Postwar Engine Pulling Power - Effects of Traction Tires, Magne-traction, Engine Weight, and Track Electrical Resistance on for Nine Track Types
Data is from CTT Oct 2004 article by Phil Hays titled "Testing 9 Types of Track” and can be seen and downloaded at the CTT web site.
Note: This data was originated 19 years ago, and postwar engines tested were from 1954 to 1966. Newer heavier and traction tired locomotives will have much higher pulling power than those tested.
Types of Track Rail
Locos without Traction Tires – The type of Rail affects pull power by 50 – 70%. In general, tracks made from Nickel-silver or stainless steel seem to be more slippery including those w/o Magnatraction - Steel track gives significant pulling power for Locos with magnatraction
Traction Tire Performance
Traction tires showed good performance between 78% to 100%, with Atlas Steel being the highest and Gargraves Regular, the lowest. Lionel tubular O, O-27 new and old were 90% and 86 %. New traction tires were used for all tests. Used traction tires can lose up to 22% of their traction performance. Notes: Atlas Steel and MTH Realtrax have a T shaped flat profile that provides a larger track to wheel area. Non tubular tracks were typically made from softer metals and when wheels stall and spin and tended to cut groove in the rails.
Magne-traction
Magne-traction accounts for 33 to 50 percent of total traction force on rails for lightweight locos, primarily diesels. For tubular track, the Magne-traction was 6 percent higher over the metal track ties.
Magne-traction accounts for 25 percent for heavier diesels
Magne-traction accounts for 10 – 20 percent for heavy die-cast metal steam locomotives
Magna-traction represents a clear gain in pulling capability, especially for light weight engines.
Magne-traction for Different types of Rails –
Atlas O steel T shape rail showed 100 percent on Magnetic attraction
Common tubular O track showed 45 – 53 percent Magnetic attraction
GarGraves track was 20-30 percent Magnetic attraction
Atlas O nickel-silver track and MTH RealTrax, both non-ferrous, show near
zero magnetic attraction.
Weight and Pulling Power
Loco pulling capability is related to weight. Heavier engines have better traction than lighter engines. But can added weight increase pulling power?
For light weight engines:
Lionel 211 Alco FA, years 1962-66, 28 ounces, one motor four drive wheels with one traction tire and Lionel 217 diesel, year 1959, 28.5 ounces with one motor, four Magne-traction wheels –
Both showed an increase in traction of 1 ounce gain for every 3 ounces of added weight. Summary: The pull increase is due to increased friction between wheel and rail and is proportional to the weight added and the number of driven wheels. The type of drive wheel – whether metal, rubber, or Magne-traction – makes no significant difference. For the 217, 24 ounces of weight was added without it overheating the motor and improved pulling power by 33 percent.
For heavier locomotives: Lionel 2321, year 1954, Train Master, 82 ounces, with two motors and 8 Magne-traction drive wheels – Showed 2 ounce gain in pull for every 3 ounces of added weight.
Added weight suck-up more power and showed a 15 to 20 percent increase in amperage for every 4 ounces of added weight which caused a significant increase in heat in the motors. After adding 12 additional ounces, the motors started smoking!
For postwar locomotives limiting current should be 2.5 amps per motor when adding weight. Heavier locos typically draw this much current at maximum load so you cannot add much weight. Because light engines draw much less power, weight can be increased quite a bit.
Track Electrical Resistance
Electrical characteristics of the rails may be more important than traction. Most types of track, single sections of track, showed low resistance which is good. The resistance of each tack joint is about equal to one foot of track. MTH RealTrax had the highest overall resistance per yard of track at .058 ohms whereas Lonel O tubular was .028 ohms per yard and Lionel 027 was .18 ohms per yard. Atlas steel was the best and the lowest at .010 ohms per yard. Note: Tracks with blackened center rails effects of high current arcing and burned off when a loco stalled under high loads
Most of these percentages came from simple bar grafts with a single data point for each entry. The best performing track was set as 100%. In place of the bar grafts, which represent one measurement (or an average of several tests), simple columns with track types versus the measurement, would have been more accurate and taken up less space.
Charlie
