Specialties in automonile construction
Reversing gear by the eccentric
A very compact steam motor gear for reversing is illustrated in Fig. 44. The wheel, A, carries the link lugs and is keyed to the crank shaft; D is the eccentric with a feather guide in the fixed wheel, A, and with a slot to allow it the required movement across the shaft. A link, is pivoted to the fixed wheel, A, and a bell crank link, B, is pivoted in the same manner on the opposite side with its Y-arms extending at right angles and hooked to pins on the sleeve, E. A yoke lever pivoted to the frame and traversing the groove in the sleeve, when at right angles with the shaft, brings the eccentric to a central position , and its movement either way sets the eccentric for forward or back motion of the engine, an equivalent of the link gear.
The compensating bevel gear train
The principles pertaining to the motion of an interlocked bevel gear train allows of several differential conditions in its motions that are interesting in view of its almost universal and indispensable use as the compensating gear for differentiating the speed of the driving wheels when running on curves.
There are several different conditions that can exist with a train of this character; one of which is illustrated in Fig. 45. First, let the gear or arm, A, be fixed and both B and M free to turn. Gears C and D then act as intermediate bevel gears and B and M will turn at the same speed but in opposite directions. In the transmission of power from one gear to the other the force tending to
rotate the gear or arm, A, is just half the force transmitted from B to M. Second, suppose B to be fixed and M to be driven from outside, gear A being free to revolve with its shaft. It is clear that A will make only one-half as many turns as M and in the same direction. Third, if M be fixed and B the driver, A will turn one-half as many times as B and in the same direction. Suppose both M and B to have independent motions and A to be free to revolve. If Mand B move in unison in the same direction, they will simply carry A along with them. If one moves faster than the other, A will follow that one If they have motions in opposite directions and at the same speed, A will remain stationary , and if either B or M moves faster than the other, A will follow that gear as before at a differential speed when they were turning in the same direction. The amount of motion of A will be equal to one-half the angular motion gained by either of the other gears.
These applications arc numerous and varied, and in many instances results can be accomplished through their use that would be difficult, if not impossible, without them.
A two-pinion differential gear.
The simple differential gear, Fig. 46, is an English device used on motor tricycles. The wheel hubs are fixed to the outer ends of incased shafts. The inner ends are pivoted by universal joints to pinions at an angle of about 300 from the
axle and incased in a frame or box terminating in the hollow shafts with shoulders bearing against the wheel hubs. On one of the hollow shafts the sprocket wheel and friction brake pulleys are fixed.
The power is given to the inner axles by turning the hollow shaft and gear box in which the differential pinions are journaled, thus allowing a free differential movement of the two inner axles and wheels.
The spring wheel was the unsuccessful forerunner of the rubber tire. A few trials on the early steam carriages proved their unfitness. When rubber tires were first devised there was no intention of putting them on anything except bicycles. There had been, however, back in the '40's, a man named Thomson who constructed an inflatable tire of canvas and rubber and leather to put on a wagon, but he had no success with it. When tricycles and bicycles came into use it was found quite natural to shoe them with solid rubber bands and nothing else was done for a number of years, until in the '8o's the safety bicycle was invented on account of the numerous accidents in riding the "ordinary ;" and this safety bicycle was also shod with a solid tire. In 1886, Overman , of Springfield, made a rubber tire with a hole running through the center of it, just like a piece of tubing, with very thick walls, the hole enabling the walls of the tire to yield more to the inequalities of* the road. The solid rubber tire, however, held its own until the season of 1890, there being but few " cushion" tires (as the Overman tire was called) put into use. Meanwhile in the late '8o's, in England, Mr. Dunlop invented his inner-tube tire, which consists of a rubber bag in circular form provided with a valve to inflate it; this was covered by a rubber and canvas shoe to stand the attrition of the road. The Dunlop tire was first seen in this country in September, 1890, when a man named Laurie came over and won all the races because he had pneumatic tires. Tillinghast, of Providence, invented what is now called the single-tube tire, which was a onebody tire, holding itself the valve to inflate it and having the wearing body and the air-containing body all vulcanized into one integral whole. This tire was a good deal criticised , but Tillinghast persevered, and in two or three years the single tube tire made its way in the market and is in general use. It is only seven or eight years since pneumatic tires were put upon any vehicle except bicycles and tricycles . Their first appearance was on trotting sulkies, and from these vehicles they gradually crept on to road wagons.
