The Purchase Department.
Page 29
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Where to Buy your Supplies.
You Can Get It At " K.T." (Coventry).---The brake lining for which you inquire is marketed by the Herbert Frood Co., Ltd., Chapel-en-le-Frith.
Catalogue Received.
We have received a copy of the latest catalogue issued by that well-known tire concern the Polack Tyre and Rubber Co., Ltd., Basinghall Street, London, E.C. It contains numerous illustrations of Polack tires in section, and also a good selection of representative makes of commercial vehicles running on this maker's tires. A number of apporciatory testimonials from prominent users is included ; the company also publish some remarkable mileage figures, obtained by Polack tires running on London buses.
The Royal Show.
We direct our readers' attention to the descriptions in this issue of some of the latest accessories and supplies to be on view at the Royal Show which opens at Shrewsbury on Tuesday next, Many of these up-to-date appliances have been fully described and illustrated from time to time in our " Purchase Department." The resulting business which has followed such publieity for what is a most important section of the industry has brought to us ninny letters of appreciation both from manufacturers and users.
D.B.S, Worm-driven Axles.
The smooth running and high efficiency afforded by correctly-designed and accurately-machined worm gearing have induced many chassis builders to favour it as a final drive.
A rear axle embodying this form of transmission aind which is meeting with considerable favouc throughout the industry is that constructed by David Brown and Sons (Huddersfield), Ltd.
We reproduce a photograph of the latest D.B.S. axle component. The easing is of stout design, and, with the axle tubes, forms a unit made from one steel casting. This construction, although more expensive, undoubtedly possesses advantages over the usual built-up type of housing, and in addition presents a neat and compact appearance. The whole of the worm and differential gear, complete with bearings, is mounted, as a unit, in a separate casting which goes to form a cover for the axle easing. This offers the maximum of accessibility, as the cover, complete with all the gearing, can be removed without dis
mantling the axle from the chassis. The driving shafts, which are of the floating type, can be withdrawn from each end, special facilities being provided for this purpose.
The.final drive is transmitted from the cross-sbaft s to the rom.1-.;wheel hubs through large-diameter dogs with radial I eeth, carefully case-hardened.
The axle casting is stiffened by cross tubes made from chrome-Hie-lel steel of high tensile strength, which are extended in order to carry the road wheels. The tubes are made from solid forgings.
The bevel t-:,pe of differential gear is employed, the teeth of whieh are automatically generated.
The worm and wormwheel are cut by the D.B.S. patent proeess, which ensures extreme accuracy and absolute silence of operation ; the remarkable efficiency of the company's worm gear is already well known, The design of this axle is unique in that the worm wheel is nut placed centrally between its journal bearings. Owing to the angularity of the worm teeth, the method of eccentric mounting equalizes the load on the journal hearings. This provision tends to produce longer servke and increased efficiency. The standard gear ratios for this axle are as follow: 7.75 to I ; 10 to 1 and 11.66 to 1, but other ratios can be made i o suit special requirements.
The road-wheel brakes are of large diameter and of the internal-expanding type, operated by cams and are completely encased in order to render them dust-proof.
These axles can be supplied with or without the necessary provision to accommodate torque and radius rods, according to individual requirements.