63 PASSENGERS ON NE DECK
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ALTHOUGH single-deck buses with a capacity for 20 or more standees are employed to overcome heavy traffic peaks in practically every country except Britain, it has yet to be proved to our licensing authorities that the Daimler Freeline, for instance, with Duple provincial body, can carry up to 60 or more passengers without impairing their safety. The Freeline, with seating arrangements and other special features specified by Mr. W. M. Little, General Manager of Edinburgh Transport Department, is to be operated experimentally in Edinburgh as a 36-seater, and its standee capacity will be governed following observations made by the local licensing authority while it is in service.
With the co-operation of the chassis manufacturer and operator, I was given an opportunity of trying this bus before it was ptrt into service. Loaded to the equivalent of 63 passengers and crew, its performance was on a par with that of a double-decker. Because of its lower centre of gravity, the Freeline has the added advantage of increased stability, and as a Single-decker it is more easily controlled by the crew, and fare collection would conceivably be improved.
A Matter of Experience
Experience will show whether 1145 passengers can be accommodated on the rear loading platform, which measures 7 ft. by 4 ft. 2 ins, at waist height, and if there is adequate space for 16-20 standees in the saloon. Constructed to the maximum box dimensions of 30 ft by 8 ft., the present seating plan, with double seats on each side of the body, affords a gangway width of 2 ft. at waist height. Single seats to be fitted along one side of the body have also been supplied with the bus in later service tests, so increasing the gangway width to 3 ft. 4 ins. Longitudinal seats, each for two passengers, arc provided over the front wheel boxes.
The rear entrance has a manually controlled fourpanel door, enclosing the step and riser to the loading platform, which stands 2 ft. 4 ins, above road level when the bus is empty. An 11-in. step is provided between the platform and the main saloon gangway. There is a clear opening of 2 ft. 21. ins, between the B4 doors wnen they are folded back. Adjacent to the driving seat is the unloading platform, measuring 2 ft. 7 ins. by 2 ft. 9 ins., the folding doors here being controlled by the driver: There are two steps, with 1 risers at the exit, which is forward of the axle; the clear width of the doorway between hand rails is 1 ft. 6 ins Service experience is required to show how standing time at each point will compare with that for existing double-deckers. It is possible that the • separate entrance and exit of the Freeline may enable point-to-noint tirnes to be reduced.
In. common with other underfloor-engined buses, the Daimler has a fairly high floor level, but a maximum headroom of 6 ft. 3i ins, is afforded for standing passengers, and the overall height of the bus, unladen, is under 10 ft. 3 ins. Although the absence of cross bars to the main windows, all of which are fixed, provides improved visibility for the seated passengers, I feel bound to criticize the .absence of windows at higher level for the benefit of standees. When the main body of the bus is loaded to full capacity, it may prove difficult for standMg passengers to identify stopping points with the restricted visibility afforded them.
Ventilation is provided by two large air-intakes above the windscreen and by a Clayton Dewandre underfloor heater and ventilating unit, which draws its air supply through a grille recessed in the waist rail. This Unit pumps out heated or cool air through ducts under the seats on the near side of the body.
As the Freeline will be operated in a municipal fleet which is predominantly Gardner-engined, the test vehicle was equipped with the Gardner, 6HLW horizontal six-cylindered unit, which has most parts common to the Gardner vertical engine. The HLW power unit is retained in the chassis by the maker's conventional mounting, incorporating forward rubber-bushed links arranged laterally between an engine supportmember and a chassis plate, and flexible G-mountings on both sides of the unit at the rear. An Armstrong twin-plunger hydraulic damper confrols idling vibrations, and a separate torque-reaction damper is provided. A tie rod with Metalastik bushes limits ,fore-and-aft movement.
The crankshaft centre line is located to the nearside, and provides an approximately neutral transmission line with the five-speed direct-drive-top gearbox, and offset underslung worm drive. Standard Daimler. transmission components are used, including an opencircuit fluid coupling, and preselective epicyclic gearbox.
Among the notable details of the Freeline is an underfloor radiator with contra-flow tube stack, Lockheed continuous-flow braking system with an accumulator cylinder, and central-pivot steering with the pivot mounted on the chassis frame.
Unladen, but with 36 gallons of oil fuel in the tank, the Freeline registered 7 tons 15i cwt. on its first visit to the weighbridge. Later, a number of 70-1b. castings was added, together with test equipment, to simulate
operating conditions, with crew and 63 passengers. As a transit service bus, the standing load would be greater towards the rear, so the castings were placed to represent 11 passengers on the loading platform, and additional weights, equal to 16 standing passengers, were equally proportioned over both axles.
A second visit to the weighbridge showed the groSs weight to be 11 tons 16/ cwt., so that three more passengers could be carried while still keeping the gross weight within the legal limit of 12 tons on two axles. The twin rear wheels are equipped with 10.00 by 20-in. tyres, with 14-ply tyres, each of 2 tons 71 cwt. advocated load capacity, plus 10 per cent. for bus service, on the front wheels.
The weight distribution with 63 passengers indicated that 5 tons 6i cwt. of the gross load was supported by the front axle, so some means may have to be devised to keep standing passengers towards the rear of the saloon. This could be done by using longitudinal seats over the rear-Wheel boxes, and providing more roof straps at the rear than at the front. Alternatively, tyres of a larger section having a higher load capacity might be required.
