From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Page from 'The Autocar' magazine featuring reader queries and replies on topics including crashed speedometers, tyre replacements, and specific car model experiences.
| Identifier | ExFiles\Box 170\1\ img094 | |
| Date | 27th September 1940 | |
| The Autocar September 27th, 1940. SOME QUERIES and REPLIES ADVICE to readers is freely given by The Autocar on all matters relating to cars and motoring. Each week a small selection of these questions and answers is published in this section, those of most general interest being chosen. Readers desiring a direct reply for which postal answers are required are requested to enclose a stamped and addressed envelope at the new wartime rate of 2½d.{John DeLooze - Company Secretary} for inland letters. Does it Mean Anything? The Jammed Speedometer of a Crashed Car as "Evidence" of Speed A POINT that has often been raised is whether the speedometer needle of a car involved in a crash, if the needle is jammed at some particular reading, is evidence of the speed at which the car was travelling. There certainly have been a number of instances of "pile-ups" that obviously occurred at high speed where the speedometer needle has been noticed to have stuck at 75 or 80, or even more. The question, always an interesting one, was put recently to the AC speedometer people in America. Their considered opinion is that a speedometer found jammed in the circumstances indicated would very seldom show the speed of the car at the time of the impact. As the most easily understood illustration, they suggest taking a speedometer head in the hand and giving a quick turn of the wrist, by which means the indicator can be thrown over to register as much as 100 m.p.h. Yet a car travelling at 50 m.p.h., if struck on one side, might register practically zero on the speedometer because by the direction of the blow the needle was swung in the other direction. It is also pointed out that the speed indicator of the magnetic type of speedometer is controlled by a sensitive hair spring. Any locking of the mechanism would be controlled entirely by the direction of a blow, and depend upon the exact moment at which the speedometer was stopped. Unless, a rare possibility, the indicator needle were locked immediately prior to the impact, this firm consider that it would be practically impossible for a speedometer to show the speed of the car before an accident. Answers to Mental Tune-up (See page 311) 1. (i) About 1.290 and 1.190; (ii) 0.720 to 0.780; (iii) 1. 2. Outwards. 3. 62.16; 160.9. 4. The maximum deceleration possible with a tyre-road friction coefficient of unity. About 30ft. 5. (a) 0.018-0.020; (b) 0.012-0.015. 6. When the engine is revved up and the clutch let in, the engine speed greatly exceeds the r.p.m. necessary to drive the car after the clutch has been engaged. The acceleration and jar are due to the impetus of the engine and flywheel being suddenly transmitted to, and absorbed by, the rest of the car. In the case of the free wheel, the engine speed can never exceed the equivalent r.p.m. necessary to drive the car at whatever speed it happens to be travelling. As soon as the r.p.m. reach this point the drive is automatically taken up with no more shock than when normally stamping on the accelerator in a fixed gear. 7. (a) The centre of the hub; (b) the point of contact between tread and road. This must always be stationary unless the wheel is skidding. 8. 21ft. D*N/1613 candles at 10ft. 9. D*N/2.5 in millimetres or D*N/64 in inches. 10. Unit of rate of doing work=550ft.-lb. per sec. 11. The amount of heat required to raise the temperature of 1 lb. of water at 39 deg. F.{Mr Friese} by 1 deg. F.{Mr Friese} 12. 7 lb. per b.h.p. 13. 7 to 1. Tyre Replacements ? As I am about to have new tyres fitted to my car—having made them last almost to the danger point in these hard times—I am wondering if it is necessary to have new tubes fitted also.—"L. H.{Arthur M. Hanbury - Head Complaints} T." If the present tubes are in good condition it should not be necessary to have new ones. It sometimes happens, however, that a tube gets chafed badly, even although it has not actually punctured, and in such a case it might avoid trouble later, and actually represent an economy, to have it replaced when the new covers are fitted. In short, be guided by the condition of the tubes when the new covers are fitted. 