Ignition System Using Transistors
Page 68
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DATENT No. 809,989 describes a projected ignition system using transistors. (General Motors Corp., Detroit, Michigan, U.S.A.) In a, normal ignition system, the contact-breaker points have to carry currents of the order of 10 amp. and their life is limited because of burning away. In the scheme disclosed, the points have to carry only a fraction of an amp. which acts as a trigger to a
transistor handling the main current. The points 'Should, therefore, last indefinitely.
A transistor consists of three elements, an emitter (1), a base (2) and a collector (3). If the base is positive to the emitter the' unit is non-Conductive and, therefore, no .current flows. But if it is negative .a large current will flow from the emitter to the Collector, this current being proportional to the current from emitter to base.
When the circuit is switched On there is a voltage drop across the potentiometer (4). When the points are closed, this voltage is applied to the base, rendering it negative and causing it to pass the heavy current for the coil. When the points open, the base becomes positive owing to the leak resistor (5) and the current flow is arrested. This creates the high voltage in the coil (6) in the usual way.
FIXING HALF-SHAFTS TO THEIR GEARS
PATENT No. 808,817 shows a method of fixing half-shafts into their differential sun-wheels. The scheme permits the axles to be inserted and tightened externally into a close fit with the bore of the sun-wheels. Although the specification does not mention it, the drawing suggests that the scheme is intended for independent suspension
assemblies. (The Austin Motor Co., Ltd., and J. Harnott, both of Longbridge Works, Birmingham.) The easing (1) of the differential gearing is a close fit around the sun-wheels (2) so that they lie in their correct position during assembly. The bore of the sunwheel is splined and the short half-shaft (3) is correspondingly splined to enter it. The axle is inserted froth outside and when in the correct position, a bolt (4) is tightened. This runs through the centre of the axle and has a bulbous head (5) which, when pulled into a split taper bore in the shaft, expands it tightly into the bore of the sun-wheel.
The method avoids the need for difficult spanner work in the inaccessible region (6) between the half-shafts and the planet pivot pin.
GATURBINED ROAD VEHICLE
PATENT No. 806,369 discloses a design for a road vehicle driven by a gas turbine. The patent illustrates the scheme as applied to a passenger car but is not of course limited to this applica
tion. (General Motors Corp., Detroit, Michigan, U.S.A.) The basis of the patent is the layout of the various units in a manner which eaves the middle portion of the body unobstructed. Referring to the drawing, the front assembly is the gas generator and comprises an opposed-piston compression-ignition engine complete with radiator and, cooling fans (1). The engine is of the free-piston type having no rotating parts.
The gas output from the engine is carried by a conduit to the inlet to the power turbine (2). The conduit passes along the edge of the frame so that no obstruction is created in the floor.
The final exhaust from the turbine leaves via an outlet pipe (3); this is jacketed and cooled by forced draught. No details are given of the transmission except that the main components are housed in the casing (4). The cooling fans at the front are driven by hydraulic motors powered by a pump incorporated in the transmission.
ROCKER ADJUSTMENT
THE overall height of an engine with overhead valves is affected by the dimensions of the valve gear and any height saved at this point reduces the weight and cost of the whole unit. Such are the views expressed in patent No. 809,729, which shows a rocker adjustment layout which reduces engine height. (Daimler-Benz A.G., StuttgartUntertfirkheim, Germany.)
The camshaft works rockers which in turn press down the ends of the valve stems. The effective length of the valve stem is altered to provide adjustment.
The valve is held by conical cotters engaging with the spring collar, but the stem itself does not extend far enough to touch the rocker. A hardened pressure pad (1) completes the assembly and adjustment is made by placing shim discs between it and the end_ of the stem. Alternatively, pressure pads of differing thicknesses may be used.
HUB REMOVER
HUB removers are the subject of patent No. 803,965 which deals with the type of hub having a shouldered portion to accommodate a puller. (E. Allchin, 253 Bordesley Green, Birmingham, 9.)
A split collar (1) can be parted by undoing its bolts (2) and re-assembled with its —inner flange behind the shoulder on the hub. A pair of tension arms (3) is then hooked over the edge of a flange (4). By turning, and, if necessary, hammering the tommy bar (5) the central screw is forced on to the axle and applies a povoerful.extractive effort. .
TORQUE CONVERTER TRANSMISSION
FROM General Motors Corp., Detroit, Michigan, U.S.A., come four separate patents dealing with the details of a combined torque-converter and mechanical
gearbox. The patents are numbered 809,761, 809,762, 809,763 and 809,764 VARYING TYRE PRESSURES
DATENT No. 808,659 discloses an
arrangement for varying, tyre pressures while a vehicle is in motion. The patent comes from Scovill Manufacturing Company, 99 Mill Street, Waterbury, Conn., U.S.A.