The Edinburgh Freeline is equipped with a 5.167-to-1 ratio axle as normally supplied in double-decker bus chassis, therefore no trouble is likely to be experienced
on the gradients encountered in the city area. The steepest gradient within 35 miles of Coventry is Sunrising Hill, so the first part of my trial constituted a hurried trip to Sunrising to assess the vehicle's climbing capacity and its ability to start from rest on a 1-in-6
Superb Riding Qualities
With full load, the riding qualities of the Daimler were superb and the severest of road surfaces and humped-back bridges were negotiated at a fair speed without a vestige of pitching or rolling. A ready-made test of manoeuvrability was provided in Kenilworth, where the main route takes a sharp left-hand turn in narrow streets. Despite a line of traffic along one side of the street, the Freeline, which it must be remembered is constructed to maximum box dimensions, was steered round the corner without the tyres brushing the kerb.
Weather conditions were not good. Light rain, coupled with falling leaves, made the road treacherous for braking, and although the bus was perfectly stable, it would have been unwise to indulge in fast driving. Sharp reports, when large stones were thrown up inside the wheel boxes, provided evidence that a certain measure of weight saving had been adopted by dispensing with double skinning.
It was comfortably warm inside the saloon, a thermometer suspended from the roof indicating a temperature of 61 degrees F. The mercury fell rapidly by 15 degrees when I thrust the thermometer out of the driver's signalling window, which is the only window in the bus that can be opened. During non-stop running to 'Warwick, the radiator top-tank temperature kept to a steady 130 degrees F., and it was only after a second climb of SUnrising Hill that it rose to slightly over 140 degrees F.
B6
The test hill was just over half-a-mile long, with an average gradient of 1 in 9, and two bends where the incline stiffens to 1 in 6.2. Although this is one of the severest climbs in Warwickshire, it proved no obstacle to the Daimler, which took all in its stride with second gear engaged. During the repeat trial, stops were made at the most difficult points, but here again the Freeline, on its lowest ratio, got off the mark without fuss.
1 welcomed the. invitation to use the NIA R.A. Proving Ground at Lindley for acceleration, braking and consumption trials, especially because it was intended to make comparative tests with the vehicle carrying a "crush load," and in its normal role of a 36-seater plus 5ve standing passengers. The course at Lindley provides perfect conditions for comparative tests. The speedometer was checked initially, and was found accurate.
The weight of the bus with its crush load prevented extensive wheel locking during the braking tests, and the Freeline was brought to rest in 56 ft. from 30 m.p.h. with Tapley readings ranging from 67-71 per cent. Hand brake tests -were made using the Tapley meter which registered 21, 22 and 25 per cent. from 20 m.p.h. A brake-fade test had been staged during the descents of Sunrishig, which had been made in top gear with the brakes applied to check the speed. A Tapley reading of 53 per cent. was recorded for foot-brake operation at the foot of the hill.
The acceleration rate, for a vehicle of almost 12 tons, was lively, and employing second gear when moving
away from rest, 30 m.p.h. was reached in an average of 27.1 secs. Top-gear acceleration from 10 m.p.h. took 6 secs. longer. Because this type of bus is normally employed in city service, with frequent stops, I made only one consumption trial with stops at every quarter
mile post.
Two stop-watches were employed, one tomeasure the 15-sec. period at each stop, and the other to calculate the time the bus was in motion.. After measuring a gallon of fuel into the test tank, and arranging the taps to operate from this supply, the trial was started. The outer circuit at Lindley measures 3.013 miles, so two laps were covered making a total of 6.026 miles for the complete test.
Conditions on a private course such as this prevent any unrehearsed incident which might require adjustment of readings, or doubt being cast on the accuracy of the results. The trial was completed in 19 mins. 5 secs. running time, corresponding to an average speed of 19 m.p.h.
Residual fuel drained from the test tank measured 2.3 pints, therefore 5.7 pints were used which corresponds to a fuel consumption rate of 8.43 m.p.g. This is an improvement over the average consumption rate of large-engined double-deckers.
At the end of this series of tests we discarded 22 passengers, in the form of 44 castings, mostly from the rear of the bus because the weights were more conveniently placed for handling. Iron castings are not human and no complaint was heard when they were left by the roadside, but the natives of Edinburgh might not be quite so apathetic if 22 of themwere left at a bus stop because legislation prevented them from occupying standing space in the bus.
Our laziness in not adjusting the load between axles proved detrimental during the braking trials, when the
rear wheels locked for a considerable distance on every emergency application. In this series of tests the Freeline was tested as a conventional bus carrying 36 seated and five standing passengers. Because of wheellock, the brake stopping distance was greater than before, and wheel skids of up to 30 ft. were common. The effective stopping distance from 30 m.p.h. was 58 ft.
Acceleration rate was much improved by lightening the load, and, employing the four higher ratios, 30 m.p.h. was reached from rest in 20.9 secs. I would have expected that a much shorter running time might have been obtained during the ensuing consumption trial, because, according to the acceleration trials; up to 7 secs. should have been saved when driving away from each point. The time factor, for driving two circuits with 24 stops, was, in fact, only 9 secs, less than when carrying a full load. As a possible explanation of this, rather more care was used when stopping at each point to prevent the wheels locking. Carrying 41 passengers, the consumption rate worked out to 9.9 m.p.g. at 19 m.p.h.
My test of the bus extended over 100 miles, and all the trials were made without a hitch of any kind. It will be interesting to follow the Edinburgh tests, because operators in all parts of the country have similar ideas. Buses of this type were popular during the war.