A Four-wheeled Scarab a a Lighter Routeman
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AFTER nearly 30 years of producing three-wheeled tractive units, Scammell Lorries, Ltd., Watford, announce today that their current range of Scarab three-wheeled models is to be joined by a four-wheeled 3-tonner known as the Scarab-Four. Apart from being a complete break-away from previous Scammell practice in respect of its number of wheels, the Scarab-Four design reveals a high degree of co-operation between Scammell's and another member of the Leyland Group, StandardTriumph International, Ltd., the front half of the new tractive unit consisting essentially of Standard Atlas cab and chassis components.
hi addition to announcing this new tractive unit, Scammell's release details also of a Mark II version of their Routeman rigid eight-wheeler, this model being over a quarter of a ton lighter than the equivalent version of the original design, whilst having a very full specification (power-assisted steering and handbrake, and eight-wheel brakes). and having an impressive new plastics cab, the futuristic shape of which was conceived by Michelotti, the Italian stylist responsible for the contours of a number of Standard and Triumph private cars.
The Scarab-Four has been designed primarily for use on longer-distance operations than the Scarab three-wheeler, various large operators of the three-wheeled version feeling the need for a tractive unit of about the same size and power, but which would offer better driving conditions and an improved road performance, particularly if it could combine the fuel economy of the diesel-engined Scarab three-wheeler with a slightly higher top speed. So far as the engine-transmission layout is.. concerned, the ScarabFour follows the same patterti as the three-wheeled versions,
and is suitable for use with 3(4-ton semi-trailers. c24 As can be seen from the accompanying exclusive drawing, the ScarabFour is almost identical in frontal appearance to the Standard Atlas, but although the same basic cab is employed, the interior layout is different The engine is behind the cab in the case of the Scammell, whereas it lies between the seats in the Standard installation.
This gives several improvements in driving conditions compared with those of the three-wheeled Scarabs, the driver now having more room, better placed controls, an unobstructed full-width flat floor, good all-round vision and reduced engine noise. The use of four wheels will give improved braking characteristics because the Scarab three-wheeler has no brake on its single front wheel.
So far as maximum speed is concerned, the Scarab-Four will do 40 m.p.h. at the governed engine speed of 3,000 r.p.m.; the petroland diesel-engined three-wheelers have maximum speeds of 42 m.p.h. and 36 m.p.h. with the highest available axle ratios of 6.47 and 7.5 to 1 respectively, whilst with the commonly used 9.65-to-1 axle both vehicles are limited to about 28 m.p.h.
The Standard 2.26-litre four-cylinder indirect-injection diesel engine is fitted in the Scarab-Four without option. This unit develops 52.5 b.h.p. (net) at its governed speed of 3,000 r.p.m., whilst the maximum torque output is 107 lb.-ft. (net) at 1,500, giving a bottom-gear tractive effort of 3,040 lb. The engine is behind the cab and, to reduce the height of the engine cowl, it is installed at an angle of 50° to the vertical. The pressurized Morris-block-type radiator is rubber-mounted vertically immediately ahead of the engine, and the six-bladed fan is belt driven and closely cowled. The full-width seat-box assembly in the cab forms the air duct for the radiator, air passing below the floor, between the wheels, and not through the front "radiator grille" which is only for cab ventilation and heating. A Borg and Beck 10-in.-diameter single-dry-plat!. clutch is fitted, and this has hydi aulic operation. In unit with the :.ngine is a Scammell four-speed co nstant-mesh gearbox and, as with tie three-wheelers, the engine-gearbox unit is in turn unit-mounted with the rear axle. The gearbox is basically the E ame as that employed on the three-wheelers and has the sane ratios, which are 6.3, 3,01, 1.68 and 1 to 1 forward, with reverse gearing of 8.4 to 1. The gear-change lever is to the Left of the driving seat.
The single-i eduction rear axle is a modified version of the original dc uble-reduction unit (as still used in the threewheelers): the basic case is similar, but instead of spiralbevel-and-epic yclic gearing, the four-wheeler's axle has spiral-bevel w ars only. This makes the nose of the axle shorter, so ar adaptor is used to enable the gearbox to be bolted dire t to the axle. The reduction ratio is 5.625 to 1, and the hubs, bearings, stubs and brakes are interchangeable with those of the standard Scarnrnell 3-ton semi-trailer. At its recommended gross train weight of 6 tons 7 cwt.—which permits a 4-ton payload when a flat-platform semi-trailer is used—the Scarab-Four has a bottom-gear grade ability of I in 5.2.
The engine-.clutch7gearbox-axle assembly is mounted in the frame in a similar way to that employed in the threewheelers: there is a single large rubber mounting at the extreme front of the engine,, whilst rear-end support is given by the rear springs. These springs are slipper ended, and the suspension geometry is such that when the tractive unit is unladen only the front portion of the springs are in use, the rear ends of the springs taking weight only as the load is increased: this gives a dual-rate effect. No extri
provision has to be made for absorbing t h e driving and braking torques, as these functions are performed by the rigid enginegearbox axle assembly itself.
