The trolley lines and third-rail railways of the United States have for their essential parts the generating stations and generators, feed wires, trolley wires or third rails, the cars, and the road bed. The generators are usually direct-current dynamos producing current at a pressure of about 500 volts. The positive poles of these dynamos are connected to the feed wires, trolley wires, or third rails, while the negative poles are connected to the rails, which serve as return conductors.

Feed wires are used when the line is a long one; they are connected to different sections of the trolley wire. The current goes from the trolley wire to the wheel in contact with it, down the conductor carried by the pole, to the motor, then through the car wheels to the track and then to the dynamo. The cars are in parallel, like incandescent lamps on a lighting circuit, and each takes its own current, independent of the rest. The amount of current taken by each car depends largely upon the load in the car and the grade of the road. Since the motors are subject to the severest kind of usage, they are protected with water-tight cases.

Hundreds of electric railways transport people to and from their places of business in large cities. Figure 3 shows a transcontinental passenger train on an electric railway. Another important use of motors is their application to individual machines such as printing presses, lathes, band saws, etc. Each machine can then be run separately without large waste of power through the friction of shafts and belting.

Fsubject to the severest kind of usage, they are protected with water-tight cases. IG. 3. -Electric Locomotive and Transcontinental Passenger Train in the Cascade Mountains subject to the severest kind of usage, they are protected with water-tight cases.

اخر الاخبار

اخبار العتبة العباسية المقدسة

العتبة العباسية المقدسة تعلن تأجيل مؤتمر معالم الحياة الطيبة عند أهل البيت (عليهم السلام) الدولي الثاني

قسم العلاقات العامة يقيم أمسية رمضانية ثقافية لطلبة الأقسام الداخلية في جامعة بابل

قسم الشؤون الفكرية ينظم ختمة قرآنية رمضانية في دولة تشاد بإفريقيا

ضمن مشروع بيوت النور.. المجمع العلمي ينظّم أمسية قرآنية رمضانية في كربلاء

المزيد

الآخبار الصحية

الماء المملح.. فائدة حقيقية أم "صيحة زائفة"؟

عادة بسيطة تدعم الصحة وتحافظ على الوزن المثالي

الغذاء النباتي يقلل مخاطر السرطان.. مع استثناء مهم

الحليب قليل أم كامل الدسم.. أيهما أفضل؟

المزيد

الآخبار التكنلوجية

أنثروبيك تتحدى البنتاغون.. وترامب يأمر بوقف التعامل معها

ميزة جديدة من "إنستغرام" لحماية المراهقين من الانتحار

الأولى من نوعها.. "تقنية مذهلة" في هاتف سامسونغ الجديد

لماذا تشعر المرأة بالألم أكثر من الرجل؟.. دراسة تجيب

المزيد

مواضيع ذات صلة

The Poles of a Cell

Size and E. M. F. of a Cell

Parallel Grouping

Ohms Law

Internal Resistance of a Cell

Unit of Electromotive Force, the Volt

Arrangement of Cells in a Battery; Series Grouping

The Laws of Resistance

The Unit of Resistance

The Unit of Current the Ampere

Electro-motive Force, Current, Resistance.

The Dry Cell