It was not, however, until the automobile came to the front,, along about 1894, that the pneumatic shoeing of large vehicles was adopted. There have been many attempts to make a satisfactory automobile tire. As yet no automobile tire is what it should be. No construction of canvas and rubber seems to be able to withstand the tremendous test of weight which is given it over the roads in this country. In France, with their better roads, they have better success. The driving mechanism of automobiles really requires a pneumatic tire, for a solid tire will shake most mechanism to pieces or disturb its action, especially in the case of electricity . At the same time the life of automobile tires, where there is much weight, is very short. The costly tires put on automobile cabs last something like three or four months, and as they are very expensive, the mileage required to keep such a cab shod is disastrous to economies. Figuring out the cost of tires against the cost of a horse, including his care and his wear and tear, it has been asserted that the horse costs less in feed than the tires on the vehicle. It may be said, however, that the pneumatic tire for heavy vehicles is still in an experimental stage. Just how much longer it will remain so is yet to be seen. At the present time substantially all automobile tires are single-tube tires, constructed according to the Tillinghast invention. On the lighter vehicles, tire life is much longer, and with care seems, to fill the requirement.
The later inventions and combinations in their structure and internal elastic bracing points to their ultimate best forms of structure which will probably make the pneumatic tire satisfactory and a permanent wheel shoe for all purposes.
Since all automobiles must be equipped with rubber tires of one kind or another, and no one feature is of more vital importance than the tires, it goes without saying that all users and owners of automobiles are on the watch for the latest and most improved make and style of rubber tire to be found. While it is true that rubber tires were used in Europe before they were in this country, it remained for an American inventor to produce the first real success in the way of rubber carriage tires. The method of applying the
English tire was faulty; in fact, it was necessary to make the tires so hard in order to keep them in the channels that the resiliency of the rubber was lost, and the most that could be said for the tire is that it was noiseless. Fig. 47 shows a cross-section of a special automobile tire with four retaining wires. These wires are electrically welded in the channel, and the tension to which they are drawn is only limited by the size of wire used. These tires are known in the market as the Kelly-Springfield tire, made by the Consolidated Rubber Tire Company of 40 Wall Street, New York City.
A feature that is not lost sight of by purchasers and owners of automobiles is that solid rubber tires give far less trouble and annoyance than any other style, and are fast growing in favor with the builders of automobiles.
Roller bearing axles
In Fig. 48 is illustrated the roller axle bearing, made by the Grant Axle and Wheel Co., Springfield, Ohio. It is claimed that the roller bearings are the most reliable of all the antifriction devices for automobile wheels.
The bearing lines are long on the rollers, giving greater stability and wear longer than ball bearings. They can be fitted to any wooden hub and are made for wire wheel hubs. In Fig. 49 is illustrated a roller bearing for a motor axle or any shaft.
The cone rings being loose on the spindle, allow them to turn independently on the axle or shaft, so that in case the rolls should in any way become obstructed and lock, it would not lock the wheels, for the cones can revolve on the axle or spindle as in the plain box.
Aluminium in motor vehicle construction
Although aluminum and its alloys can never compete with iron or steel in cheapness for the required strength, yet there are other qualities which recommend it as an economical material in vehicle and motor construction. In its pure state it is light and workable in all forms, as castings, plates, sheets, rods and tubing.
As no royal road for soldering this unique metal has been found, soldering should be dispensed with unless the conditions are favorable and the knowledge of its management at hand.
Riveting makes fairly good work and can be depended upon for body work on carriages. The alloys of aluminum with i0 per cent. tin are as easily worked as brass, harder than pure aluminum and can be soldered in the ordinary way with pure tin as a solder. The alloys with copper are the aluminum bronzes with from 2 to 5 per cent. of copper, are strong and stiff for all machinery parts, are of less than half the weight of iron per bulk, are rust proof and with the harder alloys make good wearing surfaces for cylinders, pistons and journals.
The new alloy of aluminum and magnesium has made possibilities of a still lighter metal than aluminum for constructive purposes. Another alloy of aluminum with small percentages of tin and copper has the low specific gravity of 3.39 with high transverse and tensile strength, 32,000 and 40,000 pounds per square inch respectively. It is workable and may be made as hard as steel.
An alloy of aluminum and tungsten having a specific gravity of 2.89 and possessing great strength is in use by the De Dion & Bouton Co., in France, for frames and bodies of automobiles. An aluminum steam motor vehicle body has been made by the Porter Motor Co., of Boston, Mass.