Train Resistance:-
Definition :-The resistance acting at the points of contact of the wheels of the vehicle with the surface of level roadway which opposes the rolling if the wheels over it and thus the movement of the vehicle.
The tractive force developed by the locomotive should be sufficient:
1. to overcome the train resistance.
2. to haul the train along the track at the desired
speed.
Types of Resisting Forces:-
- Train resistance.
- Resistances due to track profile.
- Resistances due to starting and acceleration.
- Wind resistance
1) Resistance Independent of Speed
2) Resistance Dependent On Speed
3) Atmospheric Resistance
Resistance Independent of Speed:
This resistance is due to following reasons:
1. Rolling Resistance:
This is due to friction between the metal surface of rails and the wheels. It consists of following:
(a) Journal Friction:
It is the friction of the locomotive, wagons and compartment itself. Its amount will depend upon the type of bearing, the lubricant used and the temperature of atmosphere.
(b) Frictional Resistance:
It is the resistance offered to the movement of steel wheels on steel rails. It is maximum at starting and is reduced as motion is caused and it increases as the speed increases.
(c) Track Resistance:
This is caused due to the wave action of rails
(d)Resistance Due To Internal Parts:
Its a resistance of the moving parts and locomotive.
Rt1= 0.0016w
where,
w= weight in tonnes
