Secidons Introduce Their Mk. 2 8-tonner
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ANEW 8-ton four-wheeled goods chassis has been developed by Seddon Diesel Vehicles, Ltd., Oldham, Lancs. The model has a solo gross weight rating of 12 tons, and although having some components common to the 7-tonner, a number of new features has been introduced on this model. The new Leyland 0.370 diesel engine is one of the optional power units, a plastics panelled cab has been developed (and will subsequently be used on a number of other Seddon chassis) and there are other important detail improvements compared with earlier Seddon chassis.
The new 8-ton model is offered for the same price as the previous 7-tonner (£1,671), but the cab is lower priced, being listed at £215. Eight wheelbases are offered, ranging in dimension from 9 ft. to 17 ft., whilst there is also a 7-ft.wheelbase tractive unit, which can operate with a 28-ft. 6-in, semi-trailer at a gross train weight of 18 tons. Yet another variation is a six-wheeler with York trailing-axle equipment; this has a gross weight rating of 16 tons, and is available with wheelbases of 13 ft. 11 in., or 16 ft. 5 in.
Road Tested One of the new 8-tonners was road tested a few weeks ago by John F. Moon. It had the 0.370 engine, direct-top fivespeed gearbox and single-speed axle and was running at 12 tons 21 cwt. gross weight: An outstanding feature of the test was the fuel economy, 16.3 m.p.g. at an average speed of 27.7 m.p.h. being obtained when fully laden, whilst with the load off, 22.1 m.p.g. was returned at an average speed of 29.2 m.p.h. From a standstill the 8-tonner reached 30 m.p.h. in 28.4 seconds, and the average stopping distance from 30 m.p.h. was 55 ft. These are the main test results obtained: a fully illustrated report on the test will be published in three weeks' time.
There is a choice of two power units, both being fairly similar in respect of size and output. The 0.370 is a 6.075-litre sixcylindered diesel with a net power output of 110 b.h.p. at 2,400 r.p.m. and a peak torque output of 272 lb.-ft. at 1,600 r.p.m. The alternative unit is the Perkins 6.354 5.8-litre unit-, the net output of which is 105 b.h.p. at 2,800 r.p.m. and the 'torque rating 254 lb.-ft. at 1,450 r.p.m.
Engine Lower • A notable feature of the engine installations in either case is that they are mounted 4 in. lower in the chassis frame than was previous Seddon practice: whilst this in no way interferes with front-axle vertical movement, it results in a remarkably small engine cowl inside the cab, a conveniently short gear-change lever, and an improved propeller-shaft line.
R40 The Borg and Beck 14-in.-diameter tangential-strap-type clutch has hydraulic operation. With either power unit fivespeed gearboxes are standard equipment. In the case of the 0.370 engine the box is the well-known Albion GB24I unit, which is available at extra cost with an optional sixth overdrive ratio. A David Brown gearbox is used with the Perkins engine, and this, like the Albion box, has constant-mesh gearing.
The standard rear axle is a Seddonbuilt hypoid-bevel assembly with fully floating half shafts. The standard axle ratio is 6.16 to 1, but there is an optional axle, this being an Eaton two-speed unit. Also of Seddon manufacture is the front axle, which is a slightly heavier assembly than that employed on the 7-tonner.
At both axles, 3-in.-wide semi-elliptic springs are fitted, the rear springs having helper leaves as standard whilst the front springs arc available with optional telescopic dampers. Marles 611 cam and double-roller steering gear has been adopted for the Mk. 2, this having a ratio of 24.7 to 1, giving 5:1 turns of the 21-in.diameter steering wheel from lock to lock.
The chassis frame, like that of the 7-tonner, has 1—in.-thick pressed-steel side members, these having a maximum depth of 8-11in., with 24-in. flanges. As with the 7-tonner Girling hydraulic brakes are employed, boosted by a Clayton Dewandre Hydrovac suspended-vacuum servo. The same 16-in. x 3-in, front brakes are used, but the 15i-in.-diameter rear brakes have 5-in.-wide linings, as opposed to the 41-in.-wide linings of the 7-turner. This increases the frictional area from 436 sq. in. to 480 sq. in.
The handbrake lever is mounted on the cab sub-frame instead of directly to the chassis frame and is located to the right of the driNiing seat. The lever mechanism incorporates a progressive cam so that initial movement of the lever tends to take up the slack in the linkage quickly, after which further movement moves the rear shoes by a progressively increasing mechanical leverage.
Standard tyre equipment is 9.00-20 (12ply), with 8-stud three-piece wheels. The fuel tank is a 20-gal. unit, and all fuel lines are of extruded nylon. The electrical system is 24v. and an improved type of all-metal battery box, located on the offside side member, has been developed to give easy battery access but more adequate protection.
Cab Construction
A pressed-steel base assembly, comprising the underframing. floor plates, wheel boxes and engine cowl, forms the basis of the composite-construction cab, which has timber framing and plastics panels. The engine cowl is hinged at the rear and can be supported in the raised position by a strap. To give more working room in the cab both sides of the cowl can be folded inwards and secured by a rubber clip, so giving a clear working area over the whole length of the engine. The cab base has a six-point mounting to the chassis frame.
Standard equipment includes a freshair heater and demister, fully adjustable driving seat, wind-down door windows, opening door quarter lights, twin wipers and flashing direction indicators, with steering-column "stalk "-type control. A four-headlamp layout is available at extra cost.
A safety innovation is that the windscreen panel on the driver's side contains a rectangular laminated panel which wilt not craze like the rest of the windscreen in the event of it being broken, thus ensuring that the driver's forward visibility is not suddenly completely obscured in the event of such an occurrence. The interior of the cab is nicely finished, with natural and decorative-plastic-laminate grained-wood finishes.
Relatively Simple
The engine and cab layout are such that it is a relatively simple matter to withdraw the engine and gearbox unit out through the front of the cab after removal of the radiator and radiator grille. This eliminates the need for cab removal, of course. Another improved maintenance feature is that itifie forward part of the engine cowl is easily removable for adjustment of the fan belt.
Optional extras in addition to those already mentioned include power steering, automatic chassis lubrication, Cary Laminaire fully progressive semi-elliptic springs, rear axle anti roll bar, illuminated cab-roof name box, and 30-, 40or 50-gal. fuel tanks.