390 NEWNES PRACTICAL
reader to get together the neccssary components. If You have not yet commenced construction, the first thing to do is to get together an engine, gearbox, three wheels, and the front axle. From these components you can erect the chassis, leaving the superstructure until last. The chassis consists of 4 in. x 2 in. ash bearers, and the cross-members are of similar material. Many readers have asked about the cooling system. An opening is left behind the driving seat, as can be seen from the side elevation, so that an air scoop can direct a current of air straight on to the cylinders. This is simple and certainly efficient, for the engine keeps just, as cool as it would do if mounted in the frame of a motor cycle. Observe that the engine and gearbox are carried on engine plates, bolted between the two main members by means of long bolts with suitable distance tubes for location purposes. In order to brace the two rear members and keep them in alignment a long U bolt with angle pieces
brazed at each corner are used, and the rocking members which carry the rear wheel are covered with a washer plate at the rear extremities ; bushes are placed through to suit the rear-wheel spindles. A detail of this is shown. The petrol tank can conveniently consist of a standard petrol tin.
Lubrication is by means of the pump incorporated with the engine and which merely needs to be coupled up with a small oil tank with a tap soldered into the bottom. This is conveniently mounted through one of the bearers as shown. Mild steel angle brackets could be used to connect the various wooden members together.
I have shown the position of the steering and the wheels dotted. but it will be appreciated that the position of the front wheels is provisional only, and will depend upon the type of front axle which is employed. Scale drawings of the axle will be given next month, together with details of the body, seating, and finishing. The screen, as I mentioned last month, is the id Auster type, and steering wheels can be purchased from Bluemels. I shall also include next month actual photographs of the completed car.
The whole of the wooden structure forming the chassis will be apparent
from the side and plan views. In selecting the wood, insist upon straight-grained material
free from knots and shakes. Ash must be used no other wood is suitable to resist the
stresses imposed by the engine. You will save yourself a lot of disappointment by adhering
to the specification, and using ash. Most coachbuilders will supply it or get it for you.
Wherever possible use bolts. Where wood screws are essential use a small drill to give a leading hole, and dip the point of the screws in vaseline before inserting them. This will prevent rust and make it easy for the screws to be removed. Ash is a hard wood, and any attempt to force a screw home will result in a. mutilated head and a screw which cannot be removed. Where two parts are to be screwed together the top part should have a clearing hole so that the head of the screw can draw the two parts together.
Croid or Seccotine are admirable as glues. Where a large surface is to be covered the wood should first be warmed and the glue itself heated in hot water to render it more fluid. After, the two parts are glued they should be placed under pressure for several hours until the glue has set. When using a bradawl make sure that you insert the blade with its cutting edge at right angles to the grain. This will avoid splitting. Use coach-maker's panel pins and oval section brads for nailing purposes. Such should be at least 3/4 in. long, otherwise they will vibrate loose.
Where possible use Whitworth or Camount B.S.F. bolts. Do not use stove or gutter bolts as the threads are not sufficiently accurately cut and the nuts will vibrate off. Locking washers should be used under the nuts securing the engine and gearbox plates. The bolts should be of the castellated type and split pins must be used to secure the nuts.
Metal straps should be of 16-gauge mild steel plate of the bright rolled variety. Tinned iron is unsuitable; for the spacing and distance tubes use bright drawn steel tube of 16 gauge ; the ends, of course must cut square, and the tubes should be a reasonable fit on the bolts to prevent the latter from bending.