HORSEPOWER CONSIDERATIONS FOR TRUCKS AND TRUCK COMBINATIONS

A STUDY WAS CONDUCTED ON THE HORSEPOWER REQUIRED BY TRUCKS AND TRUCK COMBINATIONS TO ACHIEVE ADEQUATE PERFORMANCE LEVELS WHEN OPERATING OVER MODERN HIGHWAYS IN ACCORDANCE WITH THE FEDERAL TRUCK SIZE AND WEIGHT STUDY. ALTHOUGH WEIGHT IS THE PRINCIPAL FACTOR DETERMINING HORSEPOWER REQUIREMENTS, THERE ARE OTHER EXTERNAL FACTORS SUCH AS AIR RESISTANCE AND ROLLING RESISTANCE WHICH INFLUENCE THE AMOUNT OF HORSEPOWER NEEDED TO PROVIDE ANY DESIRED STANDARD OF PERFORMANCE. INCREASED SPEED LIMITS, BOTH MAXIMUM AND MINIMUM, COULD ADD TO HORSEPOWER REQUIREMENTS. IN ADDITION, INTERNAL FACTORS SUCH AS FRICTION, ACCESSORIES, AND GEAR RATIOS AFFECT THE AMOUNT OF HORSEPOWER ACTUALLY AVAILABLE AT THE WHEELS. TESTS SHOW THAT THE MANUFACTURERS HAVE THE CAPACITY TO PROVIDE ENGINES WHICH WILL MEET PRESENT AND FUTURE ESTIMATED PERFORMANCE REQUIREMENTS. THE DEVELOPMENT OF ENGINES FOR HEAVY-DUTY TRUCKS IN PROGRESSING AT A RAPID PACE ALONG WITH ON-THE-ROAD TESTING. ENGINES WITH IDENTICAL HORSEPOWER RATINGS DO NOT NECESSARILY PRODUCE THE SAME PERFORMANCE LEVELS FOR ALL TRUCK OR TRUCK COMBINATIONS DUE TO DIFFERENCES IN GEAR RATIOS, ACCESSORIES, FRICTION LOSSES, THE DESIGN OF THE HOREPOWER CURVE, VEHICLE CONFIGURATION, AND MANY OTHER FACTORS. THERE IS A CONTINUING TREND TOWARD USE OF HIGHER HORSEPOWER ENGINES IN TRUCKS AND TRUCK COMBINATIONS WHICH HAS PROVIDED A STEADY UPGRADING OF PERFORMANCE LEVELS. THE GROSS WEIGHT TO NET HORSEPOWER RATIO OF 400:1 ROUGHLY EQUIVALENT TO 20 MPH ON A 3.0% GRADE APPEARS TO BE GENERALLY ACCEPTABLE AS A BASIC GUIDELINE FOR UPHILL PERFORMANCE. WHEN USED IN WEIGHT-HORSEPOWER RATIOS, GROSS HORSEPOWER VALUES ARE THE EASIEST TO OBTAIN AND TO ENFORCE AND THE MOST CONSISTENTLY ACCURATE TO APPLY BUT THE LEAST RELATED TO THE ULTIMATE PERFORMANCE. WHEEL AND NET HORSEPOWER VALUES CAN BE COMPUTED FROM GROSS HORSEPOWER WITH REASONABLE ACCURACY IF ALL COMPONENTS WHICH CAUSE APPLICABLE HORSEPOWER LOSSES ARE CONSIDERED. STREAMLINING OF TRUCKS OR TRUCK COMBINATIONS WILL NOT PROVIDE SIGNIFICANT BENEFITS TO UPHILL OR ACCELERATION PERFORMANCE DUE TO THE RELATIVELY SMALL DECREASE IN HORSEPOWER REQUIREMENTS ESPECIALLY AT SLOWER SPEEDS, WHICH RESULTS. HIGH HORSEPOWER ON A LOW COEFFICIENT OF FRICTION SURFACE MAY CAUSE WHEEL SPIN SOONER THAN WOULD A LOWER HORSEPOWER. IT IS RECOMMENDED THAT ONE TEST CODE SHOULD BE USED TO RATE THE HORSEPOWER OF TRUCK ENGINES. /AUTHOR/

  • Supplemental Notes:
    • Vol 4, No 2, PP 187-216, 20 FIG, 2 TAB, 8 REF
  • Corporate Authors:

    Western Highway Institute

    San Francisco, CA  United States 
  • Publication Date: 1969-10-1

Subject/Index Terms

Filing Info

  • Accession Number: 00203478
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 26 1970 12:00AM