On Sun, 11 Apr 2010 08:24:06 -0700 (PDT), D7666
wrote:

On Apr 11, 4:14*pm, "John Clausen" wrote:

that mating a 313 and 315 does not work. Possible they fight each
other if notching up sequence within each unit are different - rather
like the diesel 25/1 and 25/2 issue ?

How do you mean 'fight each other'? The Belgians have coupled camshaft and
thyristor units in multi since the 1970s. It batters the couplings but they
are strong enough to take it.

I don't know what the specifics of 313+315 are.

Possibly a variation on the consequences of coupling a DMMU to a DHMU
on the St Pancras line some years which resulted in the manual unit
being dragged at speed while still in first gear as the driver forgot
to use the (usually spare) gear change ? Are the electrical
differences of 313 v. others such that the presence of particular
error conditions are only revealed if the driver has to do or watch
for something that he would not have to under normal working ?

Yes camshaft + chopper/thyristor works in principle - and we had in
the past SWD 455s for example with the chopper trials units.

There must be some other reason. Wheel damage ? Rail damage? If one
unit suddenly increases or decreases tractive effort while the other
one does not then one or other of the units may slip. I'm not saying
thats what takes place, its just a possibility.

All I know was I found a document, a local WAGN (as it was then)
document, says it was not allowed, in any circumstances, not even ECS.
Tractor moves yes, with one unit dead, thats all, which presumably
allows for emergency rescue missions such as push-out of section.

Or indeed it may be something else not connected with traction
controls.

I don't know what the cause is, all I know is there was a ''Thou Shalt
Not Multiply'' restriction in WAGN days.