The rear-frame assembly to which these running units are attached consists essentially of two channel-section pressings, the rear ends of which form the coupling ramps. A single rolled-steel-channel cross-member is welded across the two side members, this being diagonally braced and carrying the coupling gear.
The complete rear assembly is connected to the front end by six bolts, the joint being in the region of the cab rear panel. The front end is essentially Standard Atlas, with box-section framing members and Atlas-type independent suspension comprising wishbones and a single rubber-mounted transverse leaf spring, controlled by telescopic dampers. Burman recirculating-ball steering is employed, the use of which should give light steering characteristics, whilst the ratio chosen necessitates only four turns of the steering wheel from lock to lock.
Girling brakes are fitted to all wheels, the fronts having 9-in. x 2.5-in, two-leading-shoe units (86 sq. in. frictional area), whilst the rear brakes are similar to those of the three-wheeled Scarab, being I2-in. x 2.5-in, leading-andtrailing-shoe equipment (104 sq. in. frictional area). . The hydraulic system is boosted by a Clayton-Dewandre Hydrovac suspended-vacuum servo. The complete installation is a marked improvement on that of the three-wheelers, for not only is the total frictional area of 190 sq. in. 86 sq. in. greater, but the original models do not have a servo to assist the tractive-unit brakes. A conventional type of handbrake leer,: with push-button release, is located to the left Of the driving seat to apply the rear-wheel brakes only.
Semi-trailer braking is effected in the usual Scammell automatic-coupling manner through a Clayton Dewandre vacuum servo, and this can be separately controlled by a small lever to the right of the driver. Power release for the automatic coupling is given by a Feeny and Johnson vacuum servo with a lever to the left of the driver.
The standard front tyres for the Scarab-Four are 6.40-13 (6-ply) and the rear tyres are 8.25-10 (10-ply), The ScarabFour, which has a wheelbase of 6 ft.-9 in., has front and rear tracks of 3 ft. 9.25 in. and 4 ft. 8 in. respectively. The turning circle measured over the front wheels is 28 ft. approximately, whilst the swept circle is 33.5 ft. Overall width over the cab is 5 ft. 7 in. and overall height is approximately 6 ft. fin., whilst the overall length of 13 ft. 4.75 in. is g. in. less than that of the 3-ton three-wheeler. The unladen weight is 3,416 lb. (30.5 cwt.).
The Standard cab is of all-steel construction and has forward-hinged doors which project 2, ft. beyond the side of the cab when fully-open. The driving seat is adjustable in a fore-and-aft direction and both seats are upholstered with Dunlopillo. The 12v. electrical system has two 6v. batteries, one behind each seat, and flashing direction indicators are standard equipment. The fuel tank, which has a capacity of 14 gal., is on the left side of the vehicle.
From a 3-ton articulated delivery vehicle to a maximumcapacity rigid eight-wheeler—the Mark II Routeman. This latest version of the Scammell eight-wheeler follows the current British trend for this class of machine in being lighter than its predecessors, although weight saving has not been obtained by skimping the specification. The appearance given by its Italian-style cab is in direct contrast to that of previous Scammell eight-wheelers, furthermore, and should make the Mark II Routeman really distinguishable.
Although the basic specification of the new Routeman does not appear at first sight to be so very' different from that of the earlier version, closer inspection reveals important detail thanges and the new model has a dry chassis-cab weight of 6 tons when equipped with the Leyland 0.600 Power-Plus engine, whereas the earlier Routeman had dry chassis cab weights of from 6 tons 6.75 cwt to '7 tons 0.25 cwt. in its lightest and heaviest forms. The relatively low weight of the latest version is even more commendable
in view of the specification of power-assisted steering, power-assisted handbrake and eight-wheel brakes as standard—unassisted steering is offered as optional equipment, in fact!
Like its immediate predecessor, the Mark 11 Routeman is offered with a choice of four power units: the Gardner 6LW and 6LX, as before, and the Leyland Power-Plus 0.600 and 0.680. These :two .Leyland engines, which have net power outputs of 140 and 200 b.h.p. respectively, are new to the Routeman range, the original models being available only with the old 0.600 and 0.680 units.
A Leyland 16.25-in.-diameter single-dry-plate clutch is used with the Leyland engines, whilst the Gardner 'have 16-in.-diameter Borg and Beck clutches: clutch operation is hydraulic, except with the 0.680 engine, which has air assistance, and a clutch brake is included. The familiar Scammell-six-speed constant-mesh gearbox is retained, and when employed with engines other than the Gardner 6LW this has forward ratios of 6.55, 4.07, 2.53, 1.61, 1 and 0.62 to I, reverse being 8.37 to 1. These ratios were available before, but when the Gardner 6LW is fitted, a 9.4-to-1 driving axle is standard, so modified gearbox ratios have been adopted, the bottom gear being 6.1 to 1, top gear 0.67 to 1 and reverse 7.8 to I. These ratios give a maximum speed of 31 m.p.h. and a gradient ability of 1 in 5.
