TIMING CARS ON BROOKLANDS,WITH STOP WATCH,THE TAPE MACHINE AND LIGHT RAY APPARATUS
The Timing-Box on the Railway Straight.
TIMING CARS ON BROOKLANDS, WITH STOP WATCH, THE TAPE MACHINE AND THE LIGHT RAY APPARATUS
AFTER making something like my twohundredth visit to Brooklands Track, it suddenly occurred to me the other day that I hardly knew anything about the way
in which records and races are timed. Like most people who visit the Track I had noticed a little hut on stilts half-way down the Railway Straight, the little Sentry Boxes at the Kilometre and Mile marks, and had even penetrated (but not for long l)
into the time-keepers’ sanctum at the Fork on one or two occasions during the course of the bigger races, only to retire a little baffled by the complicated things being done there with stop watches and charts. On mentioning this to Mr. Percy Bradley, the genial clerk of the course, he at once invited me to name a day for inspect ing the various instruments used for timing purposes, and so it came about that on one of the few sunny mornings We had in May I presented myself at the clubhouse. ” I’ve got the beam-apparatus working this morning,” said Mr. Bradley, ” shall we start off by inspecting that,” so we boarded his Rolls-Royce and sped off smoothly to the little black-and-white hut
on the Railway Straight. Expecting to see something rather like the control panel at Brookmans Park broadcasting station, I was surprised to find that the whole outfit consisted of just three units, the largest perhaps two feet square, and all of them in wooden carrying cases which enable them to be transported to any part of the country in the back of a car. The three units were respectively the chronometer, the electric clock and recording device, and the electric amplifier. The chronometer was outwardly similar to those used aboard ships, but was actually of course a much more accurate instrument, and holds the coveted Kew certificate. It was made in England, which is still the recognised home of nautical clocks, though By T. G. MOORE
the rest of the apparatus is constructed in Paris. The recording apparatus may be com pared to the ” time-clocks ” used to clock factory workers in and out of work. An electric motor rotates a system of wheels bearing figures indicating the time in hours, minutes, seconds and hundreds of a second, which appear in turn opposite an aperture in the same way as the ” trip” and “season ” figures on a speedometer. When a car passes the recording point, an electric current passes through a pair of electromagnets in the bottom of the recording de vice, and a strip of paper is forced into Contact with the revolving figures, the lap time is determined in a few seconds by sub tracting the first figures from those of the following lap. The wheels carrying the figures for the seconds and decimals of seconds are carried on springs so that they can lag behind long enough to print their impression and then catch up again, while
a small “tick ” alongside the second decimal figure gives an indication of the third figure or thousandth of a second.
The chronometer is used to keep the electric clock running at the correct. speed. Three contacts inside are connected by means of wires to the electric clock, and once the two are set to run in unison,
which is effected by regulating the speed of the motor, they remain permanently in step. The power for operating the recorder is derived from a twelve-volt accumulator. Now as to the links between the car and the timing apparatus. When flying records are being attacked, the light-beam system is used, while timing-strips are used for the standing records. There are two reasons for this. In the first place, the kilometre and mile lines are on the Bylleet Banking, and as the light-ray can only follow a straight line, it would pass right over the top of a low car running low
down the banking. Secondly the light apparatus has a certain lag, and electrical experts say that it is impossible in practice to make two identical machines. The error is very small, but the Brooklands authorities decline to take the chance, and consequently only use the light-beam where the car makes flying laps, for which only one instrument is required.
Any lag which may occur then appears in each timing and is cancelled out, but it follows that a complete lap has to be covered even for short distances such as one kilometre.
The light-beam apparatus is extremely simple. A car head-lamp is placed at one side of the track, usually opposite the hut on the Railway Straight, with the ” detector ” on the other side under the hut. The detector is a tube eighteen inches long and three in diameter, at the rear end of which is placed a photo-electric cell. When the light of the lamp is focused on it, a minute electric current is generated, but when the beam is broken by the passage of a car the current decreases. This change of current is magnified by means of a twovalve amplifier, and is then strong enough to work a relay, which in turn switches on the electric recording apparatus and makes it operate. The cell must be remarkably sensitive, as it works perfectly in the brightest sunshine, where the light from the lamp is hardly noticed in the general glare. Incidently the amplifier is only connected to the recorder when a switch is pressed, so any individual car can be timed during a race. It would be interesting if two of the light cells could he fitted up to operate during a fast race like the ” 500 ” to record speeds over, say, a quarter-mile on the Railway Straight. We now have to consider the timing strips used for the standing records. Each
of these consists of two pieces of rubberised canvas one hundred feet long, and one foot wide, these strips are laced together to form an oval tube, and the strips are kept from touching by two inflated tyre tubes, which are blown up through ordi
nary tyre valves. A single phosphor-bronze strip is fastened to the lower side of the top strip and two to the bottom strip, so that when a car wheel passes over the strip contact the ribbons touch.
