation to its strength and the fact that it is extremely difficult to obtain truly standard timber parts for replacement and mass-production purposes. In the past, the user has had two choices other than the timber-built body; these are the all-metal and the fabric types. Whilst the ail-metal body has undoubted advantages in many ways, it is only economical when built in large quantities to one particular design. The fabric type of flexible body has not met with much popularity, owing to the fact .that its wearing qualities are not considered in many quarters to be equal to the strenuous conditions of public service, although for private work, of course, this kind of body has many supporters.
It will be seen from the above remarks that the user's demand has been for a body which may be ranked, as it were, between the all-timber and the allmetal types. With a view to meeting this
demand, W. Fl. Knibbs and Son, Ltd., Tipping Street, .Ardwiek, Manchester,' has conducted experiments with a new form of construction involving the use of armoured plywood. The result has been very satisfactory and may be seen in the Kriihson system of body construction, which has recently been patented by the company.
With this method, the framework is built up of armoured plywood and jointing is made in nearly all cases by means of bolts and nuts. The cross-bearers, as used in the normal kind of body, are not incorporated in the Knibson framework, this rendering the whole struc
ture very light. Moreover, the lightness is further enhanced by the fact that the pillars used are of very small section, being only -f-56 in. thick. Those employed in the vehicle illustrated on this page weigh only 1 lb. 12 oz., as compered with the 3 lb. 12 oz. of the lightest ash pillar that could be made for the purpose. Incidentally, this body, although fitted with luxurious seats weighs only 21 cwt.
In order to avoid the use of crossbearers, as mentioned above, the pillars are supported on armoured plywood brackets extending from the chassis frame, to which they are bolted. A gusset plate is used to connect the brac kets and pillars. AngIe-brackets and bolts carry the cantrails, the waist and bottom fails being dealt with in the same way, and the panels, although fixed to the normal points, are equipped with special jointing so that they can easily be detached.
The Kuibson framework is very strong transversely, but the body incorporating it is sufficiently flexible to allow for any normal chassis distortion, Inasmuch as the form of plywood used does not resist torsional and bending stresses in a longitudinal direction to any great degree. The thin gusset plates used are of reasonably thin-gauge metal and this, of course, also makes for increased flexibility, whilst the fact that the flooring is not directly connected to the body sides other than by a leather flap and that the seats are attached only to the floorboards must render the desired movement in the body extremely free.
The plywood used is completely metal-covered and thus it cannot be attacked by moisture. Further, this material is stable, so that' precision methods can be used in making the great majority of the parts. The actual machining operations consist, however, mainly of punching holes, which much simplifies the erection of the complete framework.
Economical advantages can readily he discerned even in a brief description of this form of construction and another point is the ready interchangeability of parts, this mainly appealing to the concerns which run large fleets, where rapid repairs to the bodies of the service vehicles may often be found necessary.