CHAPTER 4 The Locomotive Steam until mid 1950s

CHAPTER 4 The Locomotive

Steam until mid 1950’s

Types of Locomotives • • Steam Diesel-Electric Hybrid

Two Factors Determine the Ability of a Locomotive to Start, Accelerate, and Obtain Top Speed Tractive Effort • The Ability to Overcome Resistance -Starting, Grade, Wind, Curve, Rolling • Tractive Force = Weight of Drivers x Coefficient of Adhesion Horse Power (mainly 1, 500 to 5, 000 hp) • Rate of Doing Work • Drawbar Horsepower: horsepower available to haul

Adhesion Control • Grip Rail without Slipping • Dependent on weather, rail conditions • Controlled automatically in modern locomotive • Sanding

Tractive Force vs. Tonnage and Grade

Performance Curve of the Locomotive (with train resistance for 420 tons trailing load of passenger stock)

Different Horsepower Ratings • Not all engine power pulls train • On average, 82% of power is left to pull train

Power Required vs. Speed and Grade

Diesel–Electric Locomotive • Diesel Engine – Prime Mover • Turbocharger / Electronic Fuel Injection • Alternator / Generator / Fans / Batteries • AC/DC Traction Motors

Locomotive Principal Components

Radial Trucks

Locomotive Controls • Minimum Levers, but Connected to Circuitry • “Microprocessor” Control • Display Screens • Interfaces with Primary Operator

Six Axle, approx. 390, 000 pounds vs. Four Axle, approx. 260, 000 pounds

Multiple Unit Arrangements Distributive Power / ECP Mid-Train or Rear End

Slugs and Mates No Prime Mover Store Excess Power Provide Weight for Tractive Effort

Maintenance and Life Span • Most New Locomotives can Self-Diagnose Problems • Different Inspections Mandatory at Daily, 92 -days, Annual, and Biennial Periods • Remote Diagnostics • Average Locomotive Service is 20 -25 Years • Used to be Returned to Manufacturer, but Now Sold to Smaller Railroads

Genset and Hybrid Locomotives (Mainly for Switching) Genset – Multiple engine-generators per vehicle Hybrid – Operates on batteries that are charged overnight