Re: Locomotives and heat/cold

["John Regan" <reganjd@clear.net.nz>]

Aus loco discussion mailing list

We have problems over here in New Zealand with locos cooking up aswell.  (I
know,  you can stop laughing now-the last iceberg left here sometime back
now!)

The main causes for this is the radiators get clogged up with dust and small
bits of vegetation which reduce the amount of airflow.  The fitters tell me
it is a "joy filled experience" blowing out the radiators with compressed
air.  Another one is the shutters not working as they should.  Once locked
open no problems normally.

One of the biggest problem areas we have here for overheating is the Otira
tunnel.  This tunnel is on a grade of 1 in 33 for 8 kilometres and we haul
1500 tonne coal trains up with 4 locos each of around 3000 horsepower.  It
takes approximately 25 minutes to get up the hole on a good day.
To assist with keeping the locos cool a number of measures have been
undertaken including fitting of shutes to the hood end of some of the DX
class to enable them to scavenge cooler air from the floor of the tunnel for
combustion purposes and the fitting of a sliding door and extractor fans at
the Otira end of the tunnel.  This enables cooler air to be sucked across
the locos as they make their way up the hill.

Prior to this it was common to have the two trailing locos over heat but
more so for the forth unit. This was not so much that the radiators were not
up to it but they were scavenging all the exhaust and radiator heat from the
leading units in run 8 notch so the air being sucked in for combustion was
so hot that the internal temp increased to or passed the overtemp setting on
the loco causing it to blow its water out and shut down.  It must be
remembered that there is only a couple of feet between the exhaust and the
roof of the tunnel so the rear units suffered badly.
So much heat was generated that it was impossible to hold the hand rails on
the locos with out wearing heavy leather gloves.

I had one trip through the hole when we stalled about half way through.  The
rear loco was so hot after being dragged out a little over two hours after
stalling that the temp gauge was still right off the top of the red sector!
When we stopped it was blowing steam out of the filler points on both sides
like a steam cleaner.  We were unable to get the motor to turn over after
topping off the water.

I am lead to believe that the air temp for the radiator does not matter a
great deal as it still is some 40 to 50 degrees cooler than the internal
water temp even on the hottest of days.  It is the combustion air being
scavenged that is important.  Some locos are fitted with after coolers to
dissipate heat prior to going into the pots.

Hopefully this is of interest

Regards

John Regan
reganjd@clear.net.nz
Christchurch
NEW ZEALAND

+64 3 338 4260 (home)
+64 21 362 143 (mobile)
ICQ #15462976

"GROWING OLD IS MANDATORY - GROWING UP IS OPTIONAL!"


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