On 24/05/18 12:07, Roger Greenwood wrote:

>

> Clearly, the Selectric frogs did not offer the same 'fail-safe' operation

> assured by the Czech system referred to by Chas.

>


Pretty well all those central European systems also have traction
batteries and automatic retrievers.
Should the worst happen, the poles automatically lower and the driver
just continues to the next convenient spot to deal with the problem.

Some systems even put pole locators at regular locations (probably the
next stop after trouble spots!) and the driver doesn't even have to get
out of his seat to re-pole, just stop in the right place and press the
button.

The capacity of the traction batteries is such now that some systems
have extensive off wire running with out the use of auxiliary diesels.

Czech Škoda have been supplying electronics kits to other builders of
trolley buses for many years and they have the hybrid battery systems
really well worked out now days.