Andrei98 scrie:Mai bine cautati niste articole mai pertinente scrise de cineva care are o anumita legatura cu domeniul feroviar decat sa cititi ce scrie cineva care doar vrea sa se faca mai cunoscut.
There are two issues concerned with the IC4 braking system. Poor braking performance on slippery rail has meant that a reduced maximum speed limit has had to be imposed, which limits the ways in which the trains can be deployed. There is also a reliability issue associated with some of the braking system components.
As built, each axle has independent Wheel Slide Protection (WSP) control, except axles 5 and 6 (on a trailer bogie) which are both controlled by one Brake Control Unit (BCU). During November 2011, two IC4 sets failed to stop at signals. As a result, the maximum brake percentage was reduced from 170% to 130% and the maximum operating speed was lowered. In addition, axle 5 was no longer braked so that it could always provide an accurate position reference for the ATC system.
These measures have led to the currently imposed 169 km/h speed restriction. During the autumn period the maximum speed is reduced further to 140km/h. The restrictions have an important impact on the operation of the IC4 fleet and the fulfilment of its deployment plan.
In January 2014, a task force was set up to eliminate the braking problems. It has identified incorrect piping of the parking brake anti- compound device, which could lead to locked wheels during braking. The parking brake was being automatically applied when the air pressure within the brake pipe and brake cylinder fell below thresholds of 2.7 bar and 2.0 bar respectively (as might occur during emergency braking). The anti-compound device then received the cylinder pressure from the WSP valve outlet instead of from the integrated relay valve outlet. During braking on slippery rail, the parking brake could therefore be applied, resulting in locked wheels.
The task force also found problems with the brake blending. IC4 has conventional pneumatic brakes and hydrodynamic brakes (HDB). Powered axles have both types, but the trailing axles only have pneumatic brakes. The HDB is prioritised in order to reduce heating and wear of the brake pads, but it is blended with the pneumatic braking on the powered axles. There is also a cross-blending function for the pneumatic braking on the trailer axles. When wheel sliding is detected, the HDB is switched off and the pneumatic brake force is increased to compensate.
The task force found that, during wheel slide conditions, the additional pneumatic braking was not always applied. When it was applied, it occurred mainly on the trailing axles. The brake system will now be simplified by removing the cross blending function and an equal brake force will be applied to all axles. There will, however, be a reduced brake force on trailer axles 5 and 6 in order to ensure a reliable speed reference for the ATC.
IC2-togsættene lever ikke op til de krav til stabilitet, som er en forudsætning for anvendelse i togdriften. Samtidig reduceres afhængigheden af både IC4 og IC2 med de planlagte materielinvesteringer – i første omgang nye el-lokomotiver. Alle 23 IC2-togsæt udfases derfor straks, og der foretages en nedskrivning af de 23 togsæt og af 5 IC4-togsæt
The IC2 train sets do not meet the requirements for stability, which are a prerequisite for use in the train operation. At the same time, the dependence on both IC4 and IC2 is reduced with the planned stock investments - initially new electric locomotives. All 23 IC2 train sets are therefore phased out and the 23 train sets and 5 IC4 train sets are written down
DSB finds buyer for AnsaldoBreda IC2 DMUs
23 Jun 2017
DENMARK: National operator DSB reached an agreement to sell 15 of its 23 AnsaldoBreda IC2 diesel multiple-units on June 16. The two-car DMUs were withdrawn from service last year after a troubled history.
DSB is selling the DMUs ‘as is’ with no warranty. The unnamed buyer has initially acquired three units, with the sale of the remaining 12 being conditional on the new owner successfully obtaining approval to use the first three.
DSB’s Director of Strategy & Rolling Stock Jürgen Müller said the foreign buyer did not wish to be identified and he could not disclose the price, but he was pleased that the sale of the units had happened relatively quickly. Another of the IC2 units has been acquired by the national railway museum.
The four-car IC4 units remain in traffic, but the national electrification is expected to enable them to be phased out from 2024.
http://www.railwaygazette.com/news/passenger/single-view/view/dsb-finds-buyer-for-ansaldobreda-ic2-dmus.html
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