These contact strips are connected up to the electrical recording device already described, by means of the overhead wires which rim all round the track, connection being made at the ” Sentry Boxes” at the Kilometre and Mile points. The car then takes its place with its wheels against the first strip, which is covered with rubber mats to give the back wheels a better grip as they climb over it. In goes the clutch, ” chunk “goes the recorder, with two more ” chunks” a few seconds later when the car crosses the Kilo and Mile strips on the other side of the track. The results of the first run are thus available almost instan
taneously, though two more have been made in the opposite direction before the anxious driver, who has probably given the transmission all it can take in getting away, knows whether his efforts have been successful.
” Well that is all extremely interesting,” I said, ” but haven’t you something else in the way of timing instruments, something with an enormous pendulum, hidden away somewhere?” “Oh, you mean the Holden apparatus,” Mr. Bradley rep!ied, ” I have never had to use that during the five years I’ve been at Brooklands. I don’t want to either, especially if there are any long distance records ta time. I remen:ber more than once seeing the whole room strewn with recording tape, with the time-keeper in terror in case someone came in and tore it.”
The Holden timing apparatus lives in the tall two-storey building in the Finishing Straight opposite the Paddock, and was invented by General Sir Capel Holden, the engineer who actually designed the track itself. On the ground floor we found the pendulum, which was in fact one of the electrically-swung Synchronome type, and only recently been installed, and this lower room was shared by even more modern apparatus, the two units of the powerful new public-address system. Up aloft was the timer itself, looking a little neglected in the centre Of a dusty bench carrying rows of switches. Ail was intact and in working order under the cover, however, and we gazed on the historic machine which had recorded those adventurous feats before the War,
Hemery’s 125.9 m.p.h. over the Flying Kilo in 1909, Percy Lambert’s Hundred in the Hour in 1913, and no less exciting Parry Thomas, Eldridge and Count Zbrowski in the decade which followed the armistice.
The principle on which the times were determined was a simple one. A narrow strip of paper was fed through the machine by means of a weight-operated mechanism. Three ” pens,” actually metal rods ending in thin pieces of copper wire, were continually in contact with -the paper. An impulse from the electric clock was applied to the centre one at regular intervals, either two seconds or two minutes, according to the length of the record being attempted. The outside:. one was connected by means of the overhead wires round the track to one or more timing strips placed there, and each time the car passed over these a kink was formed in the outer line. By comparing the distance between two kinks with the timemarks on the centre line, which was done by means of a special scale. fitted with a magnifying glass, the time over the given distance could be -determined. There was always a chance, of course, that some alien car or person might cross the line when the record was in progress, so the third pen was connected to a switch operated by the time-keeper each time the car crossed the line. Another trouble anti a more frequent one was that the pens
used to run dry. I could well imagine, too, the confusion when a roll of paper came to be measured, for on the machine was marked : ” Paper speed one foot per minute,” so it is easy to calculate how much paper would have accumulated after three or four hours.
Leaving this veteran but still workable machine, which I hope will some day find a well merited home in the South Kensington Museum, we Considered that final but highly important instrument the stop-watch, which is used for all purposes except recordtiming The type ‘in use at Brooklands differs from that usually employed by the amateur time-twper in having an hour and a minute hand and two seconds hands. These watches are stared at the beginning of a race by means of a knob at the top, which is then locked by a collar so that there is no, chance of the watch being inadvertently stopped. A second button on the side of. t lw watch controls the two seconds hands, %vhich give minimum readings of one-fifth second. A first pressure on the button locks the first hand, giving the lap time of the first car selected, and the second pressure the time of the second. With a third pressure the two needles return not to zero, as on the ordinary stop-watch, but to the time which has elapsed since the beginning of the race. Each time the particular cars which he is timing pass him therefore, the time-keeper
puts down the time shown on one or other dials of his stop-watch, the lap times being subsequently determined by subtracting the figures. Each time-keeper has two of these instruments, which cost up to .4″too, and are made in Switzerland, and so Mr. Bradley told me are sent back to their native land (the watches, not the time-keepers) for fully three months in order to be regulated and to pass their Geneva tests. Each time-keeper arranges to time a group of cars, and experienced men such as Messrs. A. V. and A. L. Ebblewhite (father and son), Mr. A. L. Dutton, who are assisted by Mr. A. G. Reynolds and Colonel Loughborough when big races are in progress, can handle up to eight, even on a short lap like that of the International Trophy.
Other tracks may have more spectacular timing-apparatus, as for instance M9nt1h6ry, where the time-keepers have to sprint across each time the car passes to attach a thread to a post at the other side, but nowhere. I am convinced, is the timing better organised or more scrupulously accurate than at Brooklands. Next time you visit the track therefore, Whether for record or race, remember the cunning little clocks in the hut on the Railway Straight and the eagle-eyed time-keepers vainly trying to drink a cup of tea between pressing of their watches in Chronograph Villa, You want the Best Time—We have them !