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RE: EE Locos and other things

Aus loco discussion mailing list

Re Tasmanian 'X' & 'Y' classes:

I agree with Mike:   There was no problem operating the 'X' & 'Y' classes together at higher speeds.  There were two main reasons why the 'XA' sub-class appeared.

Firstly, to give comparable operation with the 'Y' class at low speeds, the tractive effort curve was altered. The conversion entailed different armatures in the traction motors and the pole spacing changed.  The generator armature was also rewound. 

Secondly,  the cooling capacity of the 'X' class was much less than the 'Y'.  This applied as much to the electrical machinery as to the radiators for the motor.  The most critical unit, however, was the main generator.  On the 'Y', the generator was in the path of the air intake airflow.  The 'X' was shorter, with a more compact equipment layout and these locos always ran warmer.  It quickly became standard practice that in any lash-up combining 'Y' and 'XA' classes, the 'XA' had to lead when running north out of Hobart.  This allowed the 'XA'(s) to benefit from the cool air first when working up the 1 in 40 grade though the 3/4 mile Rhyndaston tunnel.  After the tunnel was enlarged in 1964, the practice was retained although the larger diameter did allow a little more 'breathing space' - this was soon used up by the heavier trains with three locos that had become the norm.

This information was kindly provided (many years ago) by Henry Baldwin who was Motive Power Engineer for 16 years and Locomotive Engineer when A.N.R. finally took over in 1978.  Henry played a major role in the 'Y' class construction.

Melanie Dennis
Australian Steam Group
meld.asg@netspeed.com.au


-----Original Message-----
From:	Mike Dix [SMTP:mdix@mrt.tas.gov.au]
Sent:	Thursday, December 16, 1999 8:25 AM
To:	'Aus loco discussion mailing list'
Subject:	RE: EE Locos and other things

Aus loco discussion mailing list

"TGR Xs and Ys didn't operate that well together, apparently the XA 
modification was to improve their MU performance with Ys."

Sorry but this is a leading statement that should not be given too much
weight. Who says the X and Y locos didn't operate well together? There was
no problem with MU operation, the only major problem was that X locos were
not designed for low speed slogging which the Y class were better at. The XA
modification was to lessen that problem. Otherwise they operated quite
happily together throughout their lives. The fact that the X class was not
good at low speed slog work was shown in AN days when a number of locos
suffered from burnt out generators when crawling up Kimberley bank with
heavy trains, and these mostly were in all X class combinations.

Michael Dix
mdix@mrt.tas.gov.au
Phone (03) 6233 8348



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