Belt drive

“ It is simplest and cheapest, and under good conditions an almost ideal drive.' He prefers a flat belt, of at least one inch width, and a jockey pulley on ball bearings. The jockey pulley is always abused because its purpose is misunderstood. It is not meant to jam the belt up tight, but to make it hug as much as possible of the circumference of the driving pulley. Twisted leather belts are in his opinion a nuisance. On the other hand, Mr. A. Craig of Coventry says, 'It has been a matter of surprise that the belt should have survived so long as a means of transmission in motor bicycles. ”

“ The idle wheel requires a certain amount of power to drive it, and this amount will be greater as the idle wheel is nearer to the smallest wheel of the pair connected; but on the other hand, the closer the idle wheel to the small pulley (all other factors being equal) the greater the arc of small pulley surface enveloped by the belt, and hence the greater the belt’s driving power. ”

“ Single-flanged pulley for horizontal driving.
25. Open belt gear; runs best as shown, with the slack half of the belt at top.
26. Crossed belt to reverse motion on the driven shaft. Also to obtain more grip for the belt than with open belts.
27. Mode of driving when the shafts are at right angles to one another.
28. Mode of driving with shafts at an obtuse angle, sometimes used instead of bevel wheels.
29. Arrangement adopted when the pulleys cannot be got in line with one another, or the shafts are too close together to drive well direct. Short belts seldom work well. ”

“ When a belt is used to drive, one must resort to extraordinarily large diameters in order to obtain the necessary speed, and this increases the difficulties and cost of construction in an entirely unreasonable proportion. ”

“ But under equal conditions the larger the diameter of the idle wheel the less the power required to drive it, because the less its friction on its journal bearing. A belt tightener should whenever practicable be placed on the slack side of the belt.
Belt tighteners are sometimes used to give intermittent motion, as in the case of trip hammers; the belt being vertical is made long enough to run loose, until the tightening pulley closes the belt upon the pulley, taking up its slack and increasing the arc of contact. ”

“ In the first place, belt-driving cars have usually two belts running on pulleys of different sizes, so that shifting the belts causes either one or the other of the two speed ratios to be used. The belt system generally drives the car through chains, so that whilst belt gearing is used for the speed variation, the transmission to the wheels is by chains. ”

“ In using belts care must be taken in shifting the belts to throw off one before attempting to put the other into operation, or broken belts and perhaps worse accidents may result. Belt driving is wonderfully smooth and quiet in action, and commendable from this point, but unless very carefully looked after liable to give trouble by undue slipping and breaking. ”

“ Endless leather belting was used to transmit the power from the motor to the counter-shaft, and from the latter to the driving-wheels, which were the front pair. A vertical idler-pulley was mounted in a frame over the belt from motor to counter-shaft, terminating in a vertical screw and hand-wheel for tightening the belt to increase speed, or the reverse to lower speed. ”

“ Instead of India-rubber, elastic steel is used. Since the driving-pulley has the velocity of the tight side, and the driven of the loose side of the belt, the difference in the number of their turns, if they are of equal size, will measure the work. This difference I measure by differential gearing which actuates a hand on a dial. I may turn the handle as fast as I please; the index does not move, for no work is being done. I may hold the wheel and produce a great driving-strain ”

“ The slowest that the carriage can be driven is three miles an hour and the speed can be increased to fourteen or fifteen miles an hour. The power is transferred from the driving wheel of the motor, which runs horizontally with the main shaft by an endless friction belt running on a drum wheel. The belt is controlled by a lever within easy reach of the driver and is shifted along the drum wheel to increase or decrease the speed. The driving wheel is about twenty inches in diameter, having in its center a depression to which the belt is shifted to stop the carriage. ”

“ In driving machine tools, the power delivered to a machine depends upon the diameters of the driving pulleys, and size and velocity of the belt. A wide belt running at a high velocity on pulleys of large and equal diameters develops the maximum power, and, as its speed and width are lessened, its pulling ability decreases correspondingly. Likewise, it transmits less power, as the pulley on the machine exceeds in diameter the pulley on the driving shaft, for, when the surface contact on the driver becomes smaller, the belt has a tendency to slip. ”

“ The hub is thus driven at a higher speed than the chain-wheel. For normal gear, the striking gear draws the internal mechanism of the hub towards a central position, compressing a spring, disengaging the sun-wheel and locking the drive-ring hub and annular wheel together. At low gear, the internal mechanism is drawn to the right-hand side, where the planet carrier engages with the end plate of the hub by means of claw-clutches. The annular wheel is still engaged with the drive-ring, and the sun-wheel is again locked to the spindle. The hub is thus driven at a lower speed. ”

“ Or the driving wheels may be mounted on a live rear axle, the motor driving on to the compensating gear, either by a chain, by spur gearing, or by means of worm gearing, which gives a nice silent drive, and is used in the Oppermann cars. In any case the use of a single motor involves, in addition to the motor, a differential gear. What is to be avoided is a live rear axle with the motor so mounted that any large proportion of its weight comes on this live axle. ”

“ Now to mend a belt seems the easiest thing going, and so it is when you merely have to hammer a fastening through it and turn the ends over. But in this car you have to make the joint with coils of twisted wire. Simple as it is to do in a workshop, this belt-mending is a most irritating affair by the roadside, and when done I found by subsequent experiences that the wires wear through and tear out after less than a hundred miles. ”

“ The transmission of the power from the motor shaft to the right rear wheel is accomplished by means of a leather motorcycle belt, made by fitting leather washers close together over a bicycle chain, oiling the washers with neat’s-foot oil. ”

