Under the above severe conditions, a lightweight high output engine has recently been developed and resultingly a high performance diesel rail car appears.
(5) Improvement of curve passing speed (Pendulum: Introduction of body tilting system)
To reduce an arrival time, it is necessary to improve a maximum speed and a curve passing speed. When a train passes a curved portion at a high speed more than a specified speed, the riding comfortableness is extremely deteriorated due to a centrifugal force (α in the expression below) which cannot be assured by a cant.
α = {V2/(R・g)} - (C/G)
α: Over-centrifugal accelerationC: Cant
g: Gravitational accelerationR: Curve radius
V: VelocityG: Gauge
Therefore, it is effective to offset centrifugal forces by tilting a body in accordance with the radius and cant of a curved portion. There are various systems for tilting the body but they are roughly divided into the natural pendulum system of directly using a centrifugal force and the forced pendulum system of detecting a centrifugal force and tilting a body by another force. Table 4.2-3 shows main pendulum cars in the world.
1) Natural pendulum system
The natural pendulum system tilts a body supported by rollers, bearing-guides, and air springs in accordance with a centrifugal force. Though the system has a disadvantage that the riding comfortableness is deteriorated because tilting of the body is delayed when a tilting system has a large frictional resistance, it has advantages that no trouble occurs in control and the riding comfortableness is improved by using the inertia of the body at the time of traveling on a linear portion. The initial Japanese pendulum car and "TALGO" train of the Spanish national railway are typical cases.
