Lecture 11 - Train Resistance III

Question 1

Acceleration resistance

Answer 1

When a vehicle is longitudinally accelerated, besides its total mass, all components with rotational motion, such as wheelsets motor rotors, drive shafts, gear units, …, must be rotationally accelerated

Question 2

Achievement of tractive force / Tractive force characteristic

Answer 2

Balance of tractive force is achieved:
• with specified tractive force demand
• with specified tractive force delivery
• with free adjustability of both

Question 3

Maximum pulling weight / Limit load

Answer 3

Highest possible gross train mass (load), up to which the safety and ease operation and an acceptable capacity requirement can be guaranteed
From draw-hook limit load, starting limit load and dragged limit load (trailer or towing load) the maximum pulling weight is the minimum of these

Question 4

Types of Limit Loads

Answer 4

Draw-hook limit load: Depends on the capacity of the coupling used to safety transmit tractive forces in the operation. 450 kN for screw couplings and 850 kN for automatic central buffer couplings
Starting limit load: Load which can be pulled and accelerated from zero speed by one or more traction units of the train

Question 5

Limit Load Diagram

Answer 5

Max pulling weight diagram indicates the theoretically max. possible wagon load that can be pulled by a traction unit on a straight track at a constant speed

Question 6

Dragged load vs driving speed

Answer 6

The dragged load or max. pulling weight vs speed diagram indicates the wagon load that can be pulled up a particular grade at a constant speed

Question 7

Dragged limit load vs grade

Answer 7

Dragged limit load or pulling weight vs grade diagram indicates the attached wagon load that can be transported with a particular driving speed and constant grade

Question 8

v-t diagram and draw it (11.1)

Answer 8

can be derived from the equation of aceleration as a function of speed

Question 9

x-t diagram and draw it (11.2)

Answer 9

can be derived from the equation of driving speed as a function of driven distance

Question 10

Track data

Answer 10

Track data are mostly presented in terms of distance along the track as track profile, curvature diagram and permisible driving speed