6 Volts on 12 Volts ? I am wondering if it is possible to use a 6-volt electric horn on a 12-volt circuit? I thought of connecting the horn to one half of the battery only, but am wondering if this would harm the battery?—”T. B." The horn should not be connected to one half of the battery as this might very probably result in the two sets of three cells each having different loads put on them, while they would receive the same charge, so that they would sooner or later be at different states of charge, one half tending to be overcharged and the other half to be undercharged. The horn may be used with a suitable resistance connected in series with it. INFORMATION SOUGHT Information and advice are sought by various readers regarding the following matters:— No. 13454.—1937-39 Hillman Minx Drophead Coupé "L. C. R.{Sir Henry Royce}"—General experiences and running cost data appreciated. Does the body remain weathertight and reasonably free from rattles? No. 13455.—1938-39 2-litre M.G. "L. E.{Mr Elliott - Chief Engineer} H.{Arthur M. Hanbury - Head Complaints}"—General experiences welcomed; petrol and oil m.p.g. Any troubles experienced or replacements needed after, say, 20,000 miles? No. 13456.—1935 Riley Falcon "E.{Mr Elliott - Chief Engineer} G.{Mr Griffiths - Chief Accountant / Mr Gnapp}"—Particulars regarding petrol consumption of the 1935 Riley Falcon Fifteen-Six, and points to look for when purchasing second-hand. A handbook is also required. No. 13457.—1939-40 8 h.p. Standard "R.{Sir Henry Royce} C. D.{John DeLooze - Company Secretary}"—Is performance maintained without frequent attention, and does economy remain constant? Details of any troubles; petrol and oil m.p.g.; comfort and accessibility. No. 13458.—10 h.p. B.S.A. Scout "H.{Arthur M. Hanbury - Head Complaints} C. T. H.{Arthur M. Hanbury - Head Complaints}"—General experiences wanted, also running cost particulars. Are there any real snags regarding the front wheel drive as regards use in a fairly hilly district; any special treatment with the transmission? No. 13459.—Austin Seven, Model 65 "F.{Mr Friese} H.{Arthur M. Hanbury - Head Complaints} T."—Readers' experiences are invited on the subject of lowering a 65 Austin Seven chassis (1933-34) and other conversions designed to improve performance and road holding. No. 13460.—Handbooks Wanted "P. M.{Mr Moon / Mr Moore} C."—1936 PB-type M.G. Midget. "C. J.{Mr Johnson W.M.} T."—1938 Fiat 500 two-seater. FLASHES Premises in a non-military area, preferably in a secluded spot and from 4,000 to 15,000 square feet, are required by the British Motor Boat Manufacturing Co., Ltd. They are required for light engineering work. A garage or service station at present closed or not fully utilised might meet the case. Offers should be addressed to the company at Britannia House, Ampton Street, London, W.C.1. It might also be possible to take over existing personnel. As the result of a collection sponsored by the Employees' Representatives' Committee of the Goodyear Tyre and Rubber Co., a cheque for £509 11s. 7d. has been presented to the British Red Cross Society. The collection was intended to provide for an ambulance or other equipment needed by the society. The Copper Development Association has now removed its offices, formerly in Thames House, to Grand Buildings, Trafalgar Square, London, W.C.2. The services and publications of the association are still available to all, free of charge. At the present time many firms and individuals are being called upon to undertake work involving the use of copper and its alloys, of which they have not had very much previous experience, and it is in such cases that the association can be of particular assistance. The Copper Development Association is a non-commercial organisation maintained by the British copper industry. 'THE AUTOCAR' CAN BE OBTAINED ABROAD FROM THE FOLLOWING: AUSTRALIA: Gordon and Gotch, Ltd., Melbourne (S.A.), Perth (W.A.) and Launceston (Tasmania); Auckland, Christchurch and Dunedin (N.Z.); INDIA: A.{Mr Adams} H.{Arthur M. Hanbury - Head Complaints} Wheeler & Co., Bombay, Allahabad and Calcutta. CANADA: Imperial News Co., Ltd., Toronto, Winnipeg and Vancouver; American News Co. (Central); Gordon and Gotch, Ltd., London. SOUTH AFRICA: Central News Agency, Ltd. U.S.A.: Wm. Dawson & Sons (S.A.) Ltd., Cape Town. UNITED STATES: The International News Co., New York. A 10 | ||