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make the most of new steels
Page 79
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A MONC, the nine exhibits on the stand of R. A. Dyson and Co., Ltd., at the Commercial Motor Show, will he 30-ton low-loading semi-trailer from a new range of 15to 60-ton machinery transporters designed to give a considerable reduction in unladen weight compared with earlier models. Other interesting Dyson exhibits w:11 include two Dyson-Duramin Aerovan box-van semitrailers, a tandem-axle unit with a special dual-purpose body for the transport of general goods or bulk liquids and a 29ton self-loading semi-trailer for operation in the Spanish Sahara.
The 30-ton low-loader is the second stage in the development by 'Dyson of semi-trailers of this type with a low unladen weight but with no reduction in strength. The unit to be displayed will he 34 ft. 6 in. by 8 ft. (clear laden space is 20 t t. by 8 ft.) but its unladen weight will he only 6 tons 4 cwt. This is just over 2 tons less than Dyson's existing cornparable semi-trailer and has been achieved by using a combination of Fortiweld and U.S.S.-T1 high-strength alloy steels for the construction of the chassis and platform in place of mild steel. Yield Points of Fortiweld and T1 are 72,000 and 100.000 psi. respectively, compared with 33.000 psi. for mild steel.
Except for the type of steel used, the designof the semi-trailer follows con ventional Dyson practice. Twinoscillating knock-out rear axles are employed, the tyres being 14.00-20, 22ply. Braking is by a two-line air-pressure system and the parking brake is of the hand-operated mechanical Screw type. The platform side • rails have ramping ledges and lashing shackles and jacking points are provided on both sides of the rear of the platform.
A second low-loader to be shown will be a 25-30-ton H-type semi-trailer. Fortiweld and mild steel are used in the construction of the chassis for this range. which was the first stage in Dyson's efforts to reduce weight. By. using these steels instead of all mild steel, a weight saving of 20 per cent, is obtained. Dyson now offer all their heavy-duty machinery transporters in three.forms—the• standard using all mild steel; the Lightweight using Fortiweld and Mild .steel; and the Super lightweight using Fortiweld and U.S.S.TI steel.
One of the Dyson-Duramin Aerovans will be seen on Dyson's stand, the other will he in the Demonstration park. That on the stand will measure 27 ft. 9 in. by 8 ft. by 11 ft. 10 in. It will have a. "streamlined " appearance. incorporating a '' bow " front and will he in Bass livery. Ventilation is provided by six roofmounted Flettner rotary air extractors. Access to the load is by a rear roller shutter and roller shutters at both sides of the body. An interesting interior fitting is aircraft-type load-fixing equipment made by the King Aircraft Corp. of America. This incorporates spring loaded bars which locate in perforated strips. running the full length 'of the hod!" and mounted at three levels on both interior faces. The bars are fixed so that the load cannot move about when the vehicle is partly loaded.
Running gear comprises the Dyson tandem-axle air-suspension bogie. Dunlop Mark IV disc brakes are employed. These are operated by an air-pressure assisted hydraulic system.
The dual-purpose semi-trailer is for Sutton and Sons (St. Helens), Ltd., and measures 28 ft. by 8 ft. It is similar to a number already built by Dyson for this operator, and is designed to carry hot bulk liquids in a Portolite collapsible tank or to transport general goods. The body floor has 2-in, insulation and is surfaced with 0.5-in, plywood—this is adequate to support the Portofite tank. Insulation is also provided in 3-ft. 10-in, sideboards fitted. These 'are hinged at the bottom so that they can be folded inwards to fOrm a flat platform: The outsides of the sideboards are covered in alloy chequer plate to provide an adequate surface for the platform when they are down. The tailboard and headboard are fixed. and a compartment at the rear houses the tank in its collapsed form. When used for liquids an insulating blanket is used to cover the load.
Tandem-axle air-suspension running gear is also employed on this semi-trailer but braking is by 15.5-in. by 6-in, drum brakes operated by a' two-lineair-pressure system.
The 29-ton self-loading semi-trailer for use in the desert Will be 34 ft. by 9 ft. 6in. An unsprung, walking-beam tandem-axle bogie is employed on this unit. The tyres fitted will probably be the biggest to be seen at the Show—they will he Michelin 18.00-25 ”-Sahara X."