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168 
NATIONAL CO-OPERATIVE TRAFFIC MANAGERS' CONFERENCE
Page 60
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Make the Driver Comfortable
INCREASING demands on the cortutercial driver made it important to protect him I against excessive strain, said Mr. L. Harris, director and manager of the Coachbuilding Division of Appleyard of Leeds Ltd., addressing the National Co-operative Traffic Managers' Conference at Blackpool last week-end. One way to assist towards this end was to provide the best possible working seat. Ease and posture were of first importance but although soft deep cushions could be apparently comfortable at first they could lead to congestion of the pelvic organs and interference with the circulation.
In discussions with experts from an important organization manufacturing seats. said Mr. Harris. he had been advised that dimensions had tended to be based on a person taller than 90 per Gent of his fellows. However, a seat depth of 20 in., which would be suitable for a tall driver would spell discomfort for a short man. To please everyone the depth could not really exceed 17 in. A squab 16 in. wide had been proved during research into an anatomically designed seat to give maximum comfort. So far as the back was concerned vertical centre line tests resulted in maximum support being given to the region 6 in. to 11 in. from the top of the cushion when no weight was applied. •
Researchers took a check on the horizontal curvature of the back of persons from 5 ft. 4 in. to 6 ft. tin., the deviations of the samples being small. The sides of the squab graduated from the centre line in a transverse curve were then built up so as to support parts of the back normally in the regions of the kidneys and lower shoulders, the object being to give stability to the body during sideways movement of the vehicle. The horizontal curves established showed that after 74 in. outward of each side of the centre line of the squab there was no longer contact with the body. Thus any width of squab over 16 in. served no useful purpose and only added to the cost. Filling for the squab should be of minimum even thickness and of firm density so that it would adapt to the correct shape and give support where required.
A check was made on the correct shape of the cushion with the driver seated. Maximum pressure was shown to be applied at points approximately 4+ in. apart on the centre line of the cushion and about 6} in. forward of the lower edge -of the squab. Curvatures caused by pressure of tissues and legs were measured and a shape of cushion pan was derived to give the maximum support in the minimum amount of rubber. A width of 16 in. was agreed, since anything over 15 in. did not serve a useful purpose.
Excessive softness of density was not found to be effective as this did not permit slight changes in posture and also allowed the body weight to collapse the edge of the cushion. The study showed that emphasis regarding seat comfort must be placed on the anatomical form. Adjustable seat and backrest were now B26 considered almost a matter of course; seats with a hydraulic damping action offered a variety of advantages.
Some 70 per cent of the commercial chassis for use in Britain were said to be fitted with special bodywork and many of the standard vehicles produced by the big manufacturers were modified by smaller firms.
One of the dangers that beset the bodybuilder or body engineer was a tendency to regard glass-fibre as a wonder material suitable for all purposes in coachbuilding. The wise designer must always select the best material for the job in hand and in many cases it would be found that the traditional supplies suited the purpose better. There were excellent glass-fibre bodies but the stresses involved in production were considerable and varied from those of the conventional form. Prototypes should successfully complete very rigorous road tests before acceptance.
On behalf of coachbuilders in general, Mr. Harris urged transport managers to give reasonable servicing to the bodywork as well as the mechanical parts. Frequent checking of mounting and holding-down bolts, adjustment of striking plates. oiling of hinges and locks, were essential to proper maintenance.
Diagnostic Expertise
Since mechanical wear had been much reduced the mechanic today, had to deal more and more with unseen faults, said Mr. A. N. Turnbull, sales director. Crypton Equipment Ltd. In place of the routine mechanical services of a few years past had come a need for more rapid and accurate methods of diagnosis, more critical and regular adjustments of the ignition and carburation systems. Ten years ago most engine analysers comprised a series of self-contained instruments, each designed for a specific purpose and to carry out a complete diagnosis could occupy a trained electrician two or three hours.
Area testing was the first real breakthrough in simplified engine checking and the Crypton Motormaster used only four electrical test leads; only two master switches and four minor controls were necessary. Seven area tests, using three meters, were well within the capacity of the ordinary mechanic and in the majority of cases could be completed well within the hour. For the first time a means of measuring distributor automatic and vacuum advance conditions, without removing the unit from the engine, was satisfactorily developed. Then, with the increasing complexity of engine design, the need for quicker, simpler, and deeper testing was realized, attention turning to the cathode ray oscilloscope.
Work was commenced to simplify the laboratory form of unit and to combine it with instruments so as to provide a comprehensive tester. Known as the Crypton Motorscope, the new model enabled all the work of the previous design. plus_more advanced ignition tests, to be carried out in as little as 20 minutes without alterations to engine connections and again by an average mechanic.
Three years ago Crypton, in consultation with BMC, and in association with Heenan and Fronde., commenced development of a new approach to roller testing, so as to enable performance and many transmission troubles to be quickly and accurately located inside the workshop. One objective was' to eliminate the operating complications of the more usual research dynamometer and to produce a machine especially for service conditions. The outcome was the Crypton-Heenan "Rolling Road' which comprises two pairs of 20 in.-dia. rollers on a shock' absorbent sub-frame with a pneumatic load recording cell. Power is absorbed by a 300 b.h.p. water brake which, by means of a remote load control which the driver has in the vehicle, is infinitely variable.
The Rolling Road, said Mr. Turnbull, allowed a vehicle to be tested up to 125 m.p.h. or, by use of the remote load control, under mountain conditions— where low gear driving would be necessary. Apart from this, it enabled transmission tests on slipping or dragging clutch, gearbox or axle noise, overdrive units and automatic transmissions, to be readily performed inside the workshop.
The way to successful service now lay in diagnosis, said Mr. Turnbull. With the rapid developments in this field there were frequent changes in equipment, so Crypton facilitated matters by providing adapters for existing units.
A strong trend towards leasing of equipment was evident, usually over initial periods of three or five years, with secondary periods of the same length. Cost was of the order of 9s. or 10s. a day for the most advanced type of analyser and this arrangement was of material assistance in ensuring that the newest designs were quickly brought into use.
Mr. H. M. Dick (Glasgow) was elected chairman for the ensuing year, with Mr. J. E. Gill (Swindon) as vice-chairman. Mr. A. Watch continues as hon secretary of the Association.
ASHLEY TAYLOR