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The Trek of the Double-decker

1st February 1952
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Page 34, 1st February 1952 — The Trek of the Double-decker
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A Daimler CO65o Makes an 8,aoo-mile :Tour of South • Africa Including Eve.ry Main

• . Centre of Population

By P. A. C. Brockington, A.M.I.Mech.E.

HE Voortrekkers of South Africa. started Something in 1835 when they decided that the distant• %horizon would recede if they advanced upon it. Many natives in country districts early this year took fright, or gazed in open wonderment, at a new . sign of •. advancing civ.ilization—a double-deck "bus was emulating an oxwagon on a -joUrney of adventure, It

• was the Daimler show model CD650 out for a trip of 8,000 miles to prove • that it could go anywhere.

• This article was inspired by Mr. Tom

Wood, the Daimler sales engineer, who agreed that I should take some part in its preparation, Fo that memories of travellingover the same routes during 1 10 years of residence in the country would be revived. He was the sole United Kingdom representative of the company on the trip, but never lacked bus-minded South Africans for companions, begging a lift for the enjoyment of being critical of a strange machine in familiar surroundings.

No modifications were made to the Daimler chassis and Burlingham body before the show vehicle was shipped to South Africa. The Daimler 10.6-litre engine Was governed to an output of 125 bt.h.p. at 1.650 r.p.m., and in the direct gear of the preselector gearbox, with a back-axle ratio of to 1. a maximum speed of 45 m.p.h. was available.

On the corrugated country roads, the speed of any vehicle must be A32 kept below 5 m.p.h. or inereased.to over 30 m.p.h. to avoid disintegration, and if ample power on hills be not forthcoming, there is no alternative to a lowgear crawl. Mr. Wood is adamant that at no time was crawling necessary, except when forcing his way throtigh three feet of water with eddy currents of muddy fluid in the saloon playing havoc with the drag co-efficient. In the towns, under arduous service over hilly routes, the overall bottom gear ratio of 21.44 was considered too low.

Ease of handling was a first consideration, and the Lockheed power-assisted steering was a valuable feature of the equipment, This unit, together with the power-assisted gear change, is energized by the hydraulic accumulator of the brake-servo system.

The route was planned to include :every main centre of population so that most of the large. bus-fleetOperators : Should be given the opporttinity'of testing the bus under :local conditions., Unfortunately, the visit to East London had to be abandoned because of low. bridges, but this Wasthe only concession to route difficulties during the entire: run, except for a nitmber• of

detours. . .

Within four days of .disembarkation, the bus was in regular service with the Cape Town City Tramways Co., under the direction of Mr. G. W. Robb, the general manager, who was formerly • general manager of St. Helens Transport Department, Within three weeks, the double-decker had completed 3.500 miles on the hilly Fresnaye route, working maximum shift hours. • This is. a round trip of eight miles over surfaces varying from moderate to poor, with many acute bends and sections of

severe camber.

The fuel consumed was 339 gallons, giving an average of .slightly more than 10.3 m.p.g., a figure • which was considered satisfactory, judged by the amount of climbing involved and the heavy peak traffic in the mornings and evenings, There were minor peaks at mid-day. Comments by the staff were favourable, particularly with regard to ease of handling and pulling power. The hydraulic-servo steering was described as a " revelation," corners being taken in a single arc compared with the usual series of jerky turns. It was considered that complete freedom from road shocks at the steering wheel more than compensated for the lack of castor action. The steepest hills could be negotiated in a higher gear than was normally necessary, for which credit was divided between the power of the engine and the method of gear changing.

The suspension characteristic given the most praise was the absence of bounce when the vehicle was halfempty and travelling over bad surfaces. Passenger comfort was given top marks, and the purdah glass in the saloon windows was greatly appreciated, especially in the early morning and late afternoon. Some criticism was made, however, of the blind spot formed by the two flush-fitting windows of tinted glass at the front near-side corner of the lower saloon, which obstructed the driver's view to the left rear. Deeper window louvres were said to be essential to provide adequate venting during rain storms.

Before leaving Cape Town on tour, the bus was placed at the disposal of the Golden Arrow Bus Service, operating in the northern suburbs where new housing schemes are making heavy demands on the transport facilities. The bus continued in service for three days and met with the approval of the staff, despite the unpopularity . of hydraulically operated mechanisms.

After an early start, the 540 miles to Port Elizabeth were covered in three days' travelling, with a detour over gravelled roads up the Robinson Pass in the Attaquas Mountains, which necessitated a' climb to 5,000 ft. At this stage, and later in the tour, crossing deep drifts became a regular -necessity, and in every instance the river bed was tested beforehand by one of the crew

clad only in shorts and a shirt. To be bogged even for a few minutes during the summer is highly dangerous. Following a storm in the mountains, a high wall of water may appear unexpectedly and sweep a vehicle and its occupants to destruction.

After demonstrating the bus to the Tramways Co. (which is a subsidiary of Cape Town Tramways) the doubledecker left Port Elizabeth, and with a day in Bloemfontein, the administrative centre of the Orange Free State, reached Johannesburg three days later, a total distance of some ,900 miles. Visits were next made to all the Reef municipalities and to Pretoria, after which the bus departed on a return journey to Natal; a mileage of over 800, to show the flag in Durban and later in Pietermaritzburg. The tour was completed in Johannesburg.

