Scammell Scarab 4
The Scammell Scarab-Four was intended to appeal mainly to operators of the successful Scarab. It would provide a medium haul ability that the essentially short haul Scarab lacked, whilst remaining fully interchangeable with the trailers in the fleet of the existing Scarab user.
The take-over by Leyland of Standard in 1961 provided the opportunity for Scammell engineers to develop a tractor unit more suitable to longer haul working. Leyland had a strong 'unit construction' policy that made each manufacturer's components available throughout the group and wherever possible components should be sourced within the group.
In one of the more imaginative ideas to come from the motor industry, a marriage was proposed between the 3-wheeled Scarab and the Standard Atlas van. The Scarab back end would provide the interchangeability with existing fleets of trailers and the Atlas front end would provide the larger cab and 4 wheels for better stability and a roomier cab for longer journeys.
The 3-wheeled Scarab and the Atlas were both cut just behind the rear panel of the cab. The rear section of the Scarab and front section of the Atlas were then joined using a 6 bolt arrangement.
The unitary construction of the Scarab drivetrain was retained. The constant-mesh gearbox kept the same ratios as the Scarab, being 6.3, 3.01, 1.68 and 1 to 1. This gave maximum speeds in each gear as 1st/6mph, 2nd/14, 3rd/25 and 4th/42.
The rear axle retained the Scarab casing, but was modified to be a single-reduction, rather than the double-reduction unit that continued in the 3-wheeled version. The engine used was the Standard 2.26 litre direct injection, 52.5bhp diesel, which was mounted behind the cab. It was tilted in the chassis at 50 degrees to lower the height.
The front end retained the Standard suspension, steering and brakes and whilst the cab kept the external appearance of the Standard, there were major differences. The radiator grille was used for cab ventilation only with engine cooling obtained from underfloor ducting.
The engine being mounted behind the cab removed the space consuming engine cowling from the cab interior and allowed a full width flat floor. A full width seat box was fitted with 2 adjustable Dunlopillo seats, giving, according to the Scammell sales brochure, 'a big, wide, roomy cab providing driver and mate all the comfort they need on longer runs'.
Additional features of the cab, boasted by Scammell, were, very quiet to ride in due to the externally mounted engine, twin wipers, interior light and a heater.
Despite being first announced at the 1962 Earls Court Motor Show, production of the Scarab-Four didn't get underway until the middle of 1964, when it was made available to Motor Transport and Commercial Motor for road testing. By this time the Standard Atlas had been re-named the Leyland 20.
The road-testers were complimentary about the general performance of the fully laden vehicle, particularly the stability during braking and manoeuvrability in urban conditions. The performance was regarded as lively and economical, averaging 17 mpg.
On the open road, the impressions were less enthusiastic. It was described as being less than happy when pushed hard and when cruising at a comfortable 35/40mph, it was noisy. At maximum speed of 44mph it was described as 'unbearable with everything vibrating fit to burst'. It would appear that this vibration emanated from the engine mounting, sending vibrations through the chassis and constant drumming through the cab panels. Scammell's claims of a quiet ride due to the engine being fitted outside and behind the cab seem to have been a little optimistic.
One of the reasons the Scarab-Four took 2 years from initial announcement to production was problems with the cooling system and the road tests both confirmed a tendency for the engine to boil at sustained high speed and hill climbing.
The cab, according to the sales brochure, 'takes two people in comfort and style'. However road testers were critical of the lack of room, poor ventilation and the driver's eyeline being above the windows, hampering visibility. This was particularly noticeable when reversing as the sliding windows opened barely enough to get the driver's head out and the doors were too long to open in confined spaces.
In total, fewer than 100 Scarab-Fours were produced with the majority going to South African Railways.
From my article in Vintage Roadscene, Vol 21 - 81, Dec 2004 - Feb 2005.