The Choice of Gears.
Page 20
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The rapid increase in the number of heavy motor vehicles, added to the endeavours of the motorbus engineer to lower the cost of running repairs, has created an enormous demand for gear wheels of the utmost accuracy, and machined from material of the highest. grade. In no commercial motor is the necessity for correctly-cut teeth more apparent than in public service vehicles, the transmission systems of which have to operate under unfavourable conditions, more or less, during their lifetime. The vexed question of noise depends, to a large • degree, upon the power transmission wheels in the gear box, because, unless the teeth of the wheels are correctly proportioned, of a suitable pitch, and absolutely true, undue noise and friction will result..
One of the few companies which specialises in the cutting of gears is David Brown and Sons (H.F.D.), Limited, of Lockwood, Huddersfield. This undertaking had its genesis in the year 186o, and, for the last three years, a section of the.works has been devoted to the production of gear wheels,
and toothed parts generally, of motor vehicles. This department has become such an important one, that a neW building is now in course of erection, for the making of motor parts only. New plant will be purchased for the purpose, and some new machine tools, which, for want of space, have had to find a temporary resting place in the main building, will shortly be removed to their correct,. position. The present works has six bays; it is commodious and well lighted. Over four hundred special machines are laid down, and the different departments are connected together by narrow-gauge tramrails, for transporting heavy work from one part to another.
The company cuts gear wheels for some of the prindtpal motor omnibus companies, and,. larger quantities are also machined for the trade. At present, about three hundred men are employed, but their number will be greately augmented when the new motor department is in working order.
With very few exceptions, each machine tool has been either purchased, or designed, for a special purpose, and is not used for general work. Among the more noticeable of the tools may be inentioned,a couple of large vertical turning and boring lathes, one of which, at the time of our representative's visit, was at work upon a gear wheel, 9 feet in diameter, destined for Russia; a number of spiral gem cutters; worm bobbing machines, the largest being capable of cutting the teeth on a worm wheel 8 feet in diameter; a gang of planers, for machining bevel gear wheels; and a powerful machine, specially evolved in the works, for cutting large spur gearing. Numerous turret lathes are to
be seen in one of the bays; these are arrangedin one row, and vary in size, although most of them are capable of dealing with large work. The company makes a specialityof hardened and grotind fittings, and, for this reason, some fine Brown and Sharp and Norton grinders were laid down e_arrie time ago.
The foundry equipment is very complete, and all patterns of motor castings in phosphor-bronze, aluminium, and brass, • are undertaken. The centre of the foundry is occupied by a to-ton pneumatic hammer, supplied with air at a pressure of 9o1b. on the square inch. An annexe of the foundry is used for sand-blasting the castings, to remove scale, etc., and the plant is capable of dealing expeditiously with large quantities of work: A special department is devoted to the making of milling cutters, and hobs, to he used on the various machines in the shops. A number of hobs, approaching 700, are always ready, and new ones are constantly being added.
After any piece of work has been completed, it is placed upon a truck, which travels on the rails mentioned previously, and is transported to the testing shop. This department is one of the most important in the works, and no finished part is passed out for delivery unless it is absolutely faultless; this fact is shown by a mark, which is impressed by a stamp, after satisfactory examination.
The necessary power for driving the machinery is obtained from five gas engines, which, in the aggregate, give znoh.p., and further power, to the extent of 85h.p., is supplied by electric motors.
The company believes in worm gearing as an efficient means of transmitting power, a statement which is upheld by Dennis Brothers, Limited, which company has, so successfully, applied this system to all its standard vehicles. If reports are true, and there seems no reason to doubt them, other makers are of the same opinion, and this fact will be practically demonstrated in the near future. Objections to worm gearing have been founded, to an undue extent, upon prejudice, and this has resulted from imperfectly-designed worms and worm wheels. One great advantage which is claimed for worm drive over other types of gear-transmission systems is its quietness under actual working condi tions. This well-known Huddersfield company has laid down, at a heavy outlay, expensive plant for the production of cast-steel worms, and phosphor-bronze worm wheels.
Those who visited the Motor Show at Olympia this season will, doubtless, remember the interesting exhibits on Stand No. 259 in the gallery ; these included complete live axles, gear boxes, and steering gears, all of which demonstrated the high finish which is associated with the productions emanating from the company's works. Members of the industry should apply for quotations.