About half of the 8,200 miles covered on the tour were completed on passenger-carrying ,town services, about 1,500 miles on general demonstration

work and the remaining 2,600 miles were recorded on the inter-town journeys. Over 1,000 miles were . travelled on country roads varying from good gravel surfaces to cart tracks.'

After the tour, Mr. Wood prepared an estimate of the wear-and-tear effects of similar mileages in Great Britain and South Africa. The figures are hypothetical, but they provide a useful means for making a general comparison between road conditions in the two countries. According to this estimate, 1,000 South African rough-road miles equal 4,000 United Kingdom miles; 1,500 S.A. town-to-town miles equal 2,000 U.K. miles; 4,000 S.A. townservice miles equal 5,000 U.K. miles. General-service mileages are comparable.

In a qualifying note, Mr. Wood suggests that the "rough-road" ratio of 4 to 1 is too low, and judging from personal experience, I agree that it is. Travelling continuously in a cloud of dust on gravel. roads, the resultant increase in engine wear is mainly a function of air-filter efficiency, which is extremely difficult to maintain at an optimum figure on a long journey.

The wear ratio of exposed steeringgear and chassis components is generally far in excess of the estimate, and this also applies to exposed transmission parts. Shock and twisting stresses can take heavy toll of chassis• frames and bodywork.

The human element must also be considered. Although the standards of driving and maintenance represented by the undertakings visited compare with the best in this country, some of the company-owned buses are treated quite ruthlessly. As observed by Mr. Wood, "many appear to operate in defiance of normal engineering dicta"

Over Earth, Rock-and Sand Some Of the worst surfaces encountered were between Wakkerstroom and Newcastle on the journey from Johannesburg to Durban, where the bus had to travel for many miles over stretches of arid earth with rock outcrops . and patches of soft sand. Had heavy rain fallen, the bus would undoubtedly have been brought to a standstill.

On the return journey, it was decided to keep to the main road through Standerton and to cross the river Vaal by the bridge. It transpired, however, that the girders were too low for the double-decker, and the river was eventually forded after a volunteer had Waded up to his waist to test the surface of the bed. For most of the way across, the floor of the lower 'Saloon was awash, and the flywheel Was churning the muddy water past the dislodged cover.

The comments of the municipal operators were generally similar to those heard in Cape Town. In Pietermaritzburg, where the roads are good but have many long, steep gradients, the CD.650 was considered to be fast, light to handle, to ride well and to have excellent seating. The cab was described as cool and comfortable, the rear platform spacious and the stairs commendably wide.

Tested In Durban

In Durban, the bus was tested over many miles by relays of drivers and members of the workshop staff, who found that the easy gear change raised the 'useful performance of the vehicle over that of other buses of higher power.

The altitude of the Reef towns is some 6,000 ft., at which the power output available is reduced to little more than 80 per cent. of -the sea-level rating. The check on the performance of a new vehicle is therefore important. The road surfaces vary from good to poor. To the dust of the gravel roads off the main highways must sometimes he added the fine dust from the mine dumps, which is acid. Apart from Johannesburg and Germiston, few double-deckers are in use, and the highcapacity single-decker with' one-man operation is regarded as a promising development. There are no regulations

in the Union which stipulate that a conductor shall be carried.

The fitters and -drivers of Benoni Municipality were particularly enthusiastic about the new bus; of the seven Daimlers in the fleet, each has a mileage of over 350,000 to its credit. Whilst the Daimler 8.6-litre engines fitted -to —the single-deckers of the Brakpan fleet were considered to have adequate .power (all have, completed more-than 100,000 miles), great interest was shown in the 10.6-litre unit. The power of the vehicle, its handling characteristics and 'body were commented upon favourably in Boksburg, Springs and Nigel..

Some of the roads in the -Germiston area have extremely poor surfaces. The bus was fully tested .on,service routes

and was afterwards described as "the most comfortable bus yet."

In general comments on the tour, Mr. Wood said that there had been no mechanical trouble of any kind and that bodywork defects had been limited to looseness of bolts and screws around the rear-wheel. arch. Some trouble was also experienced with flexing and drumming of the deck head panels. The fully opening windscreen and deep windows provided ample cab ventila.tion, but a scoop ventilator on the side would have been useful in hot weather to allow air to be directed on to the driver's legs. Saloon lighting should be screened as a safeguard against natives' light-fingered habits.

It was learnt that the South African Government was encouraging accelera

lion of the normal replacement programme to provide against possible future shortages. Every means would be taken to introduce the underfloorengined, one-man-operated singledecker, • and it appeared possible that this type would eventually usurp the position of the double-decker in all centres except Johannesburg, where the traffik• density is higher than in any other town in the Union.

Canadian-built Brill underfloorengined buses are operated by South African Railways on the Cape TownDurban run, which is one of the few long-distance bus services in the country. Following the tour, an order was placed by Pietermaritzburg Municipality for five Daimler Freeline .underfloor-engined buses.


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