“ More good belts are ruined by being soaked with engine oil until the points come loose and then pulled out of shape than from any other cause. Of course you may be able to keep a main engine belt that runs through a damp wheel pit and basement, and through a long damp tunnel to a main driven pulley that has two big boxes that are just as close to the pulley as a first-class machine designer could put them, and never get a drop of oil or water on it. ”

“ With heavy belts, particular care should be taken to prevent any portion of the clothing being caught either by the moving belt or pulleys, as many serious accidents have resulted in the past from carelessness in regard to this important detail. The person handling the belt should, therefore, be sure of a firm footing, and when it is impossible to secure this, it is advisable to stop the engine and fit the belt around the engine pulley as well as possible by the aid of a rope looped around the belt. ”

“ Another plan, employed however only by one or two firms, substitutes for the bevel gearing what is known as skew or screw gearing, a very smooth and silent drive without the spreading or bursting action of the bevels, the end of the driving shaft being fitted with a screw which drives a series of teeth cut diagonally around the circumference of the driven wheel. ”

“ Some have flanges on the pulley, others have guides or rollers on each side of the belt, each plan having its advantages and disadvantages; but some plan must be [29] used, otherwise the belt slips off, usually in the middle of the first-saloon dinner, and out go all the lights, besides which the belt may be considerably damaged before the engine can be stopped. Engine must work steadily. The engine must be one that will work very steadily, otherwise the lights will pulsate at each revolution of the engine, which is most unpleasant. ”

“ Screw and worm wheel gear, for the same purpose as 445.
447. The driven wheel A has a limited travel up and down the slot, the idle wheel B being kept in gear by the link suspension.
448. Idle wheel and slot. A common device for changing direction or speed in driving gear by connecting or disconnecting it with intermediate gearing between a fixed driving and a driven shaft.
449. Parallel motion radiating driving device, with a limited vertical travel and a radial motion.
450. Motion by belt is conveyed to a driven shaft having a radial motion in a vertical plane. ”

“ This is the disagreeable characteristic of a differential, (54) that makes one wheel spin when it touches a slippery spot on the road, and stalls the car, because the other wheels cannot get any driving power.
(55)
CHAPTER VI
THE DRIVE
The term used to designate the transmission of power from the engine to the wheels, is called the drive.
In nearly all cars the engine shaft runs fore and aft, and consequently is at right angles to the axles. This, of course, necessitates some sort of gearing between the engine shaft and axle. This change is made in the bevel gear drive hereafter explained. ”

“ Locomotive driving at a hundred miles an hour is but mild exhilaration as compared to the feelings of the motor-car driver who travels at fifty miles an hour on the public highway.
Gigantic motor trucks carrying tons of freight twist in and out through crowded streets, controlled by one man more easily than a driver guides a spirited horse on a country road.
Frail motor bicycles dash round the platter-like curves of cycle tracks at railroad speed, and climb hills while the riders sit at ease with feet on coasters. ”

“ The car would hold two people, the seat being suspended on posts and the body on elliptical springs. There were two speeds one of ten and the other of twenty miles an hour obtained by shifting the belt, which was done by a clutch lever in front of the driving seat. Thrown for- ward, the lever put in the high speed; thrown back, the low speed; with the lever upright the engine could run free. To start the car it was necessary to turn the motor over by hand with the clutch free. To stop the car one simply released the clutch and applied the foot brake. ”

“ Large belts of engines, dynamos, motors, etc., when in need of taking-up are usually attended to when the plant is shut down; that is, nights, Sundays or legal holidays. At such times power is not to be had; and if the spliced part of the belt, which must be opened, shortened, scraped, re-cemented and hammered, happens to be resting against the face of one of the pulleys, is up between some beams or down in a pit, the chances of the job, if done at all, being any good are very slim. ”

“ The pinions mesh with two wheels that are mounted on a countershaft, on which is also fixed a chain-sprocket, from which the drive is transmitted, through a long chain, to a chain-wheel surrounding the differential gear mounted on the back axle. Traction-engine type of steering gear, with revolving fore-carriage, is most generally adopted, and is rendered sufficiently rapid in its movement by suitable gear, operated by a diagonal shaft and wheel, from the driver’s footplate. ”

“ The reason is that the load was all taken off the inside half of the belt by point slipping, thereby making the inside of the belt too long and putting all the load on the outside. The outside will continue to do all the work until it stretches enough to bring the inside back into service again. ”

“ From the last change-speed shaft the power must be transmitted to the road wheels through a differential gear and through one or other of the types of final drive which are now employed by representative makers. The great distinction from the axle of a horse-drawn vehicle is that there must be both a mechanical connexion, yet a differential action, between the two back wheels. ”

“ If now, D accelerates slightly, C will turn, slowly retarding E, while if E accelerates, C will turn slowly in the opposite direction retarding D. This is precisely what is required in turning a corner. Now fix these in a box, driven as a whole by the bevel or ring gear B driven by the driving pinion gear A. When the car is on the straight ahead drive D, C, E are locked. ”

“ The adjustment of the driving belt is also readily effected by mounting the front or driving crank shaft in an eccentric on the hanger boxing. The tread of the machine is made as narrow as possible by the use of flattened tubing in the rear forks, and by cranking the driving rods, the crank portion being reinforced by a forged connection. The outward appearance of the wheel is attractive, and in quality of material and workmanship, and elegance of finish, it upholds the standard heretofore maintained on all products of the Dayton factory. ”

“ The driver of the motor should then talk soothingly to the horse, and the groom should also encourage it as much as possible. The horse will follow with his eyes the movements of the car, and, as a rule, in a little while will allow it to be driven close by without any further signs of fear. The horse should then be harnessed and taken out on the road, the motor-car driven out to meet it, and sent a number of times past it until the animal takes little or no notice. ”