The Mark II Routeman is available with a single-drive rear bogie only, and the driving axle is the same as that formerly employed, being a fully floating double-reduction assembly with spiral-bevel-and-epicyclic gearing contained in a cast-steel housing. Optional ratios in addition to that standardized for the 6LW are 7.13, 7.78 and 8.56 to I. The trailing axle is of Scammell construction also, with the same brake assemblies as the driving axle. Albion Clydesdale front axles are used, these having phosphor-bronze thrust washers instead of the tapered-roller thrust bearings of the former Routeman front axle.
As with the original single-drive model, the rear suspension consists, of four underslung semi-elliptic springs .joined by balance beams, the geometry of which is claimed to give reduced wheel hop compared with bogies with overslung springs, whilst the front bogie has four separate semi-elliptic springs. The rear springs are 3.4 in, wide, and the front springs 3 in. wide.
Air-pressure braking is standard. Albion I5.5-in. x 4.5-in, cam brakes are used on each of the front axles, with Leyland 15.5-in. x 7-in, cam brakes on the rear, In all cases the linings are 0.625-in, thick, and the total footbrake frictional area is 1,243 sq. in., the rear-bogie area being 757 sq. in. Axle-mounted diaphragm chambers (16 sq. in. at the front and 20 sq. in. at the rear) operate the brakes, with Albion-type adjusters at the front and BendixWestinghouse worm adjusters at the rear.
The handbrake lever is of the single-pull type and assistance is provided by a 30-sq.-in, diaphragm servo mounted on the cross-member immediately ahead of the driving axle and acting on the handbrake linkage through a series of relay rods. The circuit for the handbrake servo is quite independent of that of the footbrake, so the assisted handbrake should still remain effective in the event of footbrake failure.
The braking system of the new Routeman promises to be considerably more efficient than that of the earlier model, which had six-wheel braking as standard and areas of 840 sq. in. or 916 sq. in., according to whether the chassis had single or double-drive, with the option of eight-wheel braking, in which case the areas were 1,074 sq. in. or 1,150 sq, in., again according to whether it was a single or doubledrive model. The old front brakes had piston-type airpressure actuators, whilst the single-drive model had two air-pressure cylinders actuating the four rear-bogie brakes through a cross-shaft and cables. A handbrake servo was not offered at all.
Although having slightly lighter members in its latest form, the Routeman's chassis frame is still pretty robust: the side members are 11.875-in. x 3-in. x 0.25-in, channelsection pressings (the earlier model had 12-in. x 3-in. x 0.3125-in, side members) and there are two tubular and four channel-section cross-members bolted in position.
The Mark II Routeman has a wheelbase of 17 ft.., and this is 9 in. less than that of the long-wheelbase version of the original series. The reduced wheelbase results from having moved the front bogie back relative to the driving position so that cab steps can be provided ahead of the front wheel. The chassis frame itself has an overall length of 29 ft. 4.5 in. (with cab the length is 5.3125 in. greater) and the rear overhang is 8 ft. 3.8125 in.
Mantes cam and double roller is employed, and this has an Adament hydraulic servo as standard, the rain acting on a relay lever just ahead. of the second axle, The box ratio is 28.5 to 1, giving 4.75 turns of the 21-in.-diameter steering wheel from lock to lock, and the calculated swept turning circle is 67 ft.
The standard tyres are 9.00-20 (12-ply) on three-piece wheels, and optional equipment includes 10.00-20 (12-ply) or 9.00-24 (12-ply) with twin rears, or 9.00-24 (12-ply) front and single 14.00-20 (18-ply) rears. The 36-gal, fuel tank is carried mid-wheelbase on the right-hand side -member, and the exhaust system is located transversely across the front of the vehicle. The electrical system is 24v. doublepole, with four 6v. 108 amp.-hr. batteries in the cab.
The new M ichelotti-designed cab is of striking appearance, and in addition provides good driving conditions, easy access to the seats and a commendable range of all-round vision. It has a steel-reinforced plastics base which is moulded in one piece and which includes the two seat boxes. There are no holes in the floor on the mate's side, and only two on the driver's side, thus penetration by draughts, fumes and noise should be at a minimum. The plastics engine cowl is in three separate pieces. The base is rubber-mounted to the frame at four points, and the Routeman is to be made available with this base alone as an alternative to having the complete plastics cab.
Apart from its curvaceous lines, the new cab's external appearance is notable for its extensive glazed area, with two-piece windscreen, wind-down door windows and deep back lights (the central one of which is optional). The screen panels are not as sharply curved as those of certain contemporary heavy-vehicle cabs, and beneath the screen there is a large removable panel, primarily for the purposes of engine removal. The access steps are moulded in the front skirt panels, virtually all of the cab being ahead of the front-axle centre-line. A Chapman Leverex fully adjustable driving seat is provided.
The impressive list of optional equipment for the Mark It Routeman includes Varivane radiator shutters, gearbox power take-off, radial air compressor or discharge pump, automatic chassis lubrication, 48-gal fuel tank, front bumper bar, spare wheel and carrier, cab roof ventilator, windscreen washers, paired headlamps instead of the standard single headlamps and flashing direction indicators.