I am not sure of the reason behind any of the down rating. The Z class were 12CSVT Mk II 2025 hp at 850 revs DC generator, the ZA 12CSVT Mk III 2550 hp at 900 revs via three phase main alternator. The ex QR ZB 12CSVT Mk III 2640 hp at 900 revs also three phase main alternator. The ZB were down rated to 1950 hp when acquired for Tasmania by Aussie National. I am not sure what the hp output of the ZA became when down rated. I was only told that the units were down rated to work better with the Z class. The ZA were not chop nosed for Driver Only Ops, the Z class were. So, a normal DOO lashup was Z ZA ZA Z combination during my era. The ZB class being Westinghouse could not mu with the Z or ZA which were Davies Metcalfe air brake.
@@aussiealco Original horsepower. Z’s were 2025 ZA 1 to ZA 4 2550 ZA 5 & ZA 6 2640 ZB’s 2350 The Z’s and ZA’s always were Davies and Metcalfe for Vacuum and Air. When they got converted to air brake they used the Westinghouse M6A system then found the brake head could not feed the brake brake pipe fast enough, the Westinghouse M9A system then used.
Good scenery to work with Steve
Sadly, Hobart rail yard is no more.
Used to be hectic shunting due to the short roads in the yard.
Steve.
At 2350 HP they were the same as the BR class 50's I wonder what brought about the down rating. Was the Koyo alternator not up to it?
I am not sure of the reason behind any of the down rating. The Z class were 12CSVT Mk II 2025 hp at 850 revs DC generator, the ZA 12CSVT Mk III 2550 hp at 900 revs via three phase main alternator. The ex QR ZB 12CSVT Mk III 2640 hp at 900 revs also three phase main alternator. The ZB were down rated to 1950 hp when acquired for Tasmania by Aussie National. I am not sure what the hp output of the ZA became when down rated. I was only told that the units were down rated to work better with the Z class. The ZA were not chop nosed for Driver Only Ops, the Z class were. So, a normal DOO lashup was Z ZA ZA Z combination during my era. The ZB class being Westinghouse could not mu with the Z or ZA which were Davies Metcalfe air brake.
@@aussiealco
Original horsepower.
Z’s were 2025
ZA 1 to ZA 4 2550
ZA 5 & ZA 6 2640
ZB’s 2350
The Z’s and ZA’s always were Davies and Metcalfe for Vacuum and Air.
When they got converted to air brake they used the Westinghouse M6A system then found the brake head could not feed the brake brake pipe fast enough, the Westinghouse M9A system then used.