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Manawatu Times, Volume 61, Issue 47, 26 February 1936, Page 13

Motor

CHALLENGE TO VEHICULAR

What is a “phon”? It is a unit of loudness arrived at by a special committee set up by the British Minister of Transport to investigate noise problems. Some idea of the phon can perhaps be obtained from this noiso chart. Wireless enthusiasts will note the similarity with the very widely-uso American measure of volume, the decibel: Phons.

130 Threshold of feeling or pain. 110 120 Vicinity of aeroplane engine. 103-110 Vivinity of pnuamatie drill. 100-105 Vicinity of loud motor horn. 90- 95 Interior of tube train, windows open.

SO- S 3 Interior of express train, windows open. 60- 75 Conversation (average to loud). 40- 50 Quiet street. 20- 30 Quiet country house. 0 Threshold of audibility.

The noise committee, with Dr. G. W. C. Kaye of the National Physical Laboratory as chairman, decided that the first step in their investigations was to find some standard of noiso measurement —hence tho phon. The committee reached the view that ‘‘overall” noise was thp important factor. This then, automatically lakes into account every factor such as silencer, engine, gears, horns, etc.

The committee therefore carried out a number of tests with new vehicles. These were the tests devised:

1. Stationary, with engine running at maximum speed. 2, At various steady and accelerated speeds on the level.

3. With full throttle on hills. The tests led to the following broad* conclusions:

1. The average present-day “ordinary” motor car under normal conditional conditions of use is not unduly noisy.

2. Certain types of sports cars are too noisy.

3. Except of moderate steady speeds, many cycles are too noisy as a result, doubtless, of the high power in relation to the size of the machine. 4. Certain commercial vehicles are somewhat noisy; improvements could be effected by attention to engine and gear noises.

As a result of these tests the committee recommends that after an approved date no vehicle shall be sold until it can pass the following tests: Normal Punning Test. —When the vehicle is driven with full throttle at 30 ui.p.h. (or at the maximum legal or possible speed, if less than 30 m.p.h.) using the gear preferred by the driver, the loudness measured at a point 18 feet to one side of the vehicle shall not exceed 90 phons. Running Engine Test.—When the vehicle is stationary with tho engine running at the speed which would give maximum power output the loudness IS feet behind the exhaust pipe shall exceed 95 phons. It is suggested that iii the case of motor cycles and commercial vehicles these noiso levels shall be relaxed to the extent of iivo phons in order to give manufacturers time to carry out necessary experiments ancl improvements.

. Regarding the use of vehicles after being sold to the publie, it is recommended that the practice of racing engines of stationary" vehicles should be prohibited. The report of the committee has been referred to the motor trade for its views and it was expected that the industry" will co operate iu carrying out the proposed tests. It is also possible that in time a portable testing apparatus will be available for police use. Two very important sources of noise, it is interesting to note, have not been clealth with —railways and' trams. There is a legitimate excuse in the case of trams as these vehicles are boing gradually abolished in favour of trolley ’buses.

HYDRAULIC BRAKES ON ALL NEW CHEVROLET MODELS

In changing to hydraulic brakes on both chassis models, Chevrolet has adapted this principle of brake actuation to its own design of brake mechanism within the brake drums. Instead of the cable operated floating earn formerly used at each wheel, a master hydraulic cylinder with double opposed pistons is used to actuate each pair of one-piece articulated brake shoes. The master cylinder, whose piston is moved by the brake pedal to transmit by a column of fluid to each of the wheel cylinders, is mounted on the frame.

By “Radiator."

GIVE AND TAKE

WORTH YOUR WHILE

INSTRUMENT BOARD

OPENING THE GREASE GUN

LATEST TRENCH CAR HAS A DISAPPEARING TOP

I Tho master piston is one inch in diameter, while wheel pistons are larger to give an increase of braking effect at the wheels. Front wheel pistons ate larger than those of the rear wheels, to balance the braking effect when, iu stopping, extra weight thrown on the front wheels gives them greater traction. This arrangement prevents locking the roar wheels by themselves by heavy brake application. The hand brake lever actuates both service brake shoes iu both rear wheels. Tho connection is by flexible cable, connected to a lever and toggle mechanism within the rear brake drums.

On the luxe models, brake drums are of composite construction, comprising a cast iron rim and a pressed steel web. The braking surface is accurately mechined, after assembly to the wheel hub, asuring true concentricity. Long life, freedom from scoring, and more effective braking are advantages claimed for cast-iron. The outer surface ofj the drum is machined iu deep grooves that from five ribs, to promote cooling. On tho lighter model, equally effective braking is obtained by using pressed steel drums, which are one inch larger in diameter than last year’s increasing the brake lining area to 158} inches, 17 sqquare inches more than formerly. An improved grade of closely grained steel is used for the drums, and their braking surfaces are machined to accurate from and smooth finish. . Dirt shields have been added-

A feature of some trolley ’bus chassis is what is termed regenerative braking. This is a device whereby as the brake is applied the motor, which normally drives the vehicle is converted into a dyamo and restores current to the electrical generating system, which current is used again subsequently for driving the vehicle. Regenerative anil rheostatic braking is provided by Ran somes’ patent system of control in the fleet of 50 vehicles which the Ipswich firm are supplying to Capetown. Regenerative braking is obtained compulsorily on the same foot brake pedal as applies the air brakes; the change over from regenerative to rheosatic braking takes place automatically at a set speed.

LETTERS AND PAPERS KEPT ON

Salesmen, drivers of delivery" cars, etc, will find that clips bolted to the. instrument boards of their cars arc handy for holding letters, papers, memo, pads, order slips, etc. Tho clip is a piece of clock spring w’hich is drilled at one end for stove bolts and at the other for a wood knob. If the spring is annealed at the ends by heating it to a cherry red, it can be drilled easily, after which it should be heated again and theu cooled in water to harden.

DOUBLE TRUCK WHEELS REMOVED SINGLE HANDED

Removing heavy truck wheels is made quite easy by using a strong platform which rests on lengths of pipe or iron rods. Drive the wheels to be removed on the platform and then take the weight off the axle with a jack. Loosen the axle nut and pull the wheel and platform toward you. If the platform is to be used frequently put dolly rollers under it.

When using a small grease gun and a clogged litting is encountered that requires considerable pressure to open it, the small handle of the gun is hard on the hand. To improve the handle saw it off and slip a piston pin over the remaining part. The space between the handle and pin can be filled with molten lead to hold it in place, first filing several notches in the handle to give the lead a “grip.”

Automatic disappearing top and concealed head lamps are two features of the latest model Peugeot, a French car. The lamps arc set closer together-than on American cars and are enclosed and partially hidden by a radiator grille. Controls in the driving compartments cause the top to slide automatically to the rear where it fits compactly into the rear deck, converting the vehicio into an open car