A Wireless Star.
Page 4
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A Description of Marconi's Latest Portable Field Plant.
We continue to be able to record unusual and interesting developments in the field of mechanical science, M which the commercial motor is bearing its part. For various reasons, just at present the Marconi system of wireless tele graphy is engaging the attention of the public to a remarkable extent. It is therefore with particular pleasure that we find ourselves in a position to record, pictorially and otherwise, the construction of what is, at present, the last word in regard to self-contained wireless outfits.
The Star Engineering Co., Ltd., of Wolverhampton, has just put through an interesting self-contained automobile unit for Marconi wireless field use. We here give a description of the machine and reproduce photographs of the chassis and of the complete unit.
A six-cylinder engine is mounted on a pressed-steel sub-frame. The cylinders are cast in threes, the bore and stroke being 80 mm. and 120 mm. respectively and the
R.A.C. rating of the engine is 23 The crankshaft has seven bearings. and these, together with the connecting-rod big ends, are lubricated by pressure feed through ducts drilled in the crankcase and leading to the various bearings. The valves are disposed on one side. of the engine, the valve springs being entirely enclosed by side doors.
—Power is transmitted through a leather-faced cone clutch, the thrust of which is taken up by a Duplex combined thrust ring and bearing. A noticeable feature is the chaindriven gearbox. Three speeds and reverse are fitted, the latter through spur gears. The respective chain combinations and pitches are : the constant drive, four and five links, a in. pitch ; first speed, four and five
links, in. pitch ; second speed, three and four links, in. pitch. The third speed is a direct drive. All the sliding dogs are fitted with Hoffmann bearings. The gearbox itself is mounted on three-point suspension. Transmission to the road wheels is by means of the usual pro peller shaft and bevel-driven live axle.
The foot brake is of the externalgrip type and those fitted to the road wheels are internal expanding. We noticed that the change-speed and brake hand levers were mounted upon two different centres, so that any tendency to cross jamming of the change-speed shaft on the brake-shaft mounting is entirely eliminated.
Sankey steel road wheels are fitted with the Star Co.'s detachable hubs mounted on Timken bear
ings. The tires are heavy plain Dunlop pneumatics, 820 mm. by 120 mm. -The auxiliary coil springs. fitted to the front and rear suspension, are a noteworthy provision to ensure the minimum of vibration getting through to the delicate electrical mechanism which is carried.
For the wireless installation a 2 kilowatt alternator is. fitted in the centre of the chassis over the propeller shaft, and is carried on suitable pressed-steel cross members ; its position is clearly shown in one of our illustrations. It is driven, through a shaft with a leather universal joint, by a set of spur wheels which are mounted on an extension shaft situated at the forward end of the gearbox. The leather joint is novel in that the leather is interlaced through a coupling block enclosed in an outer sleeve.
The gate quadrant is provided with an extra notch to facilitate the engagement of the gears. The speed ratio of the alternator to the engine is 3 to 1. A dynamo lighting
set is also fitted. The telescopic wireless poles and other apparatus are carried upon a neat little twowheeled trailer, as depicted in the second illustration. This is the fourth automobile plant which the Marconi Co. has ordered from the Star works.