DISTANCE RODS
As the springs are placed between the axles and body and are flexible, it is necessary to provide some method of preventing an obstruction in the road from twisting the axle, as might result if one wheel struck heavy sand or a stone while its mate was on good surface. A twist of this sort would throw the axle out of line with the drive and bind the chain or driving shaft.
Fig. 49.—Distance or Radius Rods.
To prevent this, radius or distance rods are attached to the axle, one on each side, extending to a point well forward on the frame (Fig. 49). These rods are pivoted to the frame, and have a loose joint on the axle, so that the latter is free to move up and down, but prevented from moving forward or back. Distance rods are adjustable, and on chain-driven cars serve to adjust the chains, which are tightened by lengthening the rods and slackened by shortening them.
CHAPTER XI
TROUBLES
Practice and experience are the best instructors in keeping the car running, and the operator quickly acquires the ability to recognize the source of trouble from the action of the engine in failing to deliver power, or from the manner in which it stops. Each part of the mechanism may be counted on to give trouble, and the possibilities are numerous, but in general it may be said that an interference with the proper operation of the engine may be laid to the failure of the ignition system or gasoline supply, a defect of the combustion space in not retaining the pressure, or the overheating of the engine.
IGNITION TROUBLES
The ignition system is the greatest producer of trouble, and the reason is usually difficult to locate. Any interference with the flow of the current, or leaks by which it evades passing over the entire circuit, will cause irregular running or the stopping of the engine, and the circuit must be maintained in the best possible condition in order to prevent these as much as possible. The wires should be well insulated, the insulation of the secondary circuit being heavier than that of the primary because of the higher pressure of the current that must be retained. The constant vibration to which the wires are subjected requires the use of cable composed of a number of strands of fine wire rather than a single heavy wire, for the latter is much more liable to be broken; but in securing the end of a cable under a nut, great care must be exercised that all of the strands are bound. A single strand is hardly noticeable, but if it comes into contact with uninsulated metal, it will permit the current to leak. In making connections, the best plan is to solder the end of the cable to a copper or brass terminal which holds the strands secure, and gives a firm bearing for the nut. Before making connections the terminals should be scraped bright, and after running the nuts down firmly, covered with vaseline to prevent corrosion. Corrosion of copper or brass produces a greenish deposit (copper sulphate) which is an insulator, and when it forms between the terminals of the conductor it produces high resistance, cutting down or even preventing the flow of current. A worse effect of corrosion is to bind the nuts on the screws, preventing their removal. A loose connection presents resistance to the flow of current, and the current will flow irregularly, as the vibrations bring the terminals together or separate them. A wire broken at a terminal is easily seen, but when a break occurs inside of the insulation, it is more difficult to detect. When a broken wire is suspected, its circuit may be located by testing, and new wires laid, one length at a time, until the faulty one is replaced. It is poor economy to use cheap wire, for the best is none too good for the hard use to which it is put. The wearing away of insulation by chafing will produce a short circuit, and the wires should be prevented from coming into contact with any part of the car or engine in such a manner as to give this result.