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Some Aspects of Trolleybus Development "

19th June 1936, Page 52
19th June 1936
Page 52
Page 52, 19th June 1936 — Some Aspects of Trolleybus Development "
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Which of the following most accurately describes the problem?

MR. W. MARSH opened the discussion. He said that enormous advances had been made in the trolleybus. Successive Governments had imposed fresh types of motor taxation every six years, and he was anxious as to what would happen in 1938. If it were found that the tax on trolleybuses had been doubled this would cause great difficulty.

MR. S. J. PATMORE thought that the lighting of passenger vehicles would soon have to equal that in homes, stores, etc. He would like to see the voltage for lighting raised to 40-50, so that better lamps could be employed.

A Criticism of Direct-driven Dynamos.

MR. A. W. REED criticized the type of dynamo mounted at the end of the main motor; this might affect the design of chassis and the position of cross-members, etc. It might be simple to remove from the chassis, but not so easy with the body in position. He suggested that belt drive was now so efficient that it could he used profitably; the dynamo would not then interfere with the main motor.

MR. W. VANE MDR LAN) wanted to know more about regeneration. This might he right on some systems, but assumed a new aspect where there was a long succession of severe gradients. A year or two ago at Leeds experiments were conducted on a tramcar. There was an overvoltage relay, but on one occasion this did not act and caused a sub-station fire. In respect of weight he hoped they would not be driven too far as in the evolution of the oil-engined bus, in which they often had to consider even ounces in the weights of seats and other fittings.

Should the Electrical Equipment be on the Chassis?

MR. A. E. GRIMSDALE queried the value of chassismounted electrical equipment. For the sake of two seats of doubtful value it had introduced a number of disadvantages, such as inaccessibility, increase of weight and a control gear in the dirtiest part. The choice of schedule speed in comparing electric and air braking was unfortunate; 14 ft. per sec. was too high for air braking and 2.8 too low for electric braking; by which it was possible to average 4. The advantages ot electric braking were rapid action but positive limit, freedom from skidding, negligible extra cost and saving in wear of brake facings. Electrical equipment was mainly designed for six-wheelers, and it was, therefore, often excessively heavy for four-wheelers.

Cot., Mourn., of the Ministry of Transport, said that he realized the importance of the trolley vehicle, and thought that the Ministry had encouraged its use. The comparisons between the speeds of regenerative and air braking were most instructive. He would like to see low-voltage lighting on all types; it gave 'the, advantage of emergency battery traction.

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ALD. SIR W. DAVY also pleaded for extra standing passengers, of whom one or two more might well be permitted. Seats in trolleybuses were often larger and more comfortable and this reduced the capacity. In respect of taxation two departments of the Government were fighting; one was pressing municipalities for cheap transport facilities so that people could live in outlying areas, the other increases taxation and so renders low fares uneconomic.

MR. W. V. EDWARDS said that on the hills of Hastings they were constantly retuning 120 amps. to 150 amps. by regeneration. Normally, every sub-station feeds an isolated section of line. Work was now in hand so that in each box on the margin between one area and the next they would have a contactor, and the whole of the positive line would be connected by these.

Standing Time a Third of the Total.

MR, H. P. A STBURY inqu:red as to what standing time was considered satisfactory. His experience was that this might be anything from 30 per cent. to 35 per cent, in various cities.

MR C. OWEN-SILVERS had run a sub-station similar to that mentioned by Mr. Edwards, and he thought there was a great future for this form of control. Ile regretted that vehicles had to be "cluttered up" with gadgets to prevent wireless interference, etc.; they thus lost :much of their pristine beauty.

MR. A. A. jAcicsoN asked if it would be possible to utilize electro-pneumatic as distinct from electro-magnetic control, MR. T. E. THOMAS said that he did not hold any brief for the Ministry, but the difficulties experienced in building for stock were more due to the varying demands of operators than to regulations. In London it was almost essential to have a battery for turning, and he was not worried about low-voltage lighting. He liked electric braking; this was an advantage not possessed by the motorbus.

Regeneration Not Employed on Steep Hills.

In his reply, MR. PRIDDLE said that only 8-in, clearance was required for the removal of a dynamo on the main motor; he preferred doing away with belts and pulleys. Regenerative braking had a definite field, particularly on two-axle vehicles. Servicing was very important and there was enough cable on a vehicle with regeneration to reach from end to end ,of the "Queen Mary." It was an advantage to have a large overload capacity. In rush hours people do not mind how they are taken home so long as they can get there. Regeneration cannot•be used on steep hills as it cuts out at 12-13 m.p.h., rheostatic brakinriS used after that. On fast services electric braking